Registration Dossier

Data platform availability banner - registered substances factsheets

Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Administrative data

Key value for chemical safety assessment

Effects on fertility

Description of key information

In a single generation rat oral study there were no effects on fertility or parental reproductive performance at the high dose level of 600 mg/kg bw/day. The NOEL is based on 100% glycolic acid dosed (adjusted for 70% purity of the test substance).


In three-generation reproduction and dominant lethal mutagenesis studies on rats, the analogue ethylene glycol (EG) produced no effects on fertility, fecundity, or reproductive performance. There was no evidence of a dominant lethal effect when EG treated males were mated with untreated females.


The effects of the analogue ethylene glycol (EG) on reproduction of mice were tested in a protocol which permitted continuous breeding during a specified interval. Based on the condition of the study the no-observed-adverse-effect-levels (NOAEL) were 840 mg/kg bw/day for general toxicity and 1640 mg/kg bw/day for overall reproductive & developmental toxicity.

Link to relevant study records

Referenceopen allclose all

Endpoint:
three-generation reproductive toxicity
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
Study published in 1986
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Qualifier:
no guideline followed
Principles of method if other than guideline:
The basis for the study design is the “NTP Fertility Assessment by Continuous Breeding Protocol"
GLP compliance:
not specified
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source: Corporation, Hahnville, Louisiana
- Date of receipt: 22/01/1975
- Description: the sample was 99.93% monoethylene glycol and 0.18% diethylene glycol
- Lot//batch number of test material: Not stated
- Expiration date of the lot/batch: Not stated
- Purity test date: Not stated

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material:
Assumed stable
- Stability under storage conditions:
Assumed stable
- Stability under test conditions:
Assumed stable for the duration of the study
- Solubility and stability of the test substance in the solvent/dispersant/vehicle/test medium:
Not applicable, test item administered as received, no preparation necessary.
- Reactivity of the test substance with the solvent/vehicle/test medium (if applicable): Not applicable, test item administered in diet

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Treatment of test material prior to testing:
Administered in diet

TYPE OF BIOCIDE FORMULATION (if applicable):

OTHER SPECIFICS
- measurement of pH, osmolality, and precipitate in the culture medium to which the test chemical is added: None stated
Species:
rat
Strain:
Fischer 344
Sex:
male/female
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: Charles River Laboratory, Wilmington, Mass.
- Age at study initiation: Young adult male and female nulliparous Fischer 344 rats
- Weight at study initiation: Range: Not stated
- Housing: Two per cage in stainless steel wire cage. During mating each male was hosed with two females. After mating and during lactation the female were housed individually in plastic shoebox cage with hardwood chips for nesting.
- Diet (e.g. ad libitum): Purina Formulab 5008 Chow (Ralston Purina Co. St. Louis, Mo)
- Water: ad libitum
- Acclimation period: Not stated

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 - 24°C
- Humidity (%): Not stated
- Air changes (per hr): Not stated
- Photoperiod (hrs dark / hrs light): 12-hour light/dark cycle

IN-LIFE DATES: From: Not stated
Route of administration:
oral: feed
Vehicle:
unchanged (no vehicle)
Details on exposure:
DIET PREPARATION
- Rate of preparation of diet (frequency): 2 weeks
- Mixing appropriate amounts with (Type of food): with the percentage of test item adjusted, based on the group mean body weight and food consumption, so as to maintain a relatively constant dosage level.
- Storage temperature of food: Not stated

Details on mating procedure:
- M/F ratio per cage: 1:2
- Length of cohabitation: Not stated
- Proof of pregnancy: Not stated
- After days of unsuccessful pairing replacement of first male by another male with proven fertility: Not stated
- Further matings after two unsuccessful attempts: Not stated
- After successful mating each pregnant female was caged (how): Not stated
- Any other deviations from standard protocol: Not stated
Analytical verification of doses or concentrations:
not specified
Duration of treatment / exposure:
Administration of EG to the F0 rats of both sexes began at approximately 7 weeks of age. At approximately 100 days of age, 10 males were mated to 20 females in each dosage group.

The F1 and F2 rats were treated as described for the F0 animals until approximately 100 days of age, at which time the animals were cohabited. Brother and sister mating were avoided for each generation.
Dose / conc.:
0 mg/kg bw/day
Remarks:
Untreated diet control B
Dose / conc.:
0 mg/kg bw/day
Remarks:
Untreated diet control A
Dose / conc.:
100 mg/kg bw/day
Dose / conc.:
200 mg/kg bw/day
Dose / conc.:
40 mg/kg bw/day
No. of animals per sex per dose:
10 males
20 females
Control animals:
yes, plain diet
Details on study design:
- Dose selection rationale: Not stated
- Rationale for animal assignment (if not random): Random assignment
- Fasting period before blood sampling for clinical biochemistry: Not stated
- Other: Administration of EG to the FO rats of both sexes began at approximately 7 weeks of age. At approximately 100 days of age, 10 males were mated to 20 females in each dosage group. The date of parturition and the number of live and dead newborn were recorded for each litter.
The appearance and behaviour of dams and pups were observed daily. Litter size was randomly reduced to 10, if necessary, on Day 4 postpartum. Offspring were
weighed as litters at 4 and 14 days and individually at 21days postpartum, the day they were weaned. F1 rats were randomly selected within each dosage group for the next mating. Each litter was represented
except for those conceived very late in the mating period. The F1 and F2 rats were treated as described for the F0 animals until approximately 100 days of age, at which time the animals were cohabited. Brother and sister matings were avoided for each generation.
Positive control:
No
Parental animals: Observations and examinations:
CAGE SIDE OBSERVATIONS: Not stated
- Time schedule: Not stated
- Cage side observations checked in table [No.?] were included. No

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Daily

BODY WEIGHT: Yes
- Time schedule for examinations: Not disclosed

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study): Yes
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: Yes

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): Not stated
OTHER: Dominant lethal study was also performed, 15 males of F2 per dose from reproductive study were removed from their test item dosing regimen at 155 days of age and bred to three separate sets (one set per week) of 15 untreated females. Each female was killed on Day 12 of gestation, and the ovaries and uteri were examined for the number of live and dead fetuses. In addition, 15 diet control F2 males were given an ip dose of 0.50 g/kg of triethylenemelamine (TEM, Polysciences, Inc., Warrington, Pa.) on the day before mating (positive controls), and mated with three groups of females as previously described.
Oestrous cyclicity (parental animals):
No detail on oestrous cycle was reported.
Sperm parameters (parental animals):
Parameters examined in [all/P/F1/F2] male parental generations: Testis weight & epididymis weight.
Litter observations:
STANDARDISATION OF LITTERS
- Performed on day 4 postpartum: Yes
- If yes, maximum of [...] pups/litter ([...]/sex/litter as nearly as possible); excess pups were killed and discarded. Yes

PARAMETERS EXAMINED
The following parameters were examined in [F1 / F2 ] offspring: Yes

GROSS EXAMINATION OF DEAD PUPS: Yes

ASSESSMENT OF DEVELOPMENTAL NEUROTOXICITY: No

ASSESSMENT OF DEVELOPMENTAL IMMUNOTOXICITY: No
Postmortem examinations (parental animals):
SACRIFICE: Yes
- Male animals: All surviving animals
- Maternal animals: All surviving animals
GROSS NECROPSY: Yes
HISTOPATHOLOGY / ORGAN WEIGHTS: Yes
Postmortem examinations (offspring):
SACRIFICE: Yes
- Male animals: All surviving animals
- Maternal animals: All surviving animals
GROSS NECROPSY: Yes
HISTOPATHOLOGY / ORGAN WEIGHTS: Yes
Statistics:
Continuous data such as bodyweight weights were compared by analysis of variance validated
by Bartlett’s test for homogeneity of variance. Duncan’s multiple range test was used to identify individual mean differences when indicated by a significant F value. Where Bartlett's indicated heterogenous variances, t tests for equal or unequal variances were used to delineate difference between groups. Pup weight were compared by method of Weil (Weil, 1970). Discontinuous data such as implantation and reproductive indices were compared by multiple sum of ranks test. Frequency data were compared by the x2 test and by Fisher's exact test. Reproductive indices [ fertility index (male & female), days from matting to parturition, gestation index (fraction of pregnancies that resulted in litters with live pups), gestation survival index (fraction of newborn pup alive at birth) 0 -4 day survival index, 4-14 survival index, 4- 21 day survival index] were calculated and evaluated statistically by nonparametric menthols
Reproductive indices:
Reproductive indices [ fertility index (male & female), days from matting to parturition, gestation index (fraction of pregnancies that resulted in litters with live pups), gestation survival index (fraction of newborn pup alive at birth) 0 -4 day survival index, 4-14 survival index, 4- 21 day survival index]
Offspring viability indices:
No particular indices were indicated in the report. However, offspring were examine, weighted as litters at day 4 - 14 and individually at day 21. Survival was also recorded.
Clinical signs:
no effects observed
Dermal irritation (if dermal study):
not examined
Mortality:
no mortality observed
Body weight and weight changes:
no effects observed
Food consumption and compound intake (if feeding study):
no effects observed
Food efficiency:
no effects observed
Water consumption and compound intake (if drinking water study):
not specified
Ophthalmological findings:
not examined
Haematological findings:
not examined
Clinical biochemistry findings:
not examined
Endocrine findings:
not specified
Urinalysis findings:
not examined
Behaviour (functional findings):
no effects observed
Immunological findings:
not examined
Organ weight findings including organ / body weight ratios:
effects observed, non-treatment-related
Histopathological findings: non-neoplastic:
no effects observed
Histopathological findings: neoplastic:
no effects observed
Other effects:
no effects observed
Description (incidence and severity):
The test item did not lead to statistically significant adverse effects on any of the parameters
measured in the three mating intervals. Slight apparent increases in the dominant lethal mutation index, observed during the Week 2
mating for the high-dose (1.0 g/kg/day) group and during the Week 3 mating for the low dose (0.04 g/kg/day) group, were probably random occurrences unrelated to EG treatment. This interpretation is consistent with the absence of a dose-response relationship and the fact that a negative index of similar
magnitude (-8.2%) was observed for the low dose group in the Week 2 mating. When compared to the combined control groups, significant decreases were observed as result of TEM treatment for the number of females with implants, the total number of implants and the number of live implants.
Reproductive function: oestrous cycle:
not specified
Reproductive function: sperm measures:
no effects observed
Reproductive performance:
no effects observed
There were no effects on fertility index, mating, implantation, gestation or gross histopathology observed in the liver, kidney, lung, heart, adrenals, thyroid, trachea, accessory sex glands, adipose tissue, lymph nodes, pituitary, thymus, and testes and epididymis, or uterus and ovaries.
Key result
Dose descriptor:
NOAEL
Effect level:
1 000 mg/kg bw/day
Based on:
test mat.
Sex:
male/female
Basis for effect level:
gross pathology
other: Mild focal interstitial nephritist in high dose groups and well as control group. Also unilateral hydronephrosis observed in on F2 male high dose group.
Key result
Critical effects observed:
no
Reproductive function: oestrous cycle:
not specified
Reproductive function: sperm measures:
no effects observed
Reproductive performance:
no effects observed
Key result
Dose descriptor:
NOAEL
Effect level:
1 000 mg/kg bw/day
Based on:
test mat.
Sex:
male/female
Remarks on result:
not determinable due to absence of adverse toxic effects
Key result
Critical effects observed:
no
Clinical signs:
no effects observed
Dermal irritation (if dermal study):
not specified
Mortality / viability:
no mortality observed
Body weight and weight changes:
no effects observed
Food consumption and compound intake (if feeding study):
no effects observed
Food efficiency:
no effects observed
Water consumption and compound intake (if drinking water study):
not specified
Ophthalmological findings:
not examined
Haematological findings:
not examined
Clinical biochemistry findings:
not examined
Urinalysis findings:
not examined
Sexual maturation:
not examined
Anogenital distance (AGD):
not examined
Nipple retention in male pups:
not examined
Gross pathological findings:
no effects observed
Histopathological findings:
no effects observed
Behaviour (functional findings):
not examined
Developmental immunotoxicity:
not examined
Key result
Dose descriptor:
NOAEL
Generation:
F1
Effect level:
1 000 mg/kg bw/day
Based on:
test mat.
Sex:
male/female
Remarks on result:
not determinable due to absence of adverse toxic effects
Key result
Critical effects observed:
no
Clinical signs:
no effects observed
Dermal irritation (if dermal study):
not examined
Mortality / viability:
no mortality observed
Body weight and weight changes:
no effects observed
Food consumption and compound intake (if feeding study):
no effects observed
Food efficiency:
no effects observed
Water consumption and compound intake (if drinking water study):
not examined
Ophthalmological findings:
not examined
Haematological findings:
not examined
Clinical biochemistry findings:
not examined
Urinalysis findings:
not examined
Sexual maturation:
no effects observed
Anogenital distance (AGD):
not examined
Nipple retention in male pups:
not examined
Organ weight findings including organ / body weight ratios:
no effects observed
Gross pathological findings:
no effects observed
Histopathological findings:
no effects observed
Other effects:
no effects observed
Developmental immunotoxicity:
not examined
Key result
Dose descriptor:
NOAEL
Generation:
F2
Effect level:
1 000 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male/female
Remarks on result:
not determinable due to absence of adverse toxic effects
Key result
Reproductive effects observed:
no
Conclusions:
Based on the condition reported in this study, there were no reproductive or dominant lethal effects associated with dietary administration of ethylene glycol with no-observed-adverse-effect-level (NOAEL) considered as 1000 mg/kg/day.
Executive summary:







To assess the possible effects of ethylene glycol (EG) on reproductive performance and mutagenesis, three-generation reproduction and dominant lethal mutagenesis studies were performed in the Fischer 344 rat. EG was included in the diet at approximate dosages of 1.0, 0.2, and 0.04 g/kg/day during three generations of reproduction, Each generation was bred once. In a dominant lethal mutagenesis study, the F2 males from the reproduction study were bred to three consecutive lots of untreated females at weekly intervals. Concomitantly, another group of untreated F2 males that received a single ip injection of 0.50 mg/kg triethylenemelamine (TEM) were bred similarly to serve as a positive control group.


There was no evidence of increased fetal death was observed in any of the groups receiving. EG produced no effects on fertility, fecundity, or reproductive performance. In addition, there was no evidence of a dominant lethal effect when EG treated males were mated with untreated females.


 


Endpoint:
reproductive toxicity, other
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
published 26/05/1985
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Qualifier:
no guideline followed
Principles of method if other than guideline:
The basis for the study design is the “NTP Fertility Assessment by Continuous Breeding Protocol"
GLP compliance:
not specified
Limit test:
no
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source (i.e. manufacturer or supplier) and lot/batch number of test material: EC (CAS No. 107-21-I) was obtained from Ashland Chemical Company.
- Purity, including information on contaminants, isomers, etc.: 99.6+/- 0.4%

STABILITY AND STORAGE CONDITIONS OF TEST MATERIALL: Analysed and indicated as stable.

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Treatment of test material prior to testing (e.g. warming, grinding): Administered via drinking water.
- Preliminary purification step (if any): not indicated
- Final concentration of a dissolved solid, stock liquid or gel: N/A
- Final preparation of a solid (e.g. stock crystals ground to fine powder using a mortar and pestle): N/A
Species:
mouse
Strain:
CD-1
Sex:
male/female
Details on test animals or test system and environmental conditions:
- Source: Charles River, Kingstone NY
- Females (if applicable) nulliparous and non-pregnant: Yes
- Age at study initiation: 6 weeks
- Weight at study initiation: Not stated
- Fasting period before study: Not stated
- Housing: housed by sex in solid-bottom polycarbonate cage with steel wire lids, two per cage one week pre-mating then housed as breeding pairs for 14 weeks.
- Use of restrainers for preventing ingestion (if dermal): Not stated
- Diet (e.g. ad libitum): Purina certified pelleted rodent chow (no. 5002)
- Water (e.g. ad libitum): Distilled water
- Acclimation period: 5 day
ENVIRONMENTAL CONDITIONS
- Temperature (°C): 23±2°C
- Humidity (%): 45 ± 25%
- Air changes (per hr): Not stated
- Photoperiod (hrs dark /hrs light): 10hrs dark / 14hrs light):
IN-LIFE DATES: From: To: Not stated
Route of administration:
oral: drinking water
Vehicle:
water
Details on exposure:
PREPARATION OF DOSING SOLUTIONS:
Dosing solutions were prepared at 0,0.25, 0.5, 1.0, 2.5, and 5.0% (w/v) Task 1, and 0, 0.25, 0.5, and 1.0% for Task. Dosing solutions were prepared fresh once every 2 weeks and stored in distilled water at room temperature under yellow lights. Chemical analyses performed by MRI every 6 weeks indicated that dosage solutions were within 98 to 107% intended concentrations.
DIET PREPARATION: N/A

VEHICLE
- Justification for use and choice of vehicle (if other than water): test item soluble in water.
- Concentration in vehicle: 0,0.25, 0.5, 1.0, 2.5, and 5.0% (w/v) Task 1, and 0, 0.25, 0.5, and 1.0% for Task 2
- Amount of vehicle (if gavage): As above
- Lot/batch no. (if required): N/A
- Purity: Distilled water
Details on mating procedure:
- M/F ratio per cage: 1:1
- Length of cohabitation: 14 weeks
- Proof of pregnancy: Not stated
- After days of unsuccessful pairing replacement of first male by another male with proven fertility: Not stated
- Further matings after two unsuccessful attempts: Not stated
- After successful mating each pregnant female was caged (how): Not stated
- Any other deviations from standard protocol: Not stated
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Dosing solutions were prepared at 0,0.25, 0.5, 1.0, 2.5, and 5.0% (w/v) Task 1, and 0, 0.25, 0.5, and 1.0% for Task. Dosing solutions were prepared fresh once every 2 weeks and stored in distilled water at room temperature under yellow lights. Chemical analyses performed by MRI every 6 weeks indicated that dosage solutions were within 98 to 107% intended concentrations.
Duration of treatment / exposure:
Task 1: Dose-finding 14 days
Task 2 main study F0
- 7days pre-mating
-98 days days mating
-21 days post mating and 21 for F1
Frequency of treatment:
Once a day
Details on study schedule:
Study design. The basis for the study design is the “NTP Fertility Assessment by Continuous Breeding Protocol.”
Mice were quarantined for 2 weeks prior to Task 1, the dose-finding, 14day repeated dose study
with vehicle control and five dose groups (eight males and eight females per group). Mortality, weight gain, and clinical signs of toxicity were evaluated. Histopathology was performed on a representative male and female which died during the study.

Task 2 is the continuous breeding phase of the protocol; vehicle control group (40 males and 40 females) and three dose groups (20 males and 20 females per group) were used. Because the high dose might produce some significant signs of toxicity, the dose was selected so that (1) body weight gain will not be suppressed more than 10% compared to controls. and (2) there would be 90% or greater survival in male and female mice. The mid-dose was selected to produce minimal or no systemic toxicity and the low dose was an estimated no-effect dose level. It was particularly important that the dose amounts not be so high that adverse effects on reproduction were secondary to systemic toxicity.

In the present study, 11 week-old male and female mice were exposed to the chemical during a 7day premating, after which they were randomly paired (one male: one female) within each dose group and cohabited for 98 days ( 14 weeks) while treatment continued. Newborn litters were evaluated and immediately killed. At the end of the 98-day cohabitation period, males and females were
separated to prevent further mating; litters were saved during following 21-day segregation period. Chemical exposure as continued during the 98-day cohabiting period and the 1-day segregation period which followed, throughout the life of the offspring born during the 21 days. The final litters borne to the control and high doe pairs during the 21-day segregation period were weaned and evaluated for reproductive performance in task 4 (offspring assessment).

When minimal or no reproductive effects were noted in Task 2 as was the case in the present study, then reproductive performance in the control and high dose offspring (F1) from the final Task 2 littters was evaluated (Task 4). Chemical exposure was continued throughout Task 4. At 70±10 days of age, 20 high -dose male offspring were randomly paired with 20 high-dose female offspring and 20 males & females offspring of control were paired. High dose control Task 2 litters were sampled, and sibling mating were avoided. The pairs were cohabited for 7 days, or less if a copulatory plug were observed. Reproductive performance was determined by evaluation of the litters.
Dose / conc.:
0 other:
Remarks:
% (w/v) in drinking water
Dose / conc.:
0.25 other:
Remarks:
% (w/v) in drinking water
Dose / conc.:
0.5 other:
Remarks:
% (w/v) in drinking water
Dose / conc.:
1 other:
Remarks:
% (w/v) in drinking water
No. of animals per sex per dose:
20 males and 20 females per group
Control group (40 males and 40 females)
Control animals:
yes, concurrent no treatment
yes, concurrent vehicle
Details on study design:
Study design. The basis for the study design is the “NTP Fertility Assessment by Continuous Breeding Protocol.”

Mice were quarantined for 2 weeks prior to Task 1, the dose-finding, 14day repeated dose study with vehicle control and five dose groups (eight males and eight females per group). Mortality, weight gain, and clinical signs of toxicity were evaluated. Histopathology was performed on a representative male and female which died during the study.

Task 2 is the continuous breeding phase of the protocol; vehicle control group (40 males and 40 females) and three dose groups (20 males and 20 females per group) were used. Because the high dose might produce some significant signs of toxicity, the dose was selected so that (1) body weight gain will not be suppressed more than 10% compared to controls. and (2) there would be 90% or greater survival in male and female mice. The mid-dose was selected to produce minimal or no systemic toxicity and the low dose was an estimated no-effect dose level. It was particularly important that the dose amounts not be so high that adverse effects on reproduction were secondary to systemic toxicity.

In the present study, 11 week-old male and female mice were exposed to the chemical during a 7day premating, after which they were randomly paired (one male: one female) within each dose group and cohabited for 98 days ( 14 weeks) while treatment continued. Newborn litters were evaluated and immediately killed. At the end of the 98-day cohabitation period, males and females were
separated to prevent further mating; litters were saved during following 21-day segregation period. Chemical exposure as continued during the 98-day cohabiting period and the 1-day segregation period which followed, throughout the life of the offspring born during the 21 days. The final litters borne to the control and high doe pairs during the 21-day segregation period were weaned and evaluated for reproductive performance in task 4 (offspring assessment).

When minimal or no reproductive effects were noted in Task 2 as was the case in the present study, then reproductive performance in the control and high dose offspring (F1) from the final Task 2 littters was evaluated (Task 4). Chemical exposure was continued throughout Task 4. At 70±10 days of age, 20 high -dose male offspring were randomly paired with 20 high-dose female offspring and 20 males & females offspring of control were paired. High dose control Task 2 litters were sampled, and sibling mating were avoided. The pairs were cohabited for 7 days, or less if a copulatory plug were observed. Reproductive performance was determined by evaluation of the litters.
Positive control:
N/A
Parental animals: Observations and examinations:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Twice daily
- Cage side observations checked in table [No.?] were included. Yes

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Twice daily

BODY WEIGHT: Yes
- Time schedule for examinations: Weekly and at necropsy.
FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study): Yes
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: Yes

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): Weekly intervals
OTHER: Not stated
Statistics:
Statistical analyses of the data were performed by Program Resources Inc. (Research Triangle Park, NC) with software written in APL and executed on a NIH DEC IO computer. The Chi-Square test, Mann Whitney U test (Conover, 1980), Fisher’s Exact test and Kruskal-Wallis test among others used.
Clinical signs:
no effects observed
Mortality:
mortality observed, non-treatment-related
Description (incidence):
Two females from the 0.5% group and one male and two females from the control group died before the end of the study; at least one of the two deaths from the 0.5% EG group could have been a treatment- related death since the renal tubules contained a moderate number of oxalate crystals.
Body weight and weight changes:
no effects observed
Food consumption and compound intake (if feeding study):
no effects observed
Food efficiency:
no effects observed
Water consumption and compound intake (if drinking water study):
no effects observed
Ophthalmological findings:
not examined
Haematological findings:
not examined
Clinical biochemistry findings:
not examined
Endocrine findings:
not specified
Urinalysis findings:
not examined
Behaviour (functional findings):
no effects observed
Immunological findings:
not specified
Key result
Dose descriptor:
NOAEL
Effect level:
0.5 other: % in water Eq. 840 mg/kg bw/day
Based on:
test mat.
Sex:
male/female
Basis for effect level:
reproductive performance
Remarks on result:
other: equivalent to approx. 840 mg/kg bw/d
Key result
Critical effects observed:
no
Clinical signs:
no effects observed
Dermal irritation (if dermal study):
not examined
Mortality / viability:
no mortality observed
Body weight and weight changes:
no effects observed
Food consumption and compound intake (if feeding study):
not examined
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
no effects observed
Ophthalmological findings:
not examined
Haematological findings:
not examined
Clinical biochemistry findings:
not examined
Urinalysis findings:
not examined
Sexual maturation:
not examined
Anogenital distance (AGD):
not examined
Nipple retention in male pups:
not examined
Organ weight findings including organ / body weight ratios:
not examined
Gross pathological findings:
effects observed, treatment-related
Description (incidence and severity):
At 1 % dose group facial defects, pattern of skeletal defects, affected skull, cleft lip, abnormally shaped or missing sternbrae, fused ribs and abnormally shaped vertebrae, twisting of spine were observed.
Histopathological findings:
no effects observed
Other effects:
not specified
Behaviour (functional findings):
not examined
Developmental immunotoxicity:
not examined
Exposure to ethylene glycol resulted in a small but significant decrease in the number of litters per breeding pair, in the number of live pups per pair and in the live pup weight. A significant number of pups in the 1.0% dose group were born with distinct facial deformities. In the retained litters at this dose, the facial deformities were more obvious with age. These malformed animals also exhibited fused ribs and shortened nasal, parietal, and/or frontal bones of the skull. When pups from the high dose group were raised to adulthood (with continued exposure to ethylene glycol) and mated, they exhibited decreased mating and fertility indices relative to controls handled in the same manner, but there were no effects on litter size, pup weight or sex ratio.
Key result
Dose descriptor:
NOAEL
Generation:
other: F2
Effect level:
0.5 other: % in water Eq. 840 mg/kg bw/day
Based on:
test mat.
Sex:
male/female
Basis for effect level:
gross pathology
Remarks on result:
other: equivalent to approx. 840 mg/kg bw/d
Key result
Dose descriptor:
NOAEL
Generation:
F1
Effect level:
0.5 other: % in drinking water
Based on:
test mat.
Sex:
male/female
Basis for effect level:
gross pathology
Remarks on result:
other: equivalent to approx. 840 mg/kg bw/d
Key result
Critical effects observed:
yes
Lowest effective dose / conc.:
1 other: % in drinking water, Eq. 1640 mg/kg bw/day
System:
musculoskeletal system
Organ:
other: Facial deformities
Treatment related:
yes
Dose response relationship:
not specified
Relevant for humans:
not specified
Key result
Reproductive effects observed:
yes
Lowest effective dose / conc.:
1 other: % in water Eq. 1640 mg/kg bw/day
Treatment related:
yes
Relation to other toxic effects:
not specified
Dose response relationship:
not specified
Relevant for humans:
not specified

F2 Generation: 


Fertility was 80% for the control group compared to 61% to those animals receiving 1% EG, but the difference was not statistically significant. The number of live pups per litter and the live pup weight were lower in the EG-treated group, as they were in task 2, but differences were not statistically significant in either case. Although no clinical signs of EG toxicity were reported in the study, unusual facial features were noticed in some of the offspring of the treated mice but not in the controls. The affected offspring generally had a shorter snout with wide-set eyes compared to the control CD- 1 mice. The examination revealed a pattern of skeletal defects in the treated mice affecting the skull, sternebrae, ribs, and vertebrae in both males and females. The defects included shortened frontal, nasal, and parietal bones; one or more pairs of fused ribs; abnormally shaped or missing sternebrae; abnormally shaped vertebrae; and twisting of the spine. The untreated mice showed no such defects. It was apparent from low-magnification examination of the histological sections that the size and shape of the bones in treated mice differed from the controls. Bones from treated mice were smaller and had altered shapes. However, histologic alterations were not evident when bones from treated mice were examined by light microscopy. Formation of lamellar bone, numbers and activity of osteoblasts and osteoclasts, and cartilage structure were identical in treated and control tissues. Tooth structure was normal in all treated mice. No alterations were seen in nasal turbinates, skeletal muscle, various salivary glands, eyes, or in those portions of the olfactory lobes of the brain which were frequently present in the sections. Deposition of calcium oxalate crystals were not found during careful examination of the microvasculature of bony or adjacent soft tissues. No other treatment-related effects were noted in the EG treated mice.


TASK 1: Dosing fromulation analysis


EG administered in drinking water for 2 weeks at 0.25, 0.5, 1.0, and 2.5% (w/v) dose levels (equivalent to approx. 410, 840, and 1640 mg/kg bw/d) had no significant effect on body weights of both male and female mice. Mice exposed to 5% EG lost weight. The group mean body weights for control male mice at the beginning and the end of Task 1 were 34.4 and 34.6 g, respectively. Corresponding values for the 5% EG group were 34.9 and 31.4 g.


Certain animals in the 2.5 and 5% EG groups were sluggish and appeared to have respiratory problems within one week of treatment. Hair coat changed from normal to rough. During the later part of the first week or the early part of the second week, a number of animals in these two dose groups were lethargic and hunched. A significant number of these mice died. No such symptoms were noted in the control group or in animals in the 0.25, 0.5, and 1% EG groups.


Two of the eight male mice exposed to 2.5% EG died during Task 1. None of the female mice died in this dose group. One female and three male mice died in the 5% EG group. These animals exhibited severe respiratory distress prior to death. Pathologic examination showed distinct lesions in the kidneys and dilated tubule with moderate numbers of oxalate crystals in the lumina. The lungs were moderately congested. The cause of death was diagnosed as tubular nephrosis due to oxalate crystals.


Daily consumption of distilled water by the control mice or dosed water by the animals in the different treatment groups was essentially the same except for the male mice in the 5% EG group (p<0 .001).


 


TASK 2: Continous breeding 


EG administered in drinking water at 0.25, 0.5, and 1% (w/v) dose level (equivalent to approx. 410, 840, and 1640 mg/kg bw/d) had no apparent effect on male or female body weights. The group mean body weights of male mice in the control and different treatment groups varied between 36.8 to 37.3 g at the beginning of Task 2. After 18 weeks of treatment, the group mean body weights for animals exposed to 0, 0.25, 0.5, and 1% EG were 40.3, 40.6, 40.2, and 40.3 g, respectively. Body weights for female mice varied considerably during Task 2 and the weight depended on the gestation phase.


Only five (5) mice died during 18 weeks of Task 2; one male and two females in the control group and two females in the 0.5% EG group. The cause of death for the control male mouse was mild myodegeneration of the heart and pulmonary congestion. One of the two control female mice revealed gravid uterus. Only one of the two female mice in the 0.5% EG group was necropsied. Pathologic examination revealed dilated tubule with moderate numbers of oxalate crystals in the lumina. The cause of death was suspected due to tubular nephrosis due to oxalate crystals.


The presence of ethylene glycol at a concentration of 1% or less did not significantly interfere with daily water consumption during Task 2 for both male and female mice.


Reproductive Performance and Fertility
Ethylene glycol administered continuously in drinking water at 0.25, 0 .5, and 1% dose levels had no effect on fertility in CD-1 mice. The fertility index for control and all three dose levels was 100%, i.e. every experimental pair delivered at least one litter. EG treatment at 1% dose level (approx. 1640 mg/kg bw/d) significantly reduced (p <0.05): (1) the average number of litters, 4.45 vs. 4.89 in the control group; (2) the average total litter size; (3) the average number of male pups per litter; and (4) both male and female pup weights. This is regarded as a sequel of developmental toxicity. No significant (p >0.05) differences existed between the 1% EG and the control group with respect to: (1 ) the proportion of live pups; and (2) sex ratio. EG treatment at 0.25 and 0.5% dose levels did not significantly (p >0.05) affect reproductive performace of CD-1 mice with respect to any of the above parameters. Interestingly, a significant number of pups delivered by breeding pairs in the 1% EG group showed distinct facial deformities. Six pups representing three different litters revealed a possible cleft lip/palate.


Gestation Period: EG exposure had no apparent effect on the gestation period. Cumulative days to 1st, 2nd, 3rd, 4th, and 5th litters were 28, 51, 69, 91, and 112 (days of the study), respectively. Corresponding values for the 1% EG group were 30, 55, 75, 96, and 111, respectively. It must be added that these values (days of the study) include 7 days of the premating period.


 


TASK 3& 4: Offspring assessment


The average pup weight at weaning ranged between 14.0 to 18.4 g. Offspring from both the control and 1% EG (approx. 1640 mg/kg bw/d) groups gained weight at essentially the same rate.


At least four male and four female mice among the offspring selected for Task 4 matings showed distinct facial deformities. These mice were later used for detailed skeletal examinations.


There was no mortality among the first generation offspring in the control group. Three offspring died in the 1% EG group; one male and two females. The cause of death was not treatment related.


Water consumption by first generation offspring from the control and 1% EG group was monitored on a weekly basis. There were no apparent difference in the average intake of distilled/dosed water by the control/1% EG group offspring.


 


Reproductive Performance and Fertility:
Twenty (20) pairs of first generation offspring were randomly selected from the control as well as 1% EG groups to assess their reproductive performance. The breeding pairs were mated until a copulatory plug was detected or for a maximum of seven days. The percent of plug positive/No. cohabited (mating index) for the control and treated pups was 90 and 74, respectively. Fertility was also affected by EG treatment. The percent of No. fertile/No. cohabited (fertility index) in the control and EG treated pups was 80 and 61, respectively. Other reproductive parameters were not significantly different (p>0.05) from the control values, i.e. the number of live pups per litter (males, females, or combined), proportion of pups born alive, and sex ratio.


 


Gross Necropsy:


No significant differences existed in terms of body weight, reproductive tract, and pituitary weight (p>0.05). Average brain weight of treated animals was lower than the control value (p<0.05). Organ weights were then adjusted for body weight by analysis of covariance. Male offspring body and organ weights for control and the treated animals were essentially the same except for the brain and right cauda. The brain weight was decreased by approximately 8 percent of the control value and right cauda weight by 14 percent. Male organ weights were also adjusted for body weight by analysis of covariance. It must be added here that eight animals with distinct facial deformities in the 1% EG group were not necropsied and later utilized for skeletal examinations.


 


Skeletal Examination:


A series of skeletal deformities were apparent in offspring delivered by the high dose (1% EG) group. Briefly, (a) frontal and nasal passages were significantly shortened and sometimes curved; (b) one or more pairs of ribs were fused; (c) one or more ribs were branched; (d) one or more centra were abnormal; and (e) parietals were smaller than the normal width. None of these abnormalities were noted in the untreated CD-1 mice.

Conclusions:
 Based on the condition of the study the no-observed-adverse-effect-level (NOAEL) were 840 mg/kg bw/day for general toxicity and 1640 mg/kg bw/day for overall reproductive & developmental toxicity
Executive summary:

The effects of ethylene glycol on reproduction of CD-l mice were tested in a protocol which permitted continuous breeding during a specified interval. The dosage amounts of 0, 0.25, 0.5, or 1% (Eq.  410, 840, 1640, or 2800 mg ethylene glycol/kg bw/day in drinking water) ethylene glycol by continuous administration in drinking water for male and female mice were selected from the general toxic responses observed in a 14-day pilot study.


F1 female pup weight was decreased at 840 mg/ kg bw/day was observed.   Slight reduction in the number of F1 litters per fertile pair (8%, P < 0.01) and number of live F1 pups per litter (6%, P < 0.05), as well as unusual facial features and skeletal changes in the skull, sternebrae, ribs, and vertebrae, were observed at 1640 mg/kg bw/day groups compared to control F0 mice. Neither the 0.25 nor 0.5% dose groups were significantly affected.


There were no clear treatment-related effects on parental survival, body weight gain, or water intake, and no overt signs of toxicity were observed but two deaths occurred at the 0.5% (Eq. 840 mg/kg bw/day) quantity which may have been related to oxalate crystal deposition in the kidney.


 Based on the condition of the study the no-observed-adverse-effect-level (NOAEL) were 840 mg/kg bw/day for general toxicity and 1640 mg/kg bw/day for overall reproductive & developmental toxicity.

Endpoint:
one-generation reproductive toxicity
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
comparable to guideline study
Remarks:
Guideline compliant study conducted in accordance with GLP. The additional elements added to a standard sub-chronic assay ( Commission Directive 87/302/EEC, U.S. EPA Pesticide Assessment Guidlines; Subdivisoin F, 82-1 ( 1982), OECD Test Guideline 407; Maff Japan NohSan No. 4200 ( 1985) meet the requirements for a screening test for reproductive toxicity.
Qualifier:
equivalent or similar to guideline
Guideline:
EU Method B.34 (One-Generation Reproduction Toxicity Test)
Guideline:
OECD Guideline 415 [One-Generation Reproduction Toxicity Study (before 9 October 2017)]
Deviations:
yes
Remarks:
10 pregnant females were evaluated rather than 20 per Guideline. Females given test substance 14 weeks before mating rather than 2 weeks before mating per guideline. Compound was administered only before mating and not during mating, pregnancy, or weani
GLP compliance:
yes
Remarks:
The additional elements to a standard sub-chronic assay (Com. Dir 87/302/EEC, U.S.EPA Pesticide Assessment Guidlines; Subdiv. F, 82-1 (1982), OECD 407; Maff Japan NohSan No.4200 (1985) meet the requirements for a screening test for reproductive toxicity.
Justification for study design:
Exposure of male and female rats by gavage to glycolic acid in a one-generation reproduction study at doses of 150, 300, and 600 mg/kg/day did not cause any changes in organ weights or gross pathology of the reproductive system. There were compound-related effects in the kidneys of high dose male rats (600 mg/kg/day) which caused gross lesions in four animals and mortality in one of these animals. These findings were associated with oxalate crystal nephropathy similar to that noted in glycolic acid-exposed male rats in the subchronic study (Anatomical Pathology Report, Rats Designated for Subchronic Toxicity Evaluations). Under the conditions of this study, based on gross observations and organ weights, the NOEL for pathology of the reproduction organs of P1 male and female adults was 600 mg/kg/day (the highest dose tested). There were no compound-related mortality or gross observations in the F1 weanlings. Under the conditions of this study, the NOEL for pathology of male and female weanlings was the highest dose tested (600 mg/kg/day). The NOEL for this study is based on 100% glycolic acid dosed (adjusted for 70% purity of the test substance). Glycolic acid is present extensively in many staple food items and beverages. In addition, the material has wide scale application within the human cosmetics industry. It has been well studied for its metabolism profile and for multiple endpoints in toxicity studies. Glycolic acid is metabolized to glyoxylic acid, which in turn may be metabolized to the endogenous amino acid glycine (the primary metabolic pathway) or to oxalic acid. Glycine may be incorporated into proteins or utilized to generate energy via the citric acid cycle. Oxalic acid is excreted in the urine without additional metabolism. No adverse indications have been reported for glycolic acid from the many and various potential exposure routes to suggest any significant risk to human reproductive function. The extent of data already in existence indicates that glycolic acid is unlikely to impair fertility as demonstrated in a well designed and well conducted animal study and further testing to elucidate this endpoint should not be required.
Species:
rat
Strain:
other: Crl:CD (SD) IGS.BR
Sex:
male/female
Details on test animals or test system and environmental conditions:
- Source: Charles River Laboratories, Inc., Raleigh, North Carolina
- Age at study initiation: 48 days. Birthdated 18 August 1998. Rats were circa 5 weeks old at time of receipt. Group mean bodyweight range at time of allocation to study was 229.5 to 232.6g for males and 163.7 to 165.0g for females.
- Housing: With the exception of some portions of the reproductive study, all rats were housed one per cage, sexes separate, in stainless steel, wire mesh cages suspended above cage boards.
- Diet (e.g. ad libitum): All rats were fed PMI Nutrition International, Inc. Certified Rodent Checkers LabDiet@ 5002 ad libitum.
- Water (e.g. ad libitum): Tap water was provided ad libitum
- Acclimation period: Upon arrival at Haskell Laboratory, the rats were quarantined for six days of the 13-day pretest period.
ENVIRONMENTAL CONDITIONS
- Temperature (°C): 23" +/- 1°C
- Humidity (%): 50% +/- 10%
- Photoperiod (hrs dark / hrs light): 12-hour light/dark cycle (fluorescent light)
IN-LIFE DATES: From: October 5, 1998 To: March 1, 1999
Route of administration:
oral: gavage
Vehicle:
water
Details on exposure:
Dose solutions were prepared at 15, 30 and 60 mg/mL on a daily basis and administered on same day by gavage in a dose volume of 10 mL/kg bw.
The solutions were administered daily by oral gavage at a dose volume of 10 ml/kg, to achieve dose levels of 150, 300, and 600 mg/kg/day, based on the most recently recorded weight. For pregnant rats, from gestation day 18 until delivery, dose volumes were based on the gestation day 18 body weights. Dosing solutions were stored refrigerated until used. Dosing solutions stored beyond 14 days after preparation were not administered to animals. Control animals were dosed with commercially-supplied water only.
Details on mating procedure:
Females were cohabited with males (1:1) until copulation was confirmed by the presence of a copulation plug in the vagina or on the cageboard.
Checks for copulation plugs were made each morning; the day copulation was confirmed was designated as Day 1 of gestation (Day IG)
- M/F ratio per cage: After approximately 14 weeks of exposure to the test substance, on test day 97, each female was continually housed on a 1: 1 basis with a randomly selected male of the same dietary concentration level in the male's cage. On the day copulation was confirmed, the female was
transferred back to individual cage housing.
- Length of cohabitation: Mating pairs were cohoused until evidence of copulation was observed (designated as day 0 of gestation), or until two weeks elapsed.
- Proof of pregnancy: presence of an intravaginal or extruded copulation plug was considered evidence of copulation.
- After successful mating each pregnant female was caged (how): Female rats were transferred to polycarbonate pans (on day 20 of gestation for mated females or at the end of the cohabitation period for female rats without evidence of copulation), and were observed at least twice daily for signs of delivery and pups.
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
HPLC: Hewlett-Packard 1090; UV 210 nm; column: Zorbax® SB-C18, 4.6 mm x 150 mm; 40°C
mobile phase: 2.0% acetonitrile/98.0% 3.1 mM H3P04; 1.0ml/min.,
Injection volume: 4.0 µl
Duration of treatment / exposure:
90 days with continuation of treatment through to test day 131 (males) or day 21 of lactation (females) for animals in reproduction phase.
Frequency of treatment:
daily
Details on study schedule:
No data.
Remarks:
Doses / Concentrations:
150, 300 or 600 mg/kg bw 15, 30 and 60 mg/mL administered in 10 mL/kg bw volume of water
Basis:
nominal in water
No. of animals per sex per dose:
10 per sex per concentration
Control animals:
yes, concurrent no treatment
Details on study design:
- Dose selection rationale: Dose levels for this study were selected based on results from a developmental toxicity study in which glycolic acid was administered by gavage to Crl:CD%R female rats (25/group) on days 7-21 of gestation at daily dose levels of 0, 75, 150, 300, or 600 mg/kg/day.
- Rationale for animal assignment (if not random): Rats were selected for study use on the bases of adequate body weight gain, freedom from any
clinical signs of disease or injury, and a body weight within 20% of the mean within a sex. In error, two rats with ophthalmological abnormalities were assigned to study groups in the reproduction subset (see Materials and Methods, Section M. Ophthalmology). The selected rats were distributed by computerized, stratified randomization so that there were no statistically significant differences among group body weight means within a sex. After approximately 14 weeks of exposure to the test substance, on test day 97, each female was continually housed on a 1: 1 basis with a randomly selected male of the same dietary concentration level in the male's cage. On the day copulation was confirmed, the female was transferred back to individual cage housing. Mating pairs were cohoused until evidence of copulation was observed (designated as day 0 of gestation), or until two weeks elapsed. The presence of an intravaginal or extruded copulation plug was considered evidence of copulation. Female rats were transferred to polycarbonate pans (on day 20 of gestation for mated females or at the end of the cohabitation period for female rats without evidence of copulation), and were observed at least twice daily for signs of delivery and pups. The day when delivery was complete was designated day 0 postpartum. At each examination period, pups were individually handled and examined for abnormal behavior and appearance; any dead, missing, or abnormal pups were recorded.
Parental animals: Observations and examinations:
DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Cage-site examinations to detect moribund or dead rats and abnormal behavior and appearance among rats were conducted at least once daily throughout the study. Moribund and dead rats were submitted for a gross and microscopic examination. At every weighing, each rat was
individually handled and examined for abnormal behavior and appearance. Rats designated for neurotoxicity evaluations had cage-site examinations approximately one to two hours after dosing on test day 1, and approximately one to two hours after dosing on one day during the weeks that the functional observational battery was conducted.

BODY WEIGHT: Yes
- Time schedule for examinations: All rats were weighed once per week during the 90-day feeding phase of the study. During the reproduction evaluation, male rats were weighed on a weekly schedule and female rats were weighed during gestation on days 0, 7, 14, 18, and 21, and lactation on days 0, 7, 14, and 21. Female rats without a known start of gestation and female rats that copulated but did not deliver a litter continued to be weighed weekly.

FOOD CONSUMPTION / FEEDING EFFICIENCY:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: Yes for females on days 0, 7, 14 and 21 of gestation. From these determinations and body weight data, mean daily food consumption and mean food efficiency were calculated.

All P1 parental rats, including the females that died or were sacrificed in extremis and those for which mating did not result in a production of offspring, were sacrificed by carbon dioxide asphyxiation and exsanguination and subjected to gross pathological examination. The sacrifices were on test days 131 for male rats and on test days 142 through 153 for female rats. The testes of each male rat were weighed. The uteri of all cohabited female rats were examined for the presence and number of implantation sites. All gross lesions were preserved in appropriate fixative for possible future histopathological examination.

Lactation day 21 (adult females, and weanlings) or after production of litters (adult males)/all: gross necropsy, adult males: testes weights, adult females:implantation sites

Oestrous cyclicity (parental animals):
No information
Sperm parameters (parental animals):
No information
Litter observations:
STANDARDISATION OF LITTERS
- Performed on day 4 postpartum: no data

PARAMETERS EXAMINED
The following parameters were examined in F1 offspring:
Day 0 Postpartum: Live and dead pups in each litter were counted as soon as possible after delivery was completed. Live pups in each litter were individually weighed.
Day 4 Postpartum: Litters were culled randomly to eight (four per sex when possible). Extra pups were euthanatized (by decapitation) and discarded without pathological examination. Litters of eight pups or less were not reduced. Litter counts and individual pup weights were determined prior to and after culling.
Day 7 and 14 postpartum: Pups in each litter were counted by sex and individually weighed.
Day 21 Postpartum (Weaning): Pups in each litter were counted by sex and individually weighed.

GROSS EXAMINATION OF DEAD PUPS:
yes, for external and internal abnormalities; Offspring that were found dead during the lactation period underwent gross pathological evaluation. F1 weanlings were sacrificed by carbon dioxide asphyxiation and underwent gross pathological evaluation. Gross lesions from some weanlings were evaluated microscopically.
Postmortem examinations (parental animals):
All P1 parental rats, including the females that died or were sacrificed in extremis and those for which mating did not result in a production of offspring, were sacrificed by carbon dioxide asphyxiation and exsanguination and subjected to gross pathological examination. The sacrifices were on test days 131 for male rats and on test days 142 through 153 for female rats. The testes of each male rat were weighed. The uteri of all cohabited female rats were examined for the presence and number of implantation sites. All gross lesions were preserved in appropriate fixative for possible future histopathological examination.
Lactation day 21 (adult females, and weanlings) or after production of litters (adult males)/all: gross necropsy, adult males: testes weights, adult females:implantation sites.
Postmortem examinations (offspring):
Offspring that were found dead during the lactation period underwent gross pathological evaluation. F1 weanlings were sacrificed by carbon dioxide asphyxiation and underwent gross pathological evaluation. Gross lesions from some weanlings were evaluated microscopically.
Statistics:
One way analysis of variance followed by Dunnett’s test or linear contrasts; Kruskal-Wallis test followed by Dunn’s test; Cochrane-Armitage trend test; Jonckhere-Terpstra trend test; linear contrast by least square means; Levene’s test for homogeneity, Shapiro-Wilk test for normality, Bartlett’s test.
Cf study for details.
Reproductive indices:
There were no biologically or statistically significant dose-related differences in mating, fecundity, or gestation indices, implantation efficiency, or gestation length in rats dosed with any concentration of test substance.
Clinical signs:
no effects observed
Body weight and weight changes:
no effects observed
Food consumption and compound intake (if feeding study):
no effects observed
Organ weight findings including organ / body weight ratios:
no effects observed
Histopathological findings: non-neoplastic:
no effects observed
Other effects:
not specified
Reproductive function: oestrous cycle:
not specified
Reproductive function: sperm measures:
not specified
Reproductive performance:
no effects observed
The unscheduled deaths that occurred in the male 600 mg/kg/day group (Animal No. 616645) was considered to be compound related. Based on microscopic examination, the cause of death in this animal was oxalate crystal nephropathy. This death was considered a result of compound administration. There was one animal in the 600 mg/kg/day males (Animal No. 616656) that was found dead and had lung discoloration at gross necropsy. This gross lesion was considered typical of pulmonary aspiration secondary to a gavage accident and was not compound associated.

Bodyweights for the high and intermediate dose group dams were lower than controls from the beginning of gestation and also from the beginning of lactation. However, bodyweight gains over these periods were similar to controls indicating the reduced weights were attributable to prior treatment with glycolic acid before commencing the reproduction phase of the study. There were no indications that glycolic acid was selectively toxic to pregnant or lactating female rats. Mean body weight of P1 female rats in the 300 mg/kg/day and 600 mg/kg/day groups was generally lower than that of the control group. Those differences were statistically significant on gestation day 7 for the 300 mg/kg/day group and gestation days 7 through 18 for the 600 mg/kg/day group. Over the course of gestation, body weights of female rats that received 300 mg/kg/day and 600 mg/kg/day ranged from approximately 89% to 93% and 88% to 90% of control, respectively. There were no statistically significant differences in overall mean body weight gain for P1 female rats during gestation (days 0-21), suggesting that the lower mean body weights observed during gestation were likely due to pre-existing, body weight deficits established during the premating period. Therefore, glycolic acid was considered not to be selectively toxic to pregnant female rats.

There were no significant differences between treated and control females in relation to food consumption, food conversion efficiency or in the incidence of clinical signs. On lactation day 0, the mean body weight of P1 female rats in the 600 mg/kg/day group was lower than that of the control (statistically significant). However, the 600 mg/kg/day group had an overall body weight gain during the 21-day lactation period greater than that of the control group. Therefore, as with mean gestation body weight, the lower mean body weight at the beginning of the lactation period was likely due to preexisting body weight effects that occurred during the 90-day dosing period. Therefore, glycolic acid was considered not to be selectively toxic to lactating female rats. There were no toxicologically or statistically significant differences between treated and control females in regard to mating, fecundity, gestation indices, implantation efficiency or gestation length.

FOOD CONSUMPTION (PARENTAL ANIMALS): There were no statistically significant differences in mean food consumption or mean food efficiency of pregnant females.

There were no treatment related effects on the number of pups per litter, number of liveborn pups, the pup weight during lactation, pup survival during lactation or the incidence of clinical signs among pups.

ORGAN WEIGHTS (PARENTAL ANIMALS): Final body weights determined just prior to necropsy were used in the assessment of organ weight changes. There was a statistically significant increase in mean testes weight relative to body weight in the male rats in all dose groups (150, 300, 600 mg/kg/day) of the reproductive toxicity subset. There were no changes in absolute testes weight or testes weight relative to body weight. In addition, no compound-related microscopic changes were present in the testes of glycolic acid-exposed rats in the subchronic study. Therefore, the increase in testes weight relative to body weight in glycolic acid-exposed groups in the reproductive subset was attributed to decreased mean body weights at all three dose levels.

GROSS PATHOLOGY (PARENTAL ANIMALS): There were compound-related gross lesions in the kidneys of 4/10 high dose (600 mg/kg/day) male rats. These lesions included dilatation of the pelvis, calculus, chronic progressive nephropathy, and pale discoloration. Microscopically, these gross lesions correlated with oxalate crystal nephropathy similar to that diagnosed in the subchronic toxicity animals. There were no renal gross lesions in any of the other male groups. No compound-related gross observations were noted in the P1 females.

The NOEL for reproductive toxicity was 600 mg/kg bw/day, based on the absence of treatment related effects on reproductive function. The NOEL for reproductive organ pathology in both the P1 generation and the F1 weanlings was 600 mg/kg bw/day, based on the absence of gross pathological changes.
Dose descriptor:
LOAEL
Effect level:
> 600 mg/kg bw/day
Sex:
male/female
Basis for effect level:
other: highest dose tested
Dose descriptor:
NOAEL
Effect level:
600 mg/kg bw/day
Sex:
male/female
Basis for effect level:
other: Concerning reproductive organ pathology, based on the absence of gross pathological changes
Dose descriptor:
NOAEL
Effect level:
600 mg/kg bw/day
Sex:
male/female
Basis for effect level:
other: Concerning reproductive toxicity, based on the absence of treatment related effects on reproductive function
Clinical signs:
no effects observed
Mortality / viability:
no mortality observed
Body weight and weight changes:
no effects observed
Sexual maturation:
not specified
Organ weight findings including organ / body weight ratios:
no effects observed
Gross pathological findings:
no effects observed
Histopathological findings:
no effects observed
CLINICAL SIGNS (OFFSPRING): There were no statistically significant dose-related differences in the incidences of any clinical signs among F1 litters. There was no compound associated mortality in weanling males and females.

BODY WEIGHT (OFFSPRING): The mean pup weight of the F1 litters was not affected at any time during the 21-day lactation period.

GROSS PATHOLOGY: The gross lesion “dilatation of renal pelvis” was noted in a number of male and female weanlings. This is a common gross finding, and its occurrence was not dose-related. However, all kidneys with grossly observed dilatation of the pelvis were examined histologically since kidneys are a target organ for this compound (Anatomical Pathology Report, Rats Designated for Subchronic Toxicity Evaluations). Microscopically, all of these kidneys were typical of the immature kidneys found in this age animal. No compound-associated lesions (oxalate crystal nephropathy) as seen
in male rats from the subchronic toxicity study, were present in the kidneys of the weanlings. Based on the absence of a dose-response or correlative compound-related microscopic changes, dilatation of the renal pelvis in F1 weanlings was not considered compound related.

OTHER FINDINGS:
LITTER SIZE AND PUP SURVIVAL: There were spurious statistically significant trends in the number of pups born per litter and the number of pups born alive, resulting in statistical significance assigned to the 300 mg/kg/day and 600 mg/kg/day groups. However, the trend appeared to result from the disparity between the number of pups born to litters of 150 mg/kg/day compared to the 300 mg/kg/day and 600 mg/kg/day groups; the post-implantation loss observed in the 150 mg/kg/day group was not as great as that seen in the concurrent control and the other treated groups. The number of pups born and the number of pups born alive to the concurrent control group and the treated groups fell within our historical control data range (Mean Number of F1 Pups Born: 11.2-15.3; Mean Number of F1 Pups Born Alive: 10.2-15.2) and are not statistically significantly different by pair-wise analysis. In addition, with the removal of the 150 mg/kg/day group data from the analysis, there were no longer statistically significant trends for those parameters. Therefore, because of the absence of a true dose response, those differences in the number of pups born and the number of pups born alive were considered not to be compound related. From lactation day 4 through the end of the lactation period, the mean number of pups per litter in treated groups was comparable to that of the control group.
Dose descriptor:
LOAEL
Generation:
F1
Effect level:
> 600 mg/kg bw/day
Sex:
male/female
Basis for effect level:
other: highest dose tested
Dose descriptor:
NOAEL
Generation:
F1
Effect level:
600 mg/kg bw/day
Sex:
male/female
Basis for effect level:
other: Concerning reproductive organ pathology, based on the absence of gross pathological changes
Reproductive effects observed:
no

Exposure of male and female rats by gavage to glycolic acid in this one-generation reproduction study at doses of 150, 300, and 600 mg/kg/day did not cause any changes in organ weights or gross pathology of the reproductive system. There were compound-related effects in the kidneys of high dose male rats (600 mg/kg/day) which caused gross lesions in four animals and mortality in one of these animals. These findings were associated with oxalate crystal nephropathy similar to that noted in glycolic acid-exposed male rats in the subchronic study (Anatomical Pathology Report, Rats Designated for Subchronic Toxicity Evaluations). Under the conditions of this study, based on gross observations and organ weights, the NOEL for pathology of the reproduction organs of P1 male and female adults was 600 mg/kg/day. There were no compound-related mortality or gross observations in the F1 weanlings. Under the conditions of this study, the NOEL for pathology of male and female weanlings was the highest dose tested (600 mg/kg/day).

Conclusions:
The NOEL was based upon the absence of test-substance-related effects on reproductive function or on gross observations and organ weights of the reproduction organs of P1 male and female adults.

The NOEL for reproductive toxicity was 600 mg/kg bw/day, based on the absence of treatment related effects on reproductive function. The NOEL for reproductive organ pathology in both the P1 generation and the F1 weanlings was 600 mg/kg bw/day, based on the absence of gross pathological changes.
Executive summary:

A single generation reproductive toxicity study was conducted in which four groups of rats were dosed at various levels with glycolic acid. Males and females were pair housed for mating and the females observed through gestation and F1 and P generations observed during lactation.

The NOEL for reproductive toxicity was 600 mg/kg bw/day, based on the absence of treatment related effects on reproductive function. The NOEL for reproductive organ pathology in both the P1 generation and the F1 weanlings was 600 mg/kg bw/day, based on the absence of gross pathological changes.

Effect on fertility: via oral route
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
NOAEL
600 mg/kg bw/day
Study duration:
subchronic
Species:
rat
Effect on fertility: via inhalation route
Endpoint conclusion:
no study available
Effect on fertility: via dermal route
Endpoint conclusion:
no study available
Additional information

A single generation oral reproductive toxicity study was conducted in which four groups of rats were dosed at various levels with glycolic acid. Males and females were pair housed for mating and the females observed through gestation and F1 and P1 generations observed during lactation. The NOEL for reproductive toxicity was 600 mg/kg bw/day (the highest dose tested), based on the absence of treatment related effects on reproductive function. The NOEL for reproductive organ pathology in both the P1 generation and the F1 weanlings was 600 mg/kg bw/day (the highest dose tested), based on the absence of gross pathological change. The NOEL for this study is based on 100% glycolic acid dosed (adjusted for 70% purity of the test substance).

Effects on developmental toxicity

Description of key information

In rats, both maternal and developmental toxicity were observed at 300 and 600 mg/kg/day (oral exposure). The maternal and developmental no-observed-effect level (NOEL) was 150 mg/kg/day. Thus, the results of this study suggest that glycolic acid is not likely to be uniquely toxic to the rat conceptus.


In rabbits exposed to ethylene glycol no developmental effects were observed at doses as high as 2000 mg/kg/day, a dose that resulted in significant toxicity to the does.


Based on available mechanistic data, the rabbit model may be considered more relevant to extrapolate data to human risk assessment.

Link to relevant study records

Referenceopen allclose all

Endpoint:
developmental toxicity
Type of information:
experimental study
Adequacy of study:
key study
Study period:
Study initiated on 16 October 1995. Study completed on 20 June 1996.
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Reason / purpose for cross-reference:
reference to other study
Remarks:
Test doses in the present study determined after pilot study summarised in the cross-reference
Qualifier:
according to guideline
Guideline:
OECD Guideline 414 (Prenatal Developmental Toxicity Study)
Deviations:
no
Qualifier:
according to guideline
Guideline:
other: EU Directive 87/302/EEC (OJ No L133 31.5.88)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EPA OPP 83-3 (Prenatal Developmental Toxicity Study)
Deviations:
no
Qualifier:
according to guideline
Guideline:
other: MAFF NohSan 59, No. 4200.
Deviations:
no
GLP compliance:
yes
Limit test:
no
Specific details on test material used for the study:
99.6% purity.
Species:
rat
Strain:
other: Crl:CD.BR
Remarks:
The rat was selected to provide data in a rodent species. The Crl:CD BR strain was chosen because historical control data are available from the literature, the supplier, and previous studies at the laboratory.
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: Charles River Laboratories, Inc., Raleigh, North Carolina.
- Age at study initiation: Males were 77 days old on arrival and females were 63 days old on arrival.
- Weight at study initiation: Males weighed between 306.1 and 371.6 g on arrival and females weighed between 180.6 and 230.5 g on arrival.
- Fasting period before study: N/A
- Housing: The rats were housed individually in suspended, wire-mesh, stainless steel cages. Nesting material was not provided because the dams were euthanized prior to expected parturition.
- Diet (e.g. ad libitum): The rats were provided Purina Certified Rodent Chow@ #5002 (Meal) ad libitum.
- Water (e.g. ad libitum): The rats were supplied with tap water from United Water Delaware ad libitum.
- Acclimation period: All animals were quarantined for at least 6 days and then released for the study by the laboratory veterinarian.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 23 +/- 1°C.
- Humidity (%): 50 +/- 10%.
- Photoperiod (hrs dark / hrs light): 12 hours light, 12 hours dark with fluorescent lighting.

IN-LIFE DATES: From: 16 October 1995 (first day of dosing) To: 4 December 1995 (last fetal evaluation).
Route of administration:
oral: gavage
Vehicle:
water
Details on exposure:
PREPARATION OF DOSING SOLUTIONS: Solutions of the test material in deionized water were prepared weekly during the study and stored in the refrigerator. Sufficient amounts of solution needed for dose administration were removed from the refrigerated containers daily.
Glycolic acid was administered by gavage because the oral route is a potential route of accidental human exposure. The dose volume was 10 mL/kg and individual dosages were based on the most recently recorded body weights.
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Samples (-30 mL each) of each test solution were taken three times during the study: October 16, October 30, and November 6, 1995. Analysis of the first sampling addressed concentration and stability. For the second and third samplings, analyses addressed concentration. Samples were submitted to the Analytical Group of Environmental Sciences (ES) at Haskell Laboratory.

At the first sampling, two samples from the vehicle and each test solution were collected. One set of samples was submitted and analysed shortly after submission and the remaining samples were refrigerated for 7 days and then analysed for stability. At the second and third samplings, one sample of the vehicle and each test solution were analysed shortly after submission, to verify concentration. Analysis of glycolic acid in dosing formulations was conducted according to the following method.

Aliquots of the supplied dosing samples were pipetted into a beaker containing phenyl violet indicator/ice slurry. The volume of the aliquots varied based on the concentration of the supplied dosing samples. Targeted concentrations were 75 or 150 mg of glycolic acid for each titration. The aliquots were titrated with a standardised volumetric sodium hydroxide solution (0.251N - Baker Chemical) to the free acid equivalence point of the 99% glycolic acid. All glycolic acid samples were analysed the day they were prepared and submitted.
Details on mating procedure:
- Impregnation procedure: cohoused.
- M/F ratio per cage: 1:1.
- Length of cohabitation: until copulation was confirmed. Mating began on October 9, 1995, with Gestational Day (GD) 1 occurring from October 10-13, 1995 and October 16-19, 1995.
- Proof of pregnancy: presence of a copulation plug in the vagina or on the cage board referred to as day 1 of gestation.
Duration of treatment / exposure:
On days 7-21 of gestation (14 days). Females were euthanized on gestation day 22.
Frequency of treatment:
daily
Duration of test:
14 days
Dose / conc.:
600 mg/kg bw/day (nominal)
Dose / conc.:
300 mg/kg bw/day (nominal)
Dose / conc.:
150 mg/kg bw/day (nominal)
Dose / conc.:
75 mg/kg bw/day (nominal)
No. of animals per sex per dose:
25 females
Control animals:
yes, concurrent vehicle
Details on study design:
- Dose selection rationale: Dose concentrations were based on the results of a rat pilot developmental toxicity study. In the pilot study, test concentrations of 70% technical solution were administered to groups of 8 bred rats over gestational days 7-21. Dose concentrations were 0, 125, 250, 500, and 1000 mg/kg bw. Maternal toxicity was demonstrated at 500 and 1000 mg/kg bw/day. At 1000 mg/kg bw/day, maternal effects included mortality, significantly reduced maternal body weights, weight changes and reduced food consumption. Dose-related increases of the following clinical observations were observed: abnormal gait and mobility, lung noise, salivation, stained and wet fur. At 500 mg/kg bw/day, similar, yet markedly less severe evidence of maternal toxicity was demonstrated and there was a slight but significant reduction in maternal weight gain. The incidences of lung noise and wet fur were significantly increased as well. Developmental toxicity was evident at 500 and 1000 mg/kg bw/day. At 1000 mg/kg bw/day, mean foetal weight was significantly reduced. Embryolethality was significantly increased and among the surviving foetuses, malformations and variations were significantly increased. At 500 mg/kg bw/day, the significant reduction in foetal weight persisted as did the increase in foetal variations. There was no evidence of either maternal or developmental toxicity at 250 or 125 mg/kg bw/day.

- Rationale for animal assignment (if not random): Before dosing began, females selected for the study that copulated during the first week of mating were ranked by their body weights on gestational day 1 and randomly assigned to control or experimental groups. Females selected from the second week of mating were similarly assigned. The randomization resulted in a distribution in which the mean body weights for all groups were not statistically different (p=0.9744). In addition to random assignment to groups, bias was controlled by coding all females prior to scheduled sacrifice. They remained coded during the collection of the post-mortem and foetal data.
Maternal examinations:
CAGE SIDE OBSERVATIONS / DETAILED CLINICAL OBSERVATIONS: Yes
- Observations for morbidity and mortality were made daily.
- Individual clinical signs were recorded each morning on Days 1-22G and each afternoon on Days 7-21G (the dosing period).

BODY WEIGHT: Yes
- Time schedule for examinations: Females were weighed on Days 1 and 7-22G.

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study): Yes
- Food was weighed on Days 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21 and 22G.
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: No data

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day 22
- Organs examined: the organs of the thoracic and abdominal cavities were examined for gross pathologic changes.
Ovaries and uterine content:
The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: Yes
- Number of corpora lutea: Yes
- Number of implantations: Yes
- Number of early resorptions: Yes
- Number of late resorptions: Yes
- Other:
- the types of implants (live and dead foetuses, and resorptions) were counted and their relative positions were recorded.
- the empty uterus was weighed.
Fetal examinations:
Live foetuses were weighed, sexed, and examined for external alterations.

To identify stunted foetuses for each litter, the maximum stunted weight (MSW) was calculated by subtracting the lightest weight from the total weight, dividing by the remaining number of foetuses, and multiplying by 0.666. A foetus weighing less than or equal to the MSW was considered stunted. If the lightest foetus was determined to be stunted, the procedure was repeated until all remaining foetal weights were in excess of the MSW.

Retarded renal development was classified using the schema of Woo and Hoar.

- External examinations: Yes: all per litter.
- Soft tissue examinations: Yes: half per litter. The first live foetus and thereafter each alternate one removed subsequently was decapitated and examined for visceral alterations.
- Skeletal examinations: Yes: all per litter. All foetuses were fixed, stained (Alizarin red S) and examined for skeletal alterations.
- Head examinations: Yes: all per litter.
Statistics:
Sequential trend testing was applied to the developmental toxicity data for each parameter as listed below. If a significant dose-response was detected, data from the top dose group was excluded and the test repeated until no significant trend was detected. For litter parameters, the proportion of affected foetuses per litter or the litter mean was the experimental unit for statistical evaluation. The level of significance selected was p<0.5. Where the data were tied and the standard large sample version of Jonckheere's test was not applicable, exact p values were calculated using permutation methodology.

Maternal weight, weight changes and food consumption: Linear contrast of means from ANOVA.

Live foetuses, dead foetuses, resorptions, nidations, copora lutea, incidence of foetal alterations: Jonckheere's test.

Incidence of pregnancy, clinical observations, maternal mortality, females with total resorptions early deliveries: Cochran-Armitage test.

Foetal weight, sex ratio: Linear contrast of least square means from ANCOVA.
Indices:
N/A
Historical control data:
N/A
Clinical signs:
effects observed, treatment-related
Description (incidence and severity):
At 600 mg/kg bw/day, there were significantly increased incidences of adverse clinical observations; abnormal gait/mobility was observed in 5 of 25 dams at this level. Lung noise (wheezing and/or rattling after dosing which persisted into the afternoon and occasionally until the following day) and/or irregular respiration was seen in 8 of 25 dams. Two dams were lethargic. Lung noise similar to that observed at 600 mg/kg was observed in 2 of 25 dams dosed at 300 mg/kg. This incidence approached statistical significance (p=0.0553). No remarkable clinical observations were observed at 150 or 75 mg/kg bw/day.
Mortality:
no mortality observed
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
Maternal body weights and weight changes were reduced at 600 mg/kg bw/day. Final body weight (Day 22G) and the final weight adjusted for the products of conception were significantly reduced. Statistically significant reductions in body weight changes were observed over Days 7-9,17-19, 19-21,21-22, and 7-22G. Weight changes calculated using the adjusted final body weight (final body weight minus the products of conception) were also significantly reduced (Days 7-22 and 1-22G). Maternal body weights, weight changes, and adjusted final body weights were unaffected at dose levels of 300 mg/kg bw/day and lower.
Food consumption and compound intake (if feeding study):
effects observed, treatment-related
Description (incidence and severity):
Maternal food consumption was significantly reduced at 600 mg/kg bw/day over Days 21-22G. Maternal food consumption was unaffected at dose levels of 300 mg/kg bw/day and lower.
Food efficiency:
not examined
Ophthalmological findings:
not examined
Haematological findings:
not examined
Clinical biochemistry findings:
not examined
Endocrine findings:
not examined
Urinalysis findings:
not examined
Behaviour (functional findings):
not examined
Immunological findings:
not examined
Organ weight findings including organ / body weight ratios:
not examined
Gross pathological findings:
no effects observed
Description (incidence and severity):
There were no significant post-mortem findings at any dose level.
Neuropathological findings:
not examined
Histopathological findings: non-neoplastic:
not examined
Histopathological findings: neoplastic:
not examined
Number of abortions:
not specified
Pre- and post-implantation loss:
no effects observed
Total litter losses by resorption:
no effects observed
Early or late resorptions:
no effects observed
Dead fetuses:
no effects observed
Changes in pregnancy duration:
not specified
Changes in number of pregnant:
not specified
Other effects:
no effects observed
Description (incidence and severity):
There were no dose-related effects on reproductive outcome parameters: dams with total resorptions, mean corpora lutea, mean number of implantations, litter size or sex ratio.
Details on maternal toxic effects:
N/A
Dose descriptor:
LOAEL
Effect level:
300 mg/kg bw/day
Basis for effect level:
other: maternal toxicity
Dose descriptor:
NOEL
Effect level:
150 mg/kg bw/day
Basis for effect level:
other: maternal toxicity
Abnormalities:
no effects observed
Fetal body weight changes:
effects observed, treatment-related
Description (incidence and severity):
Mean foetal weight was significantly reduced at 600 mg/kg bw/day.
Reduction in number of live offspring:
not specified
Changes in sex ratio:
not specified
Changes in litter size and weights:
not specified
Anogenital distance of all rodent fetuses:
not examined
Changes in postnatal survival:
not specified
External malformations:
not specified
Skeletal malformations:
effects observed, treatment-related
Description (incidence and severity):
The incidence of specific malformations was significantly increased at 600 mg/kg/day. These malformations were fused and absent ribs, fused and hemivertebra, and abnormally fused and cleft/non-fused sternebra. At 300 mg/kg, there was a slight increase in the incidence of two skeletal malformations, fused ribs and fused vertebra. The incidences for these findings, 2 foetuses from 2 litters, approached statistical significance (p=0.0555). There were no compound-related malformations at 150 or 75 mg/kg. The incidence of variations was increased at 600 mg/kg bw/day. The specific variations were misaligned and incompletely ossified sternebra and incompletely ossified vertebra. There were no increased foetal variations at 300 mg/kg bw/day and lower.
Visceral malformations:
not specified
Details on embryotoxic / teratogenic effects:
N/A
Dose descriptor:
LOAEL
Effect level:
300 mg/kg bw/day
Basis for effect level:
other: embryotoxicity & teratogenicity
Key result
Dose descriptor:
NOEL
Effect level:
150 mg/kg bw/day
Basis for effect level:
other: embryotoxicity & teratogenicity
Abnormalities:
not specified
Developmental effects observed:
yes
Lowest effective dose / conc.:
300 mg/kg bw/day (nominal)
Treatment related:
yes
Relation to maternal toxicity:
not specified
Dose response relationship:
not specified
Relevant for humans:
not specified

Table 6.8.1-01a   Summary of reproductive outcomes

Dose
(mg/kg bw/day)

0

75

150

300

600

Corpora lutea
 (mean /litter)

16.3

16.3

15.8

17.4

17.0

Implantations
 (mean /litter)

15.4

15.0

14.7

15.3

15.9

Total number of resorptions
 (mean /litter)

0.7

0.8

0.7

0.6

0.6

Total number of foetuses
 (mean /litter)

14.6

14.2

14.0

14.7

15.3

Total number of live foetuses
 (mean /litter)

14.6

14.2

14.0

14.7

15.3

Mean foetal weight

5.02

5.20

5.17

5.05

4.38

Sex ratio
 (No. of male foetuses /No. live foetuses)

0.44

0.49

0.50

0.50

0.48

Table 6.8.1-01b   Summary of skeletal anomalies

Dose
(mg/kg bw/day)

0

75

150

300

600

Skeletal examination
number examined (No. of litters)

366  (25)

354  (25)

321  (23)

339  (23)

351  (23)

Fused rib  (No. of litters)

0  (0)

0  (0)

0  (0)

2  (2)

9  (9)

Absent ribs  (No. of litters)

0  (0)

0  (0)

0  (0)

0  (0)

3  (3)

Fused vertebra  (No. of litters)

0  (0)

0  (0)

0  (0)

2  (2)

6  (6)

Hemi-vertebra  (No. of litters)

0  (0)

1  (1)

0  (0)

1  (1)

8  (8)

Abnormally fused sternebra 
(No. of litters)

0  (0)

0  (0)

0  (0)

0  (0)

3  (3)

Cleft/non-fused sternebra
(No. of litters)

1  (1)

0  (0)

0  (0)

1  (1)

6  (5)

Misaligned sternebra
(No. of litters)

1  (1)

1  (1)

0  (0)

1  (1)

13  (9)

Incompletely ossified sternebra
(No. of litters)

14  (6)

4  (2)

13  (2)

12  (3)

60  (14)

Incompletely ossified vertebra
(No. of litters)

95  (19)

119  (21)

68  (17)

114  (22)

204  (21)

Conclusions:
There was no evidence of either maternal or developmental toxicity at either 150 or 75 mg/kg bw/day. Thus, the maternal and developmental no-observed-effect level (NOEL) was 150 mg/kg bw/day. Therefore, the results indicate that glycolic acid is not likely to be uniquely toxic to the rat conceptus, developmental effects were only apparent at maternally toxic doses.
Executive summary:

Glycolic acid was administered by gavage to groups of 25 Crl:CD BR female rats on days 7-21 of gestation at daily dose levels of 0, 75, 150, 300, or 600 mg/kg.


Compound-related, adverse maternal and developmental toxicity was observed at 600 mg/kg. Maternal effects included significant reductions in maternal weight changes, body weights, and food consumption. Adverse clinical observations were significantly increased at this level as well as included abnormal gait/staggering, lung noise (wheezing and/or rattling), irregular respiration, and lethargy. There were no remarkable post-mortem findings in the dams. Developmental toxicity was evident at this level as well as significantly reduced mean fetal weight and a significant increase in the incidence of fetal malformations and variations.


Marginal evidence was detected at 300 mg/kg bw/day. Regarding maternal toxicity, lung noise similar to that observed at 600 mg/kg bw/day was observed in 2 of 25 dams (p=0.0553). Developmental toxicity was evident only as a slight but not statistically significant (p=0.0555) increase in the incidence of skeletal malformations. No other maternal or developmental parameters were affected.


There was no evidence of either maternal or developmental toxicity at either 150 or 75 mg/kg bw/day. Thus, the maternal and developmental no-observed-effect level (NOEL) was 150 mg/kg bw/day. Therefore, the results indicate that glycolic acid is not likely to be uniquely toxic to the rat conceptus, developmental effects were only apparent at maternally toxic doses.

Endpoint:
developmental toxicity
Type of information:
experimental study
Adequacy of study:
key study
Study period:
N/A. Article submitted for publication on 21 August 1992.
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 414 (Prenatal Developmental Toxicity Study)
Deviations:
yes
Remarks:
Kidneys from 10 randomly selected does from the control through 1000 mg/kg and all kidneys from the 2000 mg/kg group and those that died during the study were evaluated histologically.
GLP compliance:
not specified
Limit test:
no
Specific details on test material used for the study:
Ethylene glycol, obtained through Southern Research Institute (Birmingham, AL), was determined to be 98% pure by packed column gas chromatography.
Species:
rabbit
Strain:
New Zealand White
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: Hazleton Research Products, Inc. (Denver, PA).
- Age at study initiation: approximately 5 months old.
- Weight at study initiation: 2470 - 4460 g on gestation day 0.
- Fasting period before study: None.
- Housing: individually in stainless steel cages with mesh flooring.
- Diet (e.g. ad libitum): certified rabbit chow ad libitum.
- Water (e.g. ad libitum): deionized/filtered water ad libitum.
- Acclimation period: 14 days quarantine.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): mean of 67.3°F (range of 62.9 - 75.5°F).
- Humidity (%): mean of 54.1% (range of 26.8 - 81.9%).
- Air changes (per hr): Not reported.
- Photoperiod (hrs dark / hrs light): animal lights were on from 0700 to 1900 for females and 0700 to 2100 for males.
Route of administration:
oral: gavage
Vehicle:
water
Remarks:
deionized/distilled
Details on exposure:
A dose volume of 5 mL/kg bw was used for all groups. The volume administered was adjusted according to daily body weights.
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Analyses of the dosing formulations indicated that they were homogeneous and stable for at least 3 weeks. All formulations were 93.0 - 107.0% of theoretical for pre-dosing analyses; for the post-dosing analyses, all formulations were 92.6 - 109.0% of the pre-dosing measured concentrations.
Details on mating procedure:
Females were artificially inseminated. To induce ovulation, females received an intravenous injection of Pregnyl (0.1 mL/kg) immediately prior to insemination. The day of insemination was designated as Gestational Day (GD) 0. Male breeders of the same strain from the RTI breeding colony were originally from the same supplier as the females.
Duration of treatment / exposure:
Gestation Day 6-19
Frequency of treatment:
daily
Duration of test:
14 days
Dose / conc.:
100 mg/kg bw/day
Dose / conc.:
500 mg/kg bw/day
Dose / conc.:
1 000 mg/kg bw/day
Dose / conc.:
2 000 mg/kg bw/day
No. of animals per sex per dose:
24 inseminated females/dose (23 inseminated control females).
The study was performed in two replicates (11-12 inseminated females per dose per replicate) with two consecutive breeding days in each replicate. The last breeding date for the first replicate and the first breeding date for the second replicate were 5 weeks apart.
Control animals:
yes, concurrent vehicle
Details on study design:
- Dose selection rationale: The doses chosen were based on preliminary studies with non-pregnant rabbits and information from rodents which indicated developmental effects at much lower doses than maternal toxicity.
- Rationale for animal assignment (if not random): females were assigned to dose groups by stratified randomization on gestation day 0 so that body weights did not differ among groups within any individual replicate.
Maternal examinations:
CAGE SIDE OBSERVATIONS: Yes.
- Time schedule: daily throughout gestation, GD 0 - 30.

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: daily throughout gestation, GD 0 - 30.

BODY WEIGHT: Yes
- Time schedule for examinations: Gestation days 0, 6-19, 25, and 30.

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study): No data

WATER CONSUMPTION AND COMPOUND INTAKE: Yes
- Time schedule for examinations: Gestation Days 0-30.

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day 30
- Organs examined: Maternal liver and kidneys were weighed. Kidneys were bisected and fixed in 10% neutral buffered formalin. Kidneys from 10 randomly selected does from the control through the 1000 mg/kg bw/day groups and all the kidneys from the 2000 mg/kg bw/day group as well as kidneys from all does which died during the study, were sectioned, stained with haematoxylin/eosin, and evaluated histologically. The sections were also examined under polarized light for oxalate crystals.
Ovaries and uterine content:
The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: Yes
- Number of corpora lutea: Yes
- Number of implantations: Yes
- Number of early resorptions: Yes
- Number of late resorptions: No data
Blood sampling:
N/A
Fetal examinations:
- External examinations: Yes: all per litter.
- Soft tissue examinations: Yes: all per litter
- Skeletal examinations: Yes: all per litter
- Head examinations: Yes: half per litter
- Anogenital distance of all live rodent pups: N/A
Statistics:
Analyses were performed using the doe or the litter as the experimental units. General Linear Trend Models (GLM) procedures were applied for the analysis of variance (ANOVA) of maternal and foetal parameters. Prior to GLM analysis, an arcsine-square root transformation was performed on all litter-derived percentage data, and Bartlett’s test for homogeneity of variance was performed on all data to be analysed by ANOVA. GLM analysis determined the significance of dose-response relationships and the significance of dose effects, replicate effects, and dose x replicate interactions. When ANOVA revealed a significant (p<0.05) dose effect, Williams’ and Dunnett’s multiple comparison tests were used to compare treated groups to the control group. One-tailed tests were used for all pairwise comparisons except for maternal body and organ weights, water consumption, foetal body weight, and percentage males per litter, which were analysed by two-tailed tests. Nonsignificant (p>0.05) dose x replicate effects on selected foetal parametric measures were considered justification for pooling data across replicates for nonparametric analysis in related measures. There were no significant (p<0.05) dose x replicate interactions for any parameters examined in the study. Nominal scale measures were analysed by a xi-square test for independence and by a test for linear trend on proportions. When a xi-square test showed significant group differences, a one-tailed Fisher’s exact probability test was used for pairwise comparisons of treatment and control groups.
Indices:
N/A
Historical control data:
N/A
Clinical signs:
no effects observed
Mortality:
mortality observed, treatment-related
Description (incidence):
42.1% mortality (8 of 17 pregnant animals) was observed at 2000 mg/kg bw/day. One doe died on GD 9, two does died on GD 11 and one doe died on each one of GD 13, 14, 19, 21, and 25.
Body weight and weight changes:
no effects observed
Description (incidence and severity):
Periodic maternal body weights and weight changes were statistically equivalent across all groups for all intervals evaluated.
There were no significant effects of treatment on corrected (for uterine weight) maternal gestational weight change.
Food consumption and compound intake (if feeding study):
not examined
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
effects observed, non-treatment-related
Description (incidence and severity):
Water consumption, expressed as g/animal/day, was statistically equivalent across all groups for all intervals, although water consumption appeared slightly increased for all test substance-treated groups during the treatment period but not in a manner related to dose.
Ophthalmological findings:
not examined
Haematological findings:
not examined
Clinical biochemistry findings:
not examined
Endocrine findings:
not examined
Urinalysis findings:
not examined
Behaviour (functional findings):
not examined
Immunological findings:
not examined
Organ weight findings including organ / body weight ratios:
effects observed, non-treatment-related
Description (incidence and severity):
There were no significant effects of treatment on liver or kidney weight at any dose. However, maternal absolute kidney weight (but not relative weight) was slightly increased at 2000 mg/kg/day to 106.3% of the control value for the right kidney (left kidney value was 107.6% of control data).
Gross pathological findings:
no effects observed
Description (incidence and severity):
No effects were observed on liver.
Neuropathological findings:
not examined
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Description (incidence and severity):
Histologic evaluation of maternal kidneys revealed treatment-related renal lesions only at 2000 mg/kg/day. The lesions were limited to the cortical renal tubules and included intraluminal crystals (appearance consistent with oxalate), epithelial necrosis, and tubular dilatation and degeneration. The most severe findings, crystals (designated “marked”) and necrosis, were observed in the does which died on study, but the renal tubular necrosis observed in these animals was not a post-mortem event. The cause of death in these animals was determined to be renal failure.
Histopathological findings: neoplastic:
not examined
Number of abortions:
effects observed, treatment-related
Description (incidence and severity):
One doe at 2000 m/gkg/day aborted on GD20. No litters were aborted at any other doses. Increases in early abortions are usually considered indicative of maternal stress in rabbits.
Pre- and post-implantation loss:
no effects observed
Total litter losses by resorption:
no effects observed
Early or late resorptions:
no effects observed
Description (incidence and severity):
There were no statistically significant or biologically relevant differences among groups for prenatal mortality, expressed as resorptions.
Dead fetuses:
no effects observed
Description (incidence and severity):
There were no statistically significant or biologically relevant differences among groups for prenatal mortality, expressed as dead foetuses.
Changes in pregnancy duration:
effects observed, treatment-related
Description (incidence and severity):
An increase in early deliveries with three at 2000 mg/kg (and one each at all other doses) was observed. Increases in early deliveries are usually considered indicative of maternal stress in rabbits.
Changes in number of pregnant:
no effects observed
Description (incidence and severity):
Pregnancy rate was high and equivalent across all groups from 0 to 1000 mg/kg/day (95.5, 95.7, 91.3, and 95.2%, respectively); pregnancy rate as slightly lower (81.8%) at 2000 mg/kg/day.
Other effects:
effects observed, non-treatment-related
Description (incidence and severity):
There were no significant effects of treatment on gravid uterine weight.
There were no treatment-related effects on any gestational parameters, including no effects on number of ovarian corpora lutea, or on total non-live or live implantation sites per litter.

There was a statistically significant increase in the number of corpora lutea at 500 mg/kg bw/day associated, as expected, with a slight increase in the number of implantation sites/litter and a slight increase in live litter size. This finding was not observed at higher doses and is considered most likely due to biologic variation. The values at 500 mg/kg/day are still well within historical control values for these parameters in the testing laboratory.
Key result
Dose descriptor:
NOAEL
Effect level:
1 000 mg/kg bw/day
Based on:
test mat.
Basis for effect level:
histopathology: non-neoplastic
maternal abnormalities
mortality
Fetal body weight changes:
no effects observed
Description (incidence and severity):
There were no statistically significant or biologically relevant differences among groups for prenatal toxicity, expressed as foetal body weight/litter for all foetuses or for male and female foetuses separately.
Reduction in number of live offspring:
no effects observed
Changes in sex ratio:
no effects observed
Changes in litter size and weights:
not specified
Anogenital distance of all rodent fetuses:
not examined
Changes in postnatal survival:
not specified
External malformations:
no effects observed
Skeletal malformations:
no effects observed
Visceral malformations:
no effects observed
Key result
Dose descriptor:
NOAEL
Effect level:
>= 2 000 mg/kg bw/day
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: highest dose tested
Abnormalities:
no effects observed
Key result
Developmental effects observed:
no
Conclusions:
NOAEL (maternal): 1000 mg//kg bw/day.
NOAEL (developmental): 2000 mg/kg bw/day (highest dose tested).
The doses causing maternal toxicity (maternal acidosis and hyperosmolarity) apparently did not produce any foetal effects in rabbits.
The rabbit conceptus is less sensitive to EG than the rodent.
Executive summary:

Artificially inseminated New Zealand White rabbits were exposed to ethylene glycol (EG) via gavage at doses of 0, 100, 500, 1000, or 2000 mg/kg/day on gestation days (GD) 0-19. The day of insemination was defined as gestation day 0. The doses chosen were based on preliminary studies with non-pregnant rabbits and information from rodents which indicated developmental effects at much lower doses than maternal toxicity. During the in-life portion of the study, body weights, water consumption, and clinical observations were collected. Body weights and maternal water consumption were measured during the study. All surviving does were killed on GD30. Gross necropsy included and examination and description of uterine contents, including counts of corpora lutea, implantation sites, and resorptions. The maternal liver, kidneys, and intact uterus were weighed, and maternal kidneys were examined histologically. Live foetuses were dissected from the uterus and euthanized. They were weighed, sex determined, and examined for external, visceral, head, and skeletal abnormalities.


Maternal toxicity was observed at 2000 mg/kg/day, expressed as 42.1% mortality, as well as an increase in early deliveries. Additionally, one doe at 2000 mg/kg aborted on GD 20. Increases in early deliveries and abortion are usually considered indicative of maternal stress sin rabbits. Pregnancy rate was high and equivalent across all groups from 0 to 1000 mg/kg/day; pregnancy rate was slightly lower at 2000 mg/kg/day. No effects were observed in maternal body weights, body weight changes, water consumption, or clinical signs of toxicity. No significant effects of treatment were observed on corrected maternal gestational weight change, gravid uterine weight, liver weight, or kidney weight. However, maternal absolute kidney, but not relative weight, was slightly increased at 2000 mg/kg. Treatment-related effects were observed histologically as renal lesions at 2000 mg/kg. The lesions were limited to the cortical renal tubules and included intraluminal crystals (appearance consistent with oxalate), epithelial necrosis, and tubular dilation and degeneration. There were no treatment-related effects on any gestational parameters, including corpora lutea, total implantation sites/litter, or pre- or post-implantation loss. There was a statistically significant increase in the number of corpora lutea at 500 mg/kg/day associated with a slight increase in the number of implantation sites/litter and a slight increase in litter size. The finding was considered due to biologic variation as it was not observed at higher doses.


Based on maternal mortality, increases in early deliveries and abortions, and histologic effects in the kidney, the maternal NOAEL is 1000 mg/kg bw/day. The developmental NOAEL is 2000 mg/kg bw/day, the highest dose tested.

Effect on developmental toxicity: via oral route
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
NOAEL
2 000 mg/kg bw/day
Study duration:
subacute
Species:
rabbit
Effect on developmental toxicity: via inhalation route
Endpoint conclusion:
no study available
Effect on developmental toxicity: via dermal route
Endpoint conclusion:
no study available
Additional information

Glycolic acid (crystalline, 99.6% pure) was given by gavage to groups of 25 Crl:CD®BR female rats on days 7-21 of gestation at daily dose levels of 75, 150, 300, or 600 mg/kg. Compound-related, adverse maternal and developmental toxicity was seen at 600 mg/kg. Maternal effects included significant reductions in maternal weight changes, body weights, and food consumption. Adverse clinical observations were significantly increased at this level as well, and included abnormal gait/staggering, lung noise (wheezing and/or rattling), irregular respiration, and lethargy. There were no remarkable post-mortem findings in the dams. Developmental toxicity was evident at this level as significantly reduced mean foetal weight and a significant increase in the incidence of foetal malformations and variations. Marginal evidence of both maternal and developmental toxicity was detected at 300 mg/kg. Regarding maternal toxicity, lung noise similar to that seen at 600 mg/kg was seen in 2/25 dams. Developmental toxicity was evident only as a slight, but not statistically significant, increase in the incidence of skeletal malformations. No other maternal or developmental parameters were affected. There was no evidence of maternal or developmental toxicity at either 75 or 150 mg/kg. The maternal and developmental no-observed effect level (NOEL) was 150 mg/kg/day. Thus, glycolic acid is not likely to be uniquely toxic to the rat conceptus, developmental effects were only apparent at maternally toxic doses.


Tyl et al. (1993) performed a developmental toxicity study essentially equivalent to OECD 414. In this study, pregnant New Zealand white rabbits were exposed to ethylene glycol by oral gavage as dose levels of 0, 100, 500, 1000, or 2000 mg/kg/day on gestation days 6 – 19. At the high dose of 2000 mg/kg, there was 42% mortality due to kidney failure. At necropsy intraluminal crystals were observed whose appearance was consistent with calcium oxalate crystals. Lesions in the cortical renal tubules, epithelial necrosis, and tubular degeneration was also observed. This damage is consistent with calcium oxalate precipitation resulting from concentrations of oxalic acid in excess of its solubility in the kidney. Oxalic acid is a metabolite of glycolic acid, which is itself a metabolite of ethylene glycol. Therefore, the presence of high concentrations of oxalic acid in the kidneys provides strong evidence that the animals were exposed to glycolic acid in situ. There were no developmental effects observed, even at 2000 mg/kg/day, a dose that resulted in significant system toxicity in the dams (42% lethality).


 


Ethylene glycol is facilely converted to glycolic acid through glycoaldehyde. This metabolic step is rapid but follows Michaelis-Menten kinetics, meaning it is saturable at high concentrations. Glycolic acid is further metabolized to glyoxylic acid, which in turn may be metabolized to the endogenous amino acid glycine (the primary metabolic pathway) or to oxalic acid. Glycine may be incorporated into proteins or utilized to generate energy via the citric acid cycle. Oxalic acid is excreted in the urine without additional metabolism.


 


The formation of glycolic acid following exposure to ethylene glycol has been proposed as the toxicological significant event resulting in developmental toxicity (see, for example, Carney et al., 1999).


 


There are significant differences in glycolic acid distribution between rats and rabbits. In rats, the embryo:maternal blood ratio was approximately 2 (i.e., the concentration in the embryo was 150% higher relative the maternal blood). In contrast, the rabbit embryo:maternal blood ratio was 0.3 (the concentration in the embryo was 30% lower than the maternal blood). The rabbit actively excludes glycolic acid from the embryo (Carney et al. 2011 and 2008).


 


Ellis-Hutchings et al. (2014) determined that glycolic acid was actively transported into the rat embryo rather than being solely mediated by diffusion. The monocarboxylate transporter (MCT) protein family matches the characteristics of the glycolic acid transporter.


 


Members of the MCT family are present in the placenta of humans, rodents, and rabbits and are believed to mediate the transfer of lactic acid between the maternal and embryonic compartments. There are significant differences between species in the subcellular location and orientation of MCT. Nagai et al. (2010) examined the mouse placenta during gestation and showed that MCT1, which is a high-affinity transporter, is localized in the apical membrane of the synctytiotrophoblast facing the maternal blood. MCT4, a low-affinity transporter, is localized in the basal plasma membrane close to the embryofoetal blood. A similar partitioning of MCT1 and MCT4 was also identified in the CD rat placenta (Moore, et al., 2016). This polarity is reversed in the placenta of non-rodent species, including humans (Settle et al., 2004) (Moore et al. (2016)).


 


This results in a high concentration of glycolic acid (relative to the maternal blood) in the rat and mouse embryo but a low concentration in the rabbit and human embryo. This difference in MCT polarity underlies the differences in maternal-embryonal disposition and response to glycolic acid observed in rats and rabbits.


 


Hence, the rabbit seems to be a more appropriate model than the rodent for human risk assessment.


 


Physiological Based Pharmacokinetic (PBPK) modeling allows the prediction of chemical concentrations in blood. There is a fully validated PBPK model for ethylene glycol in rats and humans. In its most recent published form (Corely et al., 2011), this very sophisticated model incorporates metabolism of ethylene glycol to glycolic acid and glycolic acid to glyocylic acid and oxalic acid. Thus, this model can predict potential precipitation of calcium oxalate in the kidneys, an effect that leads to the kidney damage associated with high dose ethylene glycol exposure in mammals. This model is capable of predicting blood concentrations following oral, inhalation, dermal, intravenous, and subcutaneous exposure in both rats and humans and is validated with measured blood concentration data.


 


The effect benchmark was determined by Carney et al., (2011) as 2 mM glycolic acid in blood.


 


Using this model demonstrates that the human dose required to exceed a 2 mM threshold is approximately 1500 mg/kg. For a 60 kg female, that would correspond to consumption of nearly 100 grams of glycolic acid.


 


The PBPK model can also predict blood concentrations following exposure at the General Population Systemic Long-Term Exposure DNEL of 0.75 mg/kg/day. When this exposure is modeled, the maximum achieved blood concentration is less than 0.001 mM, a value 2000 times lower than the threshold value.


 


References


Carney EW, Freshour NL, Dittenber DA, Dryzga MD. (1999). Ethylene glycol developmental toxicity: unravelling the roles of glycolic acid and metabolic acidosis. Toxicol Sci 50:117–26.


Carney EW, Tornesi B, Markham DA, Rasoulpour RJ, Moore NP. (2008). Species-specificity of ethylene glycol-induced developmental toxicity: toxicokinetic and whole embryo culture studies in the rabbit. Birth Defects Res B 83:573–81.


Carney EW, Tornesi B, Liberacki AB, Markham DA, Weitz KK, Luders TM, Studniski KG, Blessing JC, Gies RA, Corley RA. (2011). The impact of dose rate on ethylene glycol developmental toxicity and pharmacokinetics in pregnant CD rats. Toxicol Sci 119:178–88.


Corley RA, Bartels MJ, Carney EW, Weitz KK, Soelberg JJ, Gies RA, Thrall KD. (2005). Development of a physiologically based pharmacokinetic model for ethylene glycol and its metabolite, glycolic Acid, in rats and humans. Toxicol Sci 85:476–90.


Corley RA, Saghir SA, Bartels MJ, Hansen SC, Creim J, McMartin KE, Snellings WM. (2011). Extension of a PBPK model for ethylene glycol and glycolic acid to include the competitive formation and clearance of metabolites associated with kidney toxicity in rats and humans. Toxicol Appl Pharmacol. 250:229-244.


Ellis-Hutchings RG, Moore NP, Marshall VA, Rasoulpour RJ, Carney EW. (2014). Disposition of glycolic acid into rat and rabbit embryos in vitro. Reprod Toxicol 46:46–55.


Moore NP, Picut CA, Charlap JH. (2016). Localisation of lactate transporters in rat and rabbit placentae. Int J Cell Biol 2016:208452


Nagai A, Takebe K, Nio-Kobayashi J, Takahashi-Iwanaga H, Iwanaga T. (2010). Cellular expression of the monocarboxylate transporter (MCT) family in the placenta of mice. Placenta 31:126–33.


Settle P, Mynett K, Speake P, Champion E, Doughty IM, Sibley CP, D'Souza SW, Glazier J. (2004). Polarized lactate transporter activity and expression in the syncytiotrophoblast of the term human placenta. Placenta 25:496–504.


Tyl RW, Price CJ, Marr MC, Myers CB, Seely JC, Heindel JJ, Schwetz BA. (1993). Developmental toxicity evaluation of ethylene glycol by gavage in New Zealand White rabbits. Fundam Appl Toxicol 20:402–12.

Justification for classification or non-classification

There were no reproductive toxicity effects on rats evident at the high dose level of 600 mg/kg bw/day (oral) - no evidence to indicate any classification required for reproductive or fertility effects.


The NOAEL for oral developmental toxicity in rats (for both dams and offspring) was 150 mg/kg bw/day. The NOAEL for oral developmental toxicity in rabbits in a study with ethylene glycol was 2000 mg/kg/day, with maternal toxicity already observed at 1000 mg/kg bw/day. 


According to Regulation (EC) No 1272/2008, glycolic acid does not warrant any classification for reproductive toxicity.

Additional information