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Toxicity to reproduction

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Administrative data

Endpoint:
three-generation reproductive toxicity
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
1986
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions
Justification for type of information:
The hydrolysis studies demonstrate that the test substance "reaction product ethylene glycol and para-formaldehyde” hydrolyses rapidly and completely. Therefore, data from hte hydrolysis products are regarded sufficient to fulfill the data requirements.

Data source

Reference
Reference Type:
publication
Title:
Three-generation reproduction and dominant lethal mutagenesis studies of ethylene glycol in the rat
Author:
DePass LR, Woodside MD, Maronpot RR
Year:
1986
Bibliographic source:
Fundam Appl Toxicol 7(4): 566-572.

Materials and methods

Test guideline
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 416 (Two-Generation Reproduction Toxicity Study)
Deviations:
yes
Remarks:
(15-19 pregnant rats per dose per generation; partly limited documentation)
GLP compliance:
not specified
Limit test:
no

Test material

Constituent 1
Chemical structure
Reference substance name:
Ethane-1,2-diol
EC Number:
203-473-3
EC Name:
Ethane-1,2-diol
Cas Number:
107-21-1
Molecular formula:
C2H6O2
IUPAC Name:
ethylene glycol
Details on test material:
Purity: 99.8% (analytical)

Test animals

Species:
rat
Strain:
Fischer 344
Sex:
male/female
Details on test animals or test system and environmental conditions:
Charles River Laboratories, Mass., USA
Young adult nulliparous Fischer 344 rats; two per cage; during mating, each male housed with 2 females; females housed individually after mating and during lactation.

Rats received Purina Formulab diet and tap water ad libitum, temperature 20-24°C, 12 h light and 12 h dark

Administration / exposure

Route of administration:
oral: feed
Vehicle:
other: diet
Details on exposure:
Exposure of F0 rats of both sexes started at approximately 7 weeks of age; fresh diet was prepared every 2 weeks adjusted to the group mean body weight and food consumption. Concentration of test substance in the diet was not changed during gestation or during the first week of lactation, but was reduced two- and three-fold during the second and third weeks of lactation, respectively, to adjust for increased food consumption by the dams.
Details on mating procedure:
At approximately 100 days of age, 10 F0 males were added to 20 F0 females in each dosage group; further details on mating were not given.
The F1 and F2 rats treated as described for the F0 animals until 100 days of age, at which time the rats were cohabited; brother and sister matings were avoided for each generation.
Analytical verification of doses or concentrations:
no
Details on analytical verification of doses or concentrations:
nominal doses
Duration of treatment / exposure:
Up to F3 generation
Frequency of treatment:
daily ad libitum
Details on study schedule:
Litter size was randomly reduced to 10 (if necessary) on day 4 postpartum; rats randomly selected within each dosage group for the next mating/generation; each litter represented except for those conceived very late in the mating period.
Doses / concentrationsopen allclose all
Dose / conc.:
40 mg/kg bw/day (nominal)
Remarks:
The weekly calculated dosages ranged from 40 to 50 mg/kg bw/day for males and from 40 to 60 mg/kg bw/day for females.
Dose / conc.:
200 mg/kg bw/day (nominal)
Remarks:
The weekly calculated dosages ranged from 200 to 300 mg/kg bw/day for males and from 200 to 300 mg/kg bw/day for females.
Dose / conc.:
1 000 mg/kg bw/day (nominal)
Remarks:
The weekly calculated dosages ranged from 1000 to 1300 mg/kg bw/day for males and from 900 to 1200 g/kg bw/day for females.
No. of animals per sex per dose:
10 exposed males mated with 20 exposed females in each generation
Control animals:
yes, concurrent vehicle
Details on study design:
Two control groups
Positive control:
None

Examinations

Parental animals: Observations and examinations:
Clinical signs and mortality: The appearance and behaviour of the dams and pups were observed daily.
Body weight: Body weights were recorded weekly except during gestation and lactation.
Food consumption: Food consumption was recorded weekly except during gestation and lactation.
Oestrous cyclicity (parental animals):
no data
Sperm parameters (parental animals):
no data
Litter observations:
Date of parturition, number of live and dead newborn for each litter, appearance and behavior of pups observed daily, offspring weighed as litters at 4 and 14 days and individually at 21 days postpartum (weaned).
Postmortem examinations (parental animals):
Necropsies performed on 5 males and 5 females randomly selected from each dosage level of the F2 parents. Histopathology performed of liver, kidneys, lung, heart, adrenals, thyroid, trachea, accessory sex glands, adipose tissue, lymph nodes, pituitary, thymus, testes, epididymis, uterus and ovaries.
Postmortem examinations (offspring):
Necropsies performed on 5 males and 5 females randomly selected from each dosage level of F3 weanlings. Histopathology performed of liver, kidneys, lung, heart, adrenals, thyroid, trachea, accessory sex glands, adipose tissue, lymph nodes, pituitary, thymus, testes, epididymis, uterus and ovaries.
Statistics:
Continuous data were compared by ANOVA and Bartlett’s test. Duncan’s multiple range test was used to identify individual mean differences. When Bartlett’s tests indicated heterogeneous variances, t tests were used. Pup weights were compared by the method of Weil. Discontinuous data were compared by a multiple sum of ranks test. Frequency data were compared by the x² test and Fisher’s exact test.
Reproductive indices:
Fertility index, gestation index
Offspring viability indices:
survival indices (day 0-4, 4-14 or 14-21 post partum)

Results and discussion

Results: P0 (first parental generation)

General toxicity (P0)

Clinical signs:
no effects observed
Description (incidence and severity):
No clinical signs of toxicity were noted.
Mortality:
no mortality observed
Description (incidence):
There were no mortalities amongst parental rats.
Body weight and weight changes:
no effects observed
Description (incidence and severity):
There were no effects of treatment on body weight gain.
Food consumption and compound intake (if feeding study):
no effects observed
Description (incidence and severity):
There were no effects of treatment on food consumption.
Organ weight findings including organ / body weight ratios:
not examined
Histopathological findings: non-neoplastic:
no effects observed

Reproductive function / performance (P0)

Reproductive function: oestrous cycle:
not examined
Reproductive function: sperm measures:
not examined
Reproductive performance:
no effects observed

Effect levels (P0)

Key result
Dose descriptor:
NOAEL
Effect level:
1 000 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
clinical signs
mortality
reproductive performance
Remarks on result:
other: highest dose level tested (limit dose according to OECD 416)

Target system / organ toxicity (P0)

Key result
Critical effects observed:
no

Results: P1 (second parental generation)

Effect levels (P1)

Key result
Dose descriptor:
NOAEL
Effect level:
1 000 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
clinical signs
mortality
reproductive performance
Remarks on result:
other: highest dose level tested (limit dose according to OECD 416)

Target system / organ toxicity (P1)

Key result
Critical effects observed:
no

Results: F1 generation

General toxicity (F1)

Clinical signs:
no effects observed
Mortality / viability:
no mortality observed
Body weight and weight changes:
no effects observed
Sexual maturation:
no effects observed
Organ weight findings including organ / body weight ratios:
not examined
Gross pathological findings:
no effects observed
Histopathological findings:
no effects observed

Effect levels (F1)

Key result
Dose descriptor:
NOAEL
Generation:
F1
Effect level:
1 000 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
mortality
histopathology: non-neoplastic
other: fertility, fecundity, and reproductive performance
Remarks on result:
other: highest dose level tested (limit dose according to OECD 416)

Target system / organ toxicity (F1)

Key result
Critical effects observed:
no

Results: F2 generation

General toxicity (F2)

Histopathological findings:
no effects observed

Details on results (F2)

There were no treatment-related histopathological findings in F2 parents or in F3 weanlings. One control F2 rat of each sex, and one high dose F2 rat of each sex had mild focal interstitial nephritis. Unilateral hydronephrosis occurred in another high dose F2 male. In addition, mild focal tubular hyperplasia was observed in one high dose F3 male pup, but was also diagnosed in two control male pups. There were no increases in either incidence or severity of renal lesions despite kidneys being an identified target organ for ethylene glycol nephrotoxic effects.

Effect levels (F2)

Key result
Dose descriptor:
NOAEL
Generation:
F2
Effect level:
1 000 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
clinical signs
mortality
other: fertility, fecundity, or reproductive performance
Remarks on result:
other: highest dose level tested (limit dose according to OECD 416)

Target system / organ toxicity (F2)

Key result
Critical effects observed:
no

Overall reproductive toxicity

Key result
Reproductive effects observed:
no

Any other information on results incl. tables

No treatment-related effect was observed in any generation on fertility index, gestation index and viability of offspring.

Applicant's summary and conclusion

Conclusions:
Dietary exposure of male and female rats to ethylene glycol at approximate doses as high as 1000 mg/kg/day for three generations produced no effects on fertility, fecundity, or reproductive performance. There were no signs of toxicity observed, no mortalities, and no treatment-related lesions were observed histopathologically.
Executive summary:

Ethylene glycol was tested in a three generation reproductive toxicity test. The reported study is comparable to OECD guideline 416 with acceptable restrictions: 15-19 pregnant rats per dose and generation, no data on oestrus cycle and sperm parameters, no data on organ weights at necropsy, limited documentation of mating procedure.

Male and female F344 rats of F0, F1 and F2 generation were exposed continuously via the diet to 0, 40, 200 or 1000 mg/kg bw/day. At approximately 100 days of age, F0 males were mated with females in each dosage group and reproductive toxicity parameters were recorded. The F1 and F2 rats were treated as described for the F0 animals. No effects on F0, F1, or F2 parental generations and F1, F2, or F3 offspring were noted.

Conclusion: Under the experimental conditions described in this study the test substance did not induce effects on fecundity, fertility and reproductive performance. The NOAEL is 1000 mg/kg bw/day, the highest dose level tested.