Registration Dossier

Administrative data

Key value for chemical safety assessment

Effects on fertility

Description of key information

There is screening-level information on HEMA (combined repeated dose toxicity and reproductive screening study according to OECD 422) available, but no full reproductive toxicity study. This is substantially supplemented by reliable reproductive toxicity studies from the reference chemicals which are either metabolites (EG, PG) or metabolite donors (MMA = donor substance of MAA). Regarding fertility, a 2-generation reproductive toxicity study is available on MMA by the oral route. Besides others, continuous breeding studies are available for EG (the primary alcohol metabolite of HEMA) via the oral route. For EG, the alcohol metabolite, only the most relevant key studies were selected for read across purposes.

 

Read across evaluation according to ECHA’s Read Across Assessment Framework (RAAF)

The metabolism from the category substances to their primary metabolites is well understood. The same is true for the further metabolism pathways of MAA and the alcohol metabolites EG and PG, respectively (see chapter 5.2, ATSDR 1997/ 2008/ 2010, NTP 2004a, 2004b). The endpoint specific “scientific assessment” of the read across is thus “acceptable with at least medium confidence”.

Link to relevant study records
Reference
Endpoint:
screening for reproductive / developmental toxicity
Remarks:
based on test type (migrated information)
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Well conducted study, carried out by Nippon Bioresearch Inc.Hashima Laboratory (Japan).
Qualifier:
equivalent or similar to
Guideline:
OECD Combined Repeated Dose and Reproductive / Developmental Toxicity Screening Test (Precursor Protocol of GL 422)
Deviations:
yes
Remarks:
older version of method that did not contain the functional observational battery
GLP compliance:
yes
Species:
rat
Strain:
Crj: CD(SD)
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River Japan
- Age at study initiation: 10 weeks
- Weight at study initiation: male 341~380 g; the female was 232~256 g.
- Housing: suspended, stainless steel cage; 5/cage until breeding, then divided into separate rearing cages.
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: 5 day quarantine; 7 day acclimation

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 ~ 24 ℃
- Humidity (%): 40 to 70%
- Photoperiod (hrs dark / hrs light): 12 hour light / 12 hour dark

Route of administration:
oral: gavage
Vehicle:
water
Details on exposure:
PREPARATION OF DOSING SOLUTIONS: dissolved in water
Details on mating procedure:
- M/F ratio per cage: 1/1
- Length of cohabitation: 14 days
- Proof of pregnancy: sperm in vaginal smear referred to as day 0 of pregnancy
- After successful mating each pregnant female was caged (how): separate rearing cages
Analytical verification of doses or concentrations:
not specified
Duration of treatment / exposure:
Exposure period: Males, 49 days; Females, from 14 days before mating to day 3 of lactation
Premating exposure period (males): 14 days
Premating exposure period (females): 14 days
Duration of test: Male, 50 days; Females, day 4 of lactation
Frequency of treatment:
Once daily
Remarks:
Doses / Concentrations:
0 (vehicle), 30, 100, 300, 1000 mg/kg/day
Basis:

No. of animals per sex per dose:
12
Control animals:
yes, concurrent vehicle
Details on study design:
Post-exposure period: Male, 50 days; Females, day 4 of lactation
- Dose selection rationale: based on range-finding
- Rationale for animal assignment (if not random): random

Positive control:
not applicable
Parental animals: Observations and examinations:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily
- Cage side observations checked : general condition and mortality; estrus and abnormal labor conditions in females

BODY WEIGHT: Yes
- Time schedule for examinations: twice per week in males; before mating, twice a week during the mating period, 0, 7 ,14 and 21 days duirng pregnancy, during the feeding period was measured 0 and 4 days in females

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study): one week prior to mating, then twice a week; additionally, in females, days 2,9,16 and 21 of pregnancy, four days over the feeding period.
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: No data
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: No data

FOOD EFFICIENCY:
- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data: No

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): No

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes
- Time schedule for collection of blood: day after treatment
- Anaesthetic used for blood collection: Yes; sodium pentobarbital
- Animals fasted: No data
- How many animals: No data
- Parameters checked in table [No.1] were examined.

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: day after treatment
- Animals fasted: No data
- How many animals: No data
- Parameters checked in table [No.2] were examined.

URINALYSIS: No
Oestrous cyclicity (parental animals):
Once daily from the dosing start date until successful mating was observed.
Sperm parameters (parental animals):
Parameters examined in P male parental generations:
testis weight, epididymis weight
Litter observations:
STANDARDISATION OF LITTERS
- Performed on day 4 postpartum: yes

PARAMETERS EXAMINED
The following parameters were examined in F1 offspring:
number and sex of pups, stillbirths, live births, postnatal mortality, presence of gross anomalies, weight gain

GROSS EXAMINATION OF DEAD PUPS:
yes, for external and internal abnormalities; possible cause of death was not determined for pups born or found dead
Postmortem examinations (parental animals):
Terminal kill: Males, day 50; Females, day 4 of lactation

GROSS PATHOLOGY: Yes; Thymus, liver, kidney, testis and epididymis weight in males and ovary in females was measured after removal, adrenal gland, brain, heart and spleen and 10% neutral buffered formalin solution (However, testicular and epididymal fluid Buan) was fixed. Post-mortem examination of feamles who did not give birth to Day 25 of pregnancy. Number of corpora lutea and the number of implantation scars in females.

HISTOPATHOLOGY: Yes; Paraffin-embedded specimens were prepared. Control group and 1000 mg / kg group of heart, liver, spleen, thymus, kidney, testis and epididymis in males ovary in females, adrenal and brain for the Preparation HE staining of tissue was examined histologically. In males, 1000 mg / kg in the kidney was considered to indicate a difference in the number of abnormal animals in the test group compared with the control group; 30, 100 and 300 mg / kg group were similarly examined. In females, 1000 mg / kg differences in the brain was considered to indicate an abnormal number of animals in the test group than the control group and changes in adrenal cases and 30, 100, 300 mg / kg group were similarly examined.
Statistics:
Newborn screening as a unit has an average of one litter.
Weight (the parent animals, babies), food consumption, number of estrus, days mating, pregnancy [Day delivery (feeding 0) - date confirmed mating, the number of implantation scars, the number of birth control mobilize (number of babies stillborn baby + ), the number of newborn, number of children born dead, birth rate [(number of birth control mobilize / number of implantation scars) × 100], rate of production of child [(number of infant feeding 0 days / number of implantation scars) × 100], corpus number, implantation rates [(number of implantation scars / number of corpora lutea) × 100], fertility [(number of infant feeding 0 day / mobilize all of birth control) × 100], feeding baby number four day, feeding 4 day survival rate [(number of infant feeding 4 days / 0 Number of infant feeding day) × 100], unusual occurrence rate [(number of children with abnormal/ number of newborns) × 100], sex ratio (male / female), organ weights ( including the relative weight), results of blood tests, blood biochemistry test results for the mean and standard deviation were calculated for each group.
Significant difference test, Bartlett's test and the homoscedasticity of Law, analysis of variance, Dunnett method. Kruskal-Wallis test.
Copulation rate [(number of established animal mating / number of live animals) × 100], fertility [(number of female fertility / Establishment of animal mating) × 100], the birth rate [(number of female newborns / number of female fertility) × 100] is, χ ^ 2 using the test.
Cochran • Armitage was carried out using a test of dose-response trend test.
Reproductive indices:
Copulation rate [(number of established animal mating / number of live animals) × 100], fertility [(number of female fertility / Establishment of animal mating) × 100], pregnancy [Day delivery (feeding 0) - date confirmed mating, birth rate [(number of birth control mobilize / number of implantation scars) × 100], rate of production of child [(number of infant feeding 0 days / number of implantation scars) × 100], implantation rates [(number of implantation scars / number of corpora lutea) × 100], fertility [(number of infant feeding 0 day / mobilize all of birth control) × 100]
Offspring viability indices:
the birth rate [(number of female newborns / number of female fertility) × 100], unusual occurrence rate [(number of children with abnormal/ number of newborns) × 100], feeding 4 day survival rate [(number of infant feeding 4 days / 0 Number of infant feeding day) × 100]
Clinical signs:
effects observed, treatment-related
Body weight and weight changes:
effects observed, treatment-related
Food consumption and compound intake (if feeding study):
effects observed, treatment-related
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Gross pathological findings:
effects observed, treatment-related
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Other effects:
effects observed, treatment-related
Reproductive function: oestrous cycle:
no effects observed
Reproductive function: sperm measures:
not examined
Reproductive performance:
no effects observed
Detail:[Males]
1) General condition: With the survival animals, no death and no moribund  were found for 30, 100 and 300 mg/kg/day groups. At 1000 mg/kg/day, one  death on day 20 of dosing was seen and abnormality wasn't seen except for  salivation until the previous day.  With the dead animals, no abnormality  was found for 30, 100 and 300 mg/kg/day groups.  At 1000 mg/kg/day,  salivation was seen in about 1 to 30-minutes after dosing from day 3. 2) Body weight: No significant difference from control group was seen in  30, 100, and 300 mg/kg/day groups. At 1000 mg/kg/day, the significant low  value was recorded during day 18 to day 25 of dosing andduring day 32 to  day 50 of dosing.
3) Food consumption: At 30 and 300 mg/kg/day, no significant difference  from control was seen. At 100 mg/kg/day, the significant high values were  seen on day 31. but no dose-related changes were obserbed.At 1000  mg/kg/day, the statistically significant low values were recorded on day  13, 31 and during day 38 to day 45. 
4) Hematological examination: No significant difference from control  group was seen for all groups up to 1000 mg/kg/day dose.
5) Blood chemical examination: At 30 and 300 mg/kg/day,the significant  high value in BUN were seen. As the difference was very small, this was  not considered as the adverse effect of HEMA dosing.  At 100 mg/kg/day, a  higher value of BUN but not statistically signifficant difference from  control was recorded. At 1000 mg/kg/day, the significant high values were  recorded in BUN, K, Cl,I-phosphorous and Triglyceride. 
6) Autopsy: No abnormalitywas found for 30 and 100 mg/kg groups. In the  300 mg/kg group, the albedo spot in the kidney of the unilateral in the 1  animal and, the atrophy of the testiculus of the bilaterality and  softening were observed in the 1 animal. In the 1000 mg/kg group, the  dark-red of the thymus gland in the 1 animal and the hypertrophy of the  kidney of bilaterality in the 1 animal were observed. 
7) Weight oforgans: At 30 mg/kg/day, no significant difference from  control group in absolute and relative weight was seen for all organs. At  100 and 300 mg/kg/day, the significant high value was recorded in the  absolute weight of kidneys. At 1000 mg/kg/day, the statistically  significant high values were recorded in the relative weight of liver and  kidneys.
8) Histopathological examination: At 1000 mg/kg/day in the survival  animals, the dilatation of renal tubule in 3 animals in the kidney and  the dilatation of collecting tubules in 2 animals were observed. But, all  these changes were just slight. And the dilatation of renal tubule has a  significant difference but no dose-related changes.  As for the  dilatation of collecting tubules, it has no significant difference but  increase tendency. In the other group, there were hemorrhage of thymus  gland, microgranuloma of the heart, microgranuloma of the liver and  hepatocyte vacuolar degeneration of the centrilobular, renal basophilic  tubules, eosinophilic corpuscle in proximal tubule, cyst, diffusive  mineral deposition and neutrophilic infiltration. But it was judged with  the incidental change, because they were whether it equivalently seems  even in the control group or small number animals. And no abnormality was  observed in spleen, adrenal, testiculus and brain in the control and 1000  mg/kg group. In animal of death of the 1000 mg/kg group, there were  hemorrhage of the thymus gland, edema of the lung, autolysis of adrenal  and lung and thymus gland with the deadanimal of 1000 mg/kg group. As for  those degrees, all were just slight. In the adrenal with the abnormality  in the autopsy, no change which suggested hypertrophy was seen.   
[Females]
1) General condition: With the existence animales, no death and no  moribund were seen for 30, 100 and 300 mg/kg/day groups. At 1000  mg/kg/day, three death on day 6 of dosing, one death on day 12 of dosing  and one death on day 17 of dosing were seen. Salivation, decrease in  locomotor activity, adoption of a prone position, acrimation, soiled fur,  hypothermia, bradypnea were seen at 1000 mg/kg. With the death animals,  no abnormality was found for 30, 100 and300 mg/kg/day groups.  At 1000  mg/kg/day, salivation was seen in about 1 to 30-minutes after dosing from  day 3.
2) Body weight: Before mating period, no significant difference from control  group was seen at 30, 100 and 300 mg/kg/day. At 1000 mg/kg/day, the  significant lower values were recorded on day 4 and 5 of dosing. During  gestation period, no significant difference from control groups was seen  in 30, 300 and 1000 mg/kg/day groups. At 100 mg/kg/day, the significant  high values were recorded on day 21 of gestation,  but no dose-related  changes were observed. During lactation period, no significant difference  from control groups was seen in 300 and 1000 mg/kg/day groups. At 30 and  100 mg/kg/day, the significant high values were recorded on day 4 of  lactation, but no dose-related changes were obserbed.
3) Food consumption:  Before mating period, no significant difference from control group was  seen at 30, 100 and 300 mg/kg/day. At 1000 mg/kg/day, the significant low  value from control group was recorded on day 3, 6 and 13 of dosing. During  gestation period, no significant difference from control groups was seen  in 30 and 300 mg/kg/day groups. At 100 and 1000 mg/kg/day, the  significant high value from control group was recorded on day 16 of  gestation, but no dose-related changes were observed. During lactation  period, no significant difference from control groups was seen.
4) Weight of organs: At 30 mg/kg/day, no significant difference from  control group in absolute and relative weight was seen for all organs. At  100 mg/kg/day,the significant high value was recorded in the absolute  weight of kidneys. At 1000 mg/kg/day, the significant high values were  recorded in the relative and absolute weight of kidneys. 
5) Histopathological examination: Though at 1000 mg/kg/day survival  groups, neutrophilic infiltration (unilateral ) to medulla and papilla  mammae part in the kidney were observed in the 1 animal, the degree was  slight. Though extensive softening of the medulla oblongata in the brain  was observed in the 1 example at 1000 mg/kg group, the degree was slight.   In dead 6 animals of the 1000 mg/kg group, there were the edema in 1  animal in the lung, the atrophy in 1 animal in the thymus gland, the  atrophy in 5 animals and the atrophy of a Malpighian body in 1 animals in  the spleen, the hyperplasia of zona fasciculata in 3 animals and the  autolysis in 1 animal in the the adrenal and the erosion in 1 animal in  the small intestinal mucosa. The degrees of the atrophy in the thymus  gland and the atrophy of a Malpighian body were moderate, but the others  were slight.  All the changes are noted related agonism. No changes which  suggested, though the hypertrophy of the adrenal in 2 animals, dark-red  of the glandular stomach mucosa in 2 animals and dark-red of the  intestinum tenue were observed as abnormal in the autopsy of the 1000  mg/kg group.

There were no effects of the test substance on the estrus frequency, copulation index, number of conceiving days, fertility index, length of gestation, number of corpora lutea or gestation index.
Dose descriptor:
NOAEL
Effect level:
>= 1 000 mg/kg bw/day
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: highest dose tested
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:
no effects observed
Gross pathological findings:
no effects observed
Histopathological findings:
not examined
There were no effects of the test substance on the number of live pups born, birth index, number of dead pups, number of pups born, delivery index, live birth index, sex ratio, viability index, external anomalies, body weight or necropsy findings.
Dose descriptor:
NOAEL
Generation:
F1
Effect level:
>= 1 000 mg/kg bw/day
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: highest dose tested
Reproductive effects observed:
not specified
Conclusions:
An OECD 422 study was conducted with rats by gavage at doses of 0, 30, 100, 300 and 1000 mg/kg. The NOAEL for reproductive/developmental toxicity and is considered to be greater than 1000 mg/kg.

Executive summary:

2-Hydroxyethyl methacrylate was studied for oral toxicity in rats in an OECD combined repeat dose and reproductive/developmental toxicity screening test at doses of 0, 30, 100, 300 and 1000 mg/kg/day.

There were no effects of the test substance on the estrus frequency, copulation index, number of conceiving days, fertility index, length of gestation, number of corpora lutea or gestation index.

There were no effects of the test substance on the number of live pups born, birth index, number of dead pups, number of pups born, delivery index, live birth index, sex ratio, viability index, external anomalies, body weight or necropsy findings.

Therefore, the NOAELs for reproductive/developmental toxicity are considered to be >/=1000 mg/kg/day for reproductin in both males and females and as well as for development of pups.

Effect on fertility: via oral route
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
NOAEL
1 000 mg/kg bw/day
Study duration:
subacute
Species:
rat
Additional information

 

HEMA 

In the OECD 422 study for HEMA (Furuhashi, 1997), male rats (12/group) were given daily gavage doses of 0 (vehicle), 30, 100, 300 or 1000 mg/kg for 50 days including pre-mating, mating and post-mating intervals. Females (12/group) were administered the same doses for two weeks prior to mating, during mating and gestation up until day 4 of lactation (study duration of approximately 54 days depending upon time to conception). Animals were observed for clinical symptoms of intoxication daily and food consumption and body weight were monitored throughout the study. Blood samples were taken for hematological and clinical chemistry analysis at study termination. Thymus, liver kidney, testes, epididymes, and ovaries were weighed. In addition to these tissues,adrenal gland, brain, heart and spleen were fixed in 10% neutral buffered formalin solution for subsequent staining and histopathological evaluation.

Reproductive observations included observations which permit characterization of male and female fertility and fecundity. These include:number of live births and post implantation loss; number of pups with grossly visible abnormalities, number of runts; number of implantations,corpora lutea, litter size and litter weights. Copulation, fertility, implantation, gestation, live birth, delivery, and viability indices were calculated from the data. Pup sex, body weights and viability at birth through day 4 of lactation were determined; pups were autopsied at this time.

There were no effects of HEMA on any fertility related reproductive index including: estrus frequency, copulation index, number of days to conception, fertility index, length of gestation, number ofcorpora luteaand gestation index. Further, there were no effects of HEMA on the number of live pups born, birth index, number of dead pups, number of pups born, delivery index, live birth index.. No histological changes in male and female reproductive organs were described.

The NOAEL for reproductive toxicity of HEMA was 1000 mg/kg/d, the highest dose tested, although both paternal and maternal animals showed significant toxicity: lethal effects in some animals, reduced body weight gain, reduced food consumption and changes in kidney weights and histopathology (HEMA).A 2-generation study is not available on any of the hydroxyalkyl methacrylates. 

Primary Metabolites 

MAA (donor substance: MMA) 

Methyl methacrylate has been tested in a reliable two-generation reproduction toxicity study in rats with oral administration (gavage). The study was performed according to OECD TG 416 in compliance with GLP (REACH Methyacrylate Task Force, 2009). In this study, Methyl Methacrylate was administered to groups of 25 male and 25 female healthy young Wistar rats (P parental generation) as an aqueous preparation by stomach tube at dosages of 0; 50; 150 and 400 mg/kg body weight/day. At least 73 days after the beginning of treatment, P animals were mated to produce a litter (F1). Mating pairs were from the same dose group and F1 animals selected for breeding were continued in the same dose group as their parents.

Groups of 25 males and 25 females, selected from F1 pups to become F1 parental generation, were treated with the test substance at dosages of 0; 50; 150 and 400 mg/kg body weight/day post weaning, and the breeding program was repeated to produce F2 litter. The study was terminated with the terminal sacrifice of the F2 weanlings and F1 adult animals. Control parental animals were dosed daily with the vehicle (1% Carboxymethylcellulose suspension in drinking water and four drops Cremophor EL and one drop hydrochloric acid).

The mid- and high-dose parental animals (400 mg/kg bw/d) showed clinical signs of systemic toxicity. The only relevant clinical observation was temporary salivation during a short period after dosing, which is considered to be test substance-induced. From the temporary, short appearance immediately after dosing it is likely, that this finding was induced by a bad taste of the test substance or local affection of the upper digestive tract. It is, however, not considered to be an adverse toxicologically relevant finding.

In the mid- and high-dose (150 and 400 mg/kg bw/d) P generation animals, dose-related intermittent reductions of food consumption were noted, either during premating, gestation and lactation phases of this study. Less significant changes were noted for the F1 generation animals where the effects were limited to the high-dose group. High-dose F1 parental males had statistically significant lower body weights during several study segments, which led to a statistically significant reduction of the mean terminal body weight resulting in secondary weight changes of brain. High-dose parental females had statistically significant lower body weights during the first weeks after weaning. This weight decrease during major phases of sexual maturation led to an apparent marginal delay of vaginal patency. This minor delay did, however, not result in any corroborative pathological findings nor did it adversly effect F1 female cyclicity, fertility and reproduction. Thus, an influence of the test substance on female sexual maturation is not assumed. Pathological examinations revealed no test-substance-related changes in organ weights, gross lesions, changes in differential ovarian follicle counts or microscopic findings, apart from an increase in kidney and liver weights in male and female animals in both generations which is presumably related to the treatment. There was no histopathologic lesion observed, that could explain the weight increase. It is regarded to be an adaptive change, most likely caused by an increase in metabolic activity in the two organs, which does not lead to histopathologic findings. It is not regarded to be an adverse effect. There were no indications from clinical examinations as well as gross and histopathology, that the administration of methyl methacrylate via the diet adversely affected the fertility or reproductive performance of the P or F1 parental animals up to and including a dose of 400 mg/kg bw/day. Estrous cycle data, mating behavior, conception, gestation, parturition, lactation and weaning as well as sperm parameters, sexual organ weights and gross and histopathological findings of these organs (including differential ovarian follicle counts in the F1 females) were comparable between the rats of all test groups and ranged within the historical control data of the test facility. All data recorded during gestation and lactation in terms of embryo-/fetal and pup development gave no indications for any developmental toxicity in the F1 and F2 offspring up to a dose level of 400 mg/kg bw/day. Up to this dose level, the test substance did not adversely influence pup viability and pup body weights. Sex ratio and sexual maturation was not directly affected at any dose level, inclusive the high-dose group (400 mg/kg bw/day).

The NOAEL for general, systemic toxicity was determined to be 50 mg/kg bw/day for the P and F1 parental rats, based on adverse effects on food consumption observed at the LOAEL of 150 mg/kg bw/day in the P parental females. The NOAEL for fertility and reproductive performance for the P and F1 parental rats was determined to be 400 mg/kg bw/day, the highest dose tested. The NOAEL for developmental toxicity, in the F1 and F2 progeny, of the test substance was determined to be 400 mg/kg bw/day, the highest dose tested.

EG (from HEMA)

Ethylene glycol (EG) was tested for reproductive toxicity in rats and mice. NTP-CERHR (2004) concluded that “there are sufficient data to conclude that ethylene glycol is not a reproductive toxicant in rats exposed orally to 1,000 mg/kg bw/day via diet. The study in mice was essentially negative at doses up to 2,826 mg/kg bw/day via drinking water. The studies available for review included a continuous breeding study in mice(selected for the IUCLID dataset of HEMA, also for reliability reasons – NTP study), a two-generation study in rats, and sub-chronic toxicity studies in rats.

The Expert Panel concluded that data in mice are sufficient to demonstrate no effect on fertility of male or female mice following oral exposure to up to 2,826 mg/kg bw/day ethylene glycol for approximately 22 weeks.

The Expert Panel concluded that the data are sufficient to demonstrate that ethylene glycol is not a reproductive toxicant in male and female rats following dietary exposure with up to 1,000 mg/kg bw/day for 7 weeks prior to mating in parental rats or from the time of conception through mating in their offspring.

The Expert Panel is confident that these data are useful in judging hazard to humans because the doses tested far exceeded the doses relevant to humans based on knowledge of absorption, distribution, metabolism, and excretion in rats, mice, and humans. It was further noted that the pattern of general toxicity is similar in experimental animal studies and instances of human poisoning.”

 

The following table provides information on the NOAELs of the considered fertility studies of the category substances and metabolites, expressed as applied dosage and as amount of substance (mmol) for comparison reasons: HEMA hydrolyses rapidly to MAA and the respective alcohol in a 1→1+1 ratio, see chapter5.2.

Table 5.9.3.1: Summary of NOAELs regarding fertility

NOAEL

oral fertility

HEMA

MW 130.14

HPMA

MW 144.17

MMA

MW 100.12

EG

MW 62.07

PG

MW 76.09

mg/kg bw

1000

1000

400

≥1000a

≥10,000b

ca. mmol/kg/d

7.7

6.9

4 (MAAc)

≥16.1

≥130

areference: Lambs 1985/ NTP 1984, continuous breeding study in mice

breference: NTP 1985, continuous breeding study in mice

cconsidering a rapid hydrolysis of MMA to MAA in the body, see chapter 5.2.

 

 

Human data

No reliable data available for any members of the category.

 

Summary and discussion of reproductive toxicity

HEMA: The available OECD 422 screening studies with HEMA (and HPMA) do not show any indication of reproductive effects in OECD422 studies up to 1000 mg/kg/d, i.e. above the threshold of systemic toxicity.

Metabolites: With regards to reproductive toxicity, based on a complete absence of the effects in relevant dosages in multiple generation studies with all primary metabolites (MAA and EG) it can be concluded with high confidence that the parent ester HEMA is unlikely to be a reproductive toxicant.

Based on a reliable screening study with HEMA and equally reliable and relevant higher tier multiple generation studies covering the entire metabolic pathway and in the absence of any other alert regarding reproductive tocicity, additional reproductive studies with HEMA may be waived.

Effects on developmental toxicity

Description of key information

Regarding developmental toxicity, there is screening-level information on HEMA available (combined repeated dose toxicity

and reproductive screening study according to OECD 422, teratology-related parameters). This is substantially supplemented

by reliable data from the reference chemicals which are either metabolites (EG, PG, MAA) or metabolite donors (MMA = donor

substance of MAA). There is an OECD 414 study on MAA in rats. In addition, full sets of developmental toxicity studies

according to OECD 414 are available for MMA (rat/ inhalation and rabbit/ oral) and EG with different dosing regimes (oral

gavage (bolus)/oral feed(continuous) and in different species (mouse, rat, rabbit). For the alcohol metabolite, EG, only

the most relevant key studies were selected for read across purposes.

Read across evaluation according to ECHA’s Read Across Assessment Framework (RAAF)

The metabolism from the category substances to their primary metabolites is well understood. The same is true for the

further metabolism pathways of MAA and the alcohol metabolites EG and PG, respectively (see chapter 5.2, ATSDR 1997/ 2008/

2010, NTP 2004a, 2004b). The endpoint specific “scientific assessment” of the read across is thus “acceptable with at least

medium confidence”.

Additional information

HEMA

In the OECD 422 study for HEMA (Furuhashi, 1997), male rats (12/group) were given daily gavage doses of 0 (vehicle), 30, 100, 300 or 1000 mg/kg for 50 days including pre-mating, mating and post-mating intervals. Females (12/group) were administered the same doses for two weeks prior to mating, during mating and gestation up until day 4 of lactation (study duration of approximately 54 days depending upon time to conception). Animals were observed for clinical symptoms of intoxication daily and food consumption and body weight were monitored throughout the study. Blood samples were taken for hematological and clinical chemistry analysis at study termination. Thymus, liver kidney, testes, epididymes, and ovaries were weighed. In addition to these tissues,adrenal gland, brain, heart and spleen were fixed in 10% neutral buffered formalin solution for subsequent staining and histopathological evaluation.

Reproductive observations included observations, which permit characterization of male and female fertility and fecundity. These include:number of live births and post implantation loss; number of pups with grossly visible abnormalities, number of runts; number of implantations,corpora lutea, litter size and litter weights. Copulation, fertility, implantation, gestation, live birth, delivery, and viability indices were calculated from the data. Pup sex, body weights and viability at birth through day 4 of lactation were determined; pups were autopsied at this time. There were no effects of either HEMA or of HPMA on any reproductive index. This includes reproductive parameters related to developmental toxicity including: number of live pups born, birth index, number of dead pups, number of pups born, delivery index, live birth index.. The NOAELs for reproductive/developmental toxicity in this study was 1000 mg/kg/d, the highest dose tested, although both paternal and maternal animals evidenced reduced body weight gain, reduced food consumption and changes in kidney weights and histopathology (HEMA). Developmental toxicity studies are not available for HEMA.

 

Primary Metabolites

MAA (including donor substance: MMA)

Methacrylic acid (MAA), the common metabolite for all esters, was tested in a developmental toxicity study in groups of 19-25 pregnant female rats (whole-body inhalation exposure for 6 hr/day, during days 6 to 20 of gestation), at 0, 50, 100, 200, and 300 ppm (0, 179, 358, 716 and 1076 mg/m³) and produced no embryo- or fetal lethality, nor fetal malformations after exposure with MAA at any concentration, despite overt maternal toxicity (decreased body weight and feed consumption) at 300 ppm (1076 mg/m³). The NOAEL for developmental toxicity was considered 300 ppm (1076 mg/m³) MAA (Saillenfait et al., 1999).

In a developmental toxicity study according to OECD 414 MMA was administered by inhalation exposure to 99, 304, 1178, and 2028 ppm (412, 1285, 4900, 8436 mg/m³; Solomon et al., 1993). No relevant maternal, treatment-related effects, except reduced body weight, were noted at any concentration tested. No embryo or foetal toxicity was evident and no increase in the incidence in the malformations or variations was noted at exposure levels up to and including 2028 ppm. In this study the NOAEC for developmental toxicity was 2028 ppm (8436 mg/m³).

In addition, another study with MMA has been performed, an oral OECD 414 study in rabbits at 50, 150 , and 405 mg/kg/d. The no observed adverse effect level (NOAEL) for prenatal developmental toxicity was 450 mg/kg bw/d. No adverse foetal findings of toxicological relevance were evident at any dose, even in the presence of maternal toxicity (BASF, 2009). MMA is not a selective teratogen.

EG

The developmental toxicity of ethylene glycol has been assessed by several animal studies. From those, oral studies are considered most relevant for the primary metabolite of HEMA and have thus been generally selected for the IUCLID dataset of HEMA; a dermal study is added for supportive reasons. In brief, developmental effects in animal studies have been shown to be species specific and, influenced by the dosing regime. These effects have to be interpreted in the light of the the toxicokinetics of the substance (NTP-CERHR 2004): “Ethylene glycol metabolism yields a variety of products with glycolic acid and oxalic acid of principle toxicological interest. There are several studies that have attempted to characterize the oxidation of glycolic acid to glyox­ylate, a saturable process that leads to accumulation of glycolic acid. This is reflected most clearly in the non-linear increase in glycolic acid levels in blood and urine as the dose of ethylene glycol is in­creased. This saturation occurs beginning at doses as low as 150 mg/kg bw in rodents with the mouse enzyme system appearing to be somewhat more readily saturable than the rat system (Neeper-Bradley 1995 vs. Neeper-Bradley 1990, see Table5.9.3.2: Summary of maternal toxic and developmental NOAELs in studies with ethylene glycol with respect to animal species and dosing regime of selected studies taken from NTP-CERHR monograph (2004)).It is evident that glycolic acid metabolism is saturated at the bolus doses in rats required to produce developmental toxicity (1,000 mg/kg bw).” The role of saturation kinetics in developmental toxicity is also suggested by a lack of toxicity after ethylene glycol continuous dosing (e.g., feeding, dermal) when compared to bolus dosing (gavage; Neeper-Bradley 1990 vs. Maronpot 1983, seeTable1: Summary of key physico-chemical properties). The lower dose rates in these continuous dosing studies “leads to a glycolic acid formation rate that apparently does not exceed saturation”. The NTP-CERHR expert panel stated that the continuous dosing is more relevant for human exposure than bolus dosing.

Table 5.9.3.2: Summary of maternal toxic and developmental NOAELs in studies with ethylene glycol with respect to animal species and dosing regime of selected studies taken from NTP-CERHR monograph (2004)

Study

 

Animal species

Dosing regime

NOAEL maternal

NOAEL developmental

Neeper-Bradley 1995

mouse

oral gavage (bolus)

≥ 1500 mg/kg/d

150 mg/kg/d

Neeper-Bradley 1990

Rat

oral gavage (bolus)

1000 mg/kg/d

500 mg/kg/d

Maronpot 1983

Rat

oral feed (continuous)

≥ 1000 mg/kg/d

≥ 1000 mg/kg/d

Tyl 1993

Rabbit

oral gavage (bolus)

1000 mg/kg/d

2000 mg/kg/d

Tyl 1995

Mouse

dermal (continuous)

≥ 3550 mg/kg/d

≥ 3550 mg/kg/d

 

In addition, developmental toxicity was not observed in the non-rodent species rabbit orally exposed to ethylene glycol at doses associated with severe maternal toxicity even with bolus dosing (Tyl 1993). As stated by NTP-CERHR (2004), “rabbits demonstrated no developmental toxicity following gavage exposure to doses as high as 2,000 mg/kg bw/day on gd 6–19, as noted by a lack of malformations, prenatal deaths, or decrease in fetal weights. Severe maternal toxicity was observed at 2,000 mg/kg bw/day as evidenced by maternal deaths, increased early delivery, and lesions as well as oxalate crystals in the kidneys. Maternal and fetal NOAELs were identified as 1,000 and 2,000 mg/kg bw/ day, respectively. Thus, the data were sufficient to demonstrate a lack of developmental toxicity in rabbits following oral gavage throughout organogenesis at doses ≤ 2,000 mg/kg bw/day.

The absence of developmental effects of ethylene glycol after dermal application is shown in the sensitive species mouse by Tyl (1995).

With respect to human relevance, NTP-CERHR Expert Panel noted the doses tested in animal studies “far exceeded the doses relevant to humans based on knowledge of absorption, distribution, metabolism, and excretion in rats, mice, and humans”; and this is believed especially true for ethylene glycol as primary metabolite of HEMA. In addition, the Expert Panel recognized that “the rat and mouse models are possibly more sensitive than humans because of the dependence of these species on the inverted yolk sac placenta, which is not present in humans.”

Overall, there is no concern of developmental potential for HEMA with respect to the ethylene glycol metabolite when considering relevant exposure routes and quantities.

The following table provides information on the NOAELs of the considered developmental studies of the category substances and metabolites, expressed as applied dosage and as amount of substance (mmol) for comparison reasons: HEMA and HPMA hydrolyses rapidly to MAA and the respective alcohol in a 1->1+1 ratio, see chapter5.2.

 

Table 5.9.3.3: Summary of NOAELs/ NOAECs regarding developmental toxicity

NOAEL/ NOAEC

developmental

route

HEMA

MW 130.14

HPMA

MW 144.17

MMA

MW 100.12

EG

MW 62.07

PG

MW 76.09

mg/m³

inhalation

 

 

8436

 

 

mg/kg bw

 

 

3206

 

 

ca. mmol/kg/d

 

 

32 (MAAa)

 

 

mg/kg bw

oral

1000

1000

450

≥ 1000b

≥1230c

ca. mmol/kg/d

7.7

6.9

4.5 (MAAa)

≥ 16.1

≥ 16.2

aconsidering a rapid hydrolysis of MMA to MAA in the body, see chapter 5.2.

breference: Maronpot 1983, selected for the reason of lowest NOAEL after continuous dosing (human relevant according to NTP-CERHR); seeTable 18

creference: NTP 1973, selected for the reason of lowest NOAEL

 

Human data

No reliable data available for any members of the category.

Summary and discussion of reproductive toxicity

The available OECD 422 screening studies with HEMA (and HPMA) do not show any indication of reproductive/developmental effects up to 1000 mg/kg/d, i.e. above the threshold of systemic toxicity.

For EG, the alcohol metabolite of HEMA, the observed developmental effects have to be considered in the light of possible relevance to humans. Relevant studies are then predominantly limited to those employing continuous dosage (e.g., feeding) and/or those species without dependence on the inverted yolk sac placenta during ontogenesis (excluding rodent species mouse and rat). In these relevant studies either no developmental effects were observed, or where they were observed only at maternally toxic doses. Hence, although some concern exists for reproductive effects of HEMA (triggered by the more toxic metabolite EG) there is moderate confidence that these effects would not be expressed in a study with HEMA, as doses would be limited by the systemic toxicity of HEMA.

In summary, it can be concluded with high confidence that HEMA is not a specific developmental toxicant based upon an absence of effects in the HEMA screening study, in the primary metabolite methacrylic acid (and MMA) in a relevant dose range in studies with rodent and non-rodent and in the alcohol metabolite EG in rabbits, but also in rodents if exposure schemes are considered which resemble the workplace conditions more closely (continuous dosing). The read-across to the metabolite data is justified by the short half-life of HEMA and the fact that the metabolites – in summary – possess the same modes of action.

From a read across perspective, there is high confidence that data generated on HEMA would act as a conservative surrogate for HPMA. In summary, with reliable read-across studies for all endpoints in all relevant species the dataset for HEMA is considered to be complete.

 

Justification for classification or non-classification

There are no effects on reproduction or development and no teratogenic observations were made in a reproduction/developmental toxicity screening study for HEMA.

Read-across to studies with the primary metabolites indicate no selective, relevant effects on reproduction and developmental toxicity studies in rats and rabbits.