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Developmental toxicity / teratogenicity

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Administrative data

Endpoint:
developmental toxicity
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2 Mar 1990 - 4 Jun 1990
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
test procedure in accordance with national standard methods with acceptable restrictions
Remarks:
NTP study

Data source

Referenceopen allclose all

Reference Type:
study report
Title:
Unnamed
Year:
1991
Reference Type:
publication
Title:
Evaluation of The developmental toxicity of methacrylamide an N,N'-Methylenebisacrylamide in Swiss mice.
Author:
George JD, Price C.J, Marr MC, Myers CB, Schwetz BA, Heindel JJ
Year:
1998
Bibliographic source:
Toxicological Sciences Vol 46: 124-133, first pesented at the 30th Annual Meeting of the Society of Toxicology, Dallas, TX [The Toxicologist, Vol 11: 343 (1991)]

Materials and methods

Test guideline
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 414 (Prenatal Developmental Toxicity Study)
Version / remarks:
NTP study
GLP compliance:
yes
Remarks:
FDA, 1988
Limit test:
no

Test material

Constituent 1
Chemical structure
Reference substance name:
Methacrylamide
EC Number:
201-202-3
EC Name:
Methacrylamide
Cas Number:
79-39-0
Molecular formula:
C4H7NO
IUPAC Name:
methacrylamide
Test material form:
solid
Specific details on test material used for the study:
- Supplier: Pfaltz & Baur Inc., Stamford
- Purity: 99 % (GC)
- RTI Lot-number: 5524-126-02

Test animals

Species:
mouse
Strain:
CD-1
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: Charles River Laboratories Inc., Raleigh, North Carolina, USA
- Age at study initiation: no data
- Weight at study initiation: maternal body weights ranged from 25.50 - 32.49 g on gd 0 while mean body weights/dose group ranged from
27.98 - 28.51 g
- Fasting period before study:
- Housing: individually housed in solid-bottom polycarbonate cages with stainless steel wire lids (Laboratory Products, Rochelle Park, NJ) and
Ab-Sorb-Dri cage litter (Laboratory Products, Garfield, NJ)
- Diet (e.g. ad libitum): Purina Certified Rodent Chow ad libitum
- Water (e.g. ad libitum): deionized filtered water ad libitum throughout gestation
- Acclimation period: 7 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22.22°C (original value: 72°F)
- Humidity (%): approximately 55%
- Air changes (per hr): no data
- Photoperiod: 12 hrs dark / 12 hrs light

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
water
Details on mating procedure:
- Proof of pregnancy: vaginal plug referred to as day 0 of pregnancy
Duration of treatment / exposure:
6th - 17th day of gestation
Frequency of treatment:
daily
Duration of test:
17 days
Doses / concentrationsopen allclose all
Dose / conc.:
30 mg/kg bw/day
Remarks:
After evaluation of replicate I data, the 30 mg/kg/day dose group was eliminated, since both the 30 and 60 mg/kg/day dose groups caused no effect
Dose / conc.:
60 mg/kg bw/day
Dose / conc.:
120 mg/kg bw/day
Dose / conc.:
180 mg/kg bw/day
No. of animals per sex per dose:
15-30 per dose group
Control animals:
yes, concurrent vehicle
Details on study design:
Sex: female

Examinations

Maternal examinations:

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: daily for clinical signs

BODY WEIGHT: Yes
- Time schedule for examinations: on the mornings of gd 0, 3, 6, 9, 12, 15, and 17

FOOD AND WATER CONSUMPTION: Yes
- Food and water consumption: on the mornings of gd 0, 3, 6, 9, 12, 15, and 17

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day 17
- Organs examined: The maternal body, liver, and intact uterus were weighted and corpora lutea were counted. Uteri which had no visible
implantation sites were stained with ammonium sulfide (10%) to detect very early resorptions (Salewski, 1964)
Fetal examinations:
Live fetuses were weighted, examined for external morphological abnomalities and dissected for visceral examination by a fresh tissue dissection
technique (Staples, 1974); Stuckhardt and Poppe, 1984). Half of the fetuses were decapitated prior to dissection; the heads were examined by a
free-hand sectioning technique (Wilson, 1965). All fetal carcasses were examined for skeletal malformations (Marr et al., 1988)
Statistics:
General Linear Models (GLM) procedures were applied for the analyses of variance (ANOVA) of maternal and fetal parameters (SAS Institute, 1985). Prior to GLM-ANOVA analysis, an arcsine-square root transformation was performed on all litter-derivived percentage data to normalize the means (Snedecor and Cochran, 1967) and Bartlett's test fot homogenicity of variance was performed on all data to be analyzed by ANOVA (Winer, 1962).GLM-ANOVA analysis determined the significance of dose-response relationships and the significance of dose effects, replicate effects and dose x replicate interactions.
Historical control data:
yes

Results and discussion

Results: maternal animals

General toxicity (maternal animals)

Clinical signs:
effects observed, non-treatment-related
Description (incidence and severity):
Effects observed in rnaternal animals during and after exposure to 0, 60, 120, or 180 rmg/kg/day of methacrylamide included swollen eye, swollen tail, rough coat, weight lass, and vaginal bleeding. The swollen eye and one instance of vaginal bleeding occurred in the control group, whereas the swollen tail was due to the tattooing procedure, and thus were not treatment-related
Dermal irritation (if dermal study):
not examined
Mortality:
mortality observed, non-treatment-related
Description (incidence):
Lethality occurred at 0 (1 animal), 120 (1 anirmal), and 180 (1 animal) mg/kg/day from indeterminant causes.
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
Weight loss after the onset of dosing occurred in 1-2 animals in the control group (gd 7, 8, and 9), 1-3 animals in the 120 mg/kg/day group (gd 7, 8, and 17), and 1-2 animals in the 180 mg/kg/day dose groups (gd 7,8, 9, 10, 14, and 16), and thus seemed slightly more persistent in the high dose group.
Maternal body weight on gd 17(before and after euthanasia), and maternal weight gain during treatment ·and gestation were significantly depressed in the high dose group, compared to the control group.
Food consumption and compound intake (if feeding study):
no effects observed
Description (incidence and severity):
Maternal food consumption was calculated for the intervals of gd 0 to 3, 3 to 6, 6 to 9, 9 to 12, 12 to 15, 15 to 17, 6 to 17, and 0 to 17. Relative (g/kg body weight/day) food intake did not differ noticeably between dosed groups and the controls, exhibiting only an increasing trend on gd 12 to 15
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
no effects observed
Description (incidence and severity):
Maternalwater consumption was calculated for the intervals of gd 0 to 3, 3 to 6, 6 to 9, 9 to 12, 12 to 15, 15 to 17, 6 to 17, and 0 to 17. Maternal water consumption was unaffected by treatment.
Ophthalmological findings:
not examined
Haematological findings:
not examined
Clinical biochemistry findings:
not examined
Urinalysis findings:
not examined
Immunological findings:
not examined
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Description (incidence and severity):
At necropsy on gd 17, animals from the 180 mg/kg/day methacrylamide-exposed group had significantly reduced gravid uterine weight; relative maternal liver weight (% body weight) exhibited a dose-related increase, and was significantly increased at both the 120 and 180 mg/kg/day dose levels, although absolute liver weight was not affected.
Gross pathological findings:
effects observed, non-treatment-related
Description (incidence and severity):
Effects observed in maternal animals during and after exposure to 0, 60, 120, or 180 mg/kg/day of MAC included swollen eye, swollen tail, rough coat, weight lass, and va~inal b]eeding. The swollen
eye and one instance of vaginal bleeding occurred in the control group, whereas the swollen tail was due to the tattooing procedure, and thus were not treatment-related.
Neuropathological findings:
no effects observed
Description (incidence and severity):
No signs of neurotoxicity were observed
Histopathological findings: non-neoplastic:
not examined
Histopathological findings: neoplastic:
not examined

Maternal developmental toxicity

Number of abortions:
effects observed, treatment-related
Description (incidence and severity):
All of the pregnant animals in the 0, 60, and 120 mg/kg/day methacrylamide-treated groups had one or more live fetuses, whereas only 89% (25/28) of the confinned-pregnant animals in the 180 mg/kg/day group had one or more live fetuses.
Pre- and post-implantation loss:
effects observed, treatment-related
Description (incidence and severity):
The percent nonlive implants per litter exhibited a dose-related increasing trend, with the high dose group significantly increased over the control group
Total litter losses by resorption:
effects observed, treatment-related
Description (incidence and severity):
In the high-dose group, 3 dams had totally resorbed litters (9%) while there were none in the other dose groups or control.
Early or late resorptions:
effects observed, treatment-related
Description (incidence and severity):
The percent of litters with resorptions (Ctrl 37%, 60 mg 40%, 120 mg 48% and 180 mg 50%) , or nonlive implants (late fetal deaths plus implants; Ctrl 38%, 60 mg 43%, 120 mg 48% and 180 mg 61%) exhibited dose-related increasing trends.
Dead fetuses:
no effects observed
Changes in pregnancy duration:
not specified
Changes in number of pregnant:
effects observed, non-treatment-related
Description (incidence and severity):
At necropsy on gd 17, 93% (27), 100% (30), 93% (27), and 97% (28) of the mated animals in the control through high-dose groups were confirmed to be pregnant by uterine examination.
Other effects:
no effects observed
Description (incidence and severity):
no effects observed on
- av. number of corpora lutea/dam
- number of impantation sites/litter
- percent preimplantation loss/litter
- percent resorptions/litter
- percent late fetal deaths/litter
- percent of litters with late fetal death
- number of live fetuses/ live litters

Effect levels (maternal animals)

Dose descriptor:
NOAEL
Remarks:
maternal toxicity
Effect level:
60 mg/kg bw/day
Based on:
test mat.
Basis for effect level:
organ weights and organ / body weight ratios

Maternal abnormalities

Abnormalities:
no effects observed

Results (fetuses)

Fetal body weight changes:
effects observed, treatment-related
Description (incidence and severity):
Analysis of fetal body weight data showed the existence of a significant decreasing trend for mean fetal weight (male, female, or both) per litter, with both the 120 and 180 mg/kg/day dose groups significantly below the control group by approximately 7 and 15%, respectively
Reduction in number of live offspring:
effects observed, treatment-related
Description (incidence and severity):
At 180 mg/kg bw/d, increased postimplantation death per litter was observed.
Changes in sex ratio:
no effects observed
Changes in litter size and weights:
effects observed, treatment-related
Description (incidence and severity):
Analysis of fetal body weight data showed the existence of a significant decreasing trend for mean fetal weight (male, female, or both) per litter, with both the 120 and 180 mg/kg/day dose groups significantly below the control group by approximately 7 and 15%, respectively
Changes in postnatal survival:
not specified
External malformations:
no effects observed
Description (incidence and severity):
Although there were no statistically significant effects from MAC exposure, the percent of malformed fetuses per litter was noticeably higher than expected in all groups, including the vehicle control group (i.e., 16-21% malformed/ litter as compared to 2.9% malformed litter in 234 historical control litters)
Skeletal malformations:
no effects observed
Visceral malformations:
no effects observed
Details on embryotoxic / teratogenic effects:
Embryotoxic / teratogenic effects:no effects

Effect levels (fetuses)

open allclose all
Dose descriptor:
NOAEL
Remarks:
fetotoxicity
Effect level:
60 mg/kg bw/day
Based on:
test mat.
Sex:
male/female
Basis for effect level:
fetal/pup body weight changes
Dose descriptor:
NOAEL
Remarks:
teratogenicity
Effect level:
180 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male/female
Remarks on result:
other: no effects observed

Fetal abnormalities

Abnormalities:
no effects observed

Overall developmental toxicity

Developmental effects observed:
yes
Lowest effective dose / conc.:
120 mg/kg bw/day (nominal)
Treatment related:
yes
Relation to maternal toxicity:
developmental effects as a secondary non-specific consequence of maternal toxicity effects

Any other information on results incl. tables

Results:
Symptoms: at 30 - 60 mg/kg/d: no adverse effects.
          at 120 mg/kg/d: slight maternal effects, and clear evidence of fetal toxicity observed as a decrease in mean fetal body 
          weight per litter.
          at 180 mg/kg/d: mild maternal effects, observed as an increase in relative liver weight, and clear evidence of fetal toxicity, 
          observed as an increased proportion of dead implants per litter, and decreased mean fetal body weight per litter; no external, visceral 
          and skeletal malformations of the fetuses.

Applicant's summary and conclusion

Conclusions:
In this developmental toxicity study, the NOAEL for fetal toxicity was considered to be 60 mg/kg/day because mean fetal body weight was reduced.
Executive summary:

In a developmental toxicity study (according to OECD 414) Methacrylamide (99%) was administered to female Swiss CD-1 mice/dose in deionised water by gavage at dose levels of 0, 30, 60, 120, and 180 mg/kg bw/day from days 6 through 17 of gestation.

Maternal toxicity:

No treatment-related maternal mortality was observed.

180 mg/kg/day:

Maternal body weight on GD17, maternal weight gain during treatment and gestation, and corrected maternal weight gain was decreased

Gravid uterine weight was decreased

120 mg/kg/day:

Relative maternal liver weight was increased at 120 mg/kg/day and higher;

60 mg/kg/d:

The maternal NOAEL is 60 mg/kg bw/day. 

Fetal toxicity:

180 mg/kg/day:

At 180 mg/kg/day, increased postimplantation death per litter and decrease in mean fetal body weight (-15%) were observed.

120 mg/kg/day:

Significant, but weak mean fetal body weight was observed at 120 mg/kg/day (-7%).

60 mg/kg/d

The NOAEL for fetal toxicity is 60 mg/kg bw/day.

Teratogenicity:

No effects observed.

The NOAEL for teratogenicity is 180 mg/kg bw/day.