methyl acrylate; methyl propenoate

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study comparable to current guidelines

Data source

Reference

Reference Type:

publication

Title:

Relative Developmental Toxicities of Acrylates in Rats following Inhalation Exposure.

Author:

Saillenfait AM et al.

Year:

1999

Bibliographic source:

Toxicol. Sciences 48: 240-254

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

GLP compliance:

not specified

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Methyl acrylate

EC Number:

202-500-6

EC Name:

Methyl acrylate

Cas Number:

96-33-3

Molecular formula:

C4H6O2

IUPAC Name:

methyl prop-2-enoate

Details on test material:

- Test substance: Methyl acrylate
- Analytical Purity: > 99 %
- Supplier: Fluka Chemie AG (Buchs, Switzerland)

Test animals

Species:

rat

Strain:

Sprague-Dawley

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: IFFA CREDO Breeding Laboratories (Saint-Germain-sur-l' Arbresle, France)
- Age at study initiation: Young, nulliparous females
- Weight at study initiation: 200-220 g
- Housing: Single in clear polycarbonate cages with stainless-steel wire lids and hardwood shaving as bedding.
- Diet: Food pellets (UAR Alimentation Villemoisson, France), ad libitum
- Water: Filtered tap water, ad libitum


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21 ± 2
- Humidity (%): 50 ± 5
- Photoperiod (hrs dark / hrs light): 12 hrs dark/12 hrs light

Administration / exposure

Route of administration:

inhalation: vapour

Type of inhalation exposure (if applicable):

whole body

Vehicle:

unchanged (no vehicle)

Details on exposure:

EXPOSURE
Exposures were conducted in 200-L glass/stainless-steel inhalation chambers with dynamic and adjustable laminar air flow (6-20 m3/h). The chamber temperature was set at 23 ± 2°C, and the relative humidity at 50 ± 5 %. The air-flow rate passed through the fritted disk of a heated bubbler containing the test chemical. Concentrations of acrylate ester were monitored continuously with a gas-chromatograph equipped with a flame ionization detector and an automatic gas-sampling valve. In addition, exposure levels were determined once during each 6-h exposure period by collecting atmosphere samples through glass tubes packed with activated charcoal. The charcoal samples were then desorbed with carbon disulfide. The resulting samples were analyzed by gas chromatography using appropriate internal standards. Since 2-EHA has a rather low vapour pressure (0.14 mm Hg at 20 °C), the presence of liquid particles was evaluated at the highest concentration generated (i.e. 100 ppm). Airborn particles were measured with an Aerodynamic Particle Sizer.
No differences in particle counts were observed between the clean filtered air (control) and the vapor-laden air in the exposure chambers.


GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Glass/stainless-steel inhalation chambers
- Source and rate of air: Test atmospheres were generated through an additional air-flow  rate passed through the fritted disk of a heated bubbler containing ethylhexyl acrylate.  The vaporized compound was introduced into the main air inlet pipe of the exposure chamber.
- Air flow rate: 6-20 m3/h


TEST ATMOSPHERE
- Brief description of analytical method used: GC/FID
- Samples taken from breathing zone: yes

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Analytical concentrations (mean ± SD):
25.1 ± 2.2 ppm (nominal: 25 ppm)
49.7 ± 2.1 ppm (nominal: 50 ppm)
100.4 ± 4.4 ppm (nominal: 100 ppm)

Details on mating procedure:

- Impregnation procedure: cohoused
- If cohoused:
- M/F ratio per cage: 1/2-3
- Length of cohabitation: Overnight
- Proof of pregnancy: sperm in vaginal smear referred to as day 0 of pregnancy

Duration of treatment / exposure:

day 6-20 of gestation

Frequency of treatment:

6h /day

Duration of test:

until gestation day 21

No. of animals per sex per dose:

20

Control animals:

yes, sham-exposed

Details on study design:

- Dose selection rationale:
Exposure concentrations were based on preliminary studies in which severe maternal toxicity (i.e., weight loss during GD 6-13 and pronounced reduction in weight gain during GD 13-21) was observed at 200 ppm methyl acrylate. Maternal mortality also occurred at 200 ppm methyl acrylate.

Examinations

Maternal examinations:

BODY WEIGHT: Yes
- Time schedule for examinations: On gestation day (GD) 0, 6, 13 and 21.


FOOD CONSUMPTION: YES
Food consumption was measured for the intervals GD 6-13 and 13-21.


POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day 21
- Organs examined: The uteri were removed and weighed. The number of implantation sites, resorptions, and dead and live fetuses were recorded.

Ovaries and uterine content:

The ovaries and uterine content was examined after termination: Yes
The number of implantation sites, resorptions, and dead and live fetuses were recorded. Uteri which had no visible implantation sites were stained with ammonium sulfide (10 %) to detect very early resorptions.

Examinations included:
- Gravid uterus weight: Yes
- Number of corpora lutea: No data
- Number of implantations: Yes
- Number of early resorptions: Yes
- Number of late resorptions: Yes

Fetal examinations:

Live fetuses were weighed, sexed, and examined for external anomalies including those of the oral cavity. Half of the live fetuses from each litter were preserved in Bouin's solution and examined for internal soft tissue changes. The other half were fixed in ethanol (70 %), eviscerated, and then processed for skeletal staining with alizarin red S for subsequent skeletal examination.

- External examinations: Yes: all per litter
- Soft tissue examinations: Yes: half per litter
- Skeletal examinations: Yes: half per litter
- Head examinations: Yes: all per litter

Statistics:

Data were presented as mean ± SD. The number of  implantation sites and live fetuses and the various body weights were analyzed by one-way analysis of variance (ANOVA), followed by Dunnett's test if differences were found. The percentages of non-live  implants and  resorptions and the proportions of fetuses with alterations in each litter were evaluated by using the Kruskal-Wallis test, followed by the Dixon-Massey test where appropriate. Rates of pregnancy, fetal sex ratio, and percentage of litters with malformations or external, visceral, or skeletal variations were analyzed by using Fisher's test. Where applicable, least-squares analysis was carried out. For all statistical tests, the level of significance was set a priori at alpha = 0.05.

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:

Maternal toxic effects:yes

Details on maternal toxic effects:
Exposure to methyl acrylate up to 100 ppm did not cause maternal death. Significant decrease in maternal weight gain and in food consumption were observed at 50 and 100 ppm during the entire exposure period. Exposure to 50 or 100 ppm was associated with maternal weight loss when gravid uterus weights were substracted from body weight gain.

Effect levels (maternal animals)

Dose descriptor:

NOAEC

Effect level:

ca. 0.089 mg/L air (nominal)

Basis for effect level:

other: maternal toxicity

Results (fetuses)

Details on embryotoxic / teratogenic effects:

Embryotoxic / teratogenic effects:yes

Details on embryotoxic / teratogenic effects:
No significant effect on the implantation sites, live fetuses, incidence of non-live implants and resorptions, or on fetal sex ratio was discerned in any of the groups exposed to methyl acrylate. Methyl acrylate induced a concentration-related decrease in fetal body weights that achieved significance at 100 ppm (17 % lower than control). There were no statistical significant increases in the incidences of external, visceral, or skeletal variations in any treatment group relative to control. A single case of malformation (one fetus with craniorachischisis and multiple skeletal malformation) was observed at 100 ppm.

Effect levels (fetuses)

1

Dose descriptor:

NOAEC

Effect level:

>= 0.357 mg/L air (nominal)

Basis for effect level:

other: teratogenicity

2

Dose descriptor:

LOAEC

Effect level:

ca. 0.357 mg/L air (nominal)

Basis for effect level:

other: fetotoxicity

Fetal abnormalities

Abnormalities:

not specified

Overall developmental toxicity

Developmental effects observed:

not specified

Any other information on results incl. tables

Maternal body weights:

Concentration [ppm/6h/d]	Maternal body weight GD 6 [g]	Absolute weight gain [g]
0	277 ± 20	30 ± 14
25	279 ± 21	26 ± 20
50	284 ± 20	-8 ± 21**
100	282 ± 21	-40 ± 36**

Absolute weight gain: (Day 21 body weight) - (gravid uterus weight) - (Day 6 body weight)

Reproductive parameters:

Conc. [ppm/6h/d]	No. of litters	No. of implantation sites/litter	% of non-live implants/litter	% of resorption sites/litter	No. of live fetuses/litter	Average fetal body weight/litter [g]
0	25	14.64 ± 2.69	12.82 ± 20.15	12.82±20.15	12.96 ± 4.16	5.69 ± 0.42
25	21	15.81 ± 2.94	8.49 ± 13.61	8.49 ± 13.61	14.52 ± 3.70	5.60 ± 0.29
50	23	15.13 ± 2.94	7.34 ± 11.11	7.34 ± 11.11	14.04 ± 3.25	5.31 ± 0.50
100	23	15.52 ± 2.09	5.69 ± 5.71	5.15 ± 4.96	14.61 ± 1.97	4.73 ± 0.89*

 

Concentration [ppm/6h/d]	0	25	50	100
Mean % of fetuses with:
- any malformations/litter	0	0	0	0.29 ± 1.39
- external variations/litter	0.36 ± 1.82	0	0	0
- visceral variations/litter	5.37 ± 14.27	4.76 ± 12.17	2.33 ± 5.21	5.37 ± 20.91
- skeletal variations/litter	19.68 ± 22.28	16.55 ± 21.01	14.24 ± 16.44	18.45 ± 26.44
- any variations/litter	12.87 ± 16.01	10.95 ± 12.60	8.21 ± 7.78	11.82 ± 15.12

* ,** Significant differences from the control (0 ppm) value, p 0.05, and p 0.01, respectively.