Acrylamide

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

January 27 - March 10, 1987

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Well documented report of a guideline study conducted to GLP.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1988

Report date:

1988

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

Deviations:

not specified

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Acrylamide

EC Number:

201-173-7

EC Name:

Acrylamide

Cas Number:

79-06-1

Molecular formula:

C3H5NO

IUPAC Name:

prop-2-enamide

Details on test material:

- Name of test material (as cited in study report): Acrylamide
- Substance type: organic
- Physical state: crystalline solid
- Analytical purity:95%
- Impurities (identity and concentrations): no data
- Composition of test material, percentage of components: 100%
- Purity test date: April 1987
- Lot/batch No.: 085F0006
- Expiration date of the lot/batch: no data
- Stability under test conditions: stable
- Storage condition of test material: under refigeration in amber screw-cap bottles

Test animals

Species:

rat

Strain:

Sprague-Dawley

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratories
- Age at study initiation: no data
- Weight at study initiation: 201-263 g
- Fasting period before study: no
- Housing: 1 per cage
- Diet: Purina 502 ad libitum
- Water: ad libitum
- Acclimation period: 7 days
ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22°C
- Humidity (%): 48-49%
- Air changes (per hr):12-14 per hour
- Photoperiod (hrs dark / hrs light): 12:12 (0700-1900)
IN-LIFE DATES: January 27 - March 18, 1987

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

water

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
VEHICLE
- Concentration in vehicle: 0, 0.5, 1.5 and 3 mg/ml
- Amount of vehicle (if gavage): 5 ml/kg

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

IR, UV, MS, NMR and TLC and GC, KF conducted on receipt of test article and following completion of study

Details on mating procedure:

- Impregnation procedure: cohoused
- Proof of pregnancy: sperm positive referred to as GD0

Duration of treatment / exposure:

Gestational days 6 to 20

Frequency of treatment:

Once/day

Duration of test:

20 days

Doses / concentrations

Remarks:

Doses / Concentrations:
0, 2.5, 7.5 and 15 mg/kg
Basis:
analytical conc.

No. of animals per sex per dose:

Groups of 29-30

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: based on preliminary study
- Rationale for animal assignment: body weight

Examinations

Maternal examinations:

Animals were observed daily for clinical signs.
CAGE SIDE OBSERVATIONS: No data
DETAILED CLINICAL OBSERVATIONS: Yes (neurotoxicty)
- Time schedule: daily up to GD6 the twice daily
BODY WEIGHT: Yes
- Time schedule for examinations: daily
POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day #20
- Organs examined: uterus

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

Fetal examinations:

Fetuses were thoroughly examined macroscopically for visceral and skeletal abnormalities (including the head).
- External examinations: Yes: all per litter
- Soft tissue examinations: Yes: half per litter
- Skeletal examinations: Yes: half per litter
- Head examinations: Yes: half per litter

Statistics:

GLM procedures were applied for the ANOVA of maternal and fetal parameters. GLM analysis determined the significance of dose-response relationships and the significance of dose effects, replicate effects and dose x replicate interactions. If the ANOVA was significant, William’s or Dunnett’s Multiple Comparison Tests compared ACRL exposed to control groups. One tailed tests were used for all pairwise comparisons except maternal body and organ weights and fetal body weight. Nominal scale measures were analysed by chi square test for independence and by a test for linear trend on proportions. When a chi square showed significant group differences, a one-tailed Fisher’s exact probability test was used for pairwise comparisons of ACRL and control groups

Indices:

Percent foetuses malformed per litter, percent litters with malformed foetuses, percent foetuses with variations per litter, percent litters with variations, percent foetuses with extra ribs per litter, percent litters with extra ribs

Historical control data:

Percent litters with 1 or more:
- malformed foetuses: 22.9
- non-live implants: 33.8
- dead foetuses: 1.1
- resorptions: 33.2
Percent malformed foetuses: 3.2

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:

Maternal toxic effects:yes

Details on maternal toxic effects:
There were no maternal mortalities and no clear clinical signs of toxicity. When corrected for gravid uterine weight, maternal body weight gain was decreased amongst animals receiving 7.5 and 15 mg/kg/day (12% and 18% reductions respectively).

Effect levels (maternal animals)

1

Dose descriptor:

NOAEL

Effect level:

2.5 mg/kg bw/day

Based on:

test mat.

Basis for effect level:

other: maternal toxicity

2

Dose descriptor:

NOAEL

Effect level:

15 mg/kg bw/day

Based on:

test mat.

Basis for effect level:

other: developmental toxicity

Results (fetuses)

Details on embryotoxic / teratogenic effects:

Embryotoxic / teratogenic effects:no effects

Details on embryotoxic / teratogenic effects:
There were no apparent effects on embryo/fetal viability, growth or malformations. There was a slight, but not statistically significant, increase in the incidence of skeletal variations (percentage of litters with variations - 61% in controls, 92% at 15 mg/kg/day, and percentage of foetuses with variations per litter - 14% in controls, 24% at 15 mg/kg/day). The most frequently observed variation was the presence of a rudimentary extra lumbar rib. This finding is considered likely to be an indirect consequence of maternal toxicity or stress and is of limited toxicological importance.

Fetal abnormalities

Abnormalities:

not specified

Overall developmental toxicity

Developmental effects observed:

not specified

Any other information on results incl. tables

DEVELOPMENTAL TOXICITY IN PREGNANT CD RATS FOLLOWING MATERNAL EXPOSURE TO ACRYLAMIDE BY GAVAGE ON GESTATIONAL DAYS 6 THROUGH 20
	Acrylamide (mg/kg/day, po)
	0	2.5	7.5	15
All litters^a	23	26	26	24
No. implantation sites per litter	13.5±0.9	14.6±0.8	14.8±0.7	14.5±0.8
% resorptions per litter	3.4±1.4	3.2±1.4	3.7±1.6	2.0±0.9
% litters with resorptions	30.4	26.9	26.9	20.8
Live litters^b
No. live foetuses per litter	13.0±0.9	14.1±0.8	14.2±0.6	14.3±0.8
Average male foetal body weight (g) per litter	3.72±0.17	3.44±0.12	3.38±0.14	3.52±0.12
Average female foetal body weight per litter (g)	3.44±0.13	3.29±0.11	3.20±0.13	3.29±0.11
% foetuses malformed per litter	0.3±0.3	1.7±0.6	0.2±0.2	0.8±0.6
% litters with malformed foetuses	4.4	23.1	3.8	8.3
% foetuses with variations per litter	14.3±3^+	16.5±3.6	18.3±4.5	24.0±3.9
% litters with variations	60.9^+	69.2	73.1	91.7
% foetuses with extra ribs per litter^c	11.1±3.6	11.1±2.9	13.5±4.5	16.4±4.0
% litters with extra ribs	47.8	57.7	53.8	70.8

 

a Includes all dams pregnant at termination; litter size = No. implantation sites per dam; means ± SE.

b Includes only dams with live foetuses; litter = No. live foetuses per dam; means ± SE.

c Includes foetuses with one or more rudimentary or full extra lumbar rib.

+ Linear trend test,p< 0.05.

Applicant's summary and conclusion

Conclusions:

2.5 mg/kg/d was considered to be the NOAEL for maternal toxicity (reduced body weight gain) and 15 mg/kg/d was considered to be the NOAEL for developmental toxicity.