Dimethyl malonate

Toxicity to reproduction

Administrative data

Endpoint:

screening for reproductive / developmental toxicity

Remarks:

based on test type (migrated information)

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Adopted according to OECD SIDS (publicly available peer reviewed source). Original document not available.

Data source

Reference

Reference 1

Reference Type:

study report

Title:

Unnamed

Year:

2003

Reference 2

Reference Type:

secondary source

Title:

SIDS Initial Assessment Report For SIAM 20 (Malonic Acid Diesters: Dimethylmalonate, 108-59-8; Diethylmalonate, 105-53-3), April 19-22, 2005 Paris.

Author:

OECD SIDS

Year:

2005

Bibliographic source:

UNEP Publications

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 422 (Combined Repeated Dose Toxicity Study with the Reproduction / Developmental Toxicity Screening Test)

Deviations:

no

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Dimethyl malonate

EC Number:

203-597-8

EC Name:

Dimethyl malonate

Cas Number:

108-59-8

Molecular formula:

C5H8O4

IUPAC Name:

dimethyl malonate

Details on test material:

Purity: 99.8%

Test animals

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Animals: HSDCpb-WU rats
- Age at study initiation: 11-12 weeks
- Weight at study initiation:
males: 377-379 g, females: 210-219 g

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

water

Details on exposure:

Males:
Test groups: 39 days, male recovery group: 39 exposure days, 45 test days.
Females:
Treatment groups: 51 +/- 7 days, recovery group: 39 exposure days, 45 test days.

Details on mating procedure:

- M/F ratio per cage: 1:1
- Length of cohabitation: Cohabitation period until evidence of pregnancy (sperm in vaginal smear) was observed.
- Proof of pregnancy: sperm in vaginal smear

Analytical verification of doses or concentrations:

not specified

Duration of treatment / exposure:

Premating exposure period: 2 weeks
exposure period: 39-51 days (from 14 days before mating to day 3 of lactation)

Males:
Test groups: 39 days, male recovery group: 39 exposure days
Females:
Treatment groups: 51 +/- 7 days, recovery group: 39 exposure days

Frequency of treatment:

once daily, 7 days a week

Doses / concentrations

Remarks:

Doses / Concentrations:
100, 300, 1000 mg/kg bw
Basis:
actual ingested

No. of animals per sex per dose:

Main group: 10 males, 10 females
Recovery groups: 5 males, 5 females

Control animals:

yes, concurrent vehicle

Examinations

Parental animals: Observations and examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule:
Twice daily: morbidity and mortality. Daily observations for appearance, behaviour, clinical signs and preterminal deaths. Females were observed for signs of difficult and pronlonged parturition.

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: once before exposure and at least once per week thereafter. Signs included were changes in skin, fur, eyes, mucous membranes, occurrence of secretions or excretions and autonomic activity, changes in gait, posture, response to handling, behavioural changes, difficult or
prolonged parturition.

BODY WEIGHT: Yes
- Time schedule for examinations:
Body weights were recorded at the beginning of the study, at least weekly thereafter and at termination. All dams were weighed on gestation days 0, 7, 14 and 20 and lactation days 0 and 4.

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study):
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes
- 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 data

OPHTHALMOSCOPIC EXAMINATION: No data

HAEMATOLOGY: Yes
- Time schedule for collection of blood: at the end of the pre-mating period and the recovery period
- Anaesthetic used for blood collection:No data
- Animals fasted: No data
- How many animals: 5 randomly selected males and females or each group.
- Standard haematological parameters checked

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: at the end of the pre-mating period and the recovery period
- Anaesthetic used for blood collection:No data
- Animals fasted: No data
- How many animals: 5 randomly selected males and females or each group.
- Standard clinical chemistry parameters checked

URINALYSIS: No data


NEUROBEHAVIOURAL EXAMINATION: Yes
- Time schedule for examinations: at the end of the dosing period for males and during the lactation period tor females
- Dose groups that were examined: each group
- Battery of functions tested:
handling observations, open field tests, sensory observations, neuromuscular observations and physiological observations (body temperature

Litter observations:

All pups from each litter were examined for any external deformities, litter size and sex distribution was determined. Pup weights were recorded on day 0 and 4. All pups were examined for malformations and subject to gross pathological examination. Pup survival index up to lactation day 4 was determined.

Postmortem examinations (parental animals):

Organ weights of liver, adrenals, kidneys, thymus, spleen, brain and heart were determined of 5 males and females of each group. Testes and epididymis weights of all adult males of each group were also determined.
Pathology: All adult animals and pups were examined for any structural abnormalities and pathological changes.
Histopathology: The following tissues of 5 males and females of the control and high dose group as well as all animals of the recovery and recovery control groups were examined microscopically: all gross lesions, brain, spinal cord, gastrointestinal tract, liver, kidney, adrenals, spleen, heart, thymus, thyroid, trachea, lungs, testes (fixed in Bouins fluid), epididymes (fixed in Bouins fluid), ovaries, uterus, seminal vesioles, coagulating glands, prostate, urinary bladder, axillary lymph nodes, mesenteric lymph nodes, sciatic nerve, femur with marrow, bone marrow smear. Stages of spermatogenesis and interstitial testicular structure in male gonads were determined additionally. Livers of 5 males and females in the mid and low dose groups and testes of 5 males of the mid and low dose groups were also examined.

Postmortem examinations (offspring):

Pathology: All adult animals and pups were examined for any structural abnormalities and pathological changes.

Reproductive indices:

Fertility index
Gestation index
Number of implantations
Number of corpora lutea
Percentage pre- and post implantation loss

Offspring viability indices:

Number of pubs born
Number of live litters
Mean litter size index
Mean viable litter size
No. of pubs alive on day 0
Live birth index
Sex ratio at birth (no of males/total number born x 100)
No of pups dead or cannibalised up to day 4

Results and discussion

Results: P0 (first parental generation)

Details on results (P0)

CLINICAL SIGNS AND MORTALITY
No test item related clinical signs were observed throughout the test and recovery period in any of the dose groups.

BODY WEIGHT AND WEIGHT GAIN
No treatment related effects on body weight and body weight gain were observed.

FOOD CONSUMPTION
No treatment related effects were observed.

HAEMATOLOGY
No treatment related effects were observed.

CLINICAL CHEMISTRY
No treatment related effects were observed.

NEUROBEHAVIOUR
No treatment related changes were observed.

ORGAN WEIGHTS
No treatment related effects were observed.

GROSS PATHOLOGY
No treatment related effects were observed.

HISTOPATHOLOGY:
1000 mg/kg bw: Livers of males and females showed a significantly increased incidence of hepatocellular hypertrophy. The change was considered reversible as the incidence was not significantly increased in the high dose recovery animals.
300 and 100 mg/kg bw: No treatment related changes of the liver were observed.
All other histopathological findings were not considered treatment related.

Effect levels (P0)

1

Dose descriptor:

NOAEL

Remarks:

maternal toxicity

Effect level:

300 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: Reversible hepatocellular hypertrophy.

2

Dose descriptor:

NOAEL

Remarks:

fertility

Effect level:

1 000 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: No treatment related effects have been observed.

Results: F1 generation

Details on results (F1)

Observations and necropsy findings on pups: No treatment related effects were observed.
Fertility indices for males and females were not statistically different from controls in all dose groups. In the low dose group post implantation loss and consequently the percentage of live pubs born was significantly reduced compared to controls (P <= 0.05). These changes were considered incidental and not treatment related as the effects were not observed at the higher dose groups. No statistical significant differences from controls were observed for the number of pregnancies, number littered, number of live litters, mean litter size, mean viable litter size, sex ratio at birth, number of pups dead at first observation or day 2 to 4, number of live pups on day 0, 3 and 4 and the associated survival indices, external abnormalities of life and dead pups at all dose levels.
A significantly higher percentage of male rats in the low dose group on day 4 was considered incidental and not treatment related as a similar change was not found in the higher dose groups.
The mean number and the mean weight of male and female (and both sexes combined) pups during different intervals of the lactation period were not statistically significantly different from controls except from a significantly lower (P <= 0.05) mean number of female pups on lactation day 4 in the low dose group which was considered incidental and not related to treatment. (For details see table 1 "Any other information on results incl. tables.)

Effect levels (F1)

Dose descriptor:

NOAEL

Remarks:

devlopmental

Generation:

F1

Effect level:

1 000 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: No treatment related effects have been observed.

Overall reproductive toxicity

Reproductive effects observed:

not specified

Any other information on results incl. tables

Table 1: Reproductive results and indices of various dose groups:

	Dose (mg/kg bw)
	0	100	300	1000
Fertility index (%)	100	100	100	100
Duration of gestation
Days ± SD	22±0.3	23±0.5	23±0.5	22±0.4
Gestation index (%)	100	100	100	100
Parturition (%)	100	100	100	100
Effects on sperm	No treatment related effects	No treatment related effects	No treatment related effects	No treatment related effects
Number of implantations
Number	12.3	11.8	12.0	11.6
%	88.1	84.7	88.9	88.6
Number of corpora lutea
Number	14.0	13.9	13.5	13.1
Percentage preimplantation loss	11.9	15.3	11.1	11.4
Percentage postimplantation loss	8.1	19.1	10.4	15.1
Number of pubs born	103	76	86	84
Number of live litters	9	8	8	8
Mean litter size index	11.4	9.5	10.8	10.5
Mean viable litter size	11.3	9.5	10.8	9.9
Number of pubs alive on day 0	102	76	86	79
Live birth index	99	100	100	94
Sex ratio at birth (Number of males/total number born x 100)	46.6	60.5	54.7	46.4
24 hour survival (%)	100	100	100	100
Number of pubs alive on day 4 of lactation	101	75	83	78
Day 4 survival index	99.0	98.7	96.5	98.7
Sex ratio day 4	44.7	60.5	53.5	41.7
Number of pups dead or cannibalised up to day 4	2	1	3	6