Dimethyl carbonate

Toxicity to reproduction

Administrative data

Endpoint:

one-generation reproductive toxicity

Remarks:

based on test guideline (migrated information)

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2007

Report date:

2007

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 415 [One-Generation Reproduction Toxicity Study (before 9 October 2017)]

Deviations:

no

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Dimethylcarbonate

IUPAC Name:

Dimethylcarbonate

Details on test material:

- Name of test material (as cited in study report): Dimethylcarbonate
- Substance type:
- Physical state: Colourless liquid
- Analytical purity: 99.99%
- Purity test date: 18 Mar 2002
- Lot/batch No.: 020225/7
- Expiration date of the lot/batch: 18 March 2007
- Stability under test conditions: Not stated
- Storage condition of test material: Room temperature
- Other:

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Harlan Italy s.r.l., San Pietro al Natisone (UD)
- Age at study initiation: Males 5-6 weeks; Females 8-9 weeks
- Weight at study initiation: Males: 133-154 g; Females: 198-222 g
- Fasting period before study:
- Housing:
During the pre-mating period, the animals were housed in clear polycarbonate cages measuring 59x39x20 cm with a stainless steel mesh lid and floor (Techniplast - Gazzada S.a.r.l. , Buguggiate, Varese). Each cage tray held absorbent material which was inspected and changed 3 times per week
During the mating period, the rats were housed on the basis of one male to one female in clear polycarbonate cages measuring 43x27x15 cm with a stainless steel mesh lid and floor (Techniplast Gazzada S.a.r.l.). Each cage tray held absorbent material which was inspected and changed daily.
The males were re-caged after mating as they were before mating. The females after mating were transferred to individual breeding solid bottomedcages 43x27x15 cm (Techniplast Gazzada S.a.r.l.). Suitable nesting material was provided and was changed as necessary.
- Use of restrainers for preventing ingestion (if dermal): yes/no
- Diet (e.g. ad libitum): A commercially available laboratory rodent diet (Altromin MT pelleted diet, Altromin, D32770 Lage, Postfach 1120, Germany) was offered ad libitum
- Water (e.g. ad libitum): Drinking water was supplied ad libitum to each cage via water bottles.
- Acclimation period: males 13 days, females 20 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22°C ± 2°C
- Humidity (%): 55% ± 15%
- Air changes (per hr): 15 to 20
- Photoperiod (hrs dark / hrs light): 12 hrs light/ 12 hrs dark


IN-LIFE DATES: From: 5 July 2002 To: 28 November 2002

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

water

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:

VEHICLE: Water
- Concentration in vehicle: 0.5, 5, 50 mg/mL
- Amount of vehicle (if gavage): 10 mL/kg body weight

Details on mating procedure:

- M/F ratio per cage: 1 to 1
- Length of cohabitation:
- Proof of pregnancy: sperm in vaginal smear
- After 21 days of unsuccessful pairing replacement of first male by another male with proven fertility.
- Further matings after two unsuccessful attempts: Not stated
- After successful mating each pregnant female was caged (how): Individual breeding solid bottomed cages 43x27x15 em (Techniplast Gazzada S.a.r.l.). Suitable nesting material was provided and was changed as necessary.
- Any other deviations from standard protocol:

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Before the start of the treatment, the proposed formulation procedures were checked by chemical analysis to confirm that the method was acceptable and to check the stability. Samples of the formulations prepared during the first and last week of the study were also analysed to check the concentration. Results of these analyses were within the limits of acceptance (95%-105% of the nominal concentration).

Duration of treatment / exposure:

Treatment commenced when the males are approximately 7 to 8 weeks old (Day 1 of the study) and continued for at least 10 weeks prior to mating and thereafter through the day prior to sacrifice.
Treatment commenced when the females were approximately 11 to 12 weeks old and continued for at least 2 weeks prior to pairing and thereafter through the day prior to sacrifice.

Frequency of treatment:

Daily

Details on study schedule:

- Age at mating of the mated animals in the study: males - 17 to 18 weeks; females - 13 to 14 weeks.

Doses / concentrations

Doses / concentrations 1

Remarks:

Doses / Concentrations:
5 mg/kg/day
Basis:
actual ingested
Dosed by oral gavage.

Doses / concentrations 2

Remarks:

Doses / Concentrations:
50 mg/kg/day
Basis:
actual ingested
Dosed by oral gavage.

Doses / concentrations 3

Remarks:

Doses / Concentrations:
500 mg/kg/day
Basis:
actual ingested
Dosed by oral gavage.

No. of animals per sex per dose:

24

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: Selected in consultation with the Sponsor, based on information from previous studies.
- Rationale for animal assignment (if not random): The rats were allocated to the groups by computerised stratified randomisation to give approximately equal initial group mean body weights.

Positive control:

No

Examinations

Parental animals: Observations and examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule:
- Examination of individual animals for signs of reaction to treatment was carried out daily, prior to dosing, immediately after dosing and 1 hour
after dosing.


DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Daily during treatment period


BODY WEIGHT: Yes
- Time schedule for examinations:
Males were weighed weekly from the first day of treatment to termination.
Females were weighed weekly from the first day of treatment to pairing and during
the mating period. After mating, the females were weighed on Days 0, 6, 10, 15 and 20 post-coitumand
on Days 0, 4, 7, 14 and 21 post-partum.

FOOD CONSUMPTION:
- Food consumption for each animal determined: Yes


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



OTHER:

Oestrous cyclicity (parental animals):

Vaginal smears were taken daily in the morning from the first day of treatment and up to the end of the mating period, until a positive identification of mating was made. The vaginal smear data was examined to determine the following:
a) anomalies of the oestrous cycle;
b) the pre-coital interval (i.e., the number of nights paired prior to the detection of mating).

Sperm parameters (parental animals):

Not recorded

Litter observations:

STANDARDISATION OF LITTERS
- Performed on day 4 postpartum: [yes/no] Yes
- If yes, maximum of 8 pups/litter (4 pups/sex/litter as nearly as possible); excess pups were killed and discarded.


PARAMETERS EXAMINED
The following parameters were examined in F1 offspring:
The total litter size (live and dead) was counted as soon as possible after parturition (Day 0 or 1 post-partum). Live pups were identified individually within the litter and sexed, weighed and examined for external abnormalities. All litters were examined daily for dead or abnormal young.


GROSS EXAMINATION OF DEAD PUPS:
All pups found dead were necropsied with the exception of those excessively cannibalised or autolysed.

Postmortem examinations (parental animals):

Organ Weights
The following organs from all males completing the scheduled test period were dissected free of fat and weighed:
Testes
Epididymides
Tissues Fixed and Preserved

The ratios of organ weight to body weight was calculated for each animal.
At the discretion of the pathologist, organs may be weighed from animals dying or killed prior to terminal kill.
Samples of all the tissues listed below from all parental animals were fixed and preserved in 10% buffered formol saline (except testes and epididymides which were fixed in Bouin's solution and all preserved in 70% ethyl alcohol).
Abnormalities (if found)
Ovaries
Uterus
Cervix
Vagina
Testes
Epididymides
Seminal vesicles
Prostate
Coagulating gland
Pituitary
Target organs (if identified)

Postmortem examinations (offspring):

GROSS NECROPSY
- Gross necropsy consisted of external and internal examinations

Statistics:

For the body weights , body weight gain, food consumption and organ weights the significance of the differences amongst group means was assessed by analysis of variance. Differences between each treated group and the control group were assessed by Dunnett's test using a pooled error of variance. The homogeneity of the data was assessed by Bartlett's Test before Dunnett's Test was performed. If the data were found to be inhomogeneous,a modified t test (Cochran and Cox) was applied.
The mean values, standard deviations and statistical analysis were calculated from actual values in the computer without rounding off.
The non-parametric Kruskal-Wallis analysis of variance was used for litter data, sex ratios , implantation, pre-weaning development and pre-birth loss data. Intergroup differences between the control and treated groups were assessed by the non-parametric version of the Williams test.
The criterion for statistical significance was p<0.05.

Reproductive indices:

The following reproductive indices were calculated for this study:
Males and females:
Copulatory index (%)=(Number of animals mated/number of animals paired) x 100
Fertility index (%) (males)=(Number of males which induced pregnancy/number of males mated) x 100
Fertility index (%) (females)=(number of pregnant females/number of females paired) x 100
Copulatory Interval = Mean number of days between pairing and mating
Females:
Pre-birth loss (%) = ((number of visible implantations- total litter size)/number of visible implantations) x 100
Pup loss at birth (%) = ((total litter size at birth - live litter at birth)/(Total litter size at birth)) x 100
Cumulative pup loss on Day 4 (%) = ((total litter size at birth-live litter size at day 4 before culling)/(total litter size at birth)) x 100

Offspring viability indices:

lactation index(%) was calculated:
(Number of pups surviving 21 days (weaned)/number of pups retained on day 4) x 100

Results and discussion

Results: P0 (first parental generation)

General toxicity (P0)

Clinical signs:

no effects observed

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

no effects observed

Organ weight findings including organ / body weight ratios:

no effects observed

Histopathological findings: non-neoplastic:

no effects observed

Other effects:

no effects observed

Reproductive function / performance (P0)

Reproductive function: oestrous cycle:

no effects observed

Reproductive function: sperm measures:

not examined

Reproductive performance:

no effects observed

Effect levels (P0)

Dose descriptor:

NOEL

Effect level:

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

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: Dimethylcarbonate did not induce negative effects on the developmend and behaviour of rat offspring.

Results: F1 generation

General toxicity (F1)

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:

no effects observed

Effect levels (F1)

Dose descriptor:

NOEL

Generation:

F1

Effect level:

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

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: No effects observed at the highest dose tested.

Overall reproductive toxicity

Reproductive effects observed:

not specified

Any other information on results incl. tables

One control male rat died for accidental trauma during the study. No macroscopic change was reported at necropsy in the examined organ/tissues of the animals killed at termination or the animal which died accidentally that could be considered related to the administration of the test item. The lesions observed were considered to be incidental or spontaneous in origin.

Applicant's summary and conclusion

Conclusions:

In this one-generation study, DIMETHYLCARBONATE at the dosages administered did not induce negative effects on male or female rats or on the development and behaviour of their offspring. On the basis of these results a dosage of 500 mg/kg/day can be judged as the NOEL.