Dimethyl succinate

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

1995

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Dibasic esters (DBE)

IUPAC Name:

Dibasic esters (DBE)

Details on test material:

- Name of test material: Dibasic esters
- Physical state: Liquid
- Analytical purity: >99.5%
- Composition of test material, percentage of components: Dimethyl glutarate - 65.12%; dimethyl succinate- 17.75%; dimethyl adipate - 16.83%

Test animals

Species:

rat

Strain:

Sprague-Dawley

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Breeding Laboratories Inc, Kingston, NY, USA
- Age on arrival: 63 days
- Weight on arrival: 146-198 g
- Fasting period before study: None
- Housing: Individually housed in stainless steel wire mesh cages
- Diet (e.g. ad libitum): Ad libitum except during exposure
- Water (e.g. ad libitum): Ad libitum except during exposure

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21 - 25 deg C
- Humidity (%): 40 - 60%
- Photoperiod (hrs dark / hrs light): 12 / 12

Administration / exposure

Route of administration:

inhalation: aerosol

Type of inhalation exposure (if applicable):

whole body

Vehicle:

unchanged (no vehicle)

Mass median aerodynamic diameter (MMAD):

>= 5.3 - <= 5.4 µm

Remarks on MMAD:

Particle size of 72 - 74% of generated aerosol < 10 micron

Details on exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: NYU style inhalation chamber
- Method of holding animals in test chamber: stainless steel "modules"
- Source and rate of air: Ambient air, rate not reported
- Method of conditioning air: Not reported
- System of generating particulates/aerosols: nebuliser
- Temperature, humidity, pressure in air chamber: Measured but not reported
- Air flow rate: Not reported
- Air change rate: Not reported
- Method of particle size determination: Cascade impactor
- Treatment of exhaust air: Not reported

TEST ATMOSPHERE
- Brief description of analytical method used: Mass concentration determined gravimetrically following trapping on glass fibre filters. Identity by GC analysis of solvent traps collecting both aerosol and vapour
- Samples taken from breathing zone: yes

VEHICLE (if applicable)
- Justification for use and choice of vehicle: None used

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Samples were analysed by gas chromatography (GC/FID). Isothermal separation at 1500 deg C on glass column packed with 10% SP-1000 on Chromosorb W-AW 100/120 mesh. The GC response of the samples was compared with that obtained from standard samples prepared by quantitative dilution of DBE in acetone to determine chamber concentration. The method permitted separation / identification of the 3 components to determine changes in composition

Details on mating procedure:

- Impregnation procedure: cohoused
- If cohoused:
- M/F ratio per cage: 1/1
- Length of cohabitation: Overnight
- Further matings after two unsuccessful attempts: Not reported
- Verification of same strain and source of both sexes: yes
- Proof of pregnancy: vaginal plug referred to as day 1 of pregnancy
- Any other deviations from standard protocol: No

Duration of treatment / exposure:

Daily during gestation days 7 - 16, 6 hours / day

Frequency of treatment:

Daily during gestation days 7 - 16, 6 hours / day

Duration of test:

21 days

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

0 mg/L air

Remarks:

control

Doses / concentrations 2

Dose / conc.:

0.16 mg/L air

Doses / concentrations 3

Dose / conc.:

0.4 mg/L air

Doses / concentrations 4

Dose / conc.:

1 mg/L air

No. of animals per sex per dose:

24

Control animals:

yes, sham-exposed

Details on study design:

- Dose selection rationale: Pilot study
- Rationale for animal assignment (if not random): Random following mating

Examinations

Maternal examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule:Daily

DETAILED CLINICAL OBSERVATIONS: No data

BODY WEIGHT: Yes
- Time schedule for examinations: Gestation days 1, 7, 9, 11, 13, 15, 17 and 21

FOOD CONSUMPTION: Yes - Feed was weighed on Gestation Days 1, 3, 9, 11, 13, 15, 17, 19 and 21.
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day 21
- Organs examined: Liver, ovaries (count of corpora lutea), uterus, pups

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:

- 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:

Incidence of pregnancy, clinical observations, maternal mortality – Cochran-Armitage test for linear trend, Fisher’s exact test
Maternal weight, maternal weight change, food consumption – ANOVA, Dunnet’s test
Live fetuses, dead fetuses, resorptions, nidations, corpora lutea, foetal weight, incidence of foetal alterations - Jonckheere’s test, Mann-Whitney U test.

Results and discussion

Results: maternal animals

General toxicity (maternal animals)

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

Perinasal staining and wet fur were seen in a number of animals of the 1.0 mg/L group (15 and 20 animals, respectively).
Perinasal staining was seen in 1 rat from the 0.16 mg/L group and in 4 rats from the 0.4 m/L group. Wet fur was seen in 1 rat from the 0.4 mg/L group.
Other observed clinical findings included alopecia, sores, periocular and facial staining, and swollen extremities. These were noted infrequently and with no suggestion of a dose-relationship.

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

Changes in body weight were reduced in rats exposed to either 0.4 or 1.0 m/L were reduced, This finding was not apparent in the mid-dose group (0.16 mg/L).

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

Reduced in the 0.4 and 1.0 mg/L group rats during the first 6 days of exposures.

Maternal developmental toxicity

Number of abortions:

no effects observed

Pre- and post-implantation loss:

no effects observed

Total litter losses by resorption:

no effects observed

Early or late resorptions:

no effects observed

Dead fetuses:

no effects observed

Changes in number of pregnant:

no effects observed

Details on maternal toxic effects:

Maternal toxic effects:yes

Details on maternal toxic effects:
Reduced food consumption and reduced body weight gain noted in mid and high dose groups (treated at 0.4 and 1.0 mg/L) during exposure period.
Reduced liver weight noted in mid and high dose groups (treated at 0.4 and 1.0 mg/L) on termination

Effect levels (maternal animals)

Dose descriptor:

NOAEC

Effect level:

1 mg/L air

Based on:

test mat.

Basis for effect level:

body weight and weight gain

clinical signs

food consumption and compound intake

Maternal abnormalities

Abnormalities:

no effects observed

Results (fetuses)

Reduction in number of live offspring:

no effects observed

Changes in litter size and weights:

no effects observed

External malformations:

no effects observed

Skeletal malformations:

no effects observed

Visceral malformations:

no effects observed

Details on embryotoxic / teratogenic effects:

Embryotoxic / teratogenic effects: no effects

Effect levels (fetuses)

Dose descriptor:

NOAEC

Effect level:

1 mg/L air

Based on:

test mat.

Sex:

not specified

Basis for effect level:

other: Lack of treatment-related effects in examined parameters

Fetal abnormalities

Abnormalities:

no effects observed

Overall developmental toxicity

Developmental effects observed:

no

Any other information on results incl. tables

Daily Dose (mg/L)	0	0.16	0.4	1.0
Dams/Does:         No. Pregnant         No. Corpora Lutea/dam         No. Implantations/dam	24 17.8 14.7	21 17.2 13.8	20 18.1 14.3	24 17.7 13.7
Litters:         No. Litters Evaluated         No. Live Foetuses         Mean Foetal Body Weight (g)         Foetal malformations (% / litter):              Gross External                                   Visceral Anomalies              Skeletal Anomalies         Foetal variations (% / litter):              Gross External                                   Visceral Anomalies              Skeletal Anomalies         Foetal variations due to retarded development         (% / litter):              Gross External                                   Visceral Anomalies              Skeletal Anomalies	24 326 3.36   0.0 1.1 0.6   7.4 4.5 15.9     0.0 0.0 30.5	21 265 3.55   0.3 3.1 1.7   4.3 1.3 8.0     0.0 0.0 27.7	20 263 3.32   0.0 0.7 0.4   14.9 2.0 19.0     0.0 0.0 25.2	24 300 3.35   0.3 5.1 3.4   11.7 4.2 21.4     0.0 0.0 31.7

Applicant's summary and conclusion

Conclusions:

The mixture, at the concentrations examined, does not cause developmental toxicity in the rat following inhalation exposure.

Executive summary:

The potential developmental toxicity arising from inhalation exposure to bibasic esters, a mixture of dimethyl succinate, dimethyl glutarate and dimethyl adipate has been investigated. Groups of pregnant rats were exposed to concentrations of the mixture of 0.16, 0.4 or 1.0 mg/L by inhalation daily for 6 hours/day from Day 7 through to Day 16 of gestation (Day 1 was designated as the day in which evidence of mating was detected). A control group of pregnant rats was exposed to air only. All animals were killed on gestation Day 21 and the foetuses examined.

 

Both food consumption and the rate of body weight gain was slightly reduced in the 2 higher exposure groups (0.4and 1.0 mg/L) during the first week of exposure. Necropsy examination revealed a reduction in liver weight in the 2 higher exposure groups. None of the parameters examined as markers of reproductive toxicity were affected by treatment and no foetal effects were apparent.

 

The mixture is regarded as not causing developmental toxicity in the rat following inhalation exposures at concentrations as high as 1.0 mg/L during the period of organogenesis.