Hydrocarbons, C13-16

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

May 29, 1995 to June 29, 1995.

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Some deviations such as the treatment period (from GD6 to GD15 instead of GD5 to GD15 mentioned in OECD guideline 414).

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

reference to same study

Cross-reference 2

Reason / purpose for cross-reference:

reference to other study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1996

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

Deviations:

yes

Remarks:

females were dosed from Gestation Day (GD) 6 instead of GD 5; Administration volume 5 mL/kg (instead of 4mL/kg max).

Principles of method if other than guideline:

Guideline study

GLP compliance:

not specified

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

C16-C20 n-alkanes, isoalkanes, cyclics, <2% aromatics

IUPAC Name:

C16-C20 n-alkanes, isoalkanes, cyclics, <2% aromatics

Details on test material:

- Name of test material (as cited in study report): Exxsol D130 - Study code: MRD-94-976
- Substance type: Hydrocarbon fluid
- Physical state: colorless liquid
- Analytical purity: considered as "pure" material
- Lot/batch No.: 112094
- Expiration date of the lot/batch: March 2000
- Storage condition of test material: Room temperature

Test animals

Species:

rat

Strain:

Crj: CD(SD)

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratories, Kingston Facility, New York.
- Age at study initiation: females were approximately 10 weeks at GD 0
- Weight at study initiation: 216 to 295 g at GD 0
- Housing: Single housed during the study period, except during mating
- Diet: Certified Rodent Diet (5002 meal), ad libitum
- Water: ad libitum (Elizabethtown Water company)
- Acclimation period: 14 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 - 24.4°C
- Humidity (%): 40 - 70%
- Air changes (per hr): Not mentioned
- Photoperiod: 12 hrs dark / 12 hrs light


IN-LIFE DATES: From: To:

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on exposure:

VEHICLE
- Amount of vehicle (if gavage): 5 mL/kg
- Lot/batch no. (if required): OCT1295B
- Supplier: Best Foods, CPC International

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

At analytical chemistry analysis, excellent uniformity was observed. The percent relative standard deviation (%RSD) ranged from 1.43% to 2.97%. Stability data indicated that the test material was stable in corn oil at ambient temperature for at least 13 days. Concentration verification analysis indicated that the solution in corn oil was within 12% of the nominal concentrations for Week 1 and Week 3.

Details on mating procedure:

- M/F ratio per cage: 1:1 (male:female) ratio
- Length of cohabitation: one night
- Proof of pregnancy: Mating was confirmed by observation of a copulatory plug (vaginal) and/or by the presence of sperm in a vaginal rinse. The day on which mating was confirmed was the female's Day 0 of gestation (GD 0).

Duration of treatment / exposure:

from Gestation Day (GD) 6 through GD 15

Frequency of treatment:

Once daily

Duration of test:

Inlife test period: May 29, 1995 to June 29 1995.

Doses / concentrations

Remarks:

Doses / Concentrations:
0, 400, 800 and 1000 mg/kg/day
Basis:
other: ingested doses

No. of animals per sex per dose:

25 females/dose

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: Doses were selected based on a rangefinding study with Exxsol D130. Results of this study indicated no overt or consistent signs of toxicity at 1000 mg/kg (the limit dose for developmental studies) (OECD, 1981).
- Rationale for animal assignment (if not random): sequential Physical Identification Number

Examinations

Maternal examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: at least twice daily during the treatment period, otherwise at least once daily.

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: prior the selection and daily during gestation

BODY WEIGHT: Yes
- Time schedule for examinations: on GD 0, 6, 9, 12, 15, 18, and 21

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day 21
- Organs examined: All females assigned to groups were examined by gross necropsies.

OTHER:

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:

Statistical treatment of the results was conducted where appropriate. Statistical evaluation of equality of means was done by an appropriate one way analysis of variance and a test for ordered response in the dose groups. First, Bartlett's Test was performed to determine if the dose groups had equal variance . If the variances were equal, the testing was done using parametric methods (ANOVA + Dunnett's), otherwise nonparametric techniques were used (Kruskl-Wallis + Dunn's Summed Rank Test).
Fetal malformation and variation incidence data were analyzed for statistical significance as follows: First, a standard chi-square analysis was performed to determine if the proportions of incidences differ between the groups tested. Next, each treatment group was compared to the control group using a 2 x 2 Fisher Exact Test.

Indices:

Maternal data:
Percentage of pre-implantation loss
Percentage of post-implantation loss

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:

Maternal toxic effects:no effects

Details on maternal toxic effects:
No maternal toxic effects.

Effect levels (maternal animals)

1

Dose descriptor:

NOAEL

Effect level:

> 1 000 mg/kg bw/day (nominal)

Basis for effect level:

other: maternal toxicity

2

Dose descriptor:

NOAEL

Effect level:

> 1 000 mg/kg bw/day (nominal)

Basis for effect level:

other: developmental toxicity

Results (fetuses)

Details on embryotoxic / teratogenic effects:

Embryotoxic / teratogenic effects:yes

Details on embryotoxic / teratogenic effects:
There were statistically significant differences in individual skeletal variations, but were limited to an increase in the incidence of rudimentary lumbar ribs in the 400 mg/kg dose group (14.2%) compared with controls (4.2%) on a per fetus basis. This increased incidence was within the historical control range of this laboratory (3.7-28.8), greater than that observed at higher doses, and thus, not considered biologically important.
The statistically significant increases in the total fetuses with skeletal variations in the 400 mg/kg dose groups were directly driven by the increased incidence of rib variations and thus, were similarly considered as biologically unimportant (within HC range).

Fetal abnormalities

Abnormalities:

not specified

Overall developmental toxicity

Developmental effects observed:

not specified

Any other information on results incl. tables

No remarks

Applicant's summary and conclusion

Conclusions:

In conclusion, overt signs of maternal toxicity were not apparent at any dose tested, as indicated by the absence of adverse clinical or postmortem findings or effects on body weight, food consumption, and/or uterine implantation data. Similarly, there were no treatment-related adverse effects on fetal development or growth observed at any dose level tested. Accordingly, the maternal and developmental NOAELs (No Observable Adverse Effect Level) were established at 1000 mg/kg (the limit dose) under the conditions of this study.

Executive summary:

The test material was administered by oral gavage to three groups of Crl:CDBR female rats at doses of 400, 800, and 1000 mg/kg/day. A fourth group (Group 1) served as a control and received the carrier (corn oil) only. Mated females were dosed once daily from Gestation Day (GD) 6 through GD 15. Dosing volumes were 5 mL/kg for all groups and based on the animals' most recent body weights.

There was no evidence of overt systemic maternal toxicity at any dose level tested. overt signs of maternal toxicity were not apparent at any dose tested, as indicated by the absence of adverse clinical or postmortem findings or effects on body weight, food consumption, and/or uterine implantation data.

Similarly, there were no treatment-related adverse effects on fetal development or growth observed at any dose level tested. There was a statistically significant increase in the incidence of rudimentary ribs in the low dose (400 mg/kg/day) group, but not at the higher doses, compared with controls, which resulted in an increased incidence of total fetuses with skeletal variations in the 400 mg/kg/day group. However, all these incidences were within the historical control range of this laboratory. Therefore, this common finding in fetal rats was not considered biologically important.

Accordingly, the maternal and developmental NOAELs (No Observable Adverse Effect Level) were established at 1000 mg/kg/day under the conditions of this study.