Bicyclo[2.2.1]heptan-2-ol, 1,3,3-trimethyl-, 2-acetate, (1R,2R,4S)-rel-

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

22 April 1991 - 28 May 1991

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: The analogue isobornyl acetate which shares the same functional groups with dextro alpha fenchyl acetate also has comparable values for the relevant molecular properties. Test method according to OECD 414. GLP study.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1992

Report date:

1992

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

GLP compliance:

yes

Limit test:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Exo-1,7,7-trimethylbicyclo[2.2.1]hept-2-yl acetate

EC Number:

204-727-6

EC Name:

Exo-1,7,7-trimethylbicyclo[2.2.1]hept-2-yl acetate

Cas Number:

125-12-2

Molecular formula:

C12H20O2

IUPAC Name:

(1S,2S,4S) 1,7,7-trimethylbicyclo[2.2.1]hept-2-yl acetate

Details on test material:

- Name of test material (as cited in study report): Isobornylacetat-Extra
- Molecular formula (if other than submission substance): C12H20O2
- Molecular weight (if other than submission substance): 196.286
- Smiles notation (if other than submission substance): CC(=O)O[C@H]1C[C@@H]2CC[C@@]1(C)C2(C)C
- InChl (if other than submission substance): 1/C12H20O2/c1-8(13)14-10-7-9-5-6-12(10,4)11(9,2)3/h9-10H,5-7H2,1-4H3
- Structural formula attached as image file (if other than submission substance): see Fig.
- Physical state: Liquid
- Analytical purity: 93.5 – 95.0 %
- Impurities (identity and concentrations): other terpene esters and camphene
- Lot/batch No.: 249/90
- Storage condition of test material: dark, at room temperature

Test animals

Species:

rat

Strain:

Wistar

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Hoe: WISKf (SPF71)
- Age at study initiation: 65-70 days
- Weight at study initiation: 191 ± 6 g
- Housing: individually in plastic cages
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: at least 7 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21-24 ° C
- Humidity (%): 49-53%
- Air changes (per hr): 16-20/h
- Photoperiod (hrs dark / hrs light): 12 light / 12 hours dark (450 Lux)

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

other: sesame oil

Details on exposure:

PREPARATION OF DOSING SOLUTIONS: The substance was prepared fresh daily.

VEHICLE
- Concentration in vehicle: 200 g/L
- Amount of vehicle (if gavage): 5 mL/kg bw

OTHER:
- The stability and homogeneity of the solution was ensured for a period of 4 hours

Details on mating procedure:

- Impregnation procedure: cohoused
- If cohoused: Females were mated overnight with fertile males.
- M/F ratio per cage: 1 male/1 female
- Proof of pregnancy: Sperm in vaginal smear referred to as day 1 of pregnancy

Duration of treatment / exposure:

Gestation days 7-16

Frequency of treatment:

Once daily

Duration of test:

21 days

Doses / concentrations

Remarks:

Doses / Concentrations:
1000 mg/kg bw/day
Basis:
actual ingested

No. of animals per sex per dose:

20 mated females: test group
21 mated females: control group

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: A preliminary range-finding test was performed with 3 pair of rats per dose, in a trial. Animals were exposed to 270, 500 and 1000 mg/kg bw/day between day 7-16 of gestation. On day 21, animals were sacrificed. No effects were observed at the highest dose related to maternal toxicity, embryotoxicity and teratogenicity.

Examinations

Maternal examinations:

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Daily

FOOD CONSUMPTION: Yes
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/100 g body weight/day: Yes

BODY WEIGHT: Yes
- Time schedule for examinations: Once a week and a day after the last application

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day # 21
- Organs examined: macroscopic examination and organ weighing of heart, liver, kidneys and spleen

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 resorptions: Yes
- Other: diameter of fetal resorption and placental weight

Fetal examinations:

- External examinations: Yes: all per litter
- Body weight: Yes: all per litter
- External/visceral examinations: Yes: all per litter (external/visceral, abdominal cavity, liver, kidney)
- Skeletal examinations: Yes: all per litter (skeleton, skull, thoracic vert. centra, sacral vert. arch/centra, caudal vert. centra, extra vertebrae/extra rib, sternebra, rib, extra rib, pectoral girdle, forepan, forepan-phalanx, pelvic girdle, hindpaw, hindpaw-phalanx)
- Head examinations: Yes: all per litter
- Other:
Body cross-sections for Wilson, photography: Yes: half per litter
Dead fetus in uterus were fixed, stained and examined microscopically.
Remaining fetus, were fixed in Bouin solution and examined under stereomicroscope.

Statistics:

Comparisons between body weights and organ weights in the test and control group were performed with a classical analysis of variance (MANOVA); to evaluate the relative feed intake, a analysis of variance according to Puri & Sen (1985). Corpora lutea and implantations were performed with the Mantel-Haenszel x2 test (Mantel & Haenszel, 1959), as well as live and dead fetuses and resorptions. Other parameters according to an analysis of variance. The body cross-sectional study of fetuses and skeletal findings were studied with the Fisher Exact test.

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:

Maternal toxic effects:no effects

Details on maternal toxic effects:
CLINICAL OBSERVATIONS:
No adverse effects were observed. At Day 11 of gestation one female showed hair loss in the forelimbs and at Day 19 in the belly, flanks and hind limbs.

FOOD CONSUMPTION:
No adverse effects were observed. At the end of the study the food consumption was slightly higher in the treated group comparing with the control group.

BODY WEIGHT:
No effects were observed. The body weight of the treated animals was similar to control animals.

UTERUS:
All females gave birth to live fetuses except 1 dam in the 1000 mg/kg bw group. This dam had no fetus, and only 5 empty implantations were observed. The corporea lutea were quite small too and could not be accurately determined. The treated groups had corporea lutea, number of implantations and number of live fetuses similar to the control group. No adverse effects were observed.

POST-MORTEM EXAMINATIONS:
Two females of the treatment group showed moderate enlargement of the right kidney. No other changes were observed.
The heart, kidney, liver and spleen weight did not differ from those of the control group.

Effect levels (maternal animals)

Dose descriptor:

NOEL

Effect level:

1 000 mg/kg bw/day

Based on:

test mat.

Basis for effect level:

other: maternal toxicity

Results (fetuses)

Details on embryotoxic / teratogenic effects:

Embryotoxic / teratogenic effects:no effects

Details on embryotoxic / teratogenic effects:
FETUS OBSERVATIONS:
Fetus were normally developed. Body weight and body lengths were similar from those in the control group. In the 1000 mg/kg bw treatment group, the number of live fetuses weighing less than 3 g, was lower than in the control group. The sex ratio was balanced in both groups, predominating males.

INTRAUTERINE OBSERVATIONS:
Early intrauterine deaths were observed in both groups. The total number of deaths in the treated group was low and did not differ from the control group. Only one dead fetus was observed in the control groups.

PLACENTAL WEIGHT
Placental weight in live fetuses (including) macroscopic findings, were similar in both treatment and control groups.

MORPHOLOGICAL OBSERVATIONS:
No fetal malformations were observed. The body section and cross-section observations showed 5 fetuses with hematoma in the liver overlap. Although it was statistically significant, it was in accordance with historical control values. In three fetuses at 1000 mg/kg bw group, blood was found in the abdominal cavity. Nine fetus in the control group showed enlarged renal pelvis.

SKELET OBSERVATIONS:
The skeletons were about the same stage of development in both treatment and control groups, corresponding to the 21 day of pregnancy. The number of fetuses with weak ossification of head bones, sternebrae and metacarpal 5 was significantly higher than in the control group. However, it was in line with historical control values. One fetus showed week ossidification of metatarsal 5, phalanx III, ischium and the pubis. Besides these findings, 14. thoracic vertebra with a short or normal length, corrugated/thickened rib, short of fragmented 7. cervical rib and displaces sternebrae were observed in both treatment and control groups. All the effects were within the historical control values.

OBSERVATION OF DEAD FETUS IN UTERUS:
The dead fetus of the control group was retarded in development, which is in accordance with weaker ossification. An examination of the internal organs was not possible because of the small size.

Effect levels (fetuses)

1

Dose descriptor:

NOEL

Effect level:

1 000 mg/kg bw/day

Based on:

test mat.

Basis for effect level:

other: embryotoxicity

2

Dose descriptor:

NOEL

Effect level:

1 000 mg/kg bw/day

Based on:

test mat.

Basis for effect level:

other: teratogenicity

Fetal abnormalities

Abnormalities:

not specified

Overall developmental toxicity

Developmental effects observed:

not specified

Any other information on results incl. tables

All findings did not differ from those of the control group out of the spontaneous rate.

The data matrix is included in the reporting format attached.

Applicant's summary and conclusion

Conclusions:

Based on the read-across approach from experimental data on the analogue isobornyl acetate, the NOEL for maternal and developmental toxicity after an oral exposure of dextro alpha fenchyl acetate was determined to be 1000 mg/kg bw/day in rats under test conditions.

Executive summary:

A pre-natal developmental toxicity test was performed with the analogue substance isobornyl acetate according to OECD Guideline 414. 20 female Wistar rats from were exposed by gavage to 0 (control) and 1000 mg/kg bw/day test item between Days 7 and 16 of gestation, in a limit test. On Day 21 of gestation, the animals were killed and both dams and fetus were examined. The investigations showed that the repeated oral exposure to the test item during the sensitive period of organogenesis, do not cause an impairment of the general health of dams, not disturbing the intrauterine development of fetus. The morphological examination of fetuses revealed no evidence for embryotoxic and teratogenic effects of the substance. Therefore, the NOEL of isobornyl acetate for maternal, ebryo/fetal toxicity and teratogenicity was determined to be 1000 mg/kg bw/day in rats. Based on these results, the read-across approach was applied and the NOEL of dextro alpha fenchyl acetate was determined to be 1000 mg/kg bw/day for maternal and developmental toxicity in rats.