2-methylcyclohexyl acetate

Endpoint summary

Key value for chemical safety assessment

Effects on fertility

Description of key information

Data waving (other justification):

Screening for reproductive/developmental toxicity study: In accordance to Column 2 of REACH Annex VIII, the study does not need to be conducted since a pre-natal developmental toxicity study is available.

Data waiving (other justification):

Two-generation reproductive toxicity study: In accordance with Column 1 of REACH Annex IX, the study does not need to be conducted since the 90-day study does not indicate adverse effects on reproductive organs or tissues.

Link to relevant study records

Reference

Reference 1

Endpoint:

screening for reproductive / developmental toxicity

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

the study does not need to be conducted because a pre-natal developmental toxicity study is available

Justification for type of information:

JUSTIFICATION FOR DATA WAIVING
In accordance with Column 2 of REACH Annex VIII, the screening for reproductive/developmental toxicity since pre-natal developmental toxicity studies are available. No significant alerts were observed in these studies regarding developmental toxicity.

Reproductive effects observed:

not specified

Reference 2

Endpoint:

two-generation reproductive toxicity

Data waiving:

other justification

Justification for data waiving:

the extended one-generation reproductive toxicity study does not need to be conducted because there are no results from available repeated dose toxicity studies that indicate adverse effects on reproductive organs or tissues, or reveal other concerns in relation with reproductive toxicity

Justification for type of information:

JUSTIFICATION FOR DATA WAIVING
In accordance with Column 1 of REACH Annex IX, the two-generation reproductive toxicity study does not need to be conducted since the chronic study does not indicate adverse effects on reproductive organs or tissues. According to the results obtained in the chronic studies (rats and mice), neither gross nor microscopic effects were observed in prostate, uterus, testes or ovaries. Moreover, the available developmental studies in analogue substances did not show significant alerts on developmental toxicity.

Reproductive effects observed:

not specified

Effect on fertility: via oral route

Endpoint conclusion:

no study available

Additional information

Justification for selection of Effect on fertility via oral route:

Screening for reproductive/developmental toxicity study: Data waiving (other justification): In accordance to Column 2 of REACH Annex VIII, the study does not need to be conducted since a pre-natal developmental toxicity study is available.

Two-generation reproductive toxicity study: Data waiving (other justification): In accordance with Column 1 of REACH Annex IX, the study does not need to be conducted since the 90-day study does not indicate adverse effects on reproductive organs or tissues.

Effects on developmental toxicity

Description of key information

Weight of evidence: read-across from experimental data on the analogue 4 -tert-butylcyclohexyl acetate:

In the study reported by Bathia SP et al. 2008, a developmental toxicity test was performed on the analogue substance 4-tert-butylcyclohexyl acetate in Sprague-Dawley rats (test method equivalent to OECD 414). 25 pregnants rats per dose were exposed by gavage to 0 (control, 40, 160 and 640 mg/kg bw/day) on days 7–20 of gestation. The maternal NOAEL for the analogue substance was determined to be 160 mg/kg bw/day (basis for effect: clinical signs, body weight gain and feed consumption at 640 mg/kg bw/day) and the NOAEL for developmental toxicity was 160 mg/kg bw/day (basis for effect: reduced foetal body weights, transient delay in foetal development and reversible delays in skeletal ossification at 640 mg/kg bw/day). Based on these results, the read across was applied and the NOAEL for both maternal and developmental toxicity of 2 -methylcyclohexyl acetate was determined to be 126.05 mg/kg bw/day. According to the authors, the decreased body weights and increases in variations observed in pups commonly occur when there are decreased maternal body weight and feed consumption.

Weight of evidence: read-across from experimental data on the analogue 2 -isopropyl-5 -methylcyclohexanol:

In the prenatal developmental toxicity test conducted by U.S. Food and Drug Administration (1975) on the analogue 2 -isopropyl-5-methylcyclohexanol. Groups of pregnant rat females (22 -25/group) were exposed to 0 (control) 2.18, 10.15, 47.05 and 218 mg/kg bw/day beginning on day 6 and continuing daily through day 15 of gestation. At termination (day 20) there was no evidence of maternal toxicity or developmental toxicity up to 218 mg/kg bw/day and therefore the NOAEL was determined to be 218 mg/kg bw/day. Based on these results, the read-across was applied and the NOAEL for both maternal and developmental toxicity in rats of 2 -methylcyclohexyl acetate was determined to be 217.95 mg/kg bw/day.

Supporting studies: read-across from experimental data on the analogue 2 -isopropyl-5 -methylcyclohexanol:

U.S. Food and Drug Administration (1975) also performed the above mentioned pre-natal developmental toxicity test with mice, hamsters and rabbits with the analogue 2 -isopropyl-5 -methylcyclohexanol. No evidence of maternal nor developmental toxicity was observed in neither study and the NOAELs were determined to be 185 mg/kg bw/day in mice, 405 mg/kg bw/day in hamsters and 425 mg/kg bw/day in rabbits. Based on these results, the read-across was applied and the NOAEL for both maternal and developmental toxicity of 2 -methylcyclohexyl acetate was calculated to be 184.96 mg/kg bw/day in mice, 404.91 mg/kg bw/day in hamsters and 424.90 mg/kg bw/day in rabbits.

Link to relevant study records

Reference

Reference 1

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

2007

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

GLP compliance:

not specified

Limit test:

no

Species:

rat

Strain:

Crj: CD(SD)

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Diet: ad libitum
- Water: ad libitum

Route of administration:

oral: gavage

Vehicle:

corn oil

Analytical verification of doses or concentrations:

not specified

Duration of treatment / exposure:

14 days

Frequency of treatment:

Daily via gavage on gestational days 7 through 20.

Duration of test:

21 days

Dose / conc.:

0 mg/kg bw/day (nominal)

Remarks:

volume of dose: 10 ml/kg

Dose / conc.:

40 mg/kg bw/day (nominal)

Remarks:

volume of dose: 10 ml/kg

Dose / conc.:

160 mg/kg bw/day (nominal)

Remarks:

volume of dose: 10 ml/kg

Dose / conc.:

460 mg/kg bw/day (nominal)

Remarks:

volume of dose: 10 ml/kg

No. of animals per sex per dose:

25 females per group.

Control animals:

yes, concurrent vehicle

Maternal examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Twice daily for mortality and morbidity.

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: observations for abortion and premature delivery were conducted before and approximately 1 h following dosing and once daily thereafter.

BODY WEIGHT: Yes
- Time schedule for examinations: prior to the start of the study and daily during dosage and post dosage periods.

FOOD CONSUMPTION: Yes
- Food consumption was recorded on gestation days 0, 7, 10, 12, 15, 18, 20 and 21.

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day 21. On gestation day 20 one rat from the 640 mg/kg/day dosage group was sacrificed due to body weight loss and adverse clinical conditions.

OTHER: Gross necropsy conducted on all animals.

Ovaries and uterine content:

The ovaries and uterine content was examined after termination: Yes


Examinations included:
- Gravid uterus weight: No data
- 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: No data

Details on maternal toxic effects:

Clinical signs in the remaining dams that appeared to be test article related include excess salivation in the 160 and 640 mg/kg/day groups, and sparse hair coat on the limbs, urine-stained abdominal fur and red perioral substance in the 640 mg/kg/day group. Body weight gains were reduced (32%) with weight loss at gestation day 7-8 and 8-9 and absolute and relative feed consumption values were reduced (29% and 26% respectively) in the 640 mg/kg/day group during the entire treatment period as compared to the vehicle control group.

Key result

Dose descriptor:

NOAEL

Effect level:

160 mg/kg bw/day (nominal)

Based on:

test mat.

Basis for effect level:

clinical signs

other: maternal toxicity

Key result

Dose descriptor:

NOAEL

Effect level:

160 mg/kg bw/day (nominal)

Based on:

test mat.

Basis for effect level:

other: developmental toxicity

Details on embryotoxic / teratogenic effects:

Foetal body weights (total, male and female) were significantly reduced (11%) in the 640 mg/kg/day dosage group. Foetal gross examination revealed one foetus in the 160 mg/kg/day group with an absent tail. No other gross external alterations occurred. Statistically significant increases in the incidences of moderately enlarged renal pelvis were observed at 640 mg/kg/day. Delays in skeletal ossification, including significant reductions in the average number of ossified caudal vertebrae, forelimb phalanges, and hind limb metatarsals and phalanges, were observed in the 640 mg/kg/day group.

Dose descriptor:

NOAEL

Effect level:

640 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

fetal/pup body weight changes

external malformations

skeletal malformations

Abnormalities:

not specified

Developmental effects observed:

not specified

On GD 20, one rat from the 640 mg/kg/day dosage group was euthanized, necropsied, and Caesarean-sectioned due to body weight loss (26 g loss from GD 18–20) and adverse clinical condition (cold to touch, decreased motor activity, ptosis, excess salivation, ungroomed coat, urine-stained abdominal fur, red perioral substance, soft or liquid feces, and apparent dehydration). Necropsy revealed distention of the stomach with gas and yellow fluid. All remaining rats survived to scheduled sacrifice on GD 21 (see above).

All 17 foetuses of the rat euthanized on GD 20 were found dead in utero. All appeared normal at gross external and skeletal examinations; of the eight examined for soft tissue alterations, five foetuses had moderate dilation of the renal pelvis in one or both kidneys. See above the results for the remaining foetus.

Developmental observation of offspring at 640 mg/kg/day consisted of transient retardations in foetal developmental. No foetal malformations were observed. The decreased body weights and increases in variations observed in pups at 640 mg/kg/day commonly occur when there are decreased maternal body weight and feed consumption.

Pregnancy occurred in 24, 24, 25, and 25 dams in the 0, 40, 160, and 640 mg/kg/day dosage groups, respectively.

Conclusions:

The maternal and developmental NOAEL for 4-tert-butylcyclohexyl acetate was determined to be 160 mg/kg/day.

Executive summary:

The developmental toxicity of 4-tert-butylcyclohexyl acetate was investigated in Sprague-Dawley rats. Twenty-five presumed pregnant rats were dosed via gavage on days 7–20 of presumed gestation (GDs 7–20) with 4-tert-butylcyclohexyl acetate in corn oil at 0, 40, 160, or 640 mg/kg bw/day. One rat from the 640 mg/kg bw/day group was sacrificed on GD 20, due to body-weight loss and adverse clinical condition (i.e. decreased motor activity, apparent dehydration and excess salivation). Clinical signs in the remaining dams included excess salivation in the 160 and 640 mg/kg bw/day groups and sparse hair coat on the limbs, urine-stained abdominal fur and red perioral substance in the 640 mg/kg bw/day group (statistically significant increases). Body-weight gains were reduced (32%) in the 640 mg/kg bw/day group during the dosage period with weight loss at GD 7–8, GD 8–9. Absolute and relative feed consumption values were significantly reduced (29% and 26%, respectively) in the 640 mg/kg bw/day group. Pregnancy incidence and litter parameters were not affected by 4-tert-butylcyclohexyl acetate. Fetal body weights were significantly reduced (11%) in the 640 mg/kg bw/day group, and transient delays in fetal development were seen, including statistically significant increases in the fetal (but not the litter) incidences of moderate enlargement of the renal pelvices and reversible delays in ossification of the caudal vertebrae, fore- and hind-limb phalanges and hind-limb metatarsals. No fetal malformations were observed. The maternal NOAEL was 160 mg/kg bw/day. The developmental NOAEL is 160 mg/kg bw/day based on reduced foetal body weights, transient delay in foetal development and reversible delays in skeletal ossification at 640 mg/kg bw/day. The decreased body weights and increases in variations observed in pups at 640 mg/kg/day commonly occur when there are decreased maternal body weight and feed consumption.

Reference 2

Endpoint:

developmental toxicity

Type of information:

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

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Justification for type of information:

JUSTIFICATION FOR DATA WAIVING
See attached the reporting format and read-across rationale.

Reason / purpose for cross-reference:

read-across source

GLP compliance:

no

Limit test:

no

Details on maternal toxic effects:

Maternal toxic effects:yes

Details on maternal toxic effects:
Based on the read-across approach from experimental results on analogue 2-isopropyl-5-methylcyclohexanol (NOAEL for maternal toxicity = 160 mg/kg bw/day, based on clinical signs, body weight gain and feed consumption), the NOAEL for maternal toxicity for 2-methylcyclohexyl acetate was determined to be 126 mg/kg bw/day.

Key result

Dose descriptor:

NOAEL

Effect level:

126.05 mg/kg bw/day (nominal)

Based on:

test mat.

Remarks:

(based on the analogue substance)

Basis for effect level:

other: maternal toxicity

Remarks on result:

other:

Remarks:

(Read-across approach from an analogue)

Key result

Dose descriptor:

NOAEL

Effect level:

126.05 mg/kg bw/day (nominal)

Based on:

test mat.

Remarks:

(based on the analogue substance)

Basis for effect level:

other: developmental toxicity

Remarks on result:

other:

Remarks:

(Read-across approach from an analogue)

Dose descriptor:

NOAEL

Effect level:

640 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

fetal/pup body weight changes

external malformations

skeletal malformations

Remarks on result:

other:

Remarks:

Based on rea-across analogue

Abnormalities:

not specified

Developmental effects observed:

not specified

Conclusions:

Based on the read-across approach from experimental data on the analogue 4-tert-butylcyclohexyl acetate in rats, NOAEL for both maternal and developmental toxicity of 2 -methylcyclohexyl acetate was determined to be 126.05 mg/kg bw/day.

Executive summary:

A developmental toxicity test was performed on the analogue substance 4-tert-butylcyclohexyl acetate in Sprague-Dawley rats. 25 pregnants rats per dose were exposed by gavage to 0 (control, 40, 160 and 640 mg/kg bw/day) on days 7–20 of gestation. The maternal NOAEL for the analogue substance was determined to be 160 mg/kg bw/day (basis for effect: clinical signs, body weight gain and feed consumption at 640 mg/kg bw/day) and the NOAEL for developmental toxicity was 160 mg/kg bw/day (basis for effect: reduced foetal body weights, transient delay in foetal development and reversible delays in skeletal ossification at 640 mg/kg bw/day). Based on these results, the read across was applied and the NOAEL for both maternal and developmental toxicity of 2 -methylcyclohexyl acetate was determined to be 126.05 mg/kg bw/day. According to the authors, the decreased body weights and increases in variations observed in pups commonly occur when there are decreased maternal body weight and feed consumption.

Reference 3

Endpoint:

developmental toxicity

Type of information:

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

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Justification for type of information:

JUSTIFICATION FOR DATA WAIVING
See attached the reporting format and read-across rationale.

Reason / purpose for cross-reference:

reference to other study

Key result

Dose descriptor:

NOAEL

Effect level:

217.95 mg/kg bw/day (nominal)

Based on:

test mat.

Remarks:

(based on the analogue substance)

Basis for effect level:

other: maternal toxicity

Remarks on result:

other:

Remarks:

(Read-across approach from an analogue)

Key result

Dose descriptor:

NOAEL

Effect level:

217.95 mg/kg bw/day (nominal)

Based on:

test mat.

Remarks:

(based on the analogue substance)

Basis for effect level:

other: developmental toxicity

Remarks on result:

other:

Remarks:

(Read-across approach from an analogue)

Dose descriptor:

NOAEL

Based on:

test mat.

Sex:

male/female

Basis for effect level:

reduction in number of live offspring

fetal/pup body weight changes

changes in litter size and weights

external malformations

skeletal malformations

Remarks on result:

not determinable due to adverse toxic effects at highest dose / concentration tested

Remarks:

Based on Read-across analogue

Abnormalities:

not specified

Developmental effects observed:

not specified

Conclusions:

Based on the read-across approach from experimental data on the analogue 2-isopropyl-5-methylcyclohexanol, NOAEL for both maternal and developmental toxicity in rats of 2 -methylcyclohexyl acetate was determined to be 217.95 mg/kg bw/day.

Executive summary:

A developmental toxicity test was performed on analogue substance 2 -isopropyl-5-methylcyclohexanol. Virgin adult female Wistar rats were mated with untreated young adult males and observation of vaginal sperm plugs was considered day 0 of gestation. Groups of pregnant females (22 -25/group) were exposed to 0 (control) 2.18, 10.15, 47.05 and 218 mg/kg bw/day beginning on day 6 and continuing daily through day 15 of gestation. On Day 20 all dams were subjected to Caesarian section. There was no evidence of maternal toxicity or developmental toxicity up to 218 mg/kg bw/day and therefore the NOAEL for both maternal and developmental toxicity was determined to be 218 mg/kg bw/day. Based on these results, the read-across was applied and the NOAEL for both maternal and developmental toxicity in rats of 2 -methylcyclohexyl acetate was determined to be 217.95 mg/kg bw/day.

Reference 4

Endpoint:

developmental toxicity

Type of information:

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

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Justification for type of information:

JUSTIFICATION FOR DATA WAIVING
See attached the reporting format and read-across rationale.

Reason / purpose for cross-reference:

read-across source

GLP compliance:

no

Limit test:

no

Details on maternal toxic effects:

Maternal toxic effects:yes

Details on maternal toxic effects:
Based on the read-across approach from experimental results on analogue 2-isopropyl-5-methylcyclohexanol (NOAEL for maternal toxicity = 185 mg/kg bw/day, based on no effects observed), the NOAEL for maternal toxicity in mice of 2-methylcyclohexyl acetate was determined to be 184.86 mg/kg bw/day.

Key result

Dose descriptor:

NOAEL

Effect level:

184.96 mg/kg bw/day (nominal)

Based on:

test mat.

Remarks:

(based on the analogue substance)

Basis for effect level:

other: maternal toxicity

Remarks on result:

other:

Remarks:

(Read-across approach from an analogue)

Key result

Dose descriptor:

NOAEL

Effect level:

184.96 mg/kg bw/day (nominal)

Based on:

test mat.

Remarks:

(based on the analogue substance)

Basis for effect level:

other: developmental toxicity

Remarks on result:

other:

Remarks:

(Read-across approach from an analogue)

Abnormalities:

not specified

Developmental effects observed:

not specified

Conclusions:

Based on the read-across approach from experimental data on the analogue 2-isopropyl-5-methylcyclohexanol, NOAEL for both maternal and developmental toxicity in mice of 2 -methylcyclohexyl acetate was determined to be 184.96 mg/kg bw/day.

Executive summary:

A developmental toxicity test was performed on analogue substance 2 -isopropyl-5-methylcyclohexanol. Virgin adult female CD1 mice were mated with untreated young adult males and observation of vaginal sperm plugs was considered day 0 of gestation. Groups of pregnant females (22 -23/group) were exposed to 0 (control), 1.85, 8.59, 39.9 and 185 mg/kg bw/day beginning on day 6 and continuing daily through day 15 of gestation. On Day 17 all dams were subjected to Caesarian section. There was no evidence of maternal toxicity or developmental toxicity up to 185 mg/kg bw/day and therefore the NOAEL for both maternal and developmental toxicity was determined to be 185 mg/kg bw/day. Based on these results, the read-across was applied and the NOAEL for both maternal and developmental toxicity in mice of 2 -methylcyclohexyl acetate was determined to be 184.96 mg/kg bw/day.

Reference 5

Endpoint:

developmental toxicity

Type of information:

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

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Justification for type of information:

JUSTIFICATION FOR DATA WAIVING
See attached the reporting format and read-across rationale.

Reason / purpose for cross-reference:

read-across: supporting information

Details on maternal toxic effects:

Maternal toxic effects:yes

Details on maternal toxic effects:
Based on the read-across approach from experimental results on analogue 2-isopropyl-5-methylcyclohexanol (NOAEL for maternal toxicity = 405 mg/kg bw/day, based on no effects observed), the NOAEL for maternal toxicity in hamsters of 2-methylcyclohexyl acetate was determined to be 404.91 mg/kg bw/day.

Key result

Dose descriptor:

NOAEL

Effect level:

404.91 mg/kg bw/day (nominal)

Based on:

test mat.

Remarks:

(based on the analogue substance)

Basis for effect level:

other: maternal toxicity

Remarks on result:

other:

Remarks:

(Read-across approach from an analogue)

Key result

Dose descriptor:

NOAEL

Effect level:

404.91 mg/kg bw/day (nominal)

Based on:

test mat.

Remarks:

(based on the analogue substance)

Basis for effect level:

other: developmental toxicity

Remarks on result:

other:

Remarks:

(Read-across approach from an analogue)

Abnormalities:

not specified

Developmental effects observed:

not specified

Conclusions:

Based on the read-across approach from experimental data on the analogue 2-isopropyl-5-methylcyclohexanol, NOAEL for both maternal and developmental toxicity in hamsters of 2 -methylcyclohexyl acetate was determined to be 404.91 mg/kg bw/day.

Executive summary:

A developmental toxicity test was performed on analogue substance 2 -isopropyl-5-methylcyclohexanol. Virgin adult female Golden hamsters were mated with untreated young adult males and observation of vaginal sperm plugs was considered day 0 of gestation. Groups of pregnant females (19 -23/group) were exposed to 0 (control), 4.05, 21.15, 98.2 and 405 mg/kg bw/day beginning on day 6 and continuing daily through day 10 of gestation. On Day 14 all dams were subjected to Caesarian section. There was no evidence of maternal toxicity or developmental toxicity up to 405 mg/kg bw/day and therefore the NOAEL for both maternal and developmental toxicity was determined to be 405 mg/kg bw/day. Based on these results, the read-across was applied and the NOAEL for both maternal and developmental toxicity in hamsters of 2 -methylcyclohexyl acetate was determined to be 404.91 mg/kg bw/day.

Reference 6

Endpoint:

developmental toxicity

Type of information:

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

Adequacy of study:

supporting study

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Justification for type of information:

JUSTIFICATION FOR DATA WAIVING
See attached the reporting format and read-across rationale.

Reason / purpose for cross-reference:

reference to other study

Key result

Dose descriptor:

NOAEL

Effect level:

424.9 mg/kg bw/day (nominal)

Based on:

test mat.

Remarks:

(based on the analogue substance)

Basis for effect level:

other: maternal toxicity

Remarks on result:

other:

Remarks:

(Read-across approach from an analogue)

Key result

Dose descriptor:

NOAEL

Effect level:

424.9 mg/kg bw/day (nominal)

Based on:

test mat.

Remarks:

(based on the analogue substance)

Basis for effect level:

other: developmental toxicity

Remarks on result:

other:

Remarks:

(Read-across approach from an analogue)

Abnormalities:

not specified

Developmental effects observed:

not specified

Conclusions:

Based on the read-across approach from experimental data on the analogue 2-isopropyl-5-methylcyclohexanol, NOAEL for both maternal and developmental toxicity in rabbits of 2 -methylcyclohexyl acetate was determined to be 424.90 mg/kg bw/day.

Executive summary:

A developmental toxicity test was performed on analogue substance 2 -isopropyl-5-methylcyclohexanol in Dutch belted female rabbits. On day 0, does were given an injection of 0.4 l of human chorionic gonadotropin (400 IU). Three hours later, each doe was artificially inseminated with 0.3 ml of semen from a buck. Groups of pregnant females (11 -14/group) were exposed to 0 (control), 4.25, 19.75, 91.7, 425 mg/kg bw/day beginning on day 6 and continuing daily through day 18 of gestation. On Day 29 all dams were subjected to Caesarian section. There was no evidence of maternal toxicity or developmental toxicity up to 425 mg/kg bw/day and therefore the NOAEL for both maternal and developmental toxicity was determined to be 425 mg/kg bw/day. Based on these results, the read-across was applied and the NOAEL for both maternal and developmental toxicity in rabbits of 2 -methylcyclohexyl acetate was determined to be 424.90 mg/kg bw/day.

Reference 7

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

1973

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

Deviations:

yes

Remarks:

(corporea lutea not reported, no full dam macroscopic examination)

GLP compliance:

no

Limit test:

no

Species:

rat

Strain:

Wistar

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Age at study initiation: adult
- Weight at study initiation: 204-216 g (pregnant dams)
- Housing: Individually housed in mesh bottom cages in temperature and humidity-controlled quarters.
- Diet: ad libitum
- Water: ad libitum (tap water)

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on exposure:

PREPARATION OF DOSING SOLUTIONS: A
Dosage (mg/kg) Dose (ml/kg) Concentration (mg/ml)
<250 1 <250
251-500 2 125-250
501-750 3 133-250
751-1000 4 187-250
1001-1250 5 200-250
1252-1500 6 208-250
1501-1600 6.4 135-250

Analytical verification of doses or concentrations:

not specified

Details on mating procedure:

- Impregnation procedure: Virgin adult females (1 per cage) were mated with untreated young adult males.
- Proof of pregnancy: vaginal sperm plugs, referred to as day 0 of pregnancy

Duration of treatment / exposure:

10 days: beginning on Day 6 and continuing through day 15 of gestation.

Frequency of treatment:

Daily.

Duration of test:

20 days.

Dose / conc.:

2 mg/kg bw/day (nominal)

Dose / conc.:

18 mg/kg bw/day (nominal)

Dose / conc.:

10 mg/kg bw/day (nominal)

Dose / conc.:

15 mg/kg bw/day (nominal)

Dose / conc.:

47 mg/kg bw/day (nominal)

Dose / conc.:

105 mg/kg bw/day (nominal)

Dose / conc.:

218 mg/kg bw/day (nominal)

No. of animals per sex per dose:

22-25 pregnant females per group.

Control animals:

yes, concurrent vehicle

other: Positive control: 250 mg/kg bw/day of aspirin

Maternal examinations:

CLINICAL OBSERVATIONS: Yes
- Time schedule: females were observed daily for appearance and behaviour.

BODY WEIGHT: Yes
- Time schedule for examinations: recorded on days 0, 6, 11, 15 and 20 of gestation.

FOOD CONSUMPTION: Yes

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day 20 (caesarean section under surgical anesthesia)
- Organs examined: urogenital tract of each dam was examined for anatomical abnormalities.

Ovaries and uterine content:

The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: No data
- Number of corpora lutea: No data
- Number of implantations: Yes
- Number of resorptions: Yes (% of live and % partial live resorptions)
- Others: live and dead fetuses; body weight of the live pups.

Fetal examinations:

- External examinations: Yes: mortality, litter size and weights, sex of pups and gross abnormalities.
- Soft tissue examinations: Yes: 1/3 per litter, detailed visceral examination at 10x magnification.
- Skeletal examinations: Yes: 2/3 per litter, cleared in potassium hydroxide (KOH), stained with alizarin red S dye and examined for skeletal defects (sternebrae, ribs, vertebrae, skull, extremities, miscellaneous.

Indices:

Number of implantation sites, number of resorptions, % of live and % partial live resorptions, live fetuses, dead fetuses, and body weight of live pups. Gestation index, mortality, litter size and weights, sex and sex ratio of pups, and gross abnormalities to pups.

Details on maternal toxic effects:

Daily clinical observation and measurement of body weight gain failed to show any differences between control and test groups of female rats. The number pregnant and % pregnancy were similar for all dose and control groups. No abortions were observed in any group. The number of live litters, average implant sites per dam were similar for both test and control groups. The % partial resorptions and % complete resorption were increased only for the positive control group.

Key result

Dose descriptor:

NOAEL

Effect level:

218 mg/kg bw/day (nominal)

Based on:

test mat.

Basis for effect level:

other: maternal toxicity

Key result

Dose descriptor:

NOAEL

Effect level:

218 mg/kg bw/day (nominal)

Based on:

test mat.

Basis for effect level:

other: developmental toxicity

Details on embryotoxic / teratogenic effects:

The average fetal weight of treatment and control groups were not statistically different (p>0.05). The total number of live fetuses was similar for test and negative control groups. Also, there were no dead fetuses in either the test or negative control groups. The positive control group did show dead fetuses (3) and dams with more than one dead fetus. The positive control group also exhibited a decreased number of live fetuses and decreased average fetal weight compared to those for the negative control. Skeletal examination of sternebrae, vertebrae, skull, ribs, extremities, and soft tissues showed no significant differences between test and negative control groups. The positive control group showed a significant increase in incidence of missing sternebrae. Likewise, the positive control exhibited an increase in the incidence of fetuses with more than 13 ribs, incomplete ossification of vertebrae and extremities, incomplete skull closure. Visceral examination failed to reveal any evidence of abnormalities in either negative control or test groups. In the positive control group, meningoencephalocele and spina bifida were reported.

Dose descriptor:

NOAEL

Based on:

test mat.

Sex:

male/female

Basis for effect level:

fetal/pup body weight changes

changes in litter size and weights

external malformations

skeletal malformations

Remarks on result:

not determinable due to adverse toxic effects at highest dose / concentration tested

Abnormalities:

not specified

Developmental effects observed:

not specified

There was no evidence of maternal toxicity or developmental toxicity at dose levels up to and including 218 mg/kg bw/day of test material.

Conclusions:

The maternal and developmental NOAEL for 2-Isopropyl-5-methylcyclohexanol in rats was determined to be 218 mg/kg bw/day.

Executive summary:

The developmental toxicity of 2-Isopropyl-5-methylcyclohexanol was investigated in Wistar female rats. Virgin adult female Wistar rats were mated with untreated young adult males and observation of vaginal sperm plugs was considered day 0 of gestation. Beginning on Day 6 and continuing daily through Day 15 of gestation, groups (22-23/group) of pregnant females were given 0, 2.18, 10.15, 47.05 and 218 mg/kg bw of the test material (FDA 71-57) by gavage in corn oil. A positive control group received 250 mg/kg bw/day of aspirin. On Day 20 all dams were subjected to Caesarian section. Referring to the maternal observations daily clinical observation and measurement of body weight gain failed to show any differences between control and test groups of female rats. The number pregnant and % pregnancy were similar for all dose and control groups. No abortions were observed in any group. The number of live litters, average implant sites per dam were similar for both test and control groups. The % partial resorptions and % complete resorption were increased only for the positive control group. Referring to fetal data, the average fetal weight of treatment and control groups were not statistically different (p>0.05). The total number of live fetuses was similar for test and negative control groups. Also, there were no dead fetuses in either the test or negative control groups. The positive control group did show dead fetuses (3) and dams with more than one dead fetus. The positive control group also exhibited a decreased number of live fetuses and decreased average fetal weight compared to those for the negative control. Skeletal examination of sternebrae, vertebrae, skull, ribs, extremities, and soft tissues showed no significant differences between test and negative control groups. The positive control group showed a significant increase in incidence of missing sternebrae. Likewise, the positive control exhibited an increase in the incidence of fetuses with more than 13 ribs, incomplete ossification of vertebrae and extremities, incomplete skull closure. Visceral examination failed to reveal any evidence of abnormalities in either negative control or test groups. In the positive control group, meningoencephalocele and spina bifida were reported. There was no evidence of maternal toxicity or developmental toxicity at dose levels up to and including 218 mg/kg bw/day of test material. The maternal and developmental NOAEL for 2-Isopropyl-5-methylcyclohexanol in rats was determined to be 218 mg/kg bw/day.

Reference 8

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

1973

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

Deviations:

yes

Remarks:

(corporea lutea not reported, no full dam macroscopic examination)

GLP compliance:

no

Limit test:

no

Species:

mouse

Strain:

CD-1

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Age at study initiation: adult
- Weight at study initiation: 27.0-29.8 g (pregnant dams)
- Housing: Mice were gang-housed in plastic disposable cages in a temperature- and humidity-controlled room.
- Diet: ad libitum
- Water: ad libitum (tap water)

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on exposure:

PREPARATION OF DOSING SOLUTIONS: Administration as a corn oil solution: 10 mL per kg of body weight.

Analytical verification of doses or concentrations:

not specified

Details on mating procedure:

- Impregnation procedure: Virgin adult females (1 per cage) were mated with untreated young adult males.
- Proof of pregnancy: vaginal sperm plugs, referred to as day 0 of pregnancy

Duration of treatment / exposure:

10 days: beginning on Day 6 and continuing through day 15 of gestation.

Frequency of treatment:

Daily.

Duration of test:

17 days.

Dose / conc.:

1.85 mg/kg bw/day (nominal)

Dose / conc.:

8.59 mg/kg bw/day (nominal)

Dose / conc.:

39.9 mg/kg bw/day (nominal)

Dose / conc.:

185 mg/kg bw/day (nominal)

No. of animals per sex per dose:

22-23 pregnant females per group.

Control animals:

yes, concurrent vehicle

other: Positive control: 150 mg/kg bw/day of aspirin

Maternal examinations:

CLINICAL OBSERVATIONS: Yes
- Time schedule: females were observed daily for appearance and behaviour.

BODY WEIGHT: Yes
- Time schedule for examinations: recorded on days 0, 6, 11, 15 and 17 of gestation.

FOOD CONSUMPTION: Yes

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day 17 (caesarean section under surgical anesthesia)
- Organs examined: urogenital tract of each dam was examined for anatomical abnormalities.

Ovaries and uterine content:

The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: No data
- Number of corpora lutea: No data
- Number of implantations: Yes
- Number of resorptions: Yes (% of live and % partial live resorptions)
- Others: live and dead fetuses; body weight of the live pups.

Fetal examinations:

- External examinations: Yes: mortality, litter size and weights, sex of pups and gross abnormalities to pups.
- Soft tissue examinations: Yes: 1/3 per litter, detailed visceral examination at 10x magnification.
- Skeletal examinations: Yes: 2/3 per litter, cleared in potassium hydroxide (KOH), stained with alizarin red S dye and examined for skeletal defects (sternebrae, ribs, vertebrae, skull, extremities, miscellaneous.

Indices:

Number of implantation sites, number of resorptions, % of live and % partial live resorptions, live fetuses, dead fetuses, and body weight of live pups. Gestation index, mortality, litter size and weights, sex and sex ratio of pups, and gross abnormalities to pups.

Details on maternal toxic effects:

Daily clinical observation and measurement of body weight gain failed to show any differences between control and test groups of female mice. The number pregnant and % pregnancy were similar for all dose and control groups. No abortions were observed in any group. The number of live litters, average implant sites per dam were similar for both test and control groups. The % partial resorptions and % complete resorption were increased for the 1.85 and 8.59 mg/kg bw groups, but higher dose levels exhibited lower resorption rates compared to the control groups.

Key result

Dose descriptor:

NOAEL

Effect level:

185 mg/kg bw/day (nominal)

Based on:

test mat.

Basis for effect level:

other: maternal toxicity

Key result

Dose descriptor:

NOAEL

Effect level:

185 mg/kg bw/day (nominal)

Based on:

test mat.

Basis for effect level:

other: developmental toxicity

Details on embryotoxic / teratogenic effects:

The average fetal weight of treatment and control groups were not statistically different (p>0.05). The total number of live fetuses was similar for test and control groups. Also, there was no significant difference in the number of dead fetuses between test and control groups. Skeletal examination of sternebrae showed no significant differences in the incidence of incomplete ossification or missing sternebrae for test and negative control groups. There was evidence of incomplete ossification in the positive control group. Likewise the incidences of fetuses with more than 13 ribs, incomplete ossification of vertebrae and extremities, incomplete skull closure were similar for test and negative control animals. Visceral examination failed to reveal any evidence of soft tissue abnormalities at any dose level.

Abnormalities:

not specified

Developmental effects observed:

not specified

There was no evidence of maternal toxicity or developmental toxicity at dose levels up to and including 185 mg/kg bw/day of test material.

Conclusions:

The maternal and developmental NOAEL for 2-Isopropyl-5-methylcyclohexanol in mice was determined to be 185 mg/kg bw/day.

Executive summary:

The developmental toxicity of 2-Isopropyl-5-methylcyclohexanol was investigated in CD-1 mice. Virgin adult female CD-1 outbred mice were mated with untreated young adult males and observation of vaginal sperm plugs was considered day 0 of gestation. Beginning on Day 6 and continuing daily through Day 15 of gestation, groups (22-23/group) of pregnant females were given 0, 1.85, 8.59, 39.9, 185 mg/kg bw of the test material (FDA 7157) by gavage in corn oil. A positive control group received 150 mg/kg bw/day of aspirin. Body weights were recorded on days 0, 6, 11, 15, and 17 of gestation. On Day 17 all dams were subjected to Caesarian section. Referring to the maternal observations daily clinical observation and measurement of body weight gain failed to show any differences between control and test groups of female mice. The number pregnant and % pregnancy were similar for all dose and control groups. No abortions were observed in any group. The number of live litters, average implant sites per dam were similar for both test and control groups. The % partial resorptions and % complete resorption were increased for the 1.85 and 8.59 mg/kg bw groups, but higher dose levels exhibited lower resorption rates compared to the control groups. Referring to the fetal data, the average fetal weight of treatment and control groups were not statistically different (p>0.05). The total number of live fetuses was similar for test and control groups. Also, there was no significant difference in the number of dead fetuses between test and control groups. Skeletal examination of sternebrae showed no significant differences in the incidence of incomplete ossification or missing sternebrae for test and negative control groups. There was evidence of incomplete ossification in the positive control group. Likewise the incidences of fetuses with more than 13 ribs, incomplete ossification of vertebrae and extremities, incomplete skull closure were similar for test and negative control animals. Visceral examination failed to reveal any evidence of soft tissue abnormalities at any dose level. There was no evidence of maternal toxicity or developmental toxicity at dose levels up to and including 185 mg/kg bw/day of test material. The maternal and developmental NOAEL for 2-Isopropyl-5-methylcyclohexanol in mice was determined to be 185 mg/kg bw/day.

Reference 9

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

1973

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

Deviations:

yes

Remarks:

(corporea lutea not reported, no full dam macroscopic examination)

GLP compliance:

no

Limit test:

no

Species:

hamster

Strain:

other: Golden

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Age at study initiation: adult
- Weight at study initiation: 101.5-107.5 g (pregnant dams)
- Housing: Hamsters were individually housed in mesh bottom cages in a temperature- and humidity-controlled quarters.
- Diet: ad libitum
- Water: ad libitum (tap water)

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on exposure:

PREPARATION OF DOSING SOLUTIONS: A
Dosage (mg/kg) Dose (ml/kg) Concentration (mg/ml)
<250 1 <250
251-500 2 125-250
501-750 3 133-250
751-1000 4 187-250
1001-1250 5 200-250
1252-1500 6 208-250
1501-1600 6.4 135-250

Analytical verification of doses or concentrations:

not specified

Details on mating procedure:

- Impregnation procedure: Virgin adult females (1 per cage) were mated one to one with untreated young adult males.
- Proof of pregnancy: appearance of motile sperm in the vaginal sperm, referred to as day 0 of pregnancy.

Duration of treatment / exposure:

5 days: beginning on Day 6 and continuing through day 10 of gestation.

Frequency of treatment:

Daily.

Duration of test:

14 days.

Dose / conc.:

4.05 mg/kg bw/day (nominal)

Dose / conc.:

21.15 mg/kg bw/day (nominal)

Dose / conc.:

98.2 mg/kg bw/day (nominal)

Dose / conc.:

405 mg/kg bw/day (nominal)

No. of animals per sex per dose:

21-23 pregnant females per group.

Control animals:

yes, concurrent vehicle

other: Positive control: 250 mg/kg bw/day of aspirin

Maternal examinations:

CLINICAL OBSERVATIONS: Yes
- Time schedule: females were observed daily for appearance and behaviour.

BODY WEIGHT: Yes
- Time schedule for examinations: recorded on days 0, 8, 10 and 14 of gestation.

FOOD CONSUMPTION: Yes

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day 14 (caesarean section under surgical anesthesia)
- Organs examined: urogenital tract of each dam was examined for anatomical abnormalities.

Ovaries and uterine content:

The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: No data
- Number of corpora lutea: No data
- Number of implantations: Yes
- Number of resorptions: Yes (% of live and % partial live resorptions)
- Others: live and dead fetuses; body weight of the live pups.

Fetal examinations:

- External examinations: Yes: mortality, litter size and weights, sex of pups and gross abnormalities to pups.
- Soft tissue examinations: Yes: 1/3 per litter, detailed visceral examination at 10x magnification.
- Skeletal examinations: Yes: 2/3 per litter, cleared in potassium hydroxide (KOH), stained with alizarin red S dye and examined for skeletal defects (sternebrae, ribs, vertebrae, skull, extremities, miscellaneous.

Indices:

Number of implantation sites, number of resorptions, % of live and % partial live resorptions, live fetuses, dead fetuses, and body weight of live pups. Gestation index, mortality, litter size and weights, sex and sex ratio of pups, and gross abnormalities to pups.

Details on maternal toxic effects:

Daily clinical observation and measurement of body weight gain failed to show any differences between control and test groups of female rats. The number pregnant and % pregnancy were similar for all dose and control groups. No abortions were observed in any group.

Key result

Dose descriptor:

NOAEL

Effect level:

405 mg/kg bw/day (nominal)

Based on:

test mat.

Basis for effect level:

other: maternal toxicity

Key result

Dose descriptor:

NOAEL

Effect level:

405 mg/kg bw/day (nominal)

Based on:

test mat.

Basis for effect level:

other: developmental toxicity

Details on embryotoxic / teratogenic effects:

The average fetal weight of treatment and control groups were not statistically different (p>0.05). The total number of live fetuses was similar for test and control groups. There was one dead fetus in the negative control and the 4.05 and 21.15 dose groups, but none in the higher dose groups. There were 18 dead fetuses in the positive control group. Skeletal examination of sternebrae showed no significant differences in the incidence of incomplete ossification or missing sternebrae for test and control groups. Likewise the incidences of fetuses with more than 13 ribs, incomplete ossification of vertebrae and extremities, incomplete skull closure were similar for test and control animals. An increased incidence of incomplete ossification of the vertebrae was reported in the two mid-dose groups but not in the highest (405 mg/kg bw) group. Visceral examination of tissues failed to reveal any evidence of significant abnormalities at any dose level.

Abnormalities:

not specified

Developmental effects observed:

not specified

There was no evidence of maternal toxicity or developmental toxicity at dose levels up to and including 405 mg/kg bw/day of test material.

Conclusions:

The maternal and developmental NOAEL for 2-Isopropyl-5-methylcyclohexanol in hamsters was determined to be 405 mg/kg bw/day.

Executive summary:

The developmental toxicity of 2-Isopropyl-5-methylcyclohexanol was investigated in Golden female hamsters. Virgin adult female Golden hamsters were mated with untreated young adult males and observation of vaginal sperm plugs was considered day 0 of gestation. Beginning on Day 6 and continuing daily through Day 10 of gestation, groups (19 -23/group) of pregnant females were given 0, 4.05, 21.15, 98.2 and 405 mg/kg bw of the test material (FDA 71-57) by gavage in corn oil. A positive control group received 250 mg/kg bw/day of aspirin. On Day 14 all dams were subjected to Caesarian section. Referring to the maternal observations, daily clinical observation and measurement of body weight gain failed to show any differences between control and test groups of female rats. The number pregnant and % pregnancy were similar for all dose and control groups. No abortions were observed in any group. Referring to fetal data, the average fetal weight of treatment and control groups were not statistically different (p>0.05). The total number of live fetuses was similar for test and control groups. There was one dead fetus in the negative control and the 4.05 and 21.15 dose groups, but none in the higher dose groups. There were 18 dead fetuses in the positive control group. Skeletal examination of sternebrae showed no significant differences in the incidence of incomplete ossification or missing sternebrae for test and control groups. Likewise the incidences of fetuses with more than 13 ribs, incomplete ossification of vertebrae and extremities, incomplete skull closure were similar for test and control animals. An increased incidence of incomplete ossification of the vertebrae was reported in the two mid-dose groups but not in the highest (405 mg/kg bw) group. Visceral examination of tissues failed to reveal any evidence of significant abnormalities at any dose level. There was no evidence of maternal toxicity or developmental toxicity at dose levels up to and including 405 mg/kg bw/day of test material. The maternal and developmental NOAEL for 2-Isopropyl-5-methylcyclohexanol in hamsters was determined to be 405 mg/kg bw/day.

Reference 10

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

1973

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

Deviations:

yes

Remarks:

(11-14 pregnant females per group, no full dam macroscopic examination)

GLP compliance:

no

Limit test:

no

Species:

rabbit

Strain:

Dutch

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Age at study initiation: adult
- Weight at study initiation: 2.04-2.55 kg (pregnant dams)
- Housing: Hamsters were individually housed in mesh bottom cages in a temperature- and humidity-controlled quarters.
- Diet: ad libitum
- Water: ad libitum (tap water)

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on exposure:

PREPARATION OF DOSING SOLUTIONS: A
Dosage (mg/kg) Dose (ml/kg) Concentration (mg/ml)
<250 1 <250
251-500 2 125-250
501-750 3 133-250
751-1000 4 187-250
1001-1250 5 200-250
1252-1500 6 208-250
1501-1600 6.4 135-250

Analytical verification of doses or concentrations:

not specified

Details on mating procedure:

- Impregnation procedure: On day 0, animals were given an injection of 0.4 l of human chorionic gonadotropini (400 IU). Three hours later, each doe was artificially inseminated with 0.3 ml of semen from a buck using approximately 20x10E6 motile sperm.

Duration of treatment / exposure:

13 days: beginning on Day 6 and continuing through day 18 of gestation.

Frequency of treatment:

Daily.

Duration of test:

29 days.

Dose / conc.:

4.25 mg/kg bw/day (nominal)

Remarks:

Doses / Concentrations:
4.25, 19.75, 91.7, 425 mg/kg bw/day
Basis:
nominal conc.

Dose / conc.:

19.75 mg/kg bw/day (nominal)

Dose / conc.:

91.7 mg/kg bw/day (nominal)

Dose / conc.:

425 mg/kg bw/day (nominal)

No. of animals per sex per dose:

11-14 pregnant females per group.

Control animals:

yes, concurrent vehicle

other: Positive control: 2.5 mg/kg bw/day of aminonictineamide

Maternal examinations:

CLINICAL OBSERVATIONS: Yes
- Time schedule: females were observed daily for appearance and behaviour.

BODY WEIGHT: Yes
- Time schedule for examinations: recorded on days 0, 6, 8, 12, 18 and 29 of gestation.

FOOD CONSUMPTION: Yes

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day 29
- Organs examined: urogenital tract of each dam was examined for anatomical abnormalities.

Ovaries and uterine content:

The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: No data
- Number of corpora lutea: Yes
- Number of implantations: Yes
- Number of resorptions: Yes
- Others: live and dead fetuses; body weight of the live pups.

Fetal examinations:

- External examinations: Yes: mortality, litter size and weights, sex of pups and gross abnormalities to pups.
- Soft tissue examinations: Yes: all survival pups were sacrified and subjected to detailed visceral examination at 10x magnification.
- Skeletal examinations: Yes: 2/3 per litter, cleared in potassium hydroxide (KOH), stained with alizarin red S dye and examined for skeletal defects (sternebrae, ribs, vertebrae, skull, extremities, miscellaneous.

Indices:

Number of implantation sites, number of resorptions, live fetuses, dead fetuses, and body weight of live pups. Gestation index, mortality, litter size and weights, sex and sex ratio of pups, and gross abnormalities to pups.

Details on maternal toxic effects:

Survival of dams at term was similar for test, positive, and negative control groups. Daily clinical observation and measurement of body weight gain failed to show any differences between control and test groups of female rabbits. The number pregnant and % pregnancy were similar for all dose and control groups. One to four pregnant female died in both control groups and in the four test groups. There was no dose response relationship for mortality in the test groups. There was no statistical difference in the number of live litters, corpora lutea, implantation sites, or resorption sites between the negative control group and any test group.

Key result

Dose descriptor:

NOAEL

Effect level:

425 mg/kg bw/day (nominal)

Based on:

test mat.

Basis for effect level:

other: maternal toxicity

Key result

Dose descriptor:

NOAEL

Effect level:

425 mg/kg bw/day (nominal)

Based on:

test mat.

Basis for effect level:

other: developmental toxicity

Details on embryotoxic / teratogenic effects:

The average fetal weight of treatment and control groups were not statistically different (p>0.05). The total number of live fetuses was similar for test and control groups. Also, there was no significant difference in the number of dead fetuses between test and control groups. Except for positive control group, skeletal examination of sternebrae and vertebrae showed no significant differences in the incidence of incomplete ossification or missing sternebrae for test and untreated control group. Likewise the incidences of fetuses with more than 13 ribs, incomplete ossification of vertebrae and extremities, incomplete skull closure were similar for test and the untreated control group The positive 6-aminonicotinaminde-treated control group showed increases in incidence of fused and split ribs. Visceral examination failed to reveal any evidence of abnormalities in either negative control or test groups. In the positive control group, medial rotation of the hind limb and anopia were reported in pups from 7 of the 11 litters.

Abnormalities:

not specified

Developmental effects observed:

not specified

There was no evidence of maternal toxicity or developmental toxicity at dose levels up to and including 405 mg/kg bw/day of test material.

Conclusions:

The maternal and developmental NOAEL for 2-Isopropyl-5-methylcyclohexanol in rabbits was determined to be 425 mg/kg bw/day.

Executive summary:

The developmental toxicity of 2-Isopropyl-5-methylcyclohexanol was investigated in Dutch belted female rabbits. On day 0, does were given an injection of 0.4 l of human chorionic gonadotropin (400 IU). Three hours later, each doe was artificially inseminated with 0.3 ml of semen from a buck using approximately 20 x 10e6 motile sperm. Beginning on Day 6 and continuing daily through Day 18 of gestation, groups (11-14/group) pregnant females were given 0, 4.25, 19.75, 91.7, 425 mg/kg bw of the test material (FDA 71-57) by gavage in corn oil. A positive control group received 2.5 mg/kg bw/day of 6 -aminonicotinamide. On Day 29 all dams were subjected to Caesarian section. Referring to the maternal observations, survival of dams at term was similar for test, positive, and negative control groups. Daily clinical observation and measurement of body weight gain failed to show any differences between control and test groups of female rabbits. The number pregnant and % pregnancy were similar for all dose and control groups. One to four pregnant female died in both control groups and in the four test groups. There was no dose response relationship for mortality in the test groups. There was no statistical difference in the number of live litters, corpora lutea, implantation sites, or resorption sites between the negative control group and any test group. Referring to fetal data, the average fetal weight of treatment and control groups were not statistically different (p>0.05). The total number of live fetuses was similar for test and control groups. Also, there was no significant difference in the number of dead fetuses between test and control groups. Except for positive control group, skeletal examination of sternebrae and vertebrae showed no significant differences in the incidence of incomplete ossification or missing sternebrae for test and untreated control group. Likewise the incidences of fetuses with more than 13 ribs, incomplete ossification of vertebrae and extremities, incomplete skull closure were similar for test and the untreated control group The positive 6-aminonicotinaminde-treated control group showed increases in incidence of fused and split ribs. Visceral examination failed to reveal any evidence of abnormalities in either negative control or test groups. In the positive control group, medial rotation of the hind limb and anopia were reported in pups from 7 of the 11 litters. There was no evidence of maternal toxicity or developmental toxicity at dose levels up to and including 425 mg/kg bw/day of test material. The maternal and developmental NOAEL for 2-Isopropyl-5-methylcyclohexanol in rabbits was determined to be 425 mg/kg bw/day.

Effect on developmental toxicity: via oral route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

126.05 mg/kg bw/day

Study duration:

subacute

Species:

rat

Quality of whole database:

Five studies are available (pre-natal developmental study), of which 2 were conducted in rats (weight of evidence approach, Klimisch = 2) and the other three were conducted in mouse, hamsters and rabbits (supporting studies, Klimisch 2 and 3). The overall quality of the database is adequate.

Additional information

Weight of evidence: read-across from experimental data on the analogue 4 -tert-butylcyclohexyl acetate:

In the study reported by Bathia SP et al. 2008, a developmental toxicity test was performed on the analogue substance 4-tert-butylcyclohexyl acetate in Sprague-Dawley rats (test method equivalent to OECD 414). 25 pregnants rats per dose were exposed by gavage to 0 (control, 40, 160 and 640 mg/kg bw/day) on days 7–20 of gestation. The maternal NOAEL for the analogue substance was determined to be 160 mg/kg bw/day (basis for effect: clinical signs, body weight gain and feed consumption at 640 mg/kg bw/day) and the NOAEL for developmental toxicity was 160 mg/kg bw/day (basis for effect: reduced foetal body weights, transient delay in foetal development and reversible delays in skeletal ossification at 640 mg/kg bw/day). Based on these results, the read across was applied and the NOAEL for both maternal and developmental toxicity of 2 -methylcyclohexyl acetate was determined to be 126.05 mg/kg bw/day. According to the authors, the decreased body weights and increases in variations observed in pups commonly occur when there are decreased maternal body weight and feed consumption.

Weight of evidence: read-across from experimental data on the analogue 2 -isopropyl-5 -methylcyclohexanol:

In the prenatal developmental toxicity test conducted by U.S. Food and Drug Administration (1975) on the analogue 2 -isopropyl-5-methylcyclohexanol. Groups of pregnant rat females (22 -25/group) were exposed to 0 (control) 2.18, 10.15, 47.05 and 218 mg/kg bw/day beginning on day 6 and continuing daily through day 15 of gestation. At termination (day 20) there was no evidence of maternal toxicity or developmental toxicity up to 218 mg/kg bw/day and therefore the NOAEL was determined to be 218 mg/kg bw/day. Based on these results, the read-across was applied and the NOAEL for both maternal and developmental toxicity in rats of 2 -methylcyclohexyl acetate was determined to be 217.95 mg/kg bw/day.

Supporting studies: read-across from experimental data on the analogue 2 -isopropyl-5 -methylcyclohexanol:

U.S. Food and Drug Administration (1975) also performed the above mentioned pre-natal developmental toxicity test with mice, hamsters and rabbits with the analogue 2 -isopropyl-5 -methylcyclohexanol. No evidence of maternal nor developmental toxicity was observed in neither study and the NOAELs were determined to be 185 mg/kg bw/day in mice, 405 mg/kg bw/day in hamsters and 425 mg/kg bw/day in rabbits. Based on these results, the read-across was applied and the NOAEL for both maternal and developmental toxicity of 2 -methylcyclohexyl acetate was calculated to be 184.96 mg/kg bw/day in mice, 404.91 mg/kg bw/day in hamsters and 424.90 mg/kg bw/day in rabbits.

Justification for classification or non-classification

Based on available data on toxicity to reproduction, 2 -methylcyclohexyl acetate is not classified for toxicity to reproduction in accordance with CLP Regulation (EC) no 1272/2008.