2-methylcyclohexyl acetate

Endpoint summary

Description of key information

Key study: Test method similar to OECD 451. No GLP. Based on the read-across approach from experimental data on the analogue 2-isopropyl-5-methylcyclohexanol, the NOAEL for 2-methylcyclohexyl acetate when administered to rats for 103 consecutive weeks by oral route was determined to be 7498 ppm (~375 mg/kg bw/day) in males and females under test conditions.

Key study: Test method similar to OECD 451. No GLP. Based on the read-across approach from experimental data on the analogue 2-isopropyl-5-methylcyclohexanol, the NOAEL for 2-methylcyclohexyl acetate when administered to mice for 103 consecutive weeks by oral route was determined to be 2000 ppm (~300 mg/kg bw/day) in females and 3999 ppm (~ 600 mg/kg bw/day) in males under test conditions.

Supporting study: 13 week oral toxicity study. No GLP. Based on the read-across approach from experimental data on the analogue 2-isopropyl-5-methylcyclohexanol, the NOAEL for 2 -methylcyclohexyl acetate when administered to rats for 13 consecutive weeks by oral route was determined to be 7498 ppm (~750 mg/kg bw/day) in males and 14996 ppm (~ 1500 mg/kg bw/day) in females under test conditions

Supporting study: 13 week oral toxicity study. No GLP. Based on the read-across approach from experimental data on the analogue 2-isopropyl-5-methylcyclohexanol,  the NOAEL for 2 -methylcyclohexyl acetate when administered to mice for 13 consecutive weeks by oral route was determined to be 3749 ppm (~563 mg/kg bw/day) in females and 14996 ppm (~ 2250 mg/kg bw/day) in males under test conditions.

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Reference 1

Endpoint:

repeated dose toxicity: oral

Remarks:

other: Carcinogenicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1979

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Reason / purpose for cross-reference:

reference to other study

Qualifier:

equivalent or similar to guideline

Guideline:

other: OECD 451 Carcinogenicity study

Deviations:

yes

Remarks:

(2 dose levels tested)

GLP compliance:

no

Limit test:

no

Species:

rat

Strain:

Fischer 344

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Frederick Cancer Research Center, Frederick, Maryland (USA)
- Age at study initiation: 9 weeks
- Fasting period before study: 4 weeks
- Housing: Polycarbonate cages covered with stainless steel cage lids and non-woven fiber filter bonnets. Cages were furnished with heat-treated hardwood chip bedding.
- Diet: Ad libitum
- Water: Ad libitum

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20-24 ºC
- Humidity (%): 45-55 %
- Air changes (per hr): 12 changes of room air per hour (filtered through 2-inch-thick disposable fiberglass filters).

Route of administration:

oral: feed

Vehicle:

corn oil

Details on oral exposure:

PREPARATION OF DOSING SOLUTIONS: The appropriate weight of the dl-menthol required for each dietary concentration was dissolved in corn oil by stirring over a low heat.

DIET PREPARATION
- Rate of preparation of diet (frequency): prepared each week (and used within 1 week of preparation).
- Mixing appropriate amounts with (Type of food): The test item solution was added to the Wayne Lab Blox animal meal and thoroughly mixed.
- Storage temperature of food: room temperature

VEHICLE
- Concentration: 2% by weight in the basal diets.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Duplicate 10-g dosed feed samples were extracted with 20 ml of carbon disulphide, and aliquots of the extract analysed by gas chromatography (thermal conductivity detector). The average recoveries from these spiked samples were greater than 90%.

Duration of treatment / exposure:

103 weeks

Frequency of treatment:

Daily

Dose / conc.:

3 750 ppm

Remarks:

~187 mg/kg bw/day, nominal in diet

Dose / conc.:

7 500 ppm

Remarks:

~375 mg/kg bw/day
nominal in diet

No. of animals per sex per dose:

50 animals per sex and per dose

Control animals:

yes

Details on study design:

- Dose selection rationale: A subchronic feeding study was conducted to estimate the maximum tolerated dosed of dl-menthol (see study endpoint 07.05.01_03).

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice a day.
- Observations: sings of toxicity

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Every week
- Observations: clinical signs and the presence of palpable masses

BODY WEIGHT: Yes
- Time schedule for examinations: every 2 weeks for the first 12 weeks and every month thereafter.

FOOD CONSUMPTION: YES
- Time schedule: every 2 weeks for the first 12 weeks and every month thereafter.

Sacrifice and pathology:

Animals that were moribund and those that survived to the termination of the study were killed by exsanguination under sodium pentobarbital anaesthesia. The pathologic evaluation consisted of gross and microscopic examination of major tissues, major organs, and all gross lesions from killed animals and from animals found dead. The tissues were preserved in 10% buffered formalin, embedded in paraffin, sectioned, and stained with haematoxylin and eosin. The following tissues were examined microscopically: brain (frontal cortex and basal ganglia, parietal cortex and thalamus, and cerebellum and pons), pituitary, spinal cord (if neurologic signs were present), eyes (if grossly abnormal), oesophagus, trachea, salivary gland, mandibular lymph node, thyroid, parathyroid, heart, thymus, lungs and mainstem bronchi, liver, gallbladder (mice), pancreas, spleen, kidney, adrenal, stomach, small intestine, colon, urinary bladder, prostate or uterus, testes or ovaries, sternebrae femur, or vertebrae including marrow, mammary gland, tissue masses, and any macroscopic lesions.

Statistics:

Probabilities of survival were estimated by the product-limit procedure of Kaplan and Meier (1958). Statistical analyses for a possible dose-related effect on survival used the method of Cox (1972) for testing two groups for equality and Tarone's (1975) extensions of Cox's methods for testing for a dose-related trend. The one-tailed Fisher exact test (Cox, 1970) was used to compare the tumour incidence of a control group with that of a group of dosed animals at each dose level. The Cochran-Armitage test for linear trend in proportions, with continuity correction (Armitage, 1971), was also used to determine if the slope of the dose-response curve is different from zero at the one tailed 0.05 level of significance.

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

(males and females)

Food consumption and compound intake (if feeding study):

no effects observed

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

not examined

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

not examined

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

no effects observed

Details on results:

MORTALITY:
The dose-related trend in mortality and the comparison between the survival of the control group with each dosed group are not significant in either sex. In male rats, 34/50 (68%) of the high-dose group, 33/50 (66%) of the low-dose group, and 31/50 (62%) of the controls were alive at week 105. In females, 38/50 (76%) of the high-dose group, 35/50 (70%) of the low-dose group, and 36/50 (72%) of the controls were alive at week 105. Sufficient numbers of rats of each sex were at risk for the development of late-appearing tumors.

CLINICAL SIGNS:
No clinical signs related to administration of test item were noted. Clinical signs commonly observed among rats of this strain were noted at comparable rates in the control and dosed groups, particularly during the second year of the bioassay, and increased in incidence as the animals aged. These signs included eye changes (redness, paleness, cloudiness, lacrimation, a red discharge or bloody crust, and an enlarged or protruding eye), a hunched and/or thin appearance, urine stains on the abdominal fur, and occasionally, nasal discharge, sores on the body or the extremities, soft feces, and enlarged testes. The incidence of palpable nodules and tissue masses in the dosed males was generally comparable to that in the control males, but was lower in the dosed females than in the control females.

BODY WEIGHT AND WEIGHT GAIN
Mean body weights of the dosed male and female rats were slightly lower than those of the corresponding controls throughout the bioassay.

HISTOPATHOLOGY: NON-NEOPLASTIC
Chronic inflammation of the kidney was observed with greater frequency in the dosed males than in the control males (29/49 controls, 41/50 low-dose, 41/50 high-dose); however, this finding is of questionable importance, since such lesions are often found in aged male Fischer 344 rats.

HISTOPATHOLOGY: NEOPLASTIC
Each of the tumour types observed has been encountered previously as a spontaneous lesion, and occurred with no appreciable differences in frequency between control and dosed rats with a few exceptions. In female rats, chromophobe adenomas of the pituitary gland and fibroadenomas of the mammary gland were observed with greater frequency in female control rats. Chromophobe adenomas occurred in 28/48 controls, 25/47 low-dose and 19/43 high-dose female rats. Mammary gland fibroadenomas were diagnosed in 20/50 female controls, 10/49 low-dose, and 7/49 high-dose rats. Mammary adenocarcinomas were seen in 1/50 controls, 3/49 low-dose, and 0/49 high-dose rats.

All other inflammatory, degenerative, and hyperplastic lesions that occurred were similar in incidence and kind to those naturally occurring lesions found in aged Fischer 344 rats.

Key result

Dose descriptor:

NOAEL

Effect level:

7 500 ppm

Based on:

test mat.

Sex:

male/female

Basis for effect level:

mortality

Remarks on result:

other: (~375 mg/kg bw/day)

Critical effects observed:

not specified

Based on the histopathologic examination, 2 -isopropyl-5 -methylcyclohexanol was neither toxic nor carcinogenic to Fischer 344 rats under the conditions of this bioassay.

Conclusions:

The NOAEL for 2-isopropyl-5-methylcyclohexanol when administered to rats for 103 consecutive weeks by oral route was determined to be 7500 ppm (~375 mg/kg bw/day).

Executive summary:

A 103 week oral (diet) carcinogenicity study was conducted with test item 2 -isopropyl-5 -methylcyclohexanol. Groups of 50 Fischer 344 rats of each sex were administered 0, 3750 or 7500 ppm (~ 0, 187, 375 mg/kg bw/day) dl-2-isopropy-5-methylcyclohexanol in their feed daily for 103 weeks. Animals were housed five per cage until week 48 when the male rats were divided into groups of two to three per cage. The animals were observed twice daily for signs of toxicity. Body weight and food consumption were recorded every two weeks for the first twelve weeks, and once a month thereafter. Necropsies and histological examinations were performed on all animals at the termination of the study and on those found dead during the study. The mean body weights of the male and female rats administered at 3750 or 7500 ppm (~187 or 375 mg/kg bw/day) were slightly lower when compared to the controls. Survival of the high- and low-dose groups of male (controls, 31/50; low-dose, 33/50; high-dose, 34/50) and female (controls, 36/50; low-dose, 35/50; high-dose, 38/50) rats was similar to the control animals. Chronic inflammation of the kidney observed in the dosed older males was not considered by the authors to be related to the administration of dl-2-isopropy-5-methylcyclohexanol since the effect is commonly observed in aged male Fischer 344 rats. There was no increase in the incidence of neoplasms of dosed females compared to that of control animals. In the low-dose (10/49) and high-dose (7/49) female groups, fibroadenomas of the mammary glands occurred at a lower incidence than in the control group (20/50). Alveolar/bronchiolar adenomas or carcinomas were reported only for the female control rats. Under the conditions of this study, it was concluded that 2-isopropy-5-methylcyclohexanol was neither carcinogenic nor toxic for either sex of Fischer 344 rats at dose levels of 3750 or 7500 ppm (~187 or 375 mg/kg bw/day).

Reference 2

Endpoint:

repeated dose toxicity: oral

Remarks:

other: Carcinogenicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1979

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

other: OECD 451 Carcinogenicity study

Deviations:

yes

Remarks:

(2 dose levels tested)

GLP compliance:

no

Limit test:

no

Species:

mouse

Strain:

B6C3F1

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Frederick Cancer Research Center, Frederick, Maryland (USA)
- Age at study initiation: 6 weeks
- Fasting period before study: 2 weeks
- Housing: Polycarbonate cages covered with stainless steel cage lids and non-woven fiber filter bonnets. Cages were furnished with heat-treated hardwood chip bedding.
- Diet: Ad libitum
- Water: Ad libitum
- Acclimation period:

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20-24 ºC
- Humidity (%): 45-55 %
- Air changes (per hr): 12 changes of room air per hour (filtered through 2-inch-thick disposable fiberglass filters).

Route of administration:

oral: feed

Vehicle:

corn oil

Details on oral exposure:

PREPARATION OF DOSING SOLUTIONS: The appropriate weight of the dl-menthol required for each dietary concentration was dissolved in corn oil by stirring over a low heat.

DIET PREPARATION
- Rate of preparation of diet (frequency): prepared each week (and used within 1 week of preparation).
- Mixing appropriate amounts with (Type of food): The test item solution was added to the Wayne Lab Blox animal meal and thoroughly mixed.
- Storage temperature of food: room temperature

VEHICLE
- Concentration: 2% by weight in the basal diets.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Duplicate 10-g dosed feed samples were extracted with 20 ml of carbon disulphiide, and aliquots of the extract analysed by gas chromatography (thermal conductivity detector). The average recoveries from these spiked samples were greater than 90%.

Duration of treatment / exposure:

103 weeks

Frequency of treatment:

Daily

Dose / conc.:

2 000 ppm

Remarks:

nominal in diet

Dose / conc.:

4 000 ppm

Remarks:

nominal in diet

No. of animals per sex per dose:

50 animals per sex and per dose

Control animals:

yes

Details on study design:

- Dose selection rationale: A subchronic feeding study was conducted to estimate the maximum tolerated dosed of dl-menthol (see study endpoint 07.05.01_04).

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice a day.
- Observations: sings of toxicity

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Every week
- Observations: clinical signs and the presence of palpable masses

BODY WEIGHT: Yes
- Time schedule for examinations: every 2 weeks for the first 12 weeks and every month thereafter.

FOOD CONSUMPTION: YES
- Time schedule: every 2 weeks for the first 12 weeks and every month thereafter.

Sacrifice and pathology:

Animals that were moribund and those that survived to the termination of the study were killed by exsanguination under sodium pentobarbital anaesthesia. The pathologic evaluation consisted of gross and microscopic examination of major tissues, major organs, and all gross lesions from killed animals and from animals found dead. The tissues were preserved in 10% buffered formalin, embedded in paraffin, sectioned, and stained with haematoxylin and eosin. The following tissues were examined microscopically: brain (frontal cortex and basal ganglia, parietal cortex and thalamus, and cerebellumand pons), pituitary, spinal cord (if neurologic signs were present), eyes (if grossly abnormal), oesophagus, trachea, salivary gland, mandibular lymph node, thyroid, parathyroid, heart, thymus, lungs and mainstem bronchi, liver, gallbladder (mice), pancreas, spleen, kidney, adrenal, stomach, small intestine, colon, urinary bladder, prostate or uterus, testes or ovaries, sternebrae femur, or vertebrae including marrow, mammary gland, tissue masses, and any macroscopic lesions.

Statistics:

Probabilities of survival were estimated by the product-limit procedure of Kaplan and Meier (1958). Statistical analyses for a possible dose-related effect on survival used the method of Cox (1972) for testing two groups for equality and Tarone's (1975) extensions of Cox's methods for testing for a dose-related trend. The one-tailed Fisher exact test (Cox, 1970) was used to compare the tumour incidence of a control group with that of a group of dosed animals at each dose level. The Cochran-Armitage test for linear trend in proportions, with continuity correction (Armitage, 1971), was also used to determine if the slope of the dose-response curve is different from zero at the one tailed 0.05 level of significance.

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

(females at 4000 ppm)

Mortality:

mortality observed, treatment-related

Description (incidence):

(females at 4000 ppm)

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

no effects observed

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

not examined

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

not examined

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

no effects observed

Details on results:

MORTALITY
In male mice, dose-related trend in mortality and comparing the survival of the control group with each dosed group, are not significant.
In females, dose-related trend in mortality is significant. The result comparing the survival of the control group with the high-dose group is significant, but the comparison between the control and low-dose groups is not significant. In male mice, there were 35/50 (70%) of the high-dose group, 32/50 (64%) of the low-dose group, and 32/50 (64%) of the controls still alive at week 104. In female mice, there were 36/50 (72%) of the high-dose group, 40/50 (80%) of the low-dose group, and 45/50 (90%) of the controls still alive at week 104. Sufficient numbers of mice of each sex were at risk for the development of late-appearing tumours.

CLINICAL SIGNS
The appearance and behaviour of the dosed and control groups of animals were generally similar, and clinical signs usually associated with aging were noted at comparable rates in the control and dosed groups. These signs included alopecia (generalized or localized) , sores on the back and other parts of the body, particularly in the males, anal and/or penile irritation, a hunched and/or thin appearance, and occasional abdominal distension.
The incidences of palpable nodules and tissue masses in the dosed male or female groups were generally comparable to those of corresponding control groups.

BODY WEIGHT AND WEIGHT GAIN
Mean body weights of the dosed male and female mice were slightly lower than those of the corresponding controls.

HISTOPATHOLOGY: NEOPLASTIC
A low incidence of neoplasia was observed in both control and dosed groups of mice. These neoplasms were of the usual number and type observed in mice of this age and strain. A slightly increased incidence of hepatocellular carcinomas was observed in the high-dose males (8/47 controls, 8/49 low-dose, 14/48 high-dose); however, the incidence was not increased over that observed occasionally in historical-control groups of mice of this age and strain. Alveolar/bronchiolar adenomas or carcinomas of the lung occurred primarily in the dosed females (1/49 controls, 3/47 low-dose, 5/48 high-dose). The incidence of lung neoplasms was not considered indicative of a carcinogenic effect, as this neoplasm has been commonly seen at a similar low incidence in historical-control groups.

HISTOPATHOLOGY: NON-NEOPLASTIC
Other degenerative, proliferative, and inflammatory lesions observed were also of the usual incidence and kind observed in aged B6C3F1 mice, and incidences in dosed groups were comparable with those in control groups.

Key result

Dose descriptor:

NOAEL

Effect level:

2 000 ppm

Based on:

test mat.

Sex:

female

Basis for effect level:

mortality

other: (~ 300 mg/kg bw/day) (Basis for effect: mortality trend)

Key result

Dose descriptor:

NOAEL

Effect level:

4 000 ppm

Based on:

test mat.

Sex:

male

Basis for effect level:

mortality

other: (~ 600 mg/kg bw/day) (Basis for effect: no significant effects were observed)

Critical effects observed:

not specified

Based on the histopathologic examination, 2 -isopropyl-5 -methylcyclohexanol was neither toxic nor carcinogenic to B6C3F1 mice under the conditions of this bioassay.

Conclusions:

The NOAEL for 2-isopropyl-5-methylcyclohexanol when administered to rats for 103 consecutive weeks by oral route was determined to be 2000 ppm (~300 mg/kg bw/day) for females and 4000 ppm (~600 mg/kg bw/day) for males.

Executive summary:

A carcinogenicity study was conducted in which groups of 50 B6C3F1 mice of each sex were administered 0, 2,000 or 4,000 ppm (~0, 300, 600 mg/kg bw/day) 2-isopropy-5-methylcyclohexanol in their feed daily for 103 weeks. Animals were housed five per cage and were observed twice daily for signs of toxicity. Body weights and food consumption were recorded every two weeks for the first twelve weeks, and once a month thereafter. Necropsies and histological examinations were performed on all animals at the termination of the study and on those found dead during the study. The mean body weights of the male and female mice administered 2000 or 4000 ppm (300 or 600 mg/kg bw/day) were slightly lower when compared to the controls. Survival of the high- and low-dose groups of male mice was similar to the vehicle control animals (controls, 32/50; low-dose, 32/50; high-dose, 35/50). Survival of the high-dose group of female mice was significantly less than that of the control animals (controls, 36/50; high-dose, 45/50). However, decreased survival was not accompanied by any evidence of toxicity in the high-dose group. Survival of the low-dose female mice was similar to the control animals (controls, 36/50; low-dose, 40/50). An increase in the incidence of hepatocellular carcinomas was observed in high-dose male mice (controls, 8/47; low-dose, 8/49; high-dose, 14/48), but was not statistically different from that observed historically in mice of that age and strain (Haseman et al. 1986, Use of dual control groups to estimate false positive rates in laboratory animal carcinogenicity studies. Fundamental and Applied Toxicology 7 (4), 573 -584). A low incidence of alveolar/bronchiolar adenomas of the lung was observed in both the low- and high-dose females but was not statistically different from the incidence of this neoplasm in historical control groups. Under the conditions of this study, it was concluded that 2-isopropyl-5-methylcyclohexanol was not carcinogenic and did not produce any organ-specific toxicity for either sex of B6C3F1 mice at dose levels of 2000 or 4000 ppm (300 or 600 mg/kg bw/day).

Reference 3

Endpoint:

sub-chronic toxicity: oral

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

1979

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

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

Principles of method if other than guideline:

A 13 week oral (diet) repeated dose study was conducted in rats with test item 2 -isopropyl-5 -methylcyclohexanol (dl-menthol) test item. Groups of 10 male and 10 female Fischer 344 rats were maintained on diets containing dl-2-isopropyl-5-methylcyclohexanol at dietary concentrations of 0, 930, 1870, 3750, 7500, or 15000 ppm (~ 0, 93, 187, 375, 750 or 1500 mg/kg bw/day) for 13 weeks. Necropsies were performed on all animals at the end of the study. Histopathological examination was performed on tissues from the control animals, the 15000 ppm (~1500 mg/kg bw/day) group, and selected tissues from the 7500 ppm (~750 mg/kg bw/day) group.

GLP compliance:

no

Limit test:

no

Species:

rat

Strain:

Fischer 344

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Frederick Cancer Research Center, Frederick, Maryland (USA)
- Fasting period before study: 4 weeks
- Housing: Polycarbonate cages covered with stainless steel cage lids and non-woven fiber filter bonnets. Cages were furnished with heat-treated hardwood chip bedding.
- Diet: Ad libitum
- Water: Ad libitum
- Acclimation period:

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20-24 ºC
- Humidity (%): 45-55 %
- Air changes (per hr): 12 changes of room air per hour (filtered through 2-inch-thick disposable fiberglass filters).

Route of administration:

oral: feed

Vehicle:

corn oil

Details on oral exposure:

PREPARATION OF DOSING SOLUTIONS: The appropriate weight of the dl-menthol required for each dietary concentration was dissolved in corn oil by stirring over a low heat.

DIET PREPARATION
- Rate of preparation of diet (frequency): prepared each week (and used within 1 week of preparation).
- Mixing appropriate amounts with (Type of food): The test item solution was added to the Wayne Lab Blox animal meal and thoroughly mixed.
- Storage temperature of food: room temperature

VEHICLE
- Concentration: 2% by weight in the basal diets.

Analytical verification of doses or concentrations:

no

Duration of treatment / exposure:

13 weeks

Frequency of treatment:

Daily

Dose / conc.:

930 ppm

Remarks:

(~93 mg/kg bw/day)
nominal in diet

Dose / conc.:

1 870 ppm

Remarks:

(~187 mg/kg bw/day)
nominal in diet

Dose / conc.:

3 750 ppm

Remarks:

(~375 mg/kg bw/day)
nominal in diet

Dose / conc.:

7 500 ppm

Remarks:

(~750 mg/kg bw/day)
nominal in diet

Dose / conc.:

15 000 ppm

Remarks:

(~1500 mg/kg bw/day)
nominal in diet

No. of animals per sex per dose:

10 animals per sex and per dose

Control animals:

yes

Details on study design:

- Dose selection rationale: On the basis of a 14-day range-finding study

Sacrifice and pathology:

Necropsies were performed on all animals at the end of the study. Histopathological examination was performed on tissues from the control animals, the 15000 ppm group, and selected tissues from the 7500 ppm group.

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

not examined

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

not examined

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

not examined

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

(at 15000 ppm, males)

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

no effects observed

Details on results:

CLINICAL SIGNS AND MORTALITY
There were no deaths among the rats

BODY WEIGHT AND WEIGHT GAIN
The mean body weight gains in the dosed groups were comparable to those in the control groups at all doses.

GROSS PATHOLOGY
A slight increase in the incidence of interstitial nephritis was observed in high-dose male rats.

Key result

Dose descriptor:

NOAEL

Effect level:

7 500 ppm

Based on:

test mat.

Sex:

male

Basis for effect level:

clinical signs

mortality

other: (~ 750 mg/kg bw/day) (Basis for effect: slight increase in the incidence of interstitial nephritis)

Key result

Dose descriptor:

NOAEL

Effect level:

15 000 ppm

Based on:

test mat.

Sex:

female

Basis for effect level:

clinical signs

mortality

other: (~ 1500 mg/kg bw/day) (Basis for effect: no significant effects were observed)

Critical effects observed:

not specified

Conclusions:

The NOAEL for 2-isopropyl-5-methylcyclohexanol when administered to rats for 13 consecutive weeks by oral route was determined to be 7500 ppm (~750 mg/kg bw/day) for males and 15000 ppm (~1500 mg/kg bw/day) for females.

Executive summary:

A 13 week oral (diet) repeated dose study was conducted in rats with test item 2 -isopropyl-5 -methylcyclohexanol test item. Groups of 10 male and 10 female Fischer 344 rats were maintained on diets containing test item at dietary concentrations of 0, 930, 1870, 3750, 7500, or 15000 ppm (~ 0, 93, 187, 375, 750 or 1500 mg/kg bw/day) for 13 weeks. Necropsies were performed on all animals at the end of the study. Histopathological examination was performed on tissues from the control animals, the 15000 ppm (~1500 mg/kg bw/day) group, and selected tissues from the 7500 ppm (~750 mg/kg bw/day) group. There were no deaths among the rats, and the body weight gains in the dosed groups were comparable to those in the control groups at all doses. There was a slightly increased incidence of interstitial nephritis in the male rats in the highest-dose groups. No adverse effects were reported for male or female mice administered 930, 1870, 3750 or 7500 ppm (~93, 187, 375 or 750 mg/kg bw/day). The NOAEL for 2-isopropyl-5-methylcyclohexanol was determined to be 7500 ppm (750 mg/kg bw/day) for males and 15000 ppm (~1500 mg/kg bw/day) for females.

Reference 4

Endpoint:

sub-chronic toxicity: oral

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

1979

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

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

Principles of method if other than guideline:

A 13 week oral (diet) repeated dose study was conducted in mice with test item 2 -isopropyl-5 -methylcyclohexanol (dl-menthol) test item. Groups of 10 male and 10 female B6C3F1 mice were maintained on diets containing dl-2-isopropyl-5-methylcyclohexanol at dietary concentrations of 0, 930, 1870, 3750, 7500, or 15000 ppm (~ 0, 140, 281, 563, 1125 or 2250 mg/kg bw/day) for 13 weeks. Necropsies were performed on all animals at the end of the study. Histopathological examination was performed on tissues from the control animals, the 15000 ppm (~2250 mg/kg bw/day) group, and selected tissues from the 7500 ppm (~1125 mg/kg bw/day) group.

GLP compliance:

no

Limit test:

no

Species:

mouse

Strain:

B6C3F1

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Frederick Cancer Research Center, Frederick, Maryland (USA)
- Fasting period before study: 2 weeks
- Housing: Polycarbonate cages covered with stainless steel cage lids and non-woven fiber filter bonnets. Cages were furnished with heat-treated hardwood chip bedding.
- Diet: Ad libitum
- Water: Ad libitum
- Acclimation period:

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20-24 ºC
- Humidity (%): 45-55 %
- Air changes (per hr): 12 changes of room air per hour (filtered through 2-inch-thick disposable fiberglass filters).

Route of administration:

oral: feed

Vehicle:

corn oil

Details on oral exposure:

PREPARATION OF DOSING SOLUTIONS: The appropriate weight of the dl-menthol required for each dietary concentration was dissolved in corn oil by stirring over a low heat.

DIET PREPARATION
- Rate of preparation of diet (frequency): prepared each week (and used within 1 week of preparation).
- Mixing appropriate amounts with (Type of food): The test item solution was added to the Wayne Lab Blox animal meal and thoroughly mixed.
- Storage temperature of food: room temperature

VEHICLE
- Concentration: 2% by weight in the basal diets.

Analytical verification of doses or concentrations:

no

Duration of treatment / exposure:

13 weeks

Frequency of treatment:

Daily

Dose / conc.:

930 ppm

Remarks:

~140 mg/kg bw/day
nominal in diet

Dose / conc.:

1 870 ppm

Remarks:

~281 mg/kg bw/day
nominal in diet

Dose / conc.:

3 750 ppm

Remarks:

~563 mg/kg bw/day
nominal in diet

Dose / conc.:

7 500 ppm

Remarks:

7500 ppm (~1125 mg/kg bw/day
nominal in diet

Dose / conc.:

15 000 ppm

Remarks:

~2250 mg/kg bw/day
nominal in diet

No. of animals per sex per dose:

10 animals per sex and per dose

Control animals:

yes

Details on study design:

- Dose selection rationale: On the basis of a 14-day range-finding study

Sacrifice and pathology:

Necropsies were performed on all animals at the end of the study. Histopathological examination was performed on tissues from the control animals, the 15000 ppm group, and selected tissues from the 7500 ppm group.

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

(at 15000 ppm, females)

Food consumption and compound intake (if feeding study):

not examined

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

not examined

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

not examined

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

(at 7500 and 1500 ppm, females)

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

no effects observed

Details on results:

CLINICAL SIGNS AND MORTALITY
Six deaths were observed during the study but could not be related to compound administration.

BODY WEIGHT AND WEIGHT GAIN
Final mean body weights of the male mice and female mice were not statistically different from those of the controls except for the high-dose female group which gained 2 grams less than did the controls.

GROSS PATHOLOGY
A slight increase in the incidence of perivascular lymphoid hyperplasia and interstitial nephritis was reported in the female mice given the two highest dose levels.

Key result

Dose descriptor:

NOAEL

Effect level:

3 750 ppm

Based on:

test mat.

Sex:

female

Basis for effect level:

clinical signs

mortality

other: (~ 563 mg/kg bw/day) (Basis for effect: slight increase in the incidence of perivascular lymphoid hyperplasia and interstitial nephritis)

Key result

Dose descriptor:

NOAEL

Effect level:

15 000 ppm

Based on:

test mat.

Sex:

male

Basis for effect level:

clinical signs

mortality

other: (~ 2250 mg/kg bw/day) (Basis for effect: no significant effects were observed)

Critical effects observed:

not specified

Conclusions:

The NOAEL for 2-isopropyl-5-methylcyclohexanol when administered to mice for 13 consecutive weeks by oral route was determined to be 3750 ppm (~563 mg/kg bw/day) for females and 15000 ppm (~2250 mg/kg bw/day) for males.

Executive summary:

A 13 week oral (diet) repeated dose study was conducted in mice with test item 2 -isopropyl-5 -methylcyclohexanol test item. Groups of 10 male and 10 female B6C3F1 mice were maintained on diets containing test item at dietary concentrations of 0, 930, 1870, 3750, 7500, or 15000 ppm (~ 0, 140, 281, 563, 1125 or 2250 mg/kg bw/day) for 13 weeks. Necropsies were performed on all animals at the end of the study. Histopathological examination was performed on tissues from the control animals, the 15000 ppm (~2250 mg/kg bw/day) group, and selected tissues from the 7500 ppm (~1125 mg/kg bw/day) group. Six mice died during the study but the deaths Dose Level could not be attributed to compound administration. Females receiving 15000 ppm (~2250 mg/kg bw/day) gained 2 grams less than did the controls. A slight increase in the incidence of perivascular lymphoid hyperplasia and interstitial nephritis was reported in the female mice given the two highest dose levels. No adverse effects were reported for male or female mice administered 930, 1870 or 3750 ppm (~140, 281 or 563 mg/kg bw/day). The NOAEL for 2-isopropyl-5-methylcyclohexanol was determined to be 3750 ppm (~563 mg/kg bw/day) for females and 15000 ppm (~2250 mg/kg bw/day) for males.

Reference 5

Endpoint:

repeated dose toxicity: oral, other

Remarks:

other: Carcinogenicity study

Type of information:

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

Adequacy of study:

key 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 results:

Based on the read-across approach from experimental data on the analogue substance 2-isopropyl-5-methylcyclohexanol (NOAEL male/female rats = 7500 ppm; ~ 345 mg/kg bw/day, basis for effect: no effects observed), the read-across was applied and the NOAEL for 2-methylcyclohexyl acetate was determined to be 74968 ppm (~375 mg/kg bw/day).

Key result

Dose descriptor:

NOAEL

Effect level:

7 498 ppm

Based on:

test mat.

Sex:

male/female

Basis for effect level:

mortality

Remarks on result:

other: (based on read-across from an analogue)

Critical effects observed:

not specified

Conclusions:

Based on the read-across approach from experimental data on the analogue substance 2-isopropyl-5-methylcyclohexanol, the NOAEL for 2-methylcyclohexyl acetate when administered to rats for 103 consecutive weeks by oral route was determined to be 74968 ppm (~375 mg/kg bw/day) in males and females.

Executive summary:

A 103 week oral (diet) carcinogenicity study was conducted on the analogue substance 2 -isopropyl-5 -methylcyclohexanol. Groups of 50 Fischer 344 rats per sex were daily exposed by feeding to 0, 3750 or 7500 ppm. It was concluded that the analogue 2-isopropy-5-methylcyclohexanol was neither carcinogenic nor toxic for either sex of Fischer 344 rats up to 7500 ppm (375 mg/kg bw). The 103 w-NOAEL (oral) for the analogue substance was determined to be 7500 ppm in male and female rats since no adverse effects were observed. Based on these results, the read-across was applied and the NOAEL for 2-methylcyclohexyl acetate when administered to rats for 103 consecutive weeks by oral route was determined to be 74968 ppm (~375 mg/kg bw/day) in males and females under test conditions.

Reference 6

Endpoint:

repeated dose toxicity: oral

Remarks:

other: Carcinogenicity study

Type of information:

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

Adequacy of study:

key 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

Details on results:

Based on the read-across approach from experimental data on the analogue substance 2-isopropyl-5-methylcyclohexanol, where the NOAEL in female mice was 2000 ppm (~ 300 mg/kg bw/day) based on the mortality trend and the NOAEL in male mice 4000 ppm (~ 600 m/kg bw/day) based on no adverse effects, the read-across was applied and the NOAEL for 2-methylcyclohexyl acetate in mice was determined to be 2000 ppm (~300 mg/kg bw/day) in females and 3999 ppm (~ 600 mg/kg bw/day) in males.

Key result

Dose descriptor:

NOAEL

Remarks:

~ 300 mg/kg bw/day

Effect level:

2 000 ppm

Based on:

test mat.

Sex:

female

Basis for effect level:

mortality

Remarks on result:

other: based on a read-across from an analogue substance

Key result

Dose descriptor:

NOAEL

Remarks:

~ 600 mg/kg bw/day

Effect level:

3 999 ppm

Based on:

test mat.

Sex:

male

Basis for effect level:

mortality

Remarks on result:

other: based on a read-across from an analogue substance

Critical effects observed:

not specified

Conclusions:

Based on the read-across approach from experimental data on the analogue substance 2-isopropyl-5-methylcyclohexanol, the NOAEL for 2-methylcyclohexyl acetate when administered to mice for 103 consecutive weeks by oral route was determined to be 2000 ppm (~300 mg/kg bw/day) in females and 3999 ppm (~ 600 mg/kg bw/day) in males.

Executive summary:

A 103 week oral (diet) carcinogenicity study was conducted on the analogue substance 2 -isopropyl-5 -methylcyclohexanol. Groups of 50 B6C3F1 mice per sex were daily exposed by feeding to 0, 2000 and 4000 ppm. It was concluded that the analogue substance was not carcinogenic and did not produce any organ-specific toxicity for either sex of B6C3F1 mice up to 4000 ppm ( ~ 600 mg/kg bw/day). The 103 w-NOAEL (oral) for the 2 -isopropyl-5 -methycyclohexanol was determined to be 2000 ppm (~ 300 mg/kg bw/day) in females based on the mortality trend (decreased survival was not accompanied by any evidence of toxicity) and 4000 ppm (~ 600 mg/kg bw/day) in males since no adverse effects were observed. Based on these results, the read-across was applied and the NOAEL for 2-methylcyclohexyl acetate when administered to mice for 103 consecutive weeks by oral route was determined to be 2000 ppm (~300 mg/kg bw/day) in females and 3999 ppm (~ 600 mg/kg bw/day) in males under test conditions.

Reference 7

Endpoint:

sub-chronic toxicity: oral

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:

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

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

Details on results:

Based on the read-across approach from experimental data on the analogue substance 2-isopropyl-5-methylcyclohexanol, where the NOAEL in male rats was 7500 ppm (~ 375 mg/kg bw/day) based on slight increase in the incidence of interstitial nephritis and the NOAEL in female rats was 15000 ppm (~ 750 m/kg bw/day) based on no adverse effects, the read-across was applied and the NOAEL for 2-methylcyclohexyl acetate was determined to be 7498.32 ppm (~374.92 mg/kg bw/day) in males and 14996 ppm (~ 749.83 mg/kg bw/day) in females.

Key result

Dose descriptor:

NOAEL

Effect level:

7 498 ppm

Based on:

test mat.

Sex:

male

Basis for effect level:

clinical signs

mortality

other: (~ 750 mg/kg bw/day) (Slight increase in the incidence of interstitial nephritis)

Remarks on result:

other: based on read-across from an analogue

Key result

Dose descriptor:

NOAEL

Effect level:

14 997 ppm

Based on:

test mat.

Sex:

female

Basis for effect level:

clinical signs

mortality

other: (~ 1500 mg/kg bw/day) (no significant effects were observed)

Remarks on result:

other: based on read-across from an analogue

Critical effects observed:

not specified

Conclusions:

Based on the read-across approach from experimental data on the analogue substance 2-isopropyl-5-methylcyclohexanol, the NOAEL for 2-methylcyclohexyl acetate when administered to rats for 13 consecutive weeks by oral route was determined to be 7498.32 ppm (~374.92 mg/kg bw/day) in males and 14996 ppm (~ 749.83 mg/kg bw/day) in females.

Executive summary:

A 13 week oral (diet) repeated dose study was conducted on the analogue 2 -isopropyl-5 -methylcyclohexanol test item. Groups of 10 Fischer 344 rats per sex were maintained on diets containing test item at dietary concentrations of 0, 930, 1870, 3750, 7500, or 15000 ppm for 13 weeks. The NOAEL for the analogue substance 2-isopropyl-5-methylcyclohexanol was determined to be 7500 ppm (~ 750 mg/kg bw/day) for males based on slight increase in the incidence of interstitial nephritis at the highest dose level and 15000 ppm (~1500 mg/kg bw/day) for females since no adverse effects were reported. Based on these results, the read-across was applied and the NOAEL for 2 -methylcyclohexyl acetate when administered to rats for 13 consecutive weeks by oral route was determined to be 7498.32 ppm (~374.92 mg/kg bw/day) in males and 14996 ppm (~ 749.83 mg/kg bw/day) in females under test conditions.

Reference 8

Endpoint:

sub-chronic toxicity: oral

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:

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

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

Key result

Dose descriptor:

NOAEL

Effect level:

3 749 ppm

Based on:

test mat.

Sex:

female

Basis for effect level:

clinical signs

mortality

other: (~ 563 mg/kg bw/day) (Slight increase in the incidence of perivascular lymphoid hyperplasia and interstitial nephritis)

Remarks on result:

other:

Remarks:

(read-across from an analogue)

Key result

Dose descriptor:

NOAEL

Effect level:

14 997 ppm

Based on:

test mat.

Sex:

male

Basis for effect level:

clinical signs

mortality

other: (~ 2250 mg/kg bw/day) (no significant effects were observed)

Remarks on result:

other:

Remarks:

(based on read-across from an analogue)

Critical effects observed:

not specified

Conclusions:

Based on the read-across approach from experimental data on the analogue substance 2-isopropyl-5-methylcyclohexanol, the NOAEL for 2-methylcyclohexyl acetate when administered to mice for 13 consecutive weeks by oral route was determined to be 3749 ppm (~563 mg/kg bw/day) in females and 14996 ppm (~ 2250 mg/kg bw/day) in males.

Executive summary:

A 13 week oral (diet) repeated dose study was conducted on the analogue substance 2 -isopropyl-5 -methylcyclohexanol. Groups of 10 B6C3F1 mice per sex were maintained on diets containing test item at dietary concentrations of 0, 930, 1870, 3750, 7500, or 15000 ppm for 13 weeks. The NOAEL for the analogue 2-isopropyl-5-methylcyclohexanol was determined to be 3750 ppm (~563 mg/kg bw/day) for females based on slight increase in the incidence of interstitial nephritis at 7500 and 15000 ppm dose groups, and 15000 ppm (~2250 mg/kg bw/day) for males based on no adverse effects observed. Based on these results, the read-across was applied and the NOAEL for 2 -methylcyclohexyl acetate when administered to mice for 13 consecutive weeks by oral route was determined to be 3749 ppm (~563 mg/kg bw/day) in females and 14996 ppm (~ 2250 mg/kg bw/day) in males under test conditions.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

375 mg/kg bw/day

Study duration:

chronic

Species:

rat

Quality of whole database:

Two chronic studies are available (103 week carcinogenicity study) one performed with rats and the other with mice. Both studies are key studies and have a Klimisch score = 2. Moreover two subchronic (13 weeks, rats and mice) studies are available. This studies are supporting studies and have a Klimisch score = 2. The overall quality of the database is adequate.

Additional information

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

In the study reported by the National Cancer Institute, NCI (1975), a 103 week oral (diet) carcinogenicity study was conducted on the analogue substance 2 -isopropyl-5 -methylcychlohexanol. Groups of 50 Fischer 344 rats per sex were daily exposed by feeding to 0, 3750 or 7500 ppm. It was concluded that the analogue 2-isopropy-5-methylcyclohexanol was neither carcinogenic nor toxic for either sex of Fischer 344 rats up to 7500 ppm (375 mg/kg bw). The 103 w-NOAEL (oral) for the analogue substance was determined to be 7500 ppm in male and female rats since no adverse effects were observed. Based on these results, the read-across was applied and the NOAEL for 2-methylcyclohexyl acetate when administered to rats for 103 consecutive weeks by oral route was determined to be 74968 ppm (~375 mg/kg bw/day) in males and females under test conditions.

The same carcinogenicity study (103 weeks) was performed by the National Cancer Institute, NCI (1975) in mice. Groups of 50 B6C3F1 mice of each sex were administered 0, 2,000 or 4,000 ppm of the analogue 2-isopropy-5-methylcyclohexanol in their feed daily for 103 weeks. It was concluded that the analogue was not carcinogenic and did not produce any organ-specific toxicity for either sex of B6C3F1 mice up to 4000 ppm ( ~ 600 mg/kg bw/day). The 103 w-NOAEL (oral) for the 2 -isopropyl-5 -methycyclohexanol was determined to be 2000 ppm (~ 300 mg/kg bw/day) in females based on the mortality trend (decreased survival was not accompanied by any evidence of toxicity) and 4000 ppm (~ 600 mg/kg bw/day) in males since no adverse effects were observed. Based on these results, the read-across was applied and the NOAEL for 2-methylcyclohexyl acetate when administered to mice for 103 consecutive weeks by oral route was determined to be 2000 ppm (~300 mg/kg bw/day) in females and 3999 ppm (~ 600 mg/kg bw/day) in males under test conditions.

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

As part of the above mentioned carcinogenicity studies, a 13 weeks oral (diet) repeated dose toxicity studies were performed both in rats and mice in order to estimate the maximum tolerated dosed of the analogue 2-isopropyl-5-methylcyclohexanol. Groups of 10 Fischer 344 rats per sex were maintained on diets containing concentrations of 0, 930, 1870, 3750, 7500, or 15000 ppm for 13 weeks and groups of 10 B6C3F1 mice were exposed to a dietary concentrations of 0, 930, 1870, 3750, 7500, or 15000 ppm. In the case of rats, the NOAEL for the analogue 2-isopropyl-5-methylcyclohexanol was determined to be 7500 ppm (~ 750 mg/kg bw/day) for males based on slight increase in the incidence of interstitial nephritis at the highest dose level and 15000 ppm (~1500 mg/kg bw/day) for females since no adverse effects were reported. Instead for mice, the NOAEL for the analogue was determined to be 3750 ppm (~563 mg/kg bw/day) for females based on slight increase in the incidence of interstitial nephritis at 7500 and 15000 ppm dose groups, and 15000 ppm (~2250 mg/kg bw/day) for males based on no adverse effects observed.

Based on these results, the read-across approach was applied and the NOAEL for 2 -methylcyclohexyl acetate when administered to rats for 13 consecutive weeks by oral route was determined to be 7498 ppm (~750 mg/kg bw/day) in males and 14996 ppm (~ 1500 mg/kg bw/day) in females, and when administered to mice 3749 ppm (~563 mg/kg bw/day) in females and 14996 ppm (~ 2250 mg/kg bw/day) in males under test conditions.

Justification for selection of repeated dose toxicity via oral route - systemic effects endpoint:

The study with the longest duration (103 weeks) and performed on rats was chosen.

Justification for classification or non-classification

Based on available data, the substance 2 -methylcyclohexyl acetate is not classified for specific target organ toxicity - repeated exposure (STOT-RE) in accordance with CLP Regulation (EC) no. 1272/2008.