3,5,5-trimethylcyclohex-2-enone

Repeated dose toxicity: oral

Administrative data

Endpoint:

sub-chronic toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

no data

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Data source

Reference

Reference 1

Reference Type:

study report

Title:

Unnamed

Year:

1972

Report date:

1972

Reference 2

Reference Type:

publication

Title:

Isophorone: Ambient water quality criteria

Author:

U.S. EPA (Environmental Protection Agency)

Year:

1978

Bibliographic source:

U.S. Department of Commerce, National Technical Information Service (NTIS), PB-296 798

Materials and methods

Principles of method if other than guideline:

Method: Repeated Dose Toxicity; see reference

GLP compliance:

no

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

3,5,5-trimethylcyclohex-2-enone

EC Number:

201-126-0

EC Name:

3,5,5-trimethylcyclohex-2-enone

Cas Number:

78-59-1

Molecular formula:

C9H14O

IUPAC Name:

3,5,5-trimethylcyclohex-2-enone

Details on test material:

Origin: International Chemical Corp., New York, 11 Aug 1971
- clear liquid with a mild, pungent odor
- specific gravity: 0.93

Test animals

Species:

rat

Strain:

other: Albino rats of CFE strain

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Carworth Farms
- Age at study initiation: weanling
- Diet: ad libitum
- Water: ad libitum
ENVIRONMENTAL CONDITIONS
- Temperature (°C): no data
- Humidity (%): no data
- Air changes (per hr): no data
- Photoperiod (hrs dark / hrs light): no data
- Housing: individually in wire mesh cages elevated above the droppings

Administration / exposure

Route of administration:

oral: feed

Vehicle:

corn oil

Details on oral exposure:

- Isophorone was added directly to the basal ration and thorougly blended in an Patterson Kelly Twin Shell Blendor;
- Fresh diets were prepared each week
- isophorone in corn oil (1:2) was blended with the diet

Analytical verification of doses or concentrations:

not specified

Duration of treatment / exposure:

90 days

Frequency of treatment:

daily

Doses / concentrations

Remarks:

Doses / Concentrations:
750, 1500 and 3000 ppm diet: males 57.0, 102.5 and 233.8 mg/kg bw d; females 78.9, 163.8 and 311.8 mg/kg bw d
Basis:
nominal in diet

No. of animals per sex per dose:

20

Control animals:

yes, concurrent no treatment

Details on study design:

- Post-exposure period: none
- After 4 weeks, 5 animals per sex and dose group were killed for blood analysis

Positive control:

none

Examinations

Observations and examinations performed and frequency:

CLINICAL OBSERVATIONS AND FREQUENCY: 
- Clinical signs: daily
- Mortality: daily
- Body weight: weekly
- Food consumption: weekly
- Water consumption: weekly
- Ophthalmoscopic examination: none
- Hematology: after 4 weeks and at end of study: determination of  hemoglobin, hematocrit, erythrocyte counts, leukocyte counts, and  differential 
leukocyte determinations 
- Biochemistry: after 4 weeks and at end of study: blood glucose, blood  urea nitrogen, serum glutamic oxaloacetic transaminase, serum alkaline  
phosphatase, total serum protein, total serum bilirubin, serum albumin,  lactic acid dehydrogenase, cholesterol, calcium, phosphate, and uric aid 
- Urinalysis: after 4 weeks and at end of study: pH, glucose, ketones,  albumin, occult blood, microscopic examination of sediment

Sacrifice and pathology:

ORGANS EXAMINED AT NECROPSY (MACROSCOPIC AND MICROSCOPIC): 
- Organ weights: organ-body weight ratios: heart, liver, kidney,  adrenals, thyroid, brain, testes
- Macroscopic:  after 4 weeks and at study termination: lungs, heart, intestines,  kidneys, spleen, liver, urinary bladder;  - weights: heart, liver, kidney,
 adrenals, thyroid, brain, testes (males)  for 10 males and 10 females of each dose level
- Microscopic:  at study termination only: 5 males and 5 females each from high dose and  control groups: brain, pituitary, eye, thyroid, lung, heart, 
liver,  kidney, adrenals, urinary bladder, mediastinal lymph node, pancreas,  spleen, colon, bone marrow, skeletal muscle, testes and prostate (male), 
ovary and uterus (female) 5 males and 5 females each from medium and low dose groups: liver, kidney

Other examinations:

none

Statistics:

STATISTICAL METHODS: All data were evaluated statistically.

Results and discussion

Results of examinations

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Food consumption and compound intake (if feeding study):

no effects observed

Food efficiency:

no effects observed

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

no effects observed

Ophthalmological findings:

not examined

Haematological findings:

no effects observed

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

no effects observed

Behaviour (functional findings):

no effects observed

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

no effects observed

Details on results:

NOAEL: 
m: 1500 ppm diet (reduced body weight gain), equivalent to 102.5  mg/kg bw; 
f: 3000 ppm diet, equivalent to 311.8 mg/kg bw.
ACTUAL DOSE RECEIVED BY DOSE LEVEL BY SEX mean daily compound consumption (data given in study):
- males 57.0, 102.5 and 233.8 mg/kg bw d 
- females 78.9, 163.8 and 311.8 mg/kg bw d
TOXIC RESPONSE/EFFECTS BY DOSE LEVEL: 
- Mortality and time to death: 1 m (control group), 1 f (3000 ppm) 
- deaths were due to intercurrent infection
- Clinical signs: none
- Body weight gain: 3000 ppm m: significant reduced body weight gain (P <  0.01); further observed changes returned to normal in the 
subsequent weeks
- Food/water consumption: no evidence of refusal
- Clinical chemistry: all values within normal limits
- Haematology: all values within normal limits
- Urinalysis: all values comparable to controls
- Organ weights:  kidney, testes m: slightly increased mean organ to body weight ratio  (considered not compound related by the authors; 
not statistically  significant)
- Gross pathology: All viscera were normal in appearance and color, no  lesions were observed
- Histopathology: no evidence of significant pathology

Effect levels

1

Dose descriptor:

NOAEL

Effect level:

102.5 mg/kg bw/day (nominal)

Sex:

male

Basis for effect level:

other: reduced body weight gain

2

Dose descriptor:

NOAEL

Effect level:

>= 311.8 mg/kg bw/day (nominal)

Sex:

female

Basis for effect level:

other: no effects

Target system / organ toxicity

Critical effects observed:

not specified

Any other information on results incl. tables

no remarks

Applicant's summary and conclusion

Conclusions:

In this subchronic (90 day) oral feed study with rats the only observed effect was a reduced body weight gain in male animals. The No-Observed-
Adverse-Effect-Level (NOAEL) derived from this study is 102.5 mg/kg bw/day for male and 311.8 mg/kg bw/day for female rats.

Executive summary:

In this guideline-comparable study four groups of 20 male and 20 female CFE albino rats were dosed with 750, 1000, or 3000 ppm isophorone via diet - corresponding to 57.0, 102.5, 233.8 mg/kg bw/day for males and to 73.9, 163.8 and 311.8 mg/kg bw/day for females - daily for 13 weeks.

Isophorone in corn oil (ratio 1:2) was blended with the diet; fresh diets were prepared each week. Haematology, serum chemistry and urine analyses were carried out on five animals of each sex from each group at week 4 and at termination. Comprehensive histopathological examination was confined to five animals of each sex from the control and high dose groups. The liver and kindney from five animals of the intermediate dose levels were also examined histopathologically. Under the conditions of this study, no effects on the general appearance of the test animals, on their behaviour, on body weight gain or on food consumption were observed at a dietary level of 1500 mg/kg or less. Isophorone did not alter the composition of the formed elements of the blood, nor did it interfere with the general metabolism or with liver and kidney function. No detectable gross or microscopic pathological changes were noted in any the animals examined after 28 or 90 days of feeding. Organ/body weight ratios for vital organs were not changed.

The only observed effect was a reduced body weight gain (-12 to -13 %) in male rats at 3000 ppm (during weeks 6,7,8,9,10 and 11).

Therefore, the No-Observed-Adverse-Effect-Level (NOAEL) derived from this study is 102.5 mg/kg bw/day (equivalent to 1500 ppm) for male and 311.8 mg/kg bw/day (equivalent to 3000 ppm) for female rats.