3,5,5-trimethylcyclohex-2-enone

Endpoint summary

Description of key information

Among the existing valid studies following three studies were found to show the highest toxicity after oral, dermal and inhalation application of isophorone: The acute toxicity in laboratory animals is low to moderate with an oral LD50 (rat) of 1500 mg/kg bw (Günzel and Richter, Schering AG, 1968), a dermal LD50 (rabbit) of 1200 mg/kg bw (Dutertre-Catella, 1976) and an inhalative LC50 (rat, aerosol) of 7000 mg/m3 air (Esso Research, 1965).

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records

Reference

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

no data

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study well documented, meets generally accepted scientific principles, acceptable for assessment

Principles of method if other than guideline:

Method: Acute oral toxicity study in rats - single administration

GLP compliance:

no

Test type:

standard acute method

Limit test:

no

Species:

rat

Strain:

other: Breeder Voss

Sex:

male/female

Details on test animals or test system and environmental conditions:

Study performed with animals of relatively low body weight:  Weight at study initiation: 80-115 g.

Route of administration:

oral: unspecified

Vehicle:

other: Emulsion 0.5 g carboxymethyl cellulose in 100 ml dist. water

Doses:

Doses: 0.5; 1.0; 1.25; 1.50; 1.75; 2.0; 2.5 g/kg bw

No. of animals per sex per dose:

5

Control animals:

no

Details on study design:

Post dose observation period: 13 days;
EXAMINATIONS:  gross examination of: coat of fur, skin, eye and conjunctiva, nose,  mouth, ear, anus, preputial opening, vulva, subcutaneous 
connective  tissue, abdominal cavity, pelvic cavity, peritoneum, esophagus, stomach,  small intestine, large intestine, mesenteric lymph nodes, liver,  
pancreas, spleen, kidneys, urinary bladder, seminal vesicle, prostate,  testicles, epididymis, ovary, uterus, vagina, thoracic cavity, pleura,  heart, lungs,trachea, thymus gland, cerebrum, middle ear, application  sites

Statistics:

STATISTICAL METHODS: Probit analysis

Sex:

male/female

Dose descriptor:

LD50

Effect level:

1 500 mg/kg bw

Remarks on result:

other: LD50 confidence limits: 1400-1800 mg/kg

Mortality:

MORTALITY: 
- Time of death: 1 hour to 3 days after dosing
- Number of deaths at each dose:  500 mg/kg:  0/10; 1000 mg/kg:  1/10; 1250 mg/kg: 1/10; 1500 mg/kg:  5/10; 1750 mg/kg:  7/10; 2000 mg/kg: 10/10; 2500 mg/kg:  8/10;
LD50 confidence limits: 1400-1800 mg/kg

Clinical signs:

other: > 1,000 mg/kg: general apathy, lateral position, irregular respiration

Gross pathology:

NECROPSY FINDINGS:  Results of animals that died: - increased secretion in stomach and small intestine , - thickening and hermorrhagic erosions of 
proventiculus lining, - urine retention, - hyperemia of liver, - pulmonary emphysema, edema or hyperemia and - splenic enlargement

Other findings:

no data

no remarks

Conclusions:

The LD50 value of isophorone in female and male rats was estimated to be 1500 mg/kg bw. Clinical signs like general apathy, lateral position and
irregular respiration occured at doses > 1000 mg/kg bw. The test animals died 1 hour to 3 days after feeding.

Executive summary:

The acute oral toxicity to rats was evaluated by standard acute method. The test item was administered to five female and five male rats orally. The animals were observed for mortality and any sub-lethal effects for 13 days after dosing. Isophorone was orally of moderate acute toxicity: The LD₅₀ value in rats was estimated to be 1500 mg/kg bw. Clinical signs like general apathy, lateral position and irregular respiration occured at doses > 1000 mg/kg bw. Increased secretion in stomach and small intensine, thickening and hermorrhagic erosions of proventiculus lining, urine retention, hyperemia of liver, pulmonary emphysema, edema or hyperemia and splenic enlargement were found at necrospy.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LD50

Value:

1 500 mg/kg bw

Quality of whole database:

The study is well documented, meets generally accepted scientific principles, and is acceptable for assessment. Klimisch score 2 (reliable with restrictions)

Acute toxicity: via inhalation route

Link to relevant study records

Reference

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1964-12-02 - 1965-01-15

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study well documented, meets generally accepted scientific principles, acceptable for assessment

Principles of method if other than guideline:

Method: Acute Inhalation Toxicity: Whole body exposure; described in reference

GLP compliance:

no

Test type:

standard acute method

Limit test:

no

Species:

rat

Strain:

Wistar

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ORGANISMS: 
- Weight at study initiation: 200-225 grams
- Number of animals: 10
- Controls: yes

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

whole body

Vehicle:

other: unchanged (no vehicle)

Details on inhalation exposure:

- Type of exposure: inhalation, aerosol

Analytical verification of test atmosphere concentrations:

not specified

Duration of exposure:

4 h

Concentrations:

- Concentrations: 5; 7; 10; 17.8 mg/l

No. of animals per sex per dose:

10 males

Control animals:

yes

Details on study design:

EXAMINATIONS: 
- Observations for deaths and toxic signs: 30 min intervals
- post observation: 14 days, daily
- gross pathology: at end of post observation period: all surviving animals

Statistics:

no data

Sex:

male

Dose descriptor:

LC50

Effect level:

7 mg/L air

Exp. duration:

4 h

Remarks on result:

other: aerosol

Mortality:

- Number of deaths at each dose, time of death:     
5000 mg/m3: 4 hours = 0; 14 days = 1 death     
7000 mg/m3: 4 hours = 0; 14 days = 4 deaths
>= 10000 mg/m3: 4 hours = 10 deaths
LD50 confidence intervals: 5700-8600 mg/m3; slope function 1.27

Clinical signs:

other: 5000 mg/m3: none; higher doses: ataxia and coma, dyspnea, piloerection, depression,  decreased activity

Body weight:

no data

Gross pathology:

>= 10000 mg/m3:
- pulmonary congestion

Other findings:

no other findings

no remarks



 

Conclusions:

Under the conditions of this study, the acute toxicity of isophorone after inhalative exposure in male rats is very low : the LC50 value was determined to be 7 mg/l.

Executive summary:

Groups of 10 male rats were exposed to isophorone for 4 hours by whole body exposure. The observation period was 2 weeks. At a concentration of 5000 mg/m3 one animal died after the observation period of 14 days. At a concentration of 7000 mg/m3 40 % of the rats died . At very high concentrations of 10000 and 17800 mg/m3 all animals died within 4 hours. Clinical signs were ataxia and coma, dyspnea, piloerection, depression and decreased activity at doses >= 5000 mg/m3. At necropsy of the high exposure concentrations, congestion of the lungs were observed.

The LC50 value was determined to be 7 mg/l. Therefore, under the conditions of this study the acute toxicity of isophorone after inhalative exposure in rats is very low.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LC50

Value:

7 000 mg/m³ air

Quality of whole database:

The study is well documented, meets generally accepted scientific principles, and is acceptable for assessment. Klimisch score 2 (reliable with restrictions)

Acute toxicity: via dermal route

Link to relevant study records

Reference

Endpoint:

acute toxicity: dermal

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1975 - 1976-06-24

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

Principles of method if other than guideline:

Method: based on Draize, modified method

GLP compliance:

not specified

Test type:

standard acute method

Limit test:

no

Species:

rabbit

Strain:

not specified

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ORGANISMS: 
- Weight at study initiation: ca. 2.5 kg
- Controls: yes

Type of coverage:

occlusive

Vehicle:

unchanged (no vehicle)

Details on dermal exposure:

ADMINISTRATION: 
- Occlusion: yes
- Vehicle: none
- Doses: 9.2; 13.85; 23; 23; 32.3 g   
absorbed: see Results
- Removal of test substance: after 24 hours, unresorbed quantity  determined

Duration of exposure:

24 hours

Doses:

600 mg/kg, 750 mg/kg, 1700 mg/kg, 2500 mg/kg and 2850 mg/kg

No. of animals per sex per dose:

6

Control animals:

yes

Details on study design:

EXAMINATIONS: mortality, clinical signs, skin reaction, 
14 days postexposure observation, autopsy

Statistics:

no data

Sex:

male/female

Dose descriptor:

LD50

Effect level:

1 200 mg/kg bw

Mortality:

- Number of deaths and time at each dose: 
9.2 g dose(0.6 +/- 0.4 g/kg absorbed): none
13.85 g dose (0.75 +/- 0.5 g/kg): 2 after 6 and 12 hours, resp.
23 g dose (1.7 +/- 0.9 g/kg): 3 after 3, 4, and 5 hours, resp.
23 g dose (2.85 +/- 1.3 g/kg): 3 after 4, 6, and 48 hours, resp.
32.3 g dose (2.5 +/- 1 g/kg): 6 after 2.5, 4x4, 5 hours, resp.

Clinical signs:

other: CLINICAL SIGNS: accelerated breathing, prostration, narcosis, death (mostly within 6 hours) or recovery. The intensity of the erythema varied   between animals. Recovery of the skin was not always complete within the  postexposure period. Doses at which c

Gross pathology:

no data

Other findings:

- POTENTIAL TARGET ORGANS: none identified (except skin)
- SEX-SPECIFIC DIFFERENCES: none identified

no remarks

Conclusions:

Under the conditions of this study, the acute toxicity of isophorone after dermal application to male and female rabbits is moderate: the LD50 value
was determined to be 1200 mg/kg bw.

Executive summary:

The acute dermal toxicity was evaluated by standard acute method. A single application of test item to the intact skin of six female and six male rabbits was made at dosage levels of 600 mg/kg bw to 2850 mg/kg bw for 24 hours.The animals were observed for mortality and any sub-lethal effects for 14 days after application. Isophorone was dermally of moderate acute toxicity. The LD50 value in rabbits was estimated to be 1200 mg/kg bw. Clinical signs were accelerated breathing, prostration and narcosis.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LD50

Value:

1 200 mg/kg bw

Quality of whole database:

Test procedure of the study is in accordance with generally accepted scientific standards and described in sufficient detail. Klimisch score 1 (reliable without restriction).

Additional information

Oral

LD₅₀ values of isophorone in rats were 1500 mg/kg bw (Günzel and Richter, Schering AG, 1968), 2100 mg/kg bw (Dutertre-Catella, 1976) and 3450 mg/kg (Esso Research, 1964). The LD₅₀ in mice is 2200 mg/kg bw (Dutertre-Catella, 1976). Clinical signs like general apathy, depression, wearness (leading to coma) ptosis, lacrimation and laboured respiration occured at doses of >= 1450 mg/kg bw (Günzel and Richter, 1968; Dutertre-Catella, 1976; Esso Redearch 1965). At doses of >= 5000 mg/kg bw congestion of lungs, kidneys and pancreas (Esso Research, 1964) and liver lesions (Dutertre-Catella, 1976) were found at necropsy.

Inhalation

In acute inhalation studies isophorone showed very low acute toxicity with LC₅₀ values sometimes exceeding the maximum tested concentrations (LC₀ > 3500 mg/m3 and LC₅₀ = 7000 mg/m3; both aerosol) in rats, mice and guinea pigs (Esso Reserach 1964; Esso Research, 1965). Mortality was observed in another study with rats but not guinea pigs at concentrations > 10570 mg/m3 (Smyth and Seaton, 1940). Clincal signs were nose and eye irritation, accelerated, laboured respiration, intestinal peristalsis and coma at dose

>= 5000 mg/m3 (Smyth and Seaton, 1940; Esso Research, 1965). At necropsy of the high exposure concentrations, congestion of the lungs and occasionally observed liver and stomach congestion was found (Esso Research 1965; Smyth and Seaton, 1940).

Dermal

In rats, the LD₅₀ after dermal application was 1700 mg/kg bw (Günzel and Richter, Schering AG, 1968). For rabbits the LD₅₀ values were 1200 mg/kg bw (Dutertre-Catella, 1976) and > 3160 mg/kg bw (Esso Research, 1964). Clinical signs were general apathy, later on occasionally coma, cachexia, tremor, lacrimation (Günzel and Richter, 1968) and depression, accelerated/laboured respiration, sprawling, prostration and narcosis at doses of 3160 mg/kg bw at least. At necropsy uniform thickening of the cutaneous stomach mucosa and pulmonary emphysema, edema or hyperemia was observed.

Justification for selection of acute toxicity – oral endpoint
Among the excisting valid studies the selected study was found to show the highest toxicity after oral application of isophorone.

Justification for selection of acute toxicity – inhalation endpoint
Among the excisting valid studies the selected study was found to show the highest toxicity after inhalative application of isophorone.

Justification for selection of acute toxicity – dermal endpoint
Among the excisting valid studies the selected study was found to show the highest toxicity after dermal application of isophorone.

Justification for classification or non-classification

According to the criteria of CLP Regulation 1272/2008 isophorone is classified as harmful if swallowed (Acute Tox. 4; H302) as well as harmful in contact with skin (Acute Tox. 4; H312).

Based on the result of the acute inhalation studies (Esso Research, 1965; Esso Research; 1964) isophorone has a low acute toxicity if inhaled. Therefore, the test substance must not be classified.