3,5,5-trimethylcyclohex-2-enone

Endpoint summary

Description of key information

The acute toxicity in laboratory animals is low to moderate (oral LD50 = 1500 mg/kg bw; dermal LD50 = 1200 mg/kg bw; inhalative LC50 = 7000 mg/m3).

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

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

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

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 401 (Acute Oral Toxicity)

GLP compliance:

no

Test type:

standard acute method

Limit test:

no

Species:

rat

Strain:

not specified

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Voss
- Weight at study initiation: 80 - 115 g

Route of administration:

oral: unspecified

Vehicle:

CMC (carboxymethyl cellulose)

Details on oral exposure:

VEHICLE
- Concentration in vehicle: 0.5 % CMC

Doses:

500; 1000; 1250; 1500; 1750; 2000; 2500 mg/kg bw

No. of animals per sex per dose:

5

Control animals:

no

Details on study design:

- Duration of observation period following administration: 13 days
- Necropsy of survivors performed: no
- Other examinations performed: clinical signs, other: 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:

Probit analysis

Sex:

male/female

Dose descriptor:

LD50

Effect level:

1 500 mg/kg bw

95% CL:

1 400 - 1 800

Mortality:

Time to 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

Clinical signs:

other: > 1000 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 hemorrhagic erosions of proventriculus lining; urine retention; hyperemia of liver; pulmonary emphysema, edema, or hyperemia; splenic enlargement

Interpretation of results:

Category 4 based on GHS criteria

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LD50

Value:

1 500 mg/kg bw

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

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

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

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

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 ANIMALS
- Weight at study initiation: 200-225 g
- Housing: wire mesh cages

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

whole body

Vehicle:

air

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: dynami stainless steel exposure chamber
- Exposure chamber volume: 500 L
- Method of holding animals in test chamber: caged
- System of generating vapors: by means of metering predetermined amounts of the liquid material by a precision metering pump into a stainless steel spray nozzle tip operating under positive air pressure. The material metered through the nozzle were then vaporized by the pressurized air flow directly in the exposure chamber


TEST ATMOSPHERE
- Brief description of analytical method used: nominal dosage concentrations were calculated from the amount of liquid being metered and the total airflow through the chamber.

Analytical verification of test atmosphere concentrations:

no

Duration of exposure:

4 h

Concentrations:

5; 7; 10; 17.8 mg/l

No. of animals per sex per dose:

10

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations: during exposure at 30 min intervals, following exposure once daily
- Necropsy of survivors performed: yes

Sex:

male

Dose descriptor:

LC50

Effect level:

7 mg/L air

95% CL:

>= 5.7 - <= 8.6

Exp. duration:

4 h

Mortality:

Dose Mortality
[mg/L] 4 hours 14 days
------------------------------------
5 0/10 1/10
7 0/10 4/10
10 10/10 10/10
17.8 10/10 10/10

Clinical signs:

other: see "Other findings"

Gross pathology:

Autopsies of animals that died during exposure and those that survived revealed varying degrees of pulmonary congestion (slight to marked).

Other findings:

During exposure, the animals exposed to the lowest dose level (5 mg/L) showed no effects while those at the higher levels became ataxic and comatose towards the end of the 4-hour exposure period. Following exposure, the surviving animals at the lowest level appeared normal while those at the other levels demonstrated dyspnea, piloerection, depression, and decreased activity.

Interpretation of results:

GHS criteria not met

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LC50

Value:

7 000 mg/m³ air

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

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

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

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 402 (Acute Dermal Toxicity)

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 ANIMALS
- Weight at study initiation: ca 2.5 kg

Type of coverage:

occlusive

Vehicle:

unchanged (no vehicle)

Details on dermal exposure:

REMOVAL OF TEST SUBSTANCE
- Time after start of exposure: after 24 hours, unresorbed quantity determined

Duration of exposure:

24 hours

Doses:

9200; 13850; 23000; 23000; 32300 mg

No. of animals per sex per dose:

6

Control animals:

yes

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations: daily

Sex:

male/female

Dose descriptor:

LD50

Effect level:

1 200 mg/kg bw

Remarks on result:

other: according to the authors, as cited in OECD SIDS

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: 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 clinical signs appea

MORTALITY
Dose      absorbed      deaths    timepoint
[mg]      [mg/kg]                  [hours]
---------------------------------------------------
9200      600 ± 400      0/6      -
13850     750 ± 500      2/6      6, 12
23000    1700 ± 900      3/6      3, 4, 5
23000    2850 ± 1300     3/6      4, 6, 48
32300    2500 ± 1000     6/6      2.5, 4 x 4, 5

LD50: 1200 mg/kg bw (according to OECD SIDS)

CLINICAL SIGNS
Animals showed accelerated breathing, prostration and narcosis.
Death occured mostly within 6 hours, but survivors recovered.
The intensity of the erythema varied between animals, recovery of the  skin was not always complete within the postexposure period.
Doses at which clinical signs appeared were not defined in the study.

POTENTIAL TARGET ORGANS
None identified (except skin).

SEX-SPECIFIC DIFFERENCES
None identified.

Interpretation of results:

Category 4 based on GHS criteria

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LD50

Value:

1 200 mg/kg bw

Additional information

Oral toxicity

LD50 values of isophorone in rats were 1500 mg/kg bw (Schering, 1968), 2100 mg/kg bw (Dutertre-Catella, 1976) and 3450 mg/kg bw (Esso Research, 1964) The LD50 in mice is 2200 mg/kg bw (Dutertre-Catella, 1976). Clinical signs like general apathy, depression, weariness (leading to coma) ptosis, lacrimation and laboured respiration occurred at doses of ≥ 1450 mg/kg bw (Schering, 1968; Dutertre-Catella, 1976; Esso Research, 1964). 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 toxicity

In acute inhalation studies isophorone showed very low acute toxicity with LC50 values sometimes exceeding the maximal vapour concentration of 2.3 mg/l. A LC50 value of 7000 mg isophorone/m³ (aerosol) was determined in rats (Esso Research, 1965). Mortality was observed in another study with rats but not guinea pigs at concentrations ≥ 10,570 mg/m3 (Smyth, 1940). Clinical signs were nose and eye irritation, accelerated, laboured respiration, intestinal peristalsis and coma at dose ≥ 5000 mg/m3 (Smyth, 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, 1940).

Signs of respiratory tract irritation were also seen in humans (workers and volunteers) exposed to the test substance by inhalation (IUCLID chapter 7.10).

 

Dermal toxicity

For rabbits the LD50 values were 1200 mg/kg bw (Dutertre-Catella, 1976) and > 3160 mg/kg bw (Esso Research, 1965). In rats, the LD50 after dermal application was 1700 mg/kg bw (Schering, 1968).

Clinical signs were general apathy, later on occasionally coma, cachexia, tremor, lacrimation (Schering, 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 classification or non-classification

The available experimental test data are reliable and suitable for classification purposes under Regulation 1272/2008. As a result the substance is considered to be classified for acute oral and dermal toxicity as cat. 4, H302 and H312, and respiratory tract irritation STOT SE cat. 3, H335 under Regulation (EC) No. 1272/2008, as amended for the 14th time in Regulation (EU) 2020/217.