(E)-4-(2,6,6-trimethyl-1-cyclohexen-1-yl)-3-buten-2-one

Endpoint summary

Description of key information

Acute Toxicity:
- oral: LD50 5300 kg/kg bw (mouse)
- dermaL. LD50 > 2000 mg/kg bw (rat; analogy mixed isomers, CAS 8013-90-9)

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion

Dose descriptor:

LD50

Value:

5 300 mg/kg bw

Acute toxicity: via dermal route

Endpoint conclusion

Dose descriptor:

LD50

Value:

2 000 mg/kg bw

Additional information

To test for acute oral toxicity, pure beta-ionone was administered to a group of five mice at three dose levels. The resulting LD50 was 5300 mg/kg bw.

Furthermore, oral toxicity was evaluated in a 5-day test, where doses of 500, 1000, 2000, 4000 and 8000 mg/kg bw were administered to rats (Hoffmann-LaRoche, 1975). No mortality was observed up to a dosage of 2000 mg/kg bw, but higher doses showed lethality. As a clinical sign of toxicity, sedation was described at dosages of 500 mg/kg bw or higher. Because 40% of the animal at the 4000 mg/kg dose group died after 5 applications within the 15 day period, one could assume that fewer animals would have died after only one application. Thus, the LD50 for rats was estimated as >4000 mg/kg bw.

To support this low acute oral toxicity, studies with the beta-ionone isomer (CAS 14901 -07 -6) are used. In a study with rats, deaths occurring within 24 h and within 10 days after dosing were recorded (Givaudan, 1980). The calculated LD50 was 7120 +/- 1000 mg/kg bw for deaths within 24 h and 3290 +/- 500 mg/kg bw after 10 days. In the same study, the LD50 for acute oral toxicity in mice was found to be 2000 +/- 320 mg/kg bw after 10 days of observation. In another study with male mice, the LD50 was found to be 5331 +/- 755 mg/kg bw (Hoffmann-LaRoche, 1967).

Due to the lack of data for acute dermal toxicity, results from the mixed iosmers (CAS 8013 -90 -9) are taken into account. In an OECD 402 -study (Symrise, 1999) 10 Sprague Dawley rats (5/sex) had their fur clipped on their backs and flanks. 2000 mg/kg bw of undiluted test substance was applied and covered with gauze. After 24h the area was wiped to removed the test material. All animals survived to the end of the 14 -day observation period, the LD50 was found to be >2000 mg/kg bw.

Because of the structural similarities the same result for beta-ionone (CAS 79 -77 -6) has to be expected.

Justification for classification or non-classification

Due to the resulting LD50 values for acute oral and acute dermal toxicity of 5300 mg/kg bw and >2000 mg/kg bw, respectively, no classification is required.