Acetone

Neurotoxicity

Description of key information

Oral exposure: rat, up to 9 w exposure:   NOAEL    650 mg/kg bw/d
                            rat, 4 w exposure:             LOAEL 1,300 mg/kg bw/d
Inhalation: rat, acute 4 hr:                           NOAEC  9,500 mg/m3
                    rat, 13 w exposure:                  NOAEC 9,500 mg/m3 = NOAEL 1,000 mg/kg bw/d

Key value for chemical safety assessment

Effect on neurotoxicity: via oral route

Endpoint conclusion

Dose descriptor:

NOAEL

650 mg/kg bw/day

Effect on neurotoxicity: via inhalation route

Endpoint conclusion

Dose descriptor:

NOAEC

9 500 mg/m³

Additional information

There is no study on neurotoxicity available that is similar to a guideline study. The available reliable studies investigated single endpoints of neurotoxicity or behavioural toxicity and are altogether evaluated for a weight of evidence approach.

Oral exposure of male Wistar rats in drinking water studies for 4 to 9 weeks

After exposure to 10,000 mg acetone/L water for 4 weeks or to 5,000 mg acetone/L water for 9 weeks (corresponding to doses of 1,300 or 650 mg/kg bw/d, neurobehavioural toxicity was screened via a Functional Observation Battery, and weight and histopathology of the brains was examined. The only neurobehavioural effect found after the 4-week exposure to 10,000 mg/L was reduced hindlimb and forelimb grip strengths, with a significant effect on the former parameter only. The NOAEL for neurobehavioural toxicity corresponded to a dose of 650 mg/kg bw/d (9 week exposure), the LOAEL was 1,300 mg/kg bw/d (4 week exposure) (Dalgaard et al., 1999).

After dosing of rats with 5000 mg acetone/L water for 6 weeks (dose of ca. 600 mg/kg bw/d), the only effect was a slight although significant decrease of the nerve conduction velocity in acetone-treated rats compared to controls after 6 weeks of treatment (29.5 ± 1.1 vs. 31.5 ± 2.1 m/sec, P<0.05). However, as at the same timepoint the nerve conduction velocity in the acetone group showed the highest value measured at any timepoint from treatment week 3 to 6, a possible adverse neurophysiological effect is highly questionable. Weekly monitoring of behaviour as performance on a rotarod was without a significant finding (Ladefoged et al., 1989). Consequently, the resulting NOAEL of ca. 600 mg/kg bw/d is at a comparable level as in the study of Dalgaard et al. (1999).

13 -week inhalation of acetone by whole-body exposure

Groups of 10 adult male Crl:CD BR rats were used to assess whether inhalation of 0, 1,000, 2,000, or 4,000 ppm of acetone vapour (ca. 0, 2375, 4750 or 9500 mg/m³corresponding to doses of ca. 0, 250, 500, or 1000 mg/kg bw/d) for 13 weeks, 5 days/week, 6 hrs/day altered schedule-controlled operant performance. Up to 4000 ppm, acetone vapour does not appear to have enduring effects on nervous system functions that mediate the performance of a complex, learned task, that is lever-pressing on a multiple fixed-ratio-interval schedule of food presentation after extensive training (Christoph et al., 2003).

Justification for classification or non-classification

No classification according to EC regulation 1272/2008 is warranted.