MAK Value Documentation for 4‐Methyl‐3‐pentene‐2‐one
The German Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area has re‐evaluated the maximum concentration at the work place (MAK value) for 4‐methyl‐3‐pentene‐2‐one of 5 ml/m3, considering local and systemic toxicity as well as developmental toxicity. As described in the last evaluation from 2006, 4‐methyl‐3‐pentene‐2‐one is irritating to eyes and skin. Starting at the lowest concentration of 31 ml/m3 in a 49‐day‐inhalation‐study with daily exposure exudate in the olfactory epithelium is observed in 10 of 24 rats. A NAEC of 10 ml/m3 is extrapolated. Since 2014, the Commission uses an empirical approach to set MAK values for substances with critical effects on the upper respiratory tract or the eyes. Taking into consideration exposure of rats took place 7 days a week and no chronic study is available, it is assumed, that the chronic NAEC is 5 ml/m3. As olfactory epithelium is the target tissue, according to the empirical approach, the MAK‐value is reduced to 2 ml/m3. The assignment to Peak Limitation Category I, because local effects are critical, and the excursion factor of 2 are confirmed. As there are no developmental toxicity studies, the assignment to Pregnancy Risk Group D is confirmed.