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) of N‐ethyl‐2‐pyrrolidone [2687‐91‐4] of 2 ml/m3, considering the endpoints irritation of the respiratory tract and developmental toxicity.
The critical effect of N‐ethyl‐2‐pyrrolidone is degeneration of the olfactory epithelia in rats in a new 13‐week‐inhalation study. 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. According to these proposals, the NOAEC of 62.6 mg/m3 (13.3 ml/m3 vapour) corresponds to a work place air concentration of 31 mg/m3 (6.6 ml/m3). The irritating response in the 13 week study is not more pronounced than after shorter exposition times. Therefore the MAK‐value is increased to 5 ml/m3 for the vapour phase only. Local effects are critical and only minimal irritation occurs at the LOAEC, therefore the assignment of N‐ethyl‐2‐pyrrolidone to Peak Limitation Category I and excursion factor 2 established in 2014 are retained. Also with the increased MAK value, damage to the embryo or foetus is unlikely when the MAK value is observed. Therefore, classification of N‐ethyl‐2‐pyrrolidone in Pregnancy Risk Group C is confirmed.