Oxalsäuredinitril [MAK value documentation in German language, 2019]

German Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area has re‐evaluated the maximum concentration at the workplace (MAK value) and the Pregnancy Risk Group of oxalonitrile [460‐19‐5]. There are no new data. The MAK value of 5 ml/m3 was determined in analogy to the more toxic metabolite hydrogen cyanide. The MAK value for hydrogen cyanide of 1.9 ml/m3 was derived from the human detoxification capacity per kg body weight with a respiratory volume of 10 m3. Therefore, the increased respiratory volume at the workplace has already been accounted for. The MAK value of oxalonitrile, which was set at 5 ml/m3 to reflect the 2.5‐fold higher acute toxicity of hydrogen cyanide, can be retained. This is also the case for Peak Limitation Category II and the excursion factor of 2 because no irritation was observed in humans below 16 ml/m3. There are no developmental toxicity studies. Therefore, oxalonitrile is assigned to Pregnancy Risk Group D.