N,N ‐Dimethylacetamide [MAK Value Documentation, 2018]

Abstract

The 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 N,N‐dimethylacetamide [127‐19‐5]. N,N‐Dimethylacetamide causes focal cystic degenerations, peliosis, hemosiderin/lipofuscin accumulation and apoptosis in the liver of rats and male mice after chronic whole body inhalation at 100 ml/m3. The NOAEC in both species is 25 ml/m3. Elastane fibre workers with exposure to N,N‐dimethylacetamide show hepatocellular injury. The data at the workplace is not adequate to derive a MAK value. The former MAK value of 10 ml/m3 was derived from the NOAEC of 25 ml/m3 in rats and mice. The MAK value is now lowered to 5 ml/m3 which takes into account the increased respiratory volume at the workplace because the blood:air partition coefficient of N,N‐dimethylacetamide is > 5 (see List of MAK and BAT Values, Sections I b and I c). Since a systemic effect is critical, Peak Limitation Category II is retained. The default excursion factor of 2 is retained as well, as the mechanism of action and the half‐life in blood are not known. In rats and rabbits, N,N‐dimethylacetamide induces via inhalation at 450 or 570 ml/m3, respectively, and above, specific teratogenic effects, cardiovascular and skeletal malformations. The NOAEC for teratogenicity in rats and rabbits are 300 or 200 ml/m3, respectively. The lowest NOAEC for developmental toxicity in rats and rabbits are 100 and 57 ml/m3, respectively. Considering the increased respiratory volume at the workplace, the NOAEC for rabbits is only six times the MAK value. However, taking into account that the NOAEC could be higher than 57 ml/m3 and the observed effects, reduced fetal body weight and increased incidence of skeletal variations, are considered marginal, the difference to the MAK value is sufficient. Therefore, damage to the embryo or foetus is unlikely when the MAK value is observed and N,N‐dimethylacetamide remains assigned to Pregnancy Risk Group C. Skin contact should be avoided as N,N‐dimethylacetamide is designated with an “H”.