Recent studies conducted by the Research Institute for Fragrance Materials (RIFM) in support of the environmental risk assessment process

Abstract

Although the environmental risk assessments for the nitro musks, musk ketone and musk xylene, and the polycyclic musks, AHTN and HHCB, showed that the risks of these fragrance ingredients were low, questions regarding their environmental behaviour and fate stimulated further research. The removal during the sewage treatment process of AHTN, HHCB, musk ketone and musk xylene is 89, 92, 83 and 99%, respectively, which is higher than predicted on the basis of log Kow. This may, at least partly, be explained by the biotransformation of the polycyclic musks into more polar metabolites and the transformation of the nitro musks into their amino metabolites. Because of higher polarity, the transformation products of AHTN and HHCB have a lower log Kow and, therefore, it is likely that they will have a lower accumulation potential and a lower aquatic toxicity. Contrary to earlier findings, RIFM studies showed that the toxicity of the 4-amino-metabolite of musk xylene for Daphnia magna was of the same order of magnitude as musk xylene, ranging from 0.37 to 0.51 mg L-1. The phenomenon of missing tail fins observed in a fish-early-life stage test with AHTN was confirmed in another species. This effect occurred at the concentrations where growth and survival were affected as well. For the polycyclic musks with a lower market volume, ADBI, AHDI and ATII, a preliminary risk assessment was carried out on the basis of structural similarity and the proportionality of the environmental concentrations. The present findings support the earlier conclusion that the risks posed by these products are low.