Environmental risk assessment for the polycyclic musks AHTN and HHCB in the EU - I. Fate and exposure assessment

For the environmental exposure assessment of the fragrance ingredients 7-ac etyl-1,1,3,4,4,6-hexamethyl-1,2,3,4-tetrahydronaphthalene (AHTN) and 1,3,4, 6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta-gamma-2-benzopyran (HHCB) the following properties were determined: vapour pressure 0.0682 and 0.0727 Pa; water solubility 1.25 and 1.75 mg/l; log K-ow 5.7 and 5.9; log K-oc 4. 80 and 4.86; bioconcentration factor in fish: 597 and 1584 (fresh weight) f or AHTN and HHCB, respectively. Both substances are degraded to more polar metabolites in fish, in soil and during sewage treatment. A review is made of concentrations measured in sludge, in freshwater and marine systems incl uding suspended matter, sediment and fish. The 90th-percentile in more than 200 surface water samples is 0.3 mu g/l for AHTN and 0.5 mu g/l for HHCB. The 90th-percentile of the concentrations in fish is 0.12 mg/kg fresh weigh t for both substances (n = 27). These concentrations are lower by a factor of 5-15 than predicted on the basis of the yearly use volumes in Europe, 58 5 tonnes for AHTN and 1482 tonnes for HHCB. Concentrations in sludge-amende d soils and in earthworms are predicted based on concentrations measured in sludge. For AHTN, the predicted values are: PECsoil, 0.029 mg/kg and PECwo rm, 0.065 mg/kg while for HHCB the corresponding figures are 0.032 and 0.09 9 mg/kg. These concentrations assume a biodegradation half-life in the soil of 180 days based on preliminary soil biodegradation data. (C) 1999 Publis hed by Elsevier Science Ireland Ltd. All rights reserved.