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-acetyl-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-ben zopyran (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) for 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 including suspended matter, sediment and fish. The 90th-percentile in more than 200 surface water samples is 0.3 microg/l for AHTN and 0.5 microg/l for HHCB. The 90th-percentile of the concentrations in fish is 0.12 mg/kg fresh weight 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, 585 tonnes for AHTN and 1482 tonnes for HHCB. Concentrations in sludge-amended soils and in earthworms are predicted based on concentrations measured in sludge. For AHTN, the predicted values are: PECsoil, 0.029 mg/kg and PECworm, 0.065 mg/kg while for HHCB the corresponding figures are 0.032 and 0.099 mg/kg. These concentrations assume a biodegradation half-life in the soil of 180 days based on preliminary soil biodegradation data.