Environmental risk assessment for the polycyclic musks, AHTN and HHCB - II. Effect assessment and risk characterisation

Reports of the polycyclic musks AHTN and HHCB in surface water and fish, pr imarily in Europe, have prompted studies of their environmental effects. Th ese effects then are used, along with the predicted environmental concentra tions in a risk assessment according to the approach developed under Europe an Union Regulation 793/93, in line with the Technical Guidance Document fo r risk assessment of new and existing chemicals. In 72-h studies with algae (Pseudokirchneriella subcapitata), NOECs were 0.374 mg/l (AHTN) and 0.201 mg/l (HHCB). In 21-day reproductive tests with daphnia (Daphnia magna) NOEC s were 0.196 (AHTN) and 0.111 mg/l (HHCB). In 21-day growth tests with blue gill sunfish (Lepomis macrochirus), NOECs were 0.067 (AHTN) and 0.068 mg/l (HHCB). And, finally 35-day early life stage tests with fathead minnows (Pi mephales promelas) resulted in NOECs of 0.035 (AHTN) and 0.068 mg/l (HHCB). These results lead to Predicted No Effect Concentrations (PNEC) of 3.5 mu g/l (AHTN) and 6.8 mu g/l (HHCB) for aquatic organisms. For the soil compar tment, 8-week studies with earthworms (Eisenia fetida) resulted in NOECs of 105 (AHTN) and 45 mg/kg (HHCB) and 4-week studies with springtails (Folsom ia candida) resulted in a NOECs of 45 mg/kg for both substances. These valu es lead to a PNEC of 0.32 mg/kg dw for both materials. Using mammalian stud ies, PNECs for fish or worm eating predators of 10 mg/kg fw (AHTN) and 100 mg/kg fw (HHCB) can be derived. For sediment dwelling organisms, PNECs were derived by equilibrium partitioning using the aquatic PNECs. Comparing PNE Cs with the measured or predicted environmental exposures leads to risk cha racterisation ratios as follows: aquatic species: AHTN 0.086, HHCB 0.074; s ediment organisms: AHTN 0.44, HHCB 0.064; soil organisms: AHTN 0.091, HHCB 0.10; fish eating predators: AHTN 0.012, HHCB 0.001; worm eating predators: AHTN 0.007, HHCB 0.001. (C) 1999 Published by Elsevier Science Ireland Ltd . All rights reserved.