Effects of eight polycyclic aromatic compounds on the survival and reproduction of the springtail Folsomia fimetaria L. (Collembola, isotomidae).

The effects of eight polycyclic aromatic compounds on the survival and reproduction of the collembolan Folsomia fimetaria L. were investigated in a well-characterized Danish agricultural soil. With the exception of acridine, polycyclic aromatic hydrocarbons (PAHs) and neutral N-, S-, and O-monosubstituted analogues showed similar toxicities to soil collembolans when the results were expressed in relation to total soil concentrations (mg/kg). The estimated concentrations resulting in a 10% reduction of reproductive output (EC10 values) were based on measured initial concentrations and were for acridine 290 mg/kg, carbazole 10 mg/kg, dibenzofuran 19 mg/kg, dibenzothiophene 7.8 mg/kg, fluoranthene 37 mg/kg, fluorene 7.7 mg/kg, phenantrene 23 mg/kg, and pyrene 10 mg/kg. When the EC10 values were converted to soil pore-water concentrations, they showed a highly significant correlation (r2 = 0.71, p < 0.01) to no-observed-effect concentrations for the freshwater crustacean Daphnia magna, as estimated by a quantitative structure activity relation (QSAR) for baseline toxicity (nonpolar narcosis). Only carbazole and acridine were more than two times more toxic (4.9 and 3.1, respectively) than expected from the Daphnia QSAR data. The latter result indicates that the toxicity of the tested substances is close to that expected for compounds with nonpolar narcosis as the mode of action. However, the relatively large uncertainties in the extrapolation method prevent final conclusions from being drawn.