Aquatic toxicity and ecological risk assessment of seven parabens: Individual and additive approach Original Research Article

In the present study, aquatic concentrations of seven parabens were determined in urban streams highly affected by treated or untreated domestic sewage in Tokushima and Osaka, Japan. The detected highest concentrations were 670, 207, and 163 ng l− 1 for methylparaben, n-propylparaben, and n-butylparaben, respectively in sampling sites with watershed area of no sewer system in Tokushima. Conventional acute/chronic toxicity tests were conducted using medaka (Oryzias latipes), Daphnia magna, and Psuedokirchneriella subcapitata for four parabens, which was consistent with our previous study on three parabens, n-butylparaben, i-butylparaben, and benzylparaben. The aquatic toxicity on fish, daphnia, and algae was weaker for the parabens with a shorter alkyl chain than those with a longer alkyl chain as predicted by their hydrophobicity. Medaka vitellogenin assays and DNA microarray analysis were carried out for methylparaben and found induction of significant vitellogenin in male medaka at 630 μg l− 1 of methylparaben, while the expression levels of genes encoding proteins such as choriogenin and vitellogenin increased for concentrations at 10 μg l− 1 of methylparaben. Measured environmental concentrations (MECs) of seven parabens in Tokushima and Osaka were divided by predicted no effect concentrations (PNECs) and hazard quotient (MEC/PNEC) was determined for individual parabens. The MEC/PNEC was highest for n-propylparaben and was 0.010 followed by n-butylparaben (max. of 0.0086) and methylparaben (max. of 0.0042). The sum of the MEC/PNEC for the seven parabens was 0.0049. Equivalence factors were assigned for each paraben on the basis of the toxicity of n-butylparaben for each species, and n-butylparaben equivalence was calculated for the measured environmental concentrations. The MEC/PNEC approach was also conducted for the n-butylparaben-based equivalence values. The maximum MEC/PNEC was 0.018, which is lower than the trigger level for further detailed study such as large-scale monitoring for chronic toxicity tests including full-life cycle tests for fish.