期刊
CHEMOSPHERE
卷 59, 期 2, 页码 255-261出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.chemosphere.2004.11.003
关键词
Daphnia magna; toxicity; benzoic acids; hydroxyl group; log P-ow
The acute immobilization toxicity of benzoic acids substituted with hydroxyl and/or methoxyl groups on the aromatic ring was determined for the freshwater crustacean Daphnia magna under neutralized condition (initial pH: 7.45 +/- 0.05). Toxicity, expressed as EC50 value, varied depending largely on the number and position of phenolic hydroxyl groups. Especially, benzoic acids with ortho-substituted hydroxyl groups were more toxic than benzoic acids with meta- and/or para-substituted hydroxyl groups. Whereas the limited data indicated that methoxyl substitution had relatively small and variable effects on the toxicity. Of the tested compounds, 2,4,6-trihydroxybenzoic acid showed the highest toxicity with the 413 h EC50 Of 10 mu mol l(-1). This was 700 times as toxic as the parent benzoic acid (48 h EC50 = 7.0 mmol l(-1)) and about two orders of magnitude higher than those previously reported for monohalogenated benzoic acid derivatives in Daphnia. Within the subgroups based on the number of hydroxyl groups (N-OH), the toxicity variations due to the position of hydroxyl groups appeared to be correlated with the logarithms of n-octanol/water partition coefficients (logP(ow)). The toxicity of benzoic acids existing almost entirely as their ionized forms could be expressed as simple structuie-toxicity relationships using these two descriptors (N-OH and logP(ow)). (c) 2004 Elsevier Ltd. All rights reserved.
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