Acute and Subchronic Effects of Branched 4-Nonylphenol Isomers on Mysid Crustacean, Americamysis Bahia

Abstract

Nonylphenol (NP) is widely used in the manufacture of nonyphenol ethoxylates, and highly toxic to aquatic organisms. However, limited information is available on the toxic effects of NP isomers to crustaceans. In this study, we investigated the acute and subchronic effects of NP isomers on the mysid, Americamysis bahia (Crustacea: Mysidacea). In the acute toxicity test, the median lethal concentration (96 h-LC50) values of 4-NP, NP-C’, NP-I, NP-N, NP-O and NP-Q in mysids were estimated to be 78, 131, 91, 72, 144 and 89 μg/L, respectively. In order to further evaluate the subchronic effects of NP isomers on survival, growth (body and carapace length and body weight), sexual development and molting, 7-day-old mysids were exposed to NP-N and NP-Q (0.5, 5 and 50 μg/L) for 14 days. The adverse effects of NP-N and NP-Q on the body and/or carapace length were the most prominent, and the lowest observed effect concentrations (LOECs) of these NPs were 50 and < 0.5 μg/L, respectively. Furthermore, the total number of molting was significantly decreased in mysids exposed to NP-N (the LOEC value: < 0.5 μg/L) and NP-Q (5 μg/L) for 14 days. These results suggest that subchronic exposure to environmentally relevant concentrations of NP isomers affect growth and molting of the mysids. In addition, it was suggested that the toxicity may be different for each isomer.