Effects of salinity on the chronic toxicity of 4-methylbenzylidene camphor (4-MBC) in the marine copepod Tigriopus japonicus

Abstract

Organic ultraviolet filters are widely used in personal care products. 4-methylbenzylidene camphor (4-MBC) is one of the most frequently used UV filters. Due to its widespread usage 4-MBC has been detected at high concentrations in offshore waters. Previous toxicological studies have suggested that 4-MBC might induce much higher toxicity in marine organisms than freshwater species. To explore the effects of salinity on 4-MBC toxicity, the marine copepod Tigriopus japonicus was used as the model species, as it plays an important role in marine ecosystems and can be adapted to a wide range of salinity conditions. T. japonicus were adapted to three different salinity conditions (i.e., 20, 30 and 40 ppt) prior to exposure to 0, 1, and 5 μg L−1 4-MBC for multiple generations (F0-F3). Results showed that environmentally relevant concentrations of 4-MBC had toxic effects on T. japonicus and therefore, can pose a significant risk to marine copepods in the natural environment. In addition, increasing salinity levels increased the lethal, developmental and reproductive toxicities of 4-MBC in T. japonicus. This was because that higher salinity levels increased the uptake rate constant and bioconcentration factor of 4-MBC and also further exacerbated the oxidative stress induced by exposure to 4-MBC in T. japonicus. Our study demonstrated that understanding how salinity affects the toxicity of 4-MBC is important for accurate assessment of the risk of 4-MBC in the aquatic environments.