Accumulation of chlorobenzenes in Japanese medaka (Oryzias latipes) co-exposed to 10- or 45-µm polystyrene microplastics

Abstract

The co-existence of microplastics and hydrophobic organic chemicals is ubiquitous in the environment. Microplastics may act as vectors for the transmission of organic pollutants to organisms. In the present study, we co-exposed 33 adult medaka fish to a mixture of chlorobenzenes (CBs; trichlorobenzene, tetrachlorobenzene, pentachlorobenzene, and hexachlorobenzene—at 10, 10, 10, and 8 µg/L, respectively) and two different sizes of polystyrene microplastics (PS-MP)—10-µm PS-MP at 0.1 mg/L and 45-µm PS-MP at 0.45 mg/L. We exposed the fish to CBs, CB10MP (CBs+10-µm PS-MP), and CB45MP (CBs+45-µm PS-MP) for 7 days followed by 3 days for excretion. We measured the concentrations of CBs and PS-MP in the fish on days 7, 8, 9, and 10 and in the water on days 5, 6, and 7. Our results clearly indicated that there was no increase in the concentration of CBs in the medaka co-exposed to MPs and either size of PS-MP. This result might have been due to the sorption of Tri- and TetCBs to PS-MP and little or no desorption in the gut. Our study revealed the absence of a vector effect of PS-MP on the bioaccumulation of CBs in medaka.