Evaluating bioaccumulation of suspected endocrine disruptors into periphytons and benthos in the Tama River

There are two major routes through which fish are exposed to endocrine disruptors (EDs); one route is through water that is a habitat; the other is through aquatic food such as algae and benthos. Few studies on the bioaccumulation of EDs in food have been conducted. Therefore, we evaluated the concentration in food of nonylphenol (NP), bisphenol A (BPA) and 17β-estradiol (E2), which were frequently detected in river water and in final discharge of Wastewater Treatment Plants (WWTPs) in Japan. We also evaluated the estrogenicity of samples using recombinant yeast. NP concentrations ranged 0.1-0.4 mg/L in the river water, while they ranged 8-130 mg/kg-wet in the periphytons and 8-140 μg/kg-wet in the benthos. BPA concentrations ranged 0.02-0.15 μg/L in the river water, while they ranged 2-8.8 μg/kg-wet in the periphytons and 0.3-12 μg/kg-wet in the benthos. E2 concentrations ranged 0.0001-0.0076 μg/L in the water, while they ranged 0.09-2.26 μg/kg-wet in the periphytons and <0.01-0.22 μg/kg-wet in the benthos. The estrogenicity ranged 0.0001-0.0464 μg-E2equivalent/L in the water, while it ranged 3.4-66.8 μg-E2equivalent/kg-wet in the periphytons and 7.4-5458 μg-E2equivalent/kg-wet in the benthos. Bioaccumulation factors of NP are estimated as 160-650 for the periphytons, and 63-990 for the benthos, respectively. Bioaccumulation factors of BPA are estimated as 18-650 for the periphytons, and 8-170 for the benthos, respectively. Bioaccumulation factors of E2 are estimated as 64-1,200 for the periphytons, and 100-160 for the benthos, respectively. The ratios of the periphytons and the benthos to the water in terms of the estrogenicity were larger than those in terms of the chemicals. In particularly, the ratio of the benthos to the water is about 106 in the maximum. The results suggest that food may be a more important route for fish exposed to EDs in water environment.