Potential for dietary uptake of estrogens via macroinvertebrates in River Po fish

Several substances, both man-made and of natural origin, are known to potentially affect the endocrine system of fish. They generally enter the aquatic environment through the discharges of domestic and industrial origin, and particularly estrogens, perhaps the most investigated of the endocrine disrupters, are suspected to cause altered gonadal development in wild fish populations. After the observation of intersexual cyprinids in the River Po, many studies have been undertaken, particularly along its middle section where a polluted tributary, the River Lambro, is suspected to be an effective source of EDs to the major Italian watercourse. An objective of these studies was to investigate whether fish diet may be a significant route of uptake of estrogens. To this aim, several multiplate samplers were placed upstream and downstream from the confluence of the River Lambro, and after one month of exposure, macroinvertebrates were collected and identified to order or family. Gammaridae, Ephemeroptera and Trichoptera were analysed for target estrogenic compounds (E1, E2, E3, EE2, OP, NP, BPA) in High Performance Liquid Chromatography/Multiple Reaction Monitor (HPLC/MRM). The concentrations of EDs determined in the three groups of macroinvertebrates were consistently higher downstream from the confluence of the River Lambro. In the most polluted downstream stretch, t-OP was found at 100 ng/g, whereas both NP and BPA reached levels of 600 ng/g. Surprisingly, also estriol was bioaccumulated up to 800 ng/g. Marked differences in the levels of contaminations were evident among the three groups of invertebrates also suggesting that diet may differently contribute to estrogens uptake.