Exposure to bisphenol A modulates hormone concentrations in Gammarus pseudolimnaeus

Bisphenol A (BPA) is an endocrine-disrupting compound that can enter aquatic systems through landfill leachate or wastewater effluent. Although impacts of BPA on vertebrates are well documented, its effects on invertebrates are less clear. Amphipods such as Gammarus pseudolimnaeus Bousfield, 1958 are often prevalent invertebrates in freshwater ecosystems and can provide a powerful invertebrate model system to investigate the endocrine-disruptive capabilities of BPA. However, techniques to assay hormone concentrations in amphipods, especially vertebrate-like steroid sex hormones, are not widespread. In this study, we (i) quantified estrogen concentrations in juveniles and in adult female amphipods; (ii) quantified testosterone concentrations in juveniles and in adult male amphipods; and (iii) delineated changes to estrogen and testosterone concentrations of adults and juveniles following a 9-day exposure to BPA at four levels: 0 (control), 10, 50, and 100 µg/L BPA. Tissue extracts from homogenized samples were analyzed for estrogen or testosterone concentrations via radioimmunoassay for each reproductive class of amphipod. Low concentrations of BPA significantly increased estrogen concentrations in adult females and in juveniles. Moderate and high concentrations of BPA significantly increased testosterone concentrations in adult males, and low and moderate concentrations of BPA significantly increased testosterone concentrations of juveniles.