Adverse effects of bisphenol A on water louse (Asellus aquaticus)

Experiments were performed to study the effects of short and long-term exposure to bisphenol A (BPA) on a freshwater crustacean isopod Asellus aquaticus (L.). Two life stages of isopods were exposed to a range of BPA concentrations, from aqueous and two dietary sources, in the form of with BPA spiked conditioned alder leaf (Alnus glutinosa) discs, or spiked formulated sediment, to determine the relative importance of each source of exposure on the uptake of this contaminant. Several lethal and sublethal endpoints were evaluated in this study to measure the potential effects of BPA on A. aquaticus, including mortality, growth and feeding rate inhibition, mobility inhibition, de-pigmentation and molting disturbances. They signify a correlation to BPA levels and a difference in BPA uptake efficiency from different uptake sources. Results of acute exposure to BPA show a greater sensitivity of test systems using juvenile specimens with a 96 h LC₅₀ of 8.6 mg L(-1) BPA in water medium and a 96 h LC₅₀ of 13.5 mg L(-1) BPA in sediment. In comparison, adult isopods show a 96 h LC₅₀ of 25.1 mg L(-1) BPA in water medium and a 96 h LC₅₀ of 65.1 mg L(-1) BPA in sediment. Observed endpoints of chronic exposures suggest the alder leave discs to be the most efficient uptake source of BPA, in contrast to uptake from water or heterogeneous sediment. Significant (p<0.05) growth inhibition, with a 21d NOEC of 0.5/2.5 mg L(-1) (for juvenile/adult organisms), and feeding rate inhibition, with a 21d NOEC of 0.5/1.0 mg L(-1) (for juvenile/adult organisms), were proven to be the most sensitive toxicity endpoints. An even more sensitive effect turned out to be molting frequency, which was significantly reduced; a 21d NOEC was 1.0 mg L(-1) of BPA for adult organisms and an even lower 21d NOEC of 0.05 mg L(-1) of BPA for juveniles. The observed endpoints are recorded at very low, non-toxic exposure concentrations, indicating that BPA acts as an endocrine disrupting compound, as well as a toxic substance. We also determined the importance of the direct dietary uptake of the pollutants, significant for juveniles as well as adult animals.