Trans-generation study of the effects of nonylphenol ethoxylate on the reproduction of the snail Biomphalaria tenagophila.

Nonylphenols ethoxylates (NPEs) are surfactants used in a variety of products. They are found in domestic sewage, industrial effluents and as contaminants in water bodies. This study was undertaken to evaluate the effects of NPE with 9.5 ethoxylate units (NPE9.5; 0, 0.01, 0.1, 1.0 mg/L) on the reproduction of the snail Biomphalaria tenagophila. Adult snails (F0 generation) were exposed to NPE for 8 weeks. The F1 generation continued to be exposed from embryo to reproductive maturity while their descendants (F2) were exposed until day 10 after spawning. We determined the effects of NPE9.5 on the fecundity (8-week production of eggs and egg masses) of mature F0 and F1 snails. Developmental toxicity was investigated in F1 and F2 embryos. The two highest concentrations of NPE9.5 reduced the fecundity of F0. In the F1 generation, the lowest concentration enhanced the number of eggs laid per snail while the intermediate concentration had no effect and the highest one decreased the fecundity thereby suggesting a biphasic effect of NPE9.5. Study-derived NOECs (no-observed-effect-concentrations) for NPE were: fecundity, F0=10 microg/L, F1<10 microg/L; developmental toxicity, F1=100 microg/L, F2<10 microg/L. Results, therefore, indicated that B. tenagophila is highly vulnerable to NPE and that trans-generation exposure to NPE9.5 aggravates its reproductive toxicity.