Evaluation of the developmental toxicity of solvents, metals, drugs, and industrial chemicals using a freshwater snail (Biomphalaria glabrata) assay

A freshwater snail assay was employed to assess the embryotoxicity of solvents including acetone, methanol, ethanol, isopropanol, dimethyl-sulfoxide, glycerin, metals/metalloids including mercuric chloride (HgCl2), cadmium chloride (CdCl2,), antimony salts Sb+3 and Sb+5, drugs including colchicine, hydroxyurea, cyclophosphamide, an industrial chemical sodium azide (SA), an anionic surfactant dodecyl sodium sulfate-(DSS), H2O2 and sodium chloride (NaCl). The assay consists of exposing Biomphalaria glabrata egg masses (EM) to the substances for 96-hr and following up embryo/snail development for lethality, abnormal morphology (teratogenicity), and day of hatching up to day 10 or 14 after spawning. Based upon concentration-response relationships, LC50%s (embryolethality), EC50%s (teratogenicity) and IC50%s (hatching retardation) and 95%CIs were determined for tested chemicals. The LOECs indicated that HgCl2 (37 nM) and CdCl2 (140 nM) are potent embryotoxic agents in snails. Teratogenic indices (TI = LC50/EC50) for almost all tested chemicals were lower than or close to unity suggesting that these compounds were not teratogenic in this assay. The snail assay may be adequately performed in a cost-effective standardized protocol which enables testing a number of environmental chemicals over a broad concentration range. The snail assay needs to undergo further validation to be recognized for an internationally harmonized hazard identification in ecotoxicity risk assessment.