Altered developmental toxicity caused by three carrier solvents.

Many aquatic bioassays rely on chemical solvents to solubilize water-insoluble test materials. Interactions between solvents and test materials can lead to false positive or negative results. For this reason, tests for interactions between solvents and test materials were performed. The Frog Embryo Teratogenesis Assay--Xenopus (FETAX) was chosen because of its capacity to assess three different endpoints; mortality, malformation and embryo growth. Three solvents--dimethylsulfoxide (DMSO), acetone and triethylene glycol (TG)--were tested with two teratogens--methylmercury chloride (MMC) and trichloroethylene (TCE). DMSO potentiated the lethal effect of both teratogens but did not alter significantly the rate of malformation. Acetone increased the mortality for both teratogens, but only increased the MMC malformation greater than the additive effects. TG only increased the mortality and malformation with TCE. There were additive effects for growth for all solvents with the teratogens. The carrier solvents caused interactions even at their no-observable-effect concentration (NOEC). Therefore, the choice of carrier solvent should be made with caution. This study shows that different results can occur depending on the solvent used, and that a difference in one endpoint does not necessarily change the other endpoints.