Acute toxicity of industrial surfactants to Mysidopsis bahia

Three- to eight-day old Mysidopsis bahia were used to evaluate the acute toxicities of 17 industrial surfactants having a wide range of physiochemical characteristics. LC50s based on nominal concentrations covered approximately three orders of magnitude (less than 1 to greater than 4,000 mg/L). The base structure of the surfactants (i.e., aromatic or aliphatic, branched or linear) was not a factor controlling toxicity. Low solubility surfactants with low ethylene oxide (EO) molar ratios were the most toxic surfactants tested. Ethylene oxide chain length was the best predictor of toxicity, and would be a good parameter to use to "screen" for surfactant toxicity in hazard assessment. Substitution of terminal OH with SO3 or PO4 reduced toxicity of a selected group of surfactants. Sensitivity of M. bahia up to 26 days old was not significantly different from that of 3- to 8-day old animals. Use of one surfactant as a reference toxicant demonstrated that sensitivity of M. bahia was consistent throughout the various tests.