Comparative toxicities of selected industrial chemicals to microorganisms and other aquatic organisms

Biodegradation rates of 25 narcotic industrial chemicals were determined manometrically using resting cells prepared from preacclimated microorganisms. Chemical concentrations that would reduce maximum rates by 50% (BIC50) were estimated from rate inhibition data. Subsequently, the BIC50 and acute toxicities of chemicals to daphnids, barnacle larvae, copepods and fish (bleak, fathead minnow and golden orfe) were correlated. The r2 and F-statistics for all six linear correlations were significant (alpha = 0.001). This suggests, for chemicals having a non-specific mode of toxic action, the biodegradation inhibition test may be used to estimate concentrations which would be toxic to higher aquatic organisms. A comparison of toxicity data showed microorganisms were less sensitive to test chemicals than the other species.