Abstract:
Twelve substituted phenols that have a polar narcotic mode of action had their acute toxicity to the freshwater cladoceran Ceriodaphnia
cf. dubia and the marine bacterium Vibriofischeri determined. The 48-h EC50 (immobilisation) values of the chemicals to C. cf. dubia
ranged from 6.13 to 183 umol/L while the 30-min EC50 (luminescence) values of the chemicals to V.fischeri ranged from 1.39 to 1031
umol/L. Seventy-five percent of the chemicals were classed as having 'moderate toxicity' to C. cf. dubia while 25 percent had 'low
toxicity'. For V.fischeri the percentage of chemicals classified as having 'high', 'moderate' and 'low' toxicity was approximately 17%.
3% and 50% respectively. Quantitative activity-activity relationships (QAARs) that could predict the toxicity of chemicals with a polar
narcotic mode of action to C. cf. dubia were developed by regressing the toxicity data for polar narcotic chemicals to C. cf. dubio with that
of eight non-Australasian species. Those QAARs based on the toxicity data for Tetrahymena pyriformis, Chlorella vulgaris, Poecilia
reticulata and Daphnia magna were of high quality (r 0.9). Only the QAARs for T pyriformis, C. vulgaris and D.magna had sufficient
data to test their validity. This revealed that the absolute percentage difference between experimentally derived EC50 values and those
predicted by these QAARs were between I3 and 120%. These QAARs provide an easy, cost-effective means of estimating toxicity values
for polar narcotic chemicals to C. cf. dubia.
