Ref ID : 6956
Tom Aldenberg and Wout Slob; Confidence Limits for Hazardous Concentrations Based on Logistically Distributed NOEC Toxicity Data. Ecotoxicol. & Environ.Safety 25:48-63, 1993
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This paper deals with the calculation of Hazardous Concentrations of toxic substances from small sets of laboratory toxicity data, e.g., NOECs. A procedure due to Van Straalen and Denneman, as adapted from Kooijman (case n=1), in which one seeks a concentration that protects 95% of the biological species is modified of account for the uncertainty in the estimates. New constants are obtained by simulation. These allow the calculation of the one-sided 95% left confidence limit of the Hazardous Concentration, from the mean and standard deviation of a sample of (laboratory) toxicity data. This 95% confidence limit is always lower than the 95% certainty value calculated with the Kooijman (n=1)/Van Straalen method. The authors also derive constants to calculate a one-sided 50% confidence value, the overpredicts as often as it underpredicts. This value may be used as a median guess of the Hazardous concentration. It will always be higher than the 95% certainty value of the Kooijmann (n=1)/Van Straalen method. However, by using the 50% value, one runs the risk of protecting substantially less than 95% of the biological species.