A Method to Screen for Consistency of Effect in Laboratory Toxicity Tests: A Case Study with Anurans and the Herbicide Atrazine.

This paper presents a semiquantitative method to help ecotoxicologists evaluate the consistency of data within the available peer-reviewed literature. In this case study, we queried whether there is consistent evidence of direct toxicity in Anurans exposed to atrazine at concentrations ≤ 100 μg/L under laboratory conditions. Atrazine was selected because of the relatively large repository of Anuran toxicity data. To accomplish this, we interrogated available data found in recent quantitative weight-of-evidence risk assessments for atrazine with a series of yes or no questions developed a priori. The questions examined consistency of reported effects within and between studies, within and between species, and across a wide range of endpoints categories (e.g., survivorship, growth and development, reproduction). The analysis found no compelling evidence of a consistent direct effect in Anurans around growth and development, reproduction, or survivorship at concentrations of up to at least 100 μg/L atrazine in laboratory studies. Further work is needed to refine the approach, including accounting for the magnitude of the reported effects. However, we recommend that ecotoxicologists employ some method of formal consistency of effects assessment method routinely before performing toxicity tests, in the contextualizing of new data, and in reviews of contaminants.