Pesticide authorisation procedures fail to adequately protect biodiversity in rivers

Before a pesticide is allowed to go on sale, it has to pass a standard EU authorisation process. However, the current procedure does not sufficiently protect the environment, according to a joint study by the University of Koblenz-Landau, the Helmholtz Centre for Environmental Research (UFZ), the University of Aarhus (Denmark), and the University of Technology, Sydney just published in the international journal Environmental Science and Technology. To carry out this meta-analysis, a number of globally available field studies on the effect of pesticides were compared and evaluated. We compiled data from eight field studies conducted between 1998 and 2010 in Europe, Siberia, and Australia to derive thresholds for the effects of pesticides on macroinvertebrate communities and the ecosystem function leaf breakdown.

Dose−response models for the relationship of pesticide toxicity with the abundance of sensitive macroinvertebrate taxa showed significant differences to reference sites at 1/1000 to 1/10 000 of the median acute effect concentration (EC50) for Daphnia magna, depending on the model specification and whether forested upstream sections were present. Hence, the analysis revealed effects well below the threshold of 1/100 of the EC50 for D. magna incorporated in the European Union Uniform Principles (UP) for registration of single pesticides. Moreover, the abundances of sensitive macroinvertebrates in the communities were reduced by 27% to 61% at concentrations related to 1/100 of the EC50 for D. magna. The invertebrate leaf breakdown rate was positively linearly related to the abundance of pesticide-sensitive macroinvertebrate species in the communities, though only for two of the three countries examined. We argue that the low effect thresholds observed were not mainly because of an underestimation of field exposure or confounding factors. From the results gathered we derive that the UP threshold for single pesticides based on D. magna is not protective for field communities subject to multiple stressors, pesticide mixtures, and repeated exposures and that risk mitigation measures, such as forested landscape patches, can alleviate effects of pesticides.

Source: Ralf B. Schäfer et al. dx.doi.org/10.1021/es2039882 | Environ. Sci. Technol. 2012, 46, 5134−5142 (attached)