Pesticides in South African fresh waters

Abstract

Public concern has recently escalated over pesticide contamination of South African aquatic ecosystems. This review of published literature on the occurrence of pesticides within South African freshwater systems indicates that fewer than 50 studies of selected pesticides have been undertaken, with emphasis being on organochlorines. Extensive historical usage has led to the widespread persistence of selected organochlorines. Few studies have established linkages between pesticides, exposure pathways, environmental concentrations and the monitoring of toxicological effects on non-target organisms. Emphasis is now being placed on developing more field-relevant assessments, including microcosm and mesocosm studies, in situ bioassays and field studies. There are few data relating to the extent of exposure and effects of pesticides in South African aquatic environments, and thus further research is needed. Research should focus on multidisciplinary approaches that increase effective decisionmaking in data-poor circumstances. A pesticide risk assessment programme for aquatic ecosystems needs to be implemented in South Africa, which could feed into the National Toxicity Monitoring Programme. Preliminary risk assessment models should be used to detect pesticides posing possible or definite risks, whereafter more detailed chemical, toxicological and biological monitoring assessments should be performed if risks are predicted.