The environmental cost of pesticide usage in the United Kingdom

Organic pesticides have been used for more than 50 years, and have made a major contribution to the profound alteration of agricultural practice which has occurred during this period. Among the many effects arising from these developments in agriculture, various environmental changes have been identified, which have been the subject of considerable public debate and disagreement. Attention has focussed particularly on the popularly assumed adverse influence of pesticides on the natural flora and fauna. This review examines the position in the United Kingdom where interest in wildlife has always been extensive and where many amateur observations and professional scientific studies have been brought to bear on the problem. It differentiates between ‘direct’ effects which may be attributed to particular uses of certain compounds and ‘indirect’ effects normally arising from changes in habitat or food supply brought about by pesticides. The approach adopted has been to assess the effects of pesticide use on populations rather than attempting to place a financial estimate on any adverse environmental effect attributed to pesticides. Systems of surveillance are described and their ability to detect adverse effects is assessed. The difficulty of correlating such effects with pesticide use is examined. In general, it is concluded that other than for insects the levels of surveillance have been adequate to detect adverse effects on fauna and flora arising from pesticide use. Where direct effects have been discerned in the past, action has, where possible, been taken to rectify the position and it is suggested that this will continue. Overall there is little evidence that the survival of individual species is threatened by the direct effects of pesticides. Indirect effects are neither simple to delineate nor readily corrected and it is recommended that more research be carried out to develop the ability to assess their influence.