Case Studies - Exposure to Pesticide Residues on Agricultural Spraying Equipment

During the application of agricultural pesticides, it is highly likely that some of the active ingredients will be deposited on the spray equipment. Without effective cleaning, persons subsequently working with the machinery could be inadvertently exposed to the pesticide residues. Those at risk include spray contractors and maintenance workers as well as farm workers and their families.

To assess the risks to workers, it is necessary to know the levels of residues on farm equipment. Current information is limited so HSE asked HSL, in collaboration with the Cranfield Centre for EcoChemistry, to characterise typical residues of a range of commonly used pesticides on spray equipment and to relate them to the application history and any cleaning regimes used. The study also included an assessment of a "spray train", a vehicle used for weed control on railways.

An initial survey of 250 farmers identified the type of spraying equipment used and the most commonly applied pesticides. Fourteen farms then agreed to take part in the field study, which involved two visits to each farm to coincide with the main spraying periods of the year in late spring/summer and autumn/winter. Samples of surface contaminants were taken from specific locations on the delivery system such as the nozzles, spray tank and boom and elsewhere on the tractor including windscreens and doors. Seven locations of known area were sampled on each occasion. In addition, cotton gloves were used to assess the potential exposure to the workers during typical working practices such as entering the cab, using controls, mounting equipment and changing oil filters. Each sample was analysed for thirteen of the most commonly applied pesticides.

The results obtained are in accord with previous studies, but provide far more detail. The rate of pesticide residue build-up on farm equipment and the effectiveness of cleaning procedures are now better understood. The potential for worker exposure to post-application pesticide residues has also been quantified and it is clear that these residues exist at levels that may have health implications.


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