Effect of application volume and method on spray operator contamination by insecticide during cotton spraying

The contamination of spray operators was assessed using a fluorescent dye recovery technique with disposable polymer fabric overalls. Eight different application volumes, ranging from 0.9 to 110 l ha −1 , were used with a variety of sprayer types including two types of lever-operated knapsack sprayer, a mistblower, a spinning-disc machine and an electrostatic sprayer. Total operator contamination during spray operations on a mature cotton crop was found to be dependent on the type of sprayer and application volume used: it was highest for water-based very-low-volume sprays (6–12 l ha −1 ) applied by mistblower and a non-motorized sprayer and lowest for conventional applications (30–110 l ha −1 ) with non-motorized sprayers. The distribution of contamination over an operator's protective clothing varied with the sprayer type: with non-motorized sprayers the abdomen was the most heavily affected area; contamination from electrostatic and spinning-disc machines was more evenly dispersed. It was concluded that contamination occurring during the normal application of sprays is of minimal significance when compared with contamination caused by leaking and damaged sprayers.