Occupational exposure through spraying remedial pesticides

A total of 20 surveys at 15 sites of remedial in-situ timber and masonry treatment took place in the latter half of 1996. Two of these surveys concerned wall washes (biocides), the remainder were non-agricultural pesticides. The purpose was to measure the surface deposition and inhalation exposure of the operatives to the pesticide spray fluids used. The diluted spray fluids were found to have significantly different concentrations from those intended by the sprayer. The pesticides were applied at pressures between 320 and 1050 kPa. Deposition rates for spray fluid on coveralls covered a wide range, with more than 30 fold difference between the median and the highest results (median 209 mg/minute; range 27.4 to 6550 mg/min). Contamination of coveralls occurred in all surveys, with the pesticide getting beneath the coveralls in 95% of surveys, with a median 5% contamination beneath the overall. The averaged and normalised deposition pattern was 75% legs, 11% arms, 12% torso and 2% head. Exposure of hands to pesticide (expressed as spray fluid) beneath protective gloves occurred in 89% of surveys (median 5.78 mg/minute; range 0.23 to 358 mg/min) and contamination of socks by spray fluid in 78% of surveys (median 2.08 mg/minute; range 0.12 to 260 mg/min). Exposure by inhalation to spray fluid was measurable in 72% of surveys (median 53.5 mg/m3 TWA; range 4.33 to 1320 mg/m3; 2 data excluded). Inhalation exposure and deposition on coveralls rose markedly at spray pressures above 700 kPa (100 psi).