Occupational exposure of grain farmers to carbofuran

Six prairie grain farmers were monitored for pesticide exposure and related adverse effects while they mixed and/or sprayed carbofuran (Furadan^® 480F) with ground rig application equipment to control grasshoppers in southern Alberta, Canada. Dermal exposure was estimated with Tegaderm patches placed at seventeen locations on the skin beneath the work clothes. Hand and wrist exposure was determined by the amount of chemical found in hand rinses and on wrist patches. Potential inhalation exposure was measured with an air sampler using polyurethane foam as the adsorbent. Urine samples were collected at 24-hr intervals after exposure and monitored for carbofuran. Blood samples were analyzed for acetylcholinesterase (AChE), pseudocholinesterase (ChE) and several other blood parameters. The results indicated that during the mixing and/or spraying operation, a farmer could potentially be exposed to a total of 1,264 g carbofuran per kg of active ingredient (a.i.) used. Of this amount, 1,262 g/kg (or 99.8%) was dermal and 2 g/kg (or 0.2%) could be through the inhalation route. Hand and wrist exposure was about 1,100 g/kg a.i. (or 87% of total exposure). Excretion of the chemical in the urine amounted to 28 g/kg a.i. No ChE inhibition was observed. Other blood measurements were within normal ranges. The farmers showed no acute adverse effects during exposure and for four days after exposure. These results are discussed in relation to the mammalian toxicity of carbofuran.