Evaluation of Dermal Exposure to the Herbicide Alachlor Among Vegetable Farmers in Thailand

Abstract

Vegetable farmers applying the herbicide alachlor may be highly exposed through dermal contact when spraying. Dermal patches were attached to 10 locations on the farmers' skin when they mixed and applied alachlor in vegetable farming areas in Thailand. Measurements were made on farmers using either a backpack sprayer with a 2 stroke gasoline motor and fan or a battery operated pump. Forty-seven vegetable farmers in Bungphra subdistrict of Thailand participated in this study. Both motorized and battery pump backpack sprayers wearing long-sleeve shirts had significantly lower alachlor concentrations on the dermal patches under their long-sleeve shirts compared to those who wore only short-sleeve shirts, regardless of the sprayer type. Moreover, sprayers wearing long pants had significantly lower alachlor concentrations on dermal patches placed under the pants on the lower legs than those wearing short pants, regardless of the sprayer type. The highest estimated alachlor exposures were found on the upper legs (median = 9.29 µg/h) for those using a 2 stroke engine/fan backpack sprayer and on the lower legs (2.87 µg/h) for those using the battery operated pump backpack sprayer. The estimated total body alachlor exposures of applicators using the 2 stroke engine/fan backpack sprayer (219.48 µg/h) were significantly higher than those using the battery operated pump backpack sprayer (15.50 µg/h). Using long-sleeve shirts as personal protection reduced alachlor exposures for the arms 97-99% and wearing long pants reduced alachlor exposure to the legs for 81-99%. Thus, training about the protection provided by clothing choices would be one step in improving the health and safety of Thai farmers.

Paraquat exposure of backpack sprayers in agricultural area in Thailand

“…The majority of sprayers in this study were male, as has been reported in related studies of occupational paraquat exposure (Swan 1969;Howard 1982;Chester et al 1993;Lee et al 2009) mainly due to the strength needed to lift and carry the 25 liters motorized backpack for extended periods. The average sprayers in this study were middle aged, which was similar to related studies in Thailand in that young workers tend to work in the urban industrial sector, not the rural agricultural sector (Kongtip et al 2018;Mahaboonpeeti et al 2018).…”

“…This could be in part because of the increased capacity (25 liters) compared with that of the battery backpack sprayers (16 to 20 liters). In addition, the motorized sprayers could produce a higher-velocity air stream with a wider range of spray droplets than battery backpack sprayers could (Mahaboonpeeti et al 2018). Additionally, a motorized sprayer may increase the fraction of respirable particles (Swan 1969).…”

“…The sprayers can be exposed dermally during mixing, to the mist of pesticides while spraying or to leakage from the tank of the backpack sprayer during use. Study of dermal exposure to the herbicide among vegetable farmers in Thailand found that vegetable farmers using a two-stroke engine/fan backpack sprayer had higher total body alachlor exposure than those using a battery backpack sprayer (Mahaboonpeeti et al 2018).…”

Urinary glyphosate biomonitoring of sprayers in vegetable farm in Thailand

“…Cotton cloth (10 × 10 cm) was sewed on top of an aluminum foil pad (11 × 11 cm) at the edge. The aluminum foil pads were attached to the bare skin of sprayers with adhesive tape at 10 locations, including the forehead, upper back, right upper arm, left upper arm, right forearm, left forearm, right upper leg, left upper leg, right lower leg, and left lower leg before mixing and spraying glyphosate as shown in Figure 3 (Mahaboonpeeti et al 2018;United States Environmental Protection Agency 2009). The cotton patches were placed on the skin under the clothing farmers wore while spraying.…”

Commentary: Novel strategies and new tools to curtail the health effects of pesticides

“…Actual exposures derived from field-level biomonitoring studies are often far higher than what the EPA has estimated [ 56 ]. This is especially true in the case of applicators spraying pesticides with handheld and backpack sprayers [ 57 , 58 ]. A person applying one pound of pesticide active ingredient in a 6-h workday using handheld equipment will almost always experience tenfold to 100-fold higher exposure than the operator of a modern pesticide sprayer who sits in a glass-steel cab and sprays 1,000 lb of pesticide in a day [ 59 ].…”