The Washington aerial spray drift study: Children's exposure to methamidophos in an agricultural community following fixed-wing aircraft applications

Abstract

This study characterized exposures of eight children living in an agricultural community near potato fields that were treated by aerial application with the organophosphorus (OP) insecticide, methamidophos (O,S-dimethyl phosphoramidothioate). Exposure monitoring included air and deposition samples in the outdoor community environment, outdoor and indoor air samples at each residence, wipe samples of playground equipment, toys, indoor surfaces, and children's hands, and periodic urine samples. Monitoring occurred prior to, the day of, and 1 day following applications. Methamidophos deposition in the community was very low compared to deposition inside the boundaries of the treated fields. Community air concentrations increased from 0.05 mg/ m 3 (prespray) to 0.11 and 0.48 mg/m 3 (spray day morning and afternoon, respectively), decreasing to 0.10 mg/m 3 on the postspray day. Air concentrations outside residences followed a similar pattern; indoor levels did not exceed 0.03 pg/m 3 . Methamidophos residues were found on playground equipment following applications, but not on indoor residential surfaces. The median hand wipe levels increased from o0.02 (prespray) to 0.08 mg/sample (spray day), decreasing to 0.05 mg/sample (postspray day). Median concentrations of the primary methamidophos urinary metabolite were 61 mg/l before 1100 hours on the spray day, 170 mg/l after 1100 hours on the spray day, and 114 mg/l on the postspray day. Spray day metabolite levels were correlated with time outside on the spray day (r s ¼ 0.68), with spray day hand wipe levels (r s ¼ 0.67), and with postspray day metabolite levels (r s ¼ 0.64). Postspray day metabolites levels were also positively associated with postspray day hand wipe levels (r s ¼ 0.66). The documentation of children's exposure in this study does not necessarily mean that risks for these children were significantly altered, since nearly all children in the United States are exposed to some level of OP pesticides through dietary intake and other pathways. The association of metabolite levels with time spent outside, and the absence of methamidophos in homes indicates that children's exposures occurred primarily outdoors.

Acute Pesticide Illnesses Associated with Off-Target Pesticide Drift from Agricultural Applications: 11 States, 1998–2006

“…Aerial application was the most frequent application method found in drift events, accounting for 249 events (39%). Drift hazards from aerial applications have been well documented (CDC 2008; Weppner et al 2006). Applicators should use all available drift management measures and equipment to reduce drift exposure, including new validated drift reduction technologies as they become available.…”

Pesticide Urinary Metabolite Levels of Children in Eastern North Carolina Farmworker Households

“…Earlier research in North Carolina showed that farmworkers had little knowledge of the pesticides used where they work, and that they did not have information about pesticides applied to dwellings that were rented or grower-provided (Arcury et al 2001; Early et al 2006). Drift has been shown to result in the dispersal of agricultural pesticides to dwellings on surrounding land (Fenske et al 2000b; Ward et al 2006; Weppner et al 2006). Finally, agricultural communities have generally higher levels of environmental pesticides compared with nonagricultural communities, with residues from discontinued pesticides found in contemporary rural environments and homes (Lu et al 2004; Quandt et al 2004; Wolz et al 2003).…”

Agricultural pesticides and risk of childhood cancers

“…Several studies have reported that, in agricultural communities, residues in house dust and yard soil of the most common category of agricultural pesticides, organophosphates, are inversely associated with distance from treated fields (Simcox et al, 1995; Loewenherz et al, 1997; Lu et al, 2000). Lu et al (2000) found that children living near treated orchards had statistically significantly higher levels of pesticide metabolites in their urine as compared to children living more distant, and Weppner et al (2006) confirmed pesticide residues on playground equipment, toys and childrens’ hands after aerial spraying of surrounding potato, corn and wheat fields. In a study of adult NHL, homes within 750 meters of crop fields had concentrations of agricultural herbicides more than 4-fold higher than those with no crops (Ward et al, 2000).…”