Academic journal article Environmental Health Perspectives

Distribution of 2,4-D in Air and on Surfaces Inside Residences after Lawn Applications: Comparing Exposure Estimates from Various Media for Young Children

Academic journal article Environmental Health Perspectives

Distribution of 2,4-D in Air and on Surfaces Inside Residences after Lawn Applications: Comparing Exposure Estimates from Various Media for Young Children

Article excerpt

We collected indoor air, surface wipes (floors, table tops, and window sills), and floor dust samples at multiple locations within 11 occupied and two unoccupied homes both before and after lawn application of the herbicide 2,4-D. We measured residues 1 week before and after application. We used collected samples to determine transport routes of 2,4-D from the lawn into the homes, its subsequent distribution between the indoor surfaces, and air concentration as a function of airborne particle size. We used residue measurements to estimate potential exposures within these homes. After lawn application, 2,4-D was detected in indoor air and on all surfaces throughout all homes. Track-in by an active dog and by the homeowner applicator were the most significant factors for intrusion. Resuspension of floor dust was the major source of 2,4-D in indoor air, with highest levels of 2,4-D found in the particle size range of 2.5-10 [micro]m. Resuspended floor dust was also a major source of 2,4-D on tables and window sills. Estimated postapplication indoor exposure levels for young children from nondietary ingestion may be 1-10 [micro]g/day from contact with floors, and 0.2-30 [micro]g/day from contact with table tops. These are estimated to be about 10 times higher than the preapplication exposures. By comparison, dietary ingestion of 2,4-D is approximately 1.3 [micro]g/day. Key words:. 2,4-D, indoor air, particle size, pesticide exposure, pesticide transport, residential exposure. Environ Health Perspect 109:1185-1191 (2001). [Online 6 November 2001] http://ehpnet1.niehs.nih.gov/docs/2001/109p1185-1191nishioka/abstract.html

A recent review of occupational studies identified numerous cases in which workplace chemicals such as lead, asbestos, and dichlorobenzidine were transported from the workplace to the home. Analyses to document this transport included measurements made in home areas such as the laundry, in clean clothing drawers, and in house dust (1). In some cases, the levels of transported occupational chemicals were sufficiently high to cause an adverse health effect in a resident child or spouse. Other studies of the air and house dust of farmers' and farm workers' homes have shown that pesticide residues are transported from the outside to the indoor environment (2,3). In one study, organophosphate insecticides were detected in the house dust of pesticide applicators living adjacent to treated orchards, as well as in house dust of nonapplicator farm workers living more than 50 feet from the orchard, and in nearby homes of families not engaged in agricultural activities (2). Spray drift, volatilization, soil/foliar resuspension, track-in on shoes, and/or transport on clothing are assumed to have played important roles in the transport of pesticide residues in these agricultural studies.

Agricultural spray drift and residue resuspension rates have been measured for nonvolatile amine salt formulations of 2,4-dichlorophenoxyacetic acid (2,4-D) and dicamba (4-6). Because both mechanisms involve the airborne transport of submicronto micron-size particles and/or aerosols (7), it is reasonable to assume that fine particles containing 2,4-D can be resuspended from residential turf by wind, penetrate the exterior of the home through cracks and crevices, windows, and doors, and be deposited on interior surfaces. Field simulation studies following lawn applications of 2,4-D, chlorpyrifos, and chlorothalonil have shown that residential track-in of pesticide residues can occur, and that walking over treated turf as much as one week after application can transport residues on shoes from turf to carpets (8,9).

The study reported here was performed in single-story midwestern homes to determine the occurrence and distribution of 2,4-D residues on surfaces and in air within the home--before, during, and after the lawn application of this herbicide. We used these data to describe quantitatively the effects of transport factors and to estimate potential indoor residential exposures of young children. …

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