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The Movement Of Diazinon Residues Into Homes Following The Application Of A Granular Formulation To Residential Lawns
D.M. Stout II; M.K. Morgan; and P.P. Egeghy.
U.S.EPA, National Exposure Research Laboratory, Research Triangle Park, NC, USA
A pilot study was conducted to examine the movement of diazinon following applications of a granular formulation to residential lawns. The objectives included evaluating methods for collecting environmental samples and examining the transport and fate of diazinon from a source to the indoor living areas of homes. Although not discussed here, the study also emphasized the role of pet dogs as vehicles for the translocation of diazinon residues and potential human exposures.
Measures included the formulation, soil, particles from doormats, transferable residues from residential turf and indoor flooring, indoor air from living rooms and children’s bedrooms, and vacuum dislodgeable dust. Samples were collected from six single family homes located in the mid-Atlantic region of the USA in the summer of 2001. Environmental samples were collected prior to the application and at days 1, 2, 4, and 8 following the application. Soil concentrations, an indicator of source strength, were highest immediately following the application and declined by an average of 51% by day 8. Polyurethane foam (PUF) roller samples collected from turf ranged from 0.1 to 970 ng/cm2 over the study period. Particle-associated residues collected from doormats located at entryways into the home declined from day 1 to day 8 by an average of 75%.
Doormat concentrations demonstrate the movement of residues from the source towards the indoors of the homes. Indoor air concentrations reached maximal levels from 1 to 2 days following the application and declined over the remainder of the study. Indoor PUF roller measures showed little to no increase above background. Concentrations in vacuum dislodgeable dust were variable over time, but consistently above background concentrations.
Results demonstrate that both the physical translocation of particle-bound residues and the intrusion of volatilized diazinon contribute to indoor levels. Physical processes such as pet activity and foot traffic moved particle-bound residues to the entryway of the homes. Increased airborne concentrations demonstrate the intrusion of diazinon from the outdoor source. Elevated diazinon concentrations measured from vacuum dislodgeable dust suggests the movement and deposition of volatilized and/or particle-bound residues. In summary, applications to residential lawns resulted in an increase of diazinon above background concentrations in all homes. Lawn applications are a source for potential occupant exposures both on treated lawns and inside homes.
Disclaimer: Although this work was reviewed by EPA and approved for publication, it may not necessarily reflect official Agency policy.