You are here:
TRANSPORT OF LAWN-APPLIED 2,4-D FROM TURF TO HOME: ASSESSING THE RELATIVE IMPORTANCE OF TRANSPORT MECHANISMS AND EXPOSURE PATHWAYS
Citation:
Nishioka, M. G., H. M. Burkholder, M. C. Brinkman, AND C. E. Hines. TRANSPORT OF LAWN-APPLIED 2,4-D FROM TURF TO HOME: ASSESSING THE RELATIVE IMPORTANCE OF TRANSPORT MECHANISMS AND EXPOSURE PATHWAYS. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-99/040 (NTIS PB99-156358), 1999.
Description:
Transport of 2,4-D from the residential lawn into the home was measured following both homeowner and commercial application of this herbicide. Collection of floor dust in five rooms of each house, both prior to and after application, indicated that turf residues are transported indoors and that the gradient in 2,4-D surface loading (ug/m2) through the house follows the traffic pattern from the entry. Removal of shoes at the door, and the activity level of the children and pets, were the most significant factors affecting residue levels indoors after application. Spray drift and fine particle intrusion accounted for relatively little of the residues on floors. Prior to application, 2,4-D floor dust surface loadings were approximately 0.1 to 5 ug/m2; one week after application, these levels were 1-228 ug/m2 on carpeted floors in occupied homes, and 0.5 to 2 ug/m2 in unoccupied homes. Dislodgeable carpet surface residues of 2,4-D were highly correlated with 2,4-D dust levels, and indicated that approximately 1% of the dust is readily available for dermal contact. Tabletop levels of 2,4-D were approximately 10% of carpet loadings, and were largely due to in-home dust resuspension.
Non-dietary ingestion of carpet dust and inhalation for a 1-yr old child in these homes may produce exposures of 0.04-7 ug/day. These exposure estimates would be substantially higher, 4-70 ug/day, if the non-dietary ingestion was based on contact and transfer from hard surfaces such as contaminated table tops. In limited cases, these hypothetical exposures would approach the U.S. EPA IRIS RfD limits for 2,4-D of 10 ug/kg/day.