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CARPET AS A SINK FOR CHLORPYRIFOS FOLLOWING THE USE OF TOTAL RELEASE AEROSOLS IN THE EPA TEST HOUSE
Citation:
Mason, M A., L S. Sheldon, Z Guo, AND D M. Stout II. CARPET AS A SINK FOR CHLORPYRIFOS FOLLOWING THE USE OF TOTAL RELEASE AEROSOLS IN THE EPA TEST HOUSE. Presented at Engineering Solutions to Indoor Air Quality Problems, Raleigh, NC, July 17-19, 2000.
Description:
Pesticides may be found in homes from indoor applications to control pests or by their translocation from outdoor sources. Contaminants may persist adsorbed to surfaces and/or particles in "sinks" where over time they may dissociate as airborne vapors. Experiments were conducted to explore the relationship between the insecticide chlorpyrifos's distribution into carpet and carpet dust and it's reemission into air. An application using total release aerosols containing 0.5% chlorpyrifos was performed in the living room and den of the EPA test house. Afterwards the total deposition, total carpet extractable and total carpet dust extractable amounts were determined. In addition, over a two week period, air exchange rates and airborne concentrations were measured. Post-application sub-samples of carpeting were removed and placed in small environmental chambers (0.053 m3) to determine carpet emission factors. Findings show that airborne chlorpyrifos concentrations in the test house were initially highest in the living room and den (16 and 17 ug/m3) respectively) and declined to low levels by 14 days after application. Bedroom measurements immediately following the application were eleven times lower than the den and living room, reached maximal levels by day 2 (4.7 ug/m3) and declined to near parity by 14 days post-application. No stratification within rooms was observed. Total levels quantified from carpet and deposition coupons also showed the highest levels in rooms that received applications with negligible amounts in the bedroom. House dust levels measured for all rooms increased immediately following the application and remained above background through 14 days. Source emissions from carpet sub-samples in chamber studies suggest carpet is a latent source for the reemission of chlopryrifos into air following applications. However, inconsistencies in determining the mass balance make modeling and the calculation of emission factors difficult to interpret.