Modeling Exposures to Organophosphates and Pyrethroids for Residents of Urban Public Housing

Abstract

MAB4-O-05 Introduction: Pesticide exposure in urban public housing may be elevated as a result of persistent application due to severe pest infestation. It is unclear whether these exposures pose a potential health risk, as there are limited measurements available in urban indoor environments, and no attempts to translate concentration measurements into exposures and health risks. In this study, we use a novel dataset of pesticide concentrations in dust and floor wipe samples in a low-income urban setting and apply the Stochastic Human Exposure and Dose Simulation Model (SHEDS) to simulate exposures for a variety of hypothetical populations. Methods: As part of the Healthy Public Housing Initiative, measurements were collected in 42 low-income, multi-unit dwellings of pediatric asthmatics, including vacuum dust and floor wipe samples from the kitchens and living rooms. Concentrations were determined for 2 organophosphates (diazinon and chlorpyrifos) and 11 pyrethroids (eg, permethrin, cypermethrin, and cyfluthrin) using GC/MS. Exposure modeling of these concentration distributions will be performed using SHEDS, with incorporation of an activity pattern simulation reflective of persons living in a low-income, urban indoor environment from the Consolidated Human Activity Database (CHAD). Potential doses will be simulated for young children, who exhibit more hand-to-mouth behavior, and for adults. Potential doses associated with dust/residue concentrations will be combined with modeled dietary exposures based on dietary intake patterns and known concentrations of pesticides on and in food products, yielding a total potential dose. Comparisons will be made between the simulated distribution of potential doses to various analytes and respective reference doses (RfDs), with consideration of additive/synergistic effects. Results: Measured concentrations from kitchen floor wipes indicated detection of permethrin and chlorpyrifos in every home, with frequent detection of diazinon (98%), cypermethrin (90%), and cyfluthrin (71%). Median (range) concentrations for the frequently detected pesticides were 6.8 μg/m2 (0.2–226.5 μg/m2) for permethrin, 0.40 μg/m2 (<LOD–556.2 μg/m2) for diazinon, 0.3 μg/m2 (0.03–19.5 μg/m2) for chlorpyrifos, 3.7 μg/m2 (<LOD–330.7 μg/m2), for cypermethrin and 1.1 μg/m2 (<LOD–567.1 μg/m2) for cyfluthrin, suggesting a wide range of potential exposures. Discussion and Conclusions: Pesticide concentrations, including for some banned or restricted-use pesticides, may be at levels of concern in some urban public housing dwellings, where residents spend significant time indoors. Simulation of doses resulting from these concentrations will provide insight about the potential health risks for various subpopulations, the importance of dietary vs. nondietary pathways in low-income urban settings, and the analytes of greatest concern from a health risk perspective.