Residential environmental measurements in the National Human Exposure Assessment Survey (NHEXAS) pilot study in Arizona: Preliminary results for pesticides and VOCs

A major objective of the National Human Exposure Assessment Survey (NHEXAS) performed in Arizona was to conduct residential environmental and biomarker measurements of selected pesticides (chlorpyrifos, diazinon), volatile organic compounds (VOCs; benzene, toluene, trichloroethene, formaldehyde, 1,3-butadiene), and metals for total human exposure assessments. Both personal (e.g., blood, urine, dermal wipes, 24 h duplicate diet) and microenvironmental (e.g., indoor and outdoor air, house dust, foundation soil) samples were collected in each home in order to describe individual exposure via ingestion, inhalation, and dermal pathways, and to extrapolate trends to larger populations. This paper is a preliminary report of only the microenvironmental and dermal wipe data obtained for the target pesticides and VOCs, and provides comparisons with results from similar studies. Evaluations of total exposure from all sources and pathways will be addressed in future papers. The pesticides and VOCs all showed log-normal distributions of concentrations in the Arizona population sampled, and in most cases were detected with sufficient frequency to allow unequivocal description of the concentration by media at the 90th, 75th, and 50th (median) percentiles. Those combinations of pollutant and media, in which a large fraction of the measurements were below the detection limit of the analysis method used, included trichloroethene, 1,3-butadiene, and formaldehyde in outdoor air; chlorpyrifos and diazinon in outdoor air; and dinzinon in dermal and window sill wipes. In general, indoor air concentrations were higher than outdoor air concentrations for all VOCs and pesticides investigated, and VOC levels were in good agreement with levels reported in other studies. In addition, the agreement obtained between co- located VOC samplers indicated that the low-cost diffusional badges used to measure concentrations are probably adequate for use in future monitoring studies. For the pesticides, the median levels found in indoor samples agreed well with other studies, although the levels corresponding to the upper 0.1- 1% of the population were considerably higher than levels reported elsewhere, with indoor air levels as high as 3.3 and 20.5 μg/m³ for chlorpyrifos and diazinon, respectively. These data showed excellent correlation (Pearson and Spearman correlation coefficients of 0.998 and 0.998, respectively) between chlorpyrifos in indoor air and in the corresponding dermal wipes, and relatively poor correlation between chlorpyrifos in dust (μg/g or μg/m²) and dermal wipes (Pearson=0.055 μg/g and 0.015 μg/m²; Spearman=0.644 μg/g and 0.578 μg/m²). These data suggest the importance of dermal penetration of semi-volatiles as a route of residential human exposure.