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

Abstract

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 diazinon 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 g /m 3 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 (g /g or g /m 2 ) and dermal wipes (Pearson=0.055 g /g and 0.015 g /m 2 ; Spearman=0.644 g /g and 0.578 g /m 2 ). These data suggest the importance of dermal penetration of semi-volatiles as a route of residential human exposure.

Residential pesticide use during pregnancy among a cohort of urban minority women.

“…Specifically, the U.S. EPA has set a reference dose (RfD) of 0.00009 mg/kg/day for inhalation exposures to diazinon (of any duration) (19 Further, it is possible that the aggregate exposures associated with the air concentrations seen in this study are greater than exposures from inhalation alone, because prior data indicate that exposure from residential pesticide use may also come through dermal absorption and nonintentional ingestion (2,19,20). This is supported by studies that have shown a high correlation (r ≥ 0.7) between pesticide levels in indoor and personal air and those in carpet dust, hand wipes (including from mothers and children), and surfaces in the home (2,21,22), although uncertainty remains over the extent of exposure from these sources (23). In addition, chlorpyrifos and diazinon have similar mechanisms of action, and risks from chlorpyrifos exposure should thus be considered additive to those from diazinon exposure (24).…”

Evaluation of take-home organophosphorus pesticide exposure among agricultural workers and their children.

“…Urinary metabolite and dust residue data sets included samples containing concentrations less than the limit of quantitation (LOQ), which yielded analyte peaks with signal-to-noise ratios either greater than 3:1 (termed "< LOQ ") or less than 3:1 [termed nondetectable (ND)]. Percentile-percentile plots demonstrated that the concentrations of metabolites and pesticides above the (n = 190) Above the LOQ (%) 165 (87) 30 (16) 23 (12) 41 (22) 34 (18) 4 (2.1) < LOQ (%) b 14 (7.4) 71 (37) 42 (22) 81 (43) 17 (9.0) 12 (6.3) ND (%) 11 (5.8) 89 (47) 125 (66) 68 (36) 139 (73) 174 ( LOQ were normally distributed following a log transformation, a trend reported previously for biologic and environmental samples from residential locations (Gordon et al 1999; U.S. EPA 1998). We therefore elected to treat the censored values as log-normally distributed.…”

Aggregate exposures of nine preschool children to persistent organic pollutants at day care and at home

“…In the NHEXAS-Arizona study, the concentrations of the OP pesticide CPF in air were well correlated with hand-wipe concentrations, although those in dust were not (Gordon et al, 1999). This suggests that non dietary exposure to this class of compounds, through hand-to-mouth transfer, may contribute to the aggregate exposure.…”