National human exposure assessment survey (NHEXAS): exploratory survey of exposure among population subgroups in EPA Region V.

ABSTRACT

The National Human Exposure Assessment Survey (NHEXAS) provides a rich database of exposure and environmental measurements for persons living in EPA Region V (Great Lakes). Demographics (e.g., gender, minority status, age, income, and year home built) between U.S. Census data and the overall Region V sample were compared and showed good agreement. This representative sample was used to conduct an exploratory investigation of selected subpopulations that might exhibit higher exposures, on average, to volatile organic chemicals (VOCs) such as benzene, chloroform, etc.; inspirable particles; and metals (e.g., lead, arsenic, etc.) than the general population in Region V. Means and medians were the metrics of comparison. Personal air exposures for p-dichlorobenzene were significantly higher in adults (> 21 years old) than in children (1-14 years old) (median below detection limit vs. 0.87 microgram/m3, p = 0.0005), while a trend toward higher levels of arsenic exposure in children than adults was observed (median 1.13 vs. 0.8 ng/m3, p = 0.083). A trend towards higher personal air exposure to lead for minorities vs. nonminorities was evident (median 26 vs. 12 ng/m3, p = 0.066), but personal exposure to 1,1,1-trichloroethane tended to be higher in nonminorities (mean 22 vs. 3.7 micrograms/m3, p = 0.081). Dietary exposure to arsenic from solid foods was significantly higher in adults than children (mean 21 vs. 7.1 micrograms/kg, p = 0.0001; median 10 vs. 5.6 micrograms/kg, p = < 0.001), and for cadmium it was higher for nonminorities than minorities (median 18 vs. 15 micrograms/kg, p = 0.023). In contrast, the dietary intake for arsenic, which is based on body weight, was significantly higher in children than adults (mean 1.72 vs 1.38 micrograms/kg-1 day-1, p = < 0.0001; median 1.02 vs. 0.83, p = < 0.0001). Dietary exposure to chromium in beverages tended to be higher in minorities than nonminorities (median 16 vs. 13 micrograms/kg, p = 0.017). Lead levels in surface dust wipes tended to increase with the age of the home (mean 128 micrograms/g in homes built since 1980 to 1075 micrograms/g in homes built before 1940; median 93 to 236 micrograms/g, respectively). These findings were consistent with the observation that for persons living in older homes personal air exposures to lead are elevated compared to persons living in recently built homes (median 12 ng/m3 in homes built since 1980, vs. 24 ng/m3 in homes built before 1940, p = 0.043).