Population-based dietary intakes and tap water concentrations for selected elements in the EPA Region V National Human Exposure Assessment Survey (NHEXAS)

Abstract

A National Human Exposure Assessment Survey ( NHEXAS) field study was performed in U.S. Environmental Protection Agency (EPA) Region V, providing population-based exposure distribution data for selected elements in several personal, environmental, and biological media. Population distributions are reported for the 11 elements that were measured in water and dietary samples. Dietary intakes and home tap water concentrations of lead, arsenic, and cadmium were further examined for intermedia associations, for differences between dietary exposure for adults and children, and to estimate the proportion of the population above health-based reference values (dietary) or regulatory action levels or maximum contaminant levels (water). Water lead and arsenic concentrations were significantly associated with dietary intake. Intake of all elements was higher from solid foods than from liquid foods (including drinking water). Dietary intakes of Pb, As, and Cd were greater than those calculated for intake from home tap water or inhalation on a g /day basis. Median dietary intakes for the Region V population for Pb, As, and Cd were 0.10, 0.13, and 0.19 g / kg bw/day, respectively. While Pb, As, and Cd concentrations in the foods consumed by 0 to 6-year-old children were similar to or lower than those for adults, dietary intakes calculated on a body weight basis were 1.5 to 2.5 times higher for young children. Intrapersonal intake differences accounted for most of the variance in short-term (daily) dietary intakes for Pb and As, while interpersonal differences accounted for more of the intake variance for Cd. Only small percentages of the population exceeded health-based intake reference values or concentrations equal to regulatory levels in water for Pb, As, and Cd.

A health risk assessment for exposure to trace metals via drinking water ingestion pathway

“…Median and mean values for As, Cr, Cu, and Zn concentrations lie within the range of concentrations reported in the literature (O'Rourke et al, 1999;Thomas et al, 1999;Seifert et al, 2000;Divrikli and Elci, 2002;Sofuoglu et al, 2003;Tamasi and Cini, 2004;Gu¨lbahar and Elhatip, 2005;Xu et al, 2006). In the case of Mn, the mean concentration obtained in this study was about seven times smaller than the value reported by Thomas et al (1999).…”

“…In the case of Mn, the mean concentration obtained in this study was about seven times smaller than the value reported by Thomas et al (1999). This number would drop to five if only the mean Mn concentrations of flushed tap water samples were taken into consideration for both studies.…”

“…The concentrations of trace metals reported in drinking waters usually lie well below standards as in the examples of EPA Region V (Thomas et al, 1999), Maryland, USA (Ryan et al, 2000), South Tuscany, Italy (Tamasi and Cini, 2004), and Shanghai, China (Xu et al, 2006). However, arsenic concentrations as high as 36.7 and 40 mg/l have been detected in Arizona, USA (O'Rourke et al, 1999) and Chilean (Caceres et al, 2005) tap waters, respectively.…”

“…In the same manner, Tamasi and Cini (2004) measured a very high concentration in a spring water that is approximately 9 times and 1.7 times the measured maximum concentrations in this study in nontap and tap samples, respectively. Ni concentrations found in İzmir drinking waters were the highest (O'Rourke et al, 1999; Thomas et al, 1999;Divrikli and Elci, 2002;Sofuoglu et al, 2003;Tamasi and Cini, 2004). In short, inclusion of drinking water sources other than tap water would play an important role in characterization of population exposure.…”

Biologically based modeling of multimedia, multipathway, multiroute population exposures to arsenic

“…Drinking water concentrations are obtained from regulatory monitoring databases (such as SDWIS/FED-USEPA, 2006a) or field study measurements (such as the National Human Exposure Assessment Survey (NHEXAS)- Thomas et al, 1999;Pellizzari and Clayton, 2006). If such data are not available, the drinking water distributions are modeled using the EPANET2 model (Rossman, 2000) with treatment plant data to obtain drinking water concentrations (see e.g., Maslia et al, 2000 for a discussion of application of drinking water distribution modeling to epidemiological studies).…”