Children’s Exposure to Volatile Organic Compounds as Determined by Longitudinal Measurements in Blood

Abstract

Blood concentrations of 11 volatile organic compounds (VOCs) were measured up to four times over 2 years in a probability sample of more than 150 children from two poor, minority neighborhoods in Minneapolis, Minnesota. Blood levels of benzene, carbon tetrachloride, trichloroethene, and m-/p-xylene were comparable with those measured in selected adults from the Third National Health and Nutrition Examination Survey (NHANES III), whereas concentrations of ethylbenzene, tetrachloroethylene, toluene, 1,1,1-trichloroethane, and o-xylene were two or more times lower in the children. Blood levels of styrene were more than twice as high, and for about 10% of the children 1,4-dichlorobenzene levels were ≥10 times higher compared with NHANES III subjects. We observed strong statistical associations between numerous pairwise combinations of individual VOCs in blood (e.g., benzene and m-/p-xylene, m-/p-xylene and o-xylene, 1,1,1-trichloroethane and m-/p-xylene, and 1,1,1-trichloroethane and trichloroethene). Between-child variability was higher than within-child variability for 1,4-dichlorobenzene and tetrachloroethylene. Between- and within-child variability were approximately the same for ethylbenzene and 1,1,1-trichloroethane, and between-child was lower than within-child variability for the other seven compounds. Two-day, integrated personal air measurements explained almost 79% of the variance in blood levels for 1,4-dichlorobenzene and approximately 20% for tetrachloroethylene, toluene, m-/p-xylene, and o-xylene. Personal air measurements explained much less of the variance (between 0.5 and 8%) for trichloroethene, styrene, benzene, and ethylbenzene. We observed no significant statistical associations between total urinary cotinine (a biomarker for exposure to environmental tobacco smoke) and blood VOC concentrations. For siblings living in the same household, we found strong statistical associations between measured blood VOC concentrations.

Relationships between levels of volatile organic compounds in air and blood from the general population

“…The strengths of associations between the logged levels of individual VOCs in blood and air varied greatly, with unadjusted values of R 2 ranging between 0.02 (ethylbenzene) and 0.68 (1,4-DCB). This finding is generally consistent with results from a recent study of children in Minneapolis, Minnesota, USA (Sexton et al, 2005).…”

“…Thus, if exposures changed greatly over time scales of hours, air and blood levels in the cross-sectional NHANES database would become increasingly discordant. In a longitudinal study of VOC exposures, Sexton et al (2005) noted that air levels of 1,4-DCB were very consistent in their subjects from day to day; this could explain the particularly strong relationship between blood and air levels of 1,4-DCB in both Sexton's study and our results from the NHANES data (Table 5).…”

“…On the other hand, values of R 2 increased only marginally for chloroform, 1,4-DCB, MTBE, and tetrachloroethene, following adjustment for smoking and other covariates. Table 5 also includes results from a study of VOC levels in blood and air among Minnesota children by Sexton et al (2005), who reported unadjusted values of R 2 . Note that, aside from toluene, our findings from unadjusted analyses (adults aged 20-65 years) are comparable to the results from that earlier study in children.…”

Using exposure biomarkers in children to compare between-child and within-child variance and calculate correlations among siblings for multiple environmental chemicals

“…Biomarkers for lipophilic compounds (e.g., persistent organic chemicals) are generally measured in blood (where concentrations tend to be in equilibrium with fatty tissues), whereas biomarkers for lipophobic compounds (e.g., non-persistent organic chemicals) are usually measured in urine. In a departure from this rule of thumb for the SHIELD study (but in accordance with previous studies; see Sexton et al, 2005Sexton et al, , 2006Sexton et al, , 2011, VOCs, which are non-persistent organic chemicals that rapidly metabolize in the body and are excreted in the urine or released in exhaled breath, were measured in blood according to the method developed by Ashley et al (1992).…”

“…Current laboratory methods allow for measurement of picogram per gram levels or lower for hundreds of exposure biomarkers in relatively small amounts of blood and urine (Needham and Sexton, 2000;Sexton et al, 2004a;Needham et al, 2005). Biomarker data have been collected in children to evaluate environmental exposures to specific chemicals or chemical classes, including lead (Brody et al, 1994), pesticides (Payne-Sturges et al, 2009), environmental tobacco smoke (ETS; Sexton et al, 2004b), volatile organic chemicals (VOCs; Sexton et al, 2005), polychlorinated biphenyls (PCBs; Soechitram et al, 2004;Fukata et al, 2005), and phthalates (Silva et al, 2004;Wolff et al, 2007). But relatively few studies have been conducted that make longitudinal (over time) measurements of multiple biomarkers in the same children (Cohen Hubal et al, 2000;Needham and Sexton, 2000;Clayton et al, 2003;Sexton et al, 2006Sexton et al, , 2011.…”