Abstract C13: Use of air monitoring and urine biomarker assays to measure geographic disparities in exposure to VOCs in Washington, DC

Abstract

Abstract The District of Columbia has one of the highest cancer incidence and mortality rates in the nation in conjunction with significant cancer-related geographic and racial disparities. Increased exposure to environmental carcinogens, such as benzene, in high risk areas of DC is of public health importance and may play a role in these disparities in cancer incidences and mortality rates. Volatile Organic Compounds (VOC), such as toluene and benzene, are absorbed by the body and undergo metabolism to produce bio-activated (can lead to cancer and other serious health effects) metabolites that are excreted from the body via the urine and/or feces. Air monitoring and urinary biomarker assays are accepted methods for exposure assessment of VOCs but little is known regarding the correlation between the two. In this study we compared the urinary concentrations of hippuric acid and t,t-muconic acid (two known benzene and toluene metabolites, respectively) with indoor and outdoor exposure levels of toluene and benzene in high risk (<1 mile from highway/freeway) and low risk urban areas (>3 miles from the highway/freeway) in Washington, DC. First morning void urine samples were collected from 16 adult residents in high risk areas and 14 adult residents in low risk areas after 72 hours of air monitoring. Urine samples were sent to NMS laboratory and metabolite levels were measured using liquid chromatography/ mass spectrometry. Indoor and outdoor benzene and toluene levels were measured in the same homes over 72 hours using a 3M Organic Vapor Monitor and analyzed using gas chromatograph mass spectrometer (GC/MS). t,t-muconic acid urinary concentration levels in normal non-exposed individuals has been previously reported at .0001g/l and hippuric acid levels have been reported at <1.4 g/l. In our study participants, mean levels of urinary t,t-muconic and hippuric acid were .0003g/l and .35 g/l, respectively. Toluene levels, as measured by air monitoring, indoors (-0.34, p=0.08) and outdoors (-0.004, p=0.98) were both negatively correlated with urinary hippuric acid levels. A negative correlation was also observed between outdoor benzene levels and t,t-muconic acid (-0.23, p =0.11), however indoor levels showed a positive correlation with the urinary biomarker (0.13, p =0.52). We also observed higher levels of t,t-muconic acid in the high risk residents (87.17g/gCR) compared to low risk residents (59.54 g/gCR; p =0 .56). The positive correlation between indoor benzene levels and urinary t,t-muconic acid levels suggest the presence of additional sources of benzene inside the homes. Though air levels of VOCs are a good indicator of exposure, urinary metabolites may give a more measure of VOC exposure. Although not statistically significant, we observed a disparity in exposure to VOCs in “high risk” versus “low risk” areas in Washington, DC. Citation Format: Ashley Corrin Huderson, Chiranjeev Dash, Lucile Adams-Campbell. Use of air monitoring and urine biomarker assays to measure geographic disparities in exposure to VOCs in Washington, DC. [abstract]. In: Proceedings of the Sixth AACR Conference: The Science of Cancer Health Disparities; Dec 6–9, 2013; Atlanta, GA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2014;23(11 Suppl):Abstract nr C13. doi:10.1158/1538-7755.DISP13-C13