Abstract
Abstract 43 Background: Polycyclic aromatic hydrocarbons (PAHs) are a group of more than 100 compounds that are formed during incomplete combustion of organic materials, many of which have been classified as known carcinogens. Exposure to PAHs has been suggested as an important risk factor for developing esophageal squamous cell carcinoma (ESCC) in several high-incidence areas, such as China and Iran, but corresponding PAH assessments have not been conducted in East Africa, another ESCC hot spot. To assess the internal uptake of PAH as a result of external exposures, body fluids and tissues can be monitored for PAHs or their metabolites. The primary aim of this study was to quantify the concentration of seven PAH urine metabolites in a cross-section of participants from Bomet, Kenya, an endemic area for ESCC. An additional aim was to assess demographic and lifestyle factors that may be associated with PAH metabolites. Methods: A community-based sample of 294 asymptomatic adults were recruited. Participants collected spot urine specimens and completed a questionnaire. Urine specimens were analyzed at the National Center for Environmental Health at the Centers for Disease Control—the same lab has performed similar analyses on urine samples from the US National Health and Nutrition Examination Survey (NHANES). The seven PAH analytes were hydroxylated metabolites of naphthalene, fluorene, phenanthrene, and pyrene. Median creatinine-adjusted PAH metabolite concentrations (nanogram per gram of creatinine) were compared by all relevant questionnaire items. Results: All seven measured PAH metabolites in the study population were markedly elevated compared with the US population. For example, the median value for 1-hydroxypyrene in Bomet was 1,190 ng/g in males versus 106 ng/g in NHANES, and 2,840 ng/g in females versus 133 ng/g in NHANES. Age (< 50 years), sex (female), and performing indoor cooking were significantly ( P < .01) associated with higher PAH concentrations for all measured metabolites. Regular tobacco use was not reported by many participants (19%) and was not associated with PAH concentrations. Conclusion: PAH metabolite concentrations in Bomet were high compared with the US population. Elevated PAH concentrations were associated with age, sex, and indoor cooking. Additional studies are needed to define the association between high PAH exposure and the risk of developing ESCC as well as to determine the sources of PAH exposure in this high-risk population. Funding: The African Organization for Research and Training in Cancer’s Beginning Investigator Grant for Catalytic Research (BIG Cat) Program, in collaboration with the US National Institutes of Health’s National Cancer Institute, Office of International Affairs. AUTHORS' DISCLOSURES OF POTENTIAL CONFLICTS OF INTEREST No COIs from the authors.
Published Version
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