68 Urinary Biomarkers of Benzene Exposure and Oxidative Damage in Residents of the Oil Extraction Area of Muanda, Dr Congo

Abstract

Abstract The territory of Muanda, on the Atlantic coastline of the DR Congo, is an area of off-shore and on-shore oil extraction. Following concerns of the local population about the possible environmental and health consequences of these activities, a pilot study was performed in December 2015 to assess, among other issues, the exposure of residents of various relevant locations to oil-derived chemicals. We measured metabolites of benzene (t,t-Muconic Acid, MA, and S-Phenylmercapturic acid, S-PMA) by LC-MS and 8-hydroxy-2’-deoxyguanosine (8-OHdG, as an indicator of DNA damage) by ELISA, in urine spot samples of 53 volunteers (34 adults, 19 children, recruited by convenience sampling) living within areas of oil extraction with flaring (n=27), in an area where petroleum products were handled (n=14), and in a control area in the Mangroves National Park (n=12). Concentrations of both MA and S-PMA were increased among residents of the oil extraction areas (0.23±0.05 mg/L, 1.04±0.30 µg/L, respectively) and petroleum products area (0.32±0.08 mg/L, 1.74±0.63 µg/L, respectively) compared with controls (0.06±0.01 mg/L, 0.40±0.13 µg/L, respectively). Concentrations of of MA and S-PMA correlated with levels of 8-OHdG (RSpearman = 0.37, p<0.01). Our biomonitoring study revealed a low degree of benzene exposure among residents living in the oil extraction and petroleum handling areas compared to a control area. Although the levels of benzene metabolites were low, the positive correlation with 8-OHdG possibly indicates that pollution by hydrocarbons induced oxidative damage in this study population.