Haematological changes among Beninese motorbike taxi drivers exposed to benzene by urban air pollution

Exposure to high benzene concentrations in polluted air has been associated with bone marrow deficiency, aplastic anaemia, and leukaemia; however, epidemiological studies reported conflicting data following human exposure to benzene concentrations <1 ppm (i.e., 3.2 mg/m3). The present study investigated the effect of outdoor air benzene concentrations on peripheral blood cells among exposed motorbike taxi drivers, (MBTD) in which specific IgG antibodies against reactive benzene metabolites, e.g., hydroquinone (HQ) and para-benzoquinone (p-BQ), were identified and quantified for further use as an exposure biomarker. In total, 144 MBTD were compared with 30 unexposed age- and sex-matched controls. Mean age (standard deviation (SD; 95% confidence interval [fusion_builder_container hundred_percent="yes" overflow="visible"][fusion_builder_row][fusion_builder_column type="1_1" background_position="left top" background_color="" border_size="" border_color="" border_style="solid" spacing="yes" background_image="" background_repeat="no-repeat" padding="" margin_top="0px" margin_bottom="0px" class="" id="" animation_type="" animation_speed="0.3" animation_direction="left" hide_on_mobile="no" center_content="no" min_height="none"][CI]) were: MBTD 39.5 ( 7.82 (38.2-40.7) and village residents 40.3 ( 10.56 (39.1-43.0). Personal benzene exposure was assessed using GABIE diffusive samplers. Concentrations of specific IgG antibodies to HQ and p-BQ were detected by ELISA. Peripheral blood cells were counted by an automated analyser. Benzene, toluene, and xylene concentrations were much higher in MBTD versus the control group. Benzene exposure levels were 0.012-0.550 ppm in MBTD. Their average exposure level/wk was 0.126 ( 0.206 ppm. Accordingly, MBTD had significantly higher levels of specific IgG antibodies to HQ and p-BQ versus controls ( p <0.001). White blood cells, lymphocytes, eosinophils, and platelets were significantly decreased in MBTD; red blood cells and other blood cell numbers remained unchanged. Total white blood cell, lymphocyte, and eosinophil counts were decreased among exposed MBTD versus unexposed controls. The authors concluded that the findings suggest using these blood parameters, together with specific IgG antibodies to HQ and p-BQ, as biomarkers for biomonitoring of low level benzene exposure. Larger studies are required to validate this health survey approach in benzene-exposed workers.

Authors: Avogbe, Patrice H.; Ayi-Fanou, Lucie; Cachon, Boris; Chabi, Nicodeme; Debende, Agnes; Dewaele, Dorothee; Aissi, Faustin; Cazier, Fabrice; Sanni, Ambaliou ;Full Source: African Journal of Environmental Science and Technology [online computer file] 2011, 5(7), 464-472 (Eng) ;