Assessment of BTEX exposure and carcinogenic risks for mail carriers in Tehran, Iran

Abstract

This study investigated personal exposure of mail carriers to atmospheric benzene, toluene, ethylbenzene, and xylenes (BTEX) and estimated their carcinogenic and non-carcinogenic risks due to their exposure to these compounds. A total of 36 mail carriers and 24 post office employees as the control group working in Tehran were included in this study. Spot urine samples were also collected before and after shifts. Monte Carlo simulations were used to estimate the distributions of carcinogenic and non-carcinogenic risks from BTEX exposures. Mail carriers were exposed to 10.4 (± 6.2), 35.3 (± 15.5), 5.5 (± 2.3), and 23.1 (± 10.4) μg/m3 as the average (±SD) concentrations of benzene, toluene, ethylbenzene, and xylenes, respectively. The urinary concentrations of these compounds were 124.0 (±61.2), 242.5 (±96.9), 140.7 (±74.2), and 444.3 (±147.0) ng/L, respectively. These values were significantly higher than those observed for control group. For mail carriers, after-shift urinary concentrations of BTEX were statistically higher than before-shifts concentrations. Carcinogenic risks of mail carriers were higher than those for control group with a mean of 5.82×10−6 exceeding the US EPA limits. Sensitivity analyses showed that concentration had the highest effect on the estimated risks, followed by exposure frequency and exposure time. This study showed that mail carriers are exposed to BTEX at levels that increase their risk to develop cancer. Therefore, programs to reduce the cancer risk among mail carriers should be designed to reduce exposures, possibly by changing shift hours, working days per year, and total years of occupation.