evaluation of occupational exposure to benzene and toluene among workers in two tire manufacturing factories

backgrounds and aims: semi automated processes of iranian tire manufacturing factories lead to significant occupational exposures to benzene and toluene compounds. this study was conducted to evaluate the magnitude and risk of workers exposures. materials and methods: personal monitoring of 100 workers (10 groups) was performed using niosh method no.1501 in two tire manufacturing factories in tehran city. workplace atmospheric conditions were measured on sampling days. semi quantitative risk assessment (coshh) was carried out using questionnaire and respective matrix. data were analyzed using t-test, correlation coefficient, linear regression and one-way anova. quantitative values were reported as mean±standard error. results: age, work experience and atmospheric parameters had no significant statistical difference in two factories. occupational exposures to benzene and toluene were 1.09±0.18, 1.88±0.19 and 2.07±0.30, 3.20±0.39 ppm in factories a and b that showed significant increase in b factory and inverse significant correlation with air relative humidity. exposure to high risk of benzene and medium risk of toluene were 10, 14 and 10, 16 percent of workers in factories a and b, respectively. the correlation between occupational exposure and coshh assessment was significant. conclusion: occupational exposure to benzene in tire manufacturing personnel was higher than iranian standard, therefore, improvement of work conditions using appropriate control measures including automated processes and setting of air relative humidity is recommended. coshh assessment can be used as a simple, cheap and quick method in workers’ health promotion. control of personnel exposure through ongoing training is imperative. references: 1. seminar on energy conservation in rubber industry. united nations industrial development organisation (unido). hanoi-vietnam: ministry of industry socialist republic of vietnam1998. p. 1-22. 2. wingren g, axelson o. cancer incidence and mortality in a swedish rubber tire manufacturing plant. am j ind med. 2007;50(12):901-9. 3. vermeulen r, bos r, pertijs l, kromhout h. exposure related mutagens in urine of rubber workers associated with inhalable particulate and dermal exposure. occup environ med. 2003;60(2):97-103. 4. attarchi m, labbafinejad y, mohammadi s. occupational exposure to different levels of mixed organic solvents and colour vision impairment. neurotoxicol teratol. 2010;32(5):558-62. 5. xiao g, pan c, cai y, lin h, fu z. effect of benzene, toluene, xylene on the semen quality and the function of accessory gonad of exposed workers. ind health. 2001;39(2):206-10. 6. zobel kj, efird n. control of volatile organic emissions from manufacture of pneumatic rubber tires. north carolina: environmental protection agency research treiangle park, nc(usa)1978. 7. wijngaarden ev, stewart pa. critical literature review of determinants and levels of occupational benzene exposure for united states community-based case-control studies. appl occup environ hyg. 2003;18(9):678-93. 8. zalina h, hanachi p, shahnaz asa, norazura i, naing l, jamal hh, et al. toxic effect of naptha exposure on respiratory system among workers in the tyre industry. african journal of environmental science and technology. 2009;3(10):294-300. 9. peters jm, monson rr, burgess wa, fine lj. occupational disease in the rubber industry. environ health perspect. 1976;17:31-4. 10. wilczynska u, szadkowska-stanczyk i, dabrowska ns, sobala w, strzelecka a. cancer mortality in rubber tire workers in poland. int j occup med environ health. 2001;14(2):115-25. 11. duarte-davidson r, courage c, rushton l, levy l. benzene in the environment: an assessment of the potential risks to the health of the population. occup environ med. 2001;58(1):2–13. 12. win-shwe t-t, fujimaki h. neurotoxicity of toluene. toxicol lett. 2010;198(2):93-9. 13. hobara t, okuda m, gotoh m, oki k, segawa h, kunitsugu i. estimation of the lethal toluene concentration from the accidental death of painting workers. ind health. 2000; 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