Assessment on health risk of coal tar pitch in workers in carbon and coal tar process industries

Objective To evaluate the health risk of coal tar pitch (CTP) in workers engaged in CTP production and process and to provide evidences for occupational health risk management.Methods Two carbon plants and one coal tar processing factory were selected and air samples were collected at main working positions with CTP exposure 8 hours a day continuously for 3 days for the detection of CTP in July 2015.Literature research on CTP-related toxicology and epidemiology was conducted.Semi-quantitative risk assessment for chemical and occupational hazard risk index assessment were adopted in the assessment;relative risk (RR) and standardized rate ratio (SRR) were used to evaluate CTP-related occupational health risk.Results The time weighted average concentrations (C_TWA) of CTP at 11 working positions in the carbon plants were much higher than the Chinese standard limitation for CTP (0.2 mg/m³)due to CTP effusion resulting from poorly closed and lower automotive equipments.The C_TWA of CTP at 2 working positions(beside product discharge unit and belt conveyor with spray system)of the coal tar processing factory were 26.3 mg/m³ and 7.4 mg/m³,which were 130 and 37 folds higher than the Chinese standard limitation.The workers working at the 13 working positions mentioned above were at extremely high CTP-related health risk based on the evaluations with semi-quantitative and risk index assessment methods;the workers in the carbon plants and the tar processing factory were at moderate and extremely high risk of lung cancer according to the assessment with RR and SRR.Conclusion The workers working at main working positions with CTP exposure in carbon plant and coal tar processing factory are at moderate or higher CTP-related health risk and measures should be taken to prevent the occupational hazards.