PAH exposure-associated lung cancer: an updated meta-analysis

Background Occupational exposure to polycyclic aromatic hydrocarbons (PAHs) has been shown to be associated with lung cancer in various epidemiological studies in industries such as aluminium reduction/ smelting, coal gasification, coke production, iron/steel foundries, coal/coke and related products and carbon 'graphite electrodes production. Aims To update data on the association between PAH exposure and morbidity and mortality due to lung cancer among workers in different occupations, including smoking data. Methods A comprehensive literature search was conducted to retrieve relevant papers for meta-analysis. Cohort studies with standardized mortality ratios or standardized incidence ratios and calculated overall risk ratio with their corresponding 95% confidence intervals (CIs) were included in the analysis. Chi-square test tor heterogeneity was used to evaluate the consistency of findings between the studies. Results A significant risk of lung cancer was observed among the coal coke and related product industry 1.55 (95% Cl 1.01-2.37) and the iron/steel foundry industry 1.52 (95% CI 1.05-2.20). There was a wide variation in smoking habits and PAHs exposure among studies. Conclusions Coal/coke industry and iron/steel industry workers showed a higher risk of lung cancer compared with other occupations exposed to PAHs.The confounding effects of smoking and individual exposure levels of PAH should be taken into account.