A meta-analysis of melanoma risk in industrial workers

Industrial workers are exposed to occupational pollutants, which may cause diseases such as cancer, but links to melanoma are not established. The identification of industry-related risk factors for melanoma incidence and mortality might be of importance for workers, health providers, and insurance companies. To assess melanoma incidence and mortality among oil/petroleum, chemical, and electrical industry workers. All studies reporting standardized mortality ratios (SMR) and/or standardized incidence ratios (SIR) of melanoma in workers employed in oil/petroleum, chemical, and electrical industries were included. Random-effect meta-analyses were carried out to summarize SIR and SMR for melanoma among oil/petroleum, chemical, and electrical industry workers. Heterogeneity was assessed using χ and I statistics. Possible source bias and quality were assessed using the Strengthening the Reporting of Observational Studies in Epidemiology checklist and a modified version of the Newcastle-Ottawa scale. Of 1878 citations retrieved, we meta-analyzed 21, 6, and 9 studies for the oil/petroleum, electrical, and chemical industry, respectively. Oil/petroleum industry: summary standardized incidence ratio (SSIR)  = 1.23 [95% confidence interval (CI): 1.11-1.36, I = 45%]; summary standardized mortality ratio (SSMR) = 1.02 (95% CI: 0.81-1.28, I = 48%); subgroups: SSIR = 1.16 (95% CI: 1.01-1.32, I = 15%), SSMR = 1.19 (95% CI: 1.00-1.42, I = 20%). Electrical industry: SSIR = 1.00 (95% CI: 0.93-1.11, I = 72%); SSMR = 1.16 (95% CI: 0.74-1.81, I = 11%). Chemical industry: SSIR = 2.08 (95% CI: 0.47-9.24, I = 73%); SSMR = 2.01 (95% CI: 1.09-3.72, I = 33%). Our meta-analysis suggests a slightly increased risk of developing melanoma among oil/petroleum industry workers and an increased melanoma mortality among oil/petroleum and chemical industry workers. No increased risks were found among electrical industry workers.