Introduction Lead is considered a probable carcinogen by IARC (brain. lung, and stomach) and has been shown to increase blood pressure and damage the kidney.
Methods We have conducted an internal analyses via Cox regression of mortality in three cohorts of lead-exposed workers with blood lead data (US, UK, Finland), including over 88,000 workers and over 14,000 deaths. We used maximum blood lead (BL) as exposure. We also conducted cancer incidence analysis in Finnish workers (n = 20,752, 5057 incident cancers). Analyses were done via Cox regression
Results The combined cohort had a mean maximum BL of 26 ug/dl, and a mean first year BL of 1990. The cohort had only 4% women. Forty-six% of the cohort had more than 1 BL (mean 5), and the intraclass correlation coefficient for these was 0.74, indicating that these workers had repeat BLs which were similar to each other. Significant (p < 0.05) continuous trends in mortality using log maximum BL were found for lung cancer, COPD, stroke, and heart disease, while borderline significant trends were found for bladder cancer, brain cancer, and larynx cancer. Most results were consistent across all 3 cohorts. In the Finnish cancer incidence cohort, positive significant trends (p < 0.05) were found for brain cancer (both malignant (n = 68) and malignant/benign combined (n = 140), esophageal cancer, lung cancer, larynx cancer, and Hodgkin’s disease.
Conclusions Strong positive mortality trends were seen for outcomes associated with smoking, for which we had no data. However, a number of these endpoints may have also been affected by lead. A borderline trend was found for brain cancer death, unaffected by smoking. For cancer incidence, trends were again seen for some smoking related cancers, and pronounced trends were seen for brain cancer. Our data suggest the occupational lead exposure is associated with brain cancer, and possibly other smoking-related outcomes.