This study investigated further whether inorganic lead is a carcinogen among adults, or associated with increased blood pressure and kidney damage. The authors conducted internal analyses via Cox regression of mortality in three cohorts of lead-exposed workers with blood lead (BL) data (USA, Finland, UK), including over 88?000 workers and over 14?000 deaths. The exposure metric was maximum BL. In addition, an external analyses using country-specific background rates was conducted. The combined cohort had a median BL of 26?µg/dL, a mean first-year BL test of 1990 and was 96% male. Fifty per cent had more than one BL test (mean 7). Significant (p<0.05) positive trends, using the log of each worker's maximum BL, were found for lung cancer, chronic obstructive pulmonary disease (COPD), stroke and heart disease, while borderline significant trends (0.05?p?0.10) were found for bladder cancer, brain cancer and larynx cancer. Most results were consistent across all three cohorts. In external comparisons, the authors found significantly elevated SMRs for those with BLs>40?µg/dL; for bladder, lung and larynx cancer; and for COPD. In a small subsample of the US cohort (n=115) who were interviewed no association between smoking and BL was found. In conclusion, the authors found strong positive mortality trends, with increasing BL level, for several outcomes in internal analysis. Many of these outcomes are associated with smoking, for which we had no data. A borderline trend was found for brain cancer, not associated with smoking.
Authors: Steenland K, Barry V, Anttila A, Sallmén M, McElvenny D, Todd AC, Straif K. ;Full Source: Occupational & Environmental Medicine. 2017 May 25. pii: oemed-2017-104311. doi: 10.1136/oemed-2017-104311. [Epub ahead of print] ;