8095005 Mortality and cancer incidence in a large cohort of lead-exposed workers

<h3>Introduction</h3> Lead is a common occupational exposure, a suspected carcinogen (IARC group 2A), and associated with several other chronic diseases. Here we analyze mortality and cancer incidence in a large cohort of US workers with blood lead levels based on data from the National Institute for Occupational Safety and Health (NIOSH). <h3>Material and Methods</h3> We updated mortality follow-up for a cohort of 58,000 male lead-exposed workers through 2021. We followed a subset of 37,000 of these workers for cancer incidence through 2021. Internal exposure-response analyses used highest recorded blood lead as the exposure. <h3>Results</h3> In the cohort, the median birth year was 1959, and the average year of first blood test was 1997. Mean highest blood lead was 26 ug/dl, compared to current US general population levels of 3 ug/dl. There were 8,832 deaths. Mortality results showed positive significant trends of lung cancer, pancreatic cancer, heart disease, chronic obstructive pulmonary disease, and chronic renal disease, with increased blood lead levels. Among the subset of 37,000 workers, there were 5,832 incident cancers. Among them, only lung cancer showed a significant positive trend; brain and liver cancer showed borderline significant positive trends (p-values between 0.05 and 0.10). Thyroid and prostate cancer showed significant negative trends. While lung cancer trends might be related to smoking, there is no a priori reason why workers with higher blood lead would have smoked more, and in a subset of 200 workers with smoking data there was no such evidence. Lung cancer rate ratios on the order of 2.0-2.5 are also unlikely to be explained by smoking differences. <h3>Conclusion</h3> In this large cohort with documented blood lead levels, higher lead was associated with several causes of mortality and cancer incidence.