[EVALUATION OF THE CARCINOGENIC RISK OF LEAD IN THE COHORT STUDY OF MALE WORKERS OCCUPATIONALLY EXPOSED TO INORGANIC...

As millions of people worldwide are expoed to inorganic lead, both in the workplace and in general environment, its potential carcinogenicity is an important health problem. Although lead has been shown to be carcinogenic in laboratory animals, epidemiological studies have been inconclusive, and the relationship between lead and human cancer is still unclear. There were several limitations that complicated the analysis and evaluation of the carcinogenic potential of lead compounds. In particular, many of the cohort studies of lead and cancer, mostly among heavily lead-exposed workers, have been limited by a failure to identify and control for covariates, especially co-exposures to other metals such as arsenic, cadmium, and chromium, which have been shown to be carcinogenic. Most of the epidemiological studies unfortunately do not have data on dose-response. The scientific merit of our study is the virtual absence of confounding by other known carcinogens. Another advantage of our study is the presence of three occupational sub-cohorts with different levels and routes of lead exposure. Most previous studies have data on dose-response provided only by comparisons of exposed to unexposed persons. In summary, the results of this cohort study suggest that occupational exposure to lead may increase the risk of cancers of the pancreas, kidney and rectum. In conclusion, despite several limitations, the results of our study add to the evidence that carcinogenicity to humans may be an additional adverse health effect of lead.