Linkage study of cancer risk among lead-exposed workers in New Jersey

ObjectivesEpidemiologic studies have illustrated a possible association between occupational exposure to lead and cancer, specifically cancers of the kidney, lung, stomach, and nervous system. We performed a linkage between two New Jersey databases: the Adult Blood Lead Epidemiology and Surveillance System (ABLES) and the New Jersey State Cancer Registry (NJSCR) for 1985–2001 to ascertain the risk of cancer in lead-exposed workers and to evaluate the usefulness of this type of linkage.MethodsA cohort of 3192 men from the ABLES database met the selection criteria before the linkage. AUTOMATCH was used to link the two databases. Person-time was stratified for each worker by five-year age group and calendar year. A standardized incidence ratios (SIR) analysis was performed.Results83 cases of cancer were found among 3165 men after all exclusions were made. Workers were followed for an average of ten years and contributed 30,401 person-years. The SIR analysis showed a large overall deficit of cancer (SIR = 0.51; 95% CI 0.41 to 0.62). Cancers of the stomach, breast, larynx, intrahepatic bile duct, and chronic myeloid leukemia were non-significantly elevated. Prostate cancer showed the only statistically significant result, a deficit with an SIR of 0.35 (95% CI 0.20 to 0.57). Deficits also occurred in cancers of the lung, kidney, and brain.ConclusionsThe results do not indicate that occupational exposure to lead is associated with cancer. However, firm conclusions are not possible because of various study limitations, including small numbers, a large percentage of workers without age information, short follow-up time, and lack of vital status information. Cancer incidence in this cohort was expected to be low due to the Healthy Worker Effect and young age. Further follow-up of this cohort may be warranted since additional cancers may accrue as time from first exposure increases. Increased worker cohort information would also improve this type of study.