Inorganic lead compounds and cancer

Inorganic lead compounds are used in lead-acid storage batteries for vehicles and other uses, in some pigments, as stabilisers in plastics and several other uses. These compounds have been classified by the International Agency for Research on Cancer (IARC) as 'probably carcinogenic to humans', based on 'sufficient evidence of carcinogenicity in experimental animals' and 'limited evidence of carcinogenicity in humans'. Much of the available epidemiological evidence for carcinogenic effects comes from studies of lead workers. However, previous studies have often involved relatively small numbers of workers and had methodological limitations such as poor information on other cancer risk factors or poorly characterised exposure assessments. As part of a review of research gaps for cancer risks, IARC has recently identified that further research was needed for lead and lead compounds (1).

IOM has been funded by the Colt Foundation (www.coltfoundation.org.uk/) to study the mortality of about 10,000 UK workers who participated in the Health and Safety Executive (HSE) Lead Mortality Study between 1975 and the early 1980s. This is one of the largest studies ever undertaken amongst lead workers, which has the advantage of quantitative information about individual exposure for all participants.

The main focus of the research will be to investigate associations between lead exposure and cancer mortality. In the first instance, data on blood lead levels will be used to estimate worker exposure. However, we will also be able to use information on the factory and process where these people worked, along with data from the HSE's historic records to assign likely lead exposure and to provide a qualitative assessment for other known or potential carcinogens. Finally, we will do some preliminary work to assess what further information might be obtained from existing records for workers in the study, should it be decided that a more intensive follow-up study is needed.

Given the length of time since the workers were recruited into the study, the large number of individuals involved and the relatively high exposures that they experienced (as documented by blood lead levels), the proposed study should make a significant contribution to the evidence on the carcinogenicity of lead exposure. This study will fill an important knowledge gap identified as a research priority by IARC.

As part of this new initiative IOM has employed Prof Damien McElvenny to help coordinate the study. Damien is a very experienced epidemiologist who contributed to the IARC review that identified the need for this research. We will also work closely with HSE on this project.

Reference

1. Ward EM, Schulte PA, Straif K, Hopf NB, Caldwell JC, Carreon T, et al. Research recommendations for selected IARC-classified agents. Environ Health Perspect. 2010; 118(10): 1355-1362.

This paper is freely available from: http://ehp03.niehs.nih.gov/article/info%3Adoi%2F10.1289%2Fehp.0901828