Cohort Profile: Health Watch-a 30-year prospective cohort study of Australian petroleum industry workers.

Abstract

Health Watch was established in 1980 at the University of Melbourne to ‘explore possible links between occupational experience in the [petroleum] industry’ and subsequent mortality and cancer incidence. There was concern that occupational exposure to fossil fuels could result in occupational cancers and it was anticipated that ‘well designed epidemiological studies, and carefully planned data bases’ were ‘capable of confirming or refuting such association’ rather than relying on clinician recognition of clusters. Health Watch was ‘designed to operate as a general health surveillance system’ comparable to a contemporary USA study funded by the American Petroleum Institute. Later reports expanded the aim to be ‘a prospective epidemiological study with the capacity to test specific hypotheses regarding the possible health consequences of occupationally determined exposure to hydrocarbon and other chemical substances’. This follows efforts by the industry’s occupational hygienists to link descriptive job categories to an index of hydrocarbon exposure. The main aims of tracking mortality and cancer incidence in the cohort have not changed over time, but subanalyses have been included e.g. for tanker drivers and for a group of men at a particular refinery. After an excess of lympho-haematopoetic (LH) cancer was identified, a case-control study was instituted to investigate whether benzene exposure was associated with this increased risk. This study was followed up in 2008 with a pooled analysis to identify which subtypes of LH cancer might be most strongly associated with benzene exposure. The industry has reduced benzene exposure over the period of the cohort. In 1999, the custodianship of the cohort was transferred to the University of Adelaide and then in 2005 to Monash University’s Centre for Occupational and Environmental Health in the Department of Epidemiology and Preventive Medicine, where it currently resides. The Australian Institute of Petroleum (AIP) has funded the relevant universities, including Monash University, to implement the study with funds from their member companies in the Australian petroleum industry. The study has an advisory committee that meets regularly and includes the relevant university investigators and trades union and company representatives. The committee is chaired by a representative of the participating companies on a rotating basis and the AIP provides the secretariat.