THE HEALTH WATCH STUDY
Since 1980, the Australian Institute of Petroleum (AIP) has commissioned the development and operation of an independent epidemiology program called Health Watch.
Health Watch is a research program which studies people who have worked in the Australian petroleum (oil and gas) industry to find out what happens to them in terms of their health. Health Watch follows about 18,000 past and present employees in the petroleum industry during their time in the industry and after they leave or retire. Along the way, Health Watch records any occurrence of cancer and, eventually, the cause of death.
By comparing this information for different jobs within the petroleum industry and with the general Australian population, Health Watch tries to provide useful information about risks in jobs in the petroleum industry and risks in lifestyle. The information from the Health Watch study is important in identifying factors that may be a risk to health and ways in which these risks may be controlled.
The Health Watch study began at the University of Melbourne and was relocated to the University of Adelaide in 1998 under the direction of Dr Richie Gun, a practicing occupational physician and Senior Lecturer in Occupational and Environmental Health in the Faculty of Medicine at the University of Adelaide.
Participation in the study is voluntary with 95 per cent of employees having joined the program. This is an extraordinarily high participation rate which amazes overseas researchers. The study has historically enjoyed very strong support from employees, unions and companies and is also very well regarded internationally.
WHAT HEALTH WATCH HAS FOUND SO FAR
The cancer rate
The overall cancer rate of employees in the petroleum industry is no different to the average cancer rate for the general Australian population.
Deaths from cancer
The overall death rates from cancer are lower than the average death rates from cancer for the Australian population.
Cancers of the blood and bone marrow
The Health Watch study has shown a higher than expected number of leukaemia cases. This is not surprising given the known relationship between higher exposures and certain leukaemias. It has long been suspected that this finding was related to high benzene exposures in the past as benzene is recognised as a cause of leukaemia. The industry has taken steps, to reduce exposure to petroleum products in general and to benzene in particular.
To look into this issue further, a separate study of cancers of the blood and bone marrow was established to study whether or not being exposed to benzene in the Australian petroleum industry increases the risk of developing such cancers.
This study, called the Health Watch case control study, has been completed by a medical research team from Monash and Deakin Universities in Victoria. The case-control study shows that there is an association between higher benzene exposure and developing two kinds of leukaemia: chronic lymphocytic leukaemia (CLL) and acute myeloid leukaemia (AML).
Importantly, the study found that employees joining oil companies in more recent years have much lower rates of leukaemia than those who started working in the industry in the 1960s or earlier.
The Health Watch case control study has also clearly demonstrated that benzene exposure is not related to Non-Hodgkins Lymphoma or Multiple Myeloma.
The known association between benzene and certain leukaemias has seen the Governments around the world set occupational exposure standards for benzene and petroleum companies have taken steps to make sure that they comply with them.
Health Watch results show a higher rate of melanomas being diagnosed in workers in the petroleum industry. It appears that workers in the petroleum industry are likely to have melanomas diagnosed sooner than in the general population. This increased rate of reporting can cause an increased melanoma incidence rate. However early diagnoses increase the survival rate. Not surprisingly therefore, the death rate from melanoma in the petroleum industry is less than the Australian average. Similarly, there is an increase in reported cases of bladder cancer but not of bladder cancer deaths.
The death rates for heart disease, stroke, respiratory diseases and other causes are significantly lower than the average Australian rates.
Effects of lifestyle
Health Watch results show that smoking has a powerful effect on the risk of early death. The death rate from all causes increases significantly the more cigarettes smoked.
For those who have low to moderate alcohol consumption, the overall death rate appears to be lower compared with those who don't drink at all. Those who drink more than five glasses of alcohol daily have a higher death rate.
BENZENE - OCCUPATIONAL VERSUS COMMUNITY EXPOSURE
The Health Watch study only looks at those who work in the petroleum industry and are therefore more at risk of benzene exposure. Benzene levels in the Australian community are more than one thousand times less than the occupational exposure level and petroleum companies have been working to steadily reduce the benzene content in petrol.
THE FUTURE OF THE HEALTH WATCH STUDY
The AIP is continuing to support the Health Watch study because it is valued by the petroleum companies, their employees and the community at large.
FOR FURTHER DETAILS ABOUT HEALTH WATCH
The latest Health Watch reports give the findings in more detail. Both the 11th Health Watch Cohort Report and the Health Watch Case Control Report (called the Lympho-haematopoietic Cancer and Exposure to Benzene in the Australian Petroleum Industry, Technical Report and Appendices) are available on the AIP Website: www.aip.com.au.