What is it about?

A cohort study of the 2,783 New Zealand Vietnam war veterans that we traced using Ministry of Health databases and the electronic electoral roll. Between 1988 and 2009, 407 veterans had died. The veterans were healthier in some respects, with a reduced risk of death compared to the general population of the same age structure, the 'health soldier effect'. They had an increased risk of some cancers, especially head and neck cancers, and nearly twice the risk of Chronic Lymphatic Leukaemia.

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Why is it important?

The veterans were worried about exposure to Agent Orange, a herbicide used to kill vegetation around bases in order to deny the enemy cover and discourage attacks. It contained 2,3,7,8-tetrachlorodibenzo-para-dioxin (TCDD or simply ‘dioxin’). United States veterans had pressured the US Department of Veteran Affairs into investigating the health effects of Agent Orange, and the The Institute of Medicine of the US National Academy of Sciences (IOM) to conduct a biennial and cumulative epidemiological review of herbicide exposure. Eleven reviews have been carried out since 1994, and the 11th and final review was published in 2018. The reviews have been used in New Zealand to publish a 'presumptive list' of conditions which automatically attract compensation and health cover. Chronic Lymphatic Leukaemia is on this list because of an increased risk in agricultural workers: it had never been reported in veterans. Australian veterans also had an increased risk. Unfortunately we do not know the levels of exposure to dioxins, but the New Zealand Companies served alongside their Australian colleagues in The Nui Dat area. This lay in US Military Region 3, and approximately 20 km distant from the Rung Sat special zone, known to have been heavily sprayed. Infantry soldiers were more likely to be exposed because they more often engaged with the enemy and were, therefore, more likely to enter sprayed areas. They were also potentially exposed to other agents such as dapsone and insecticides.

Perspectives

As always, we engaged the veterans before, during and after the study. Although this is a seemingly impersonal cohort study carried out using records, the personal touch was important. We needed to listen to their concerns. Why did we want to do this study? We explained that, if we know about mortality then we know what to look for. Not all the veterans were supportive, mainly because of the way that Vietnam veterans were treated on their return to New Zealand. They have an innate sense of mistrust of 'the authorities,' which, at least to some extent, researchers are. We made sure that the veterans knew the results first. Contrary to expectation, they were actually relieved about the leukaemia finding, saying that 'we told you so,' this is something that you don't find out about unless you ask!

Dr David I McBride
University of Otago

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This page is a summary of: The mortality and cancer experience of New Zealand Vietnam war veterans: a cohort study, BMJ Open, August 2013, BMJ, DOI: 10.1136/bmjopen-2013-003379.
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