High rates of some cancers in meatworkers are being linked to viruses in livestock.
Massey University's public health research unit is investigating cancer rates among 20,000 past and present meatworkers.
The research focuses on the transmission of cancer-causing viruses from slaughtered animals to meatworkers.
Dave McLean, a researcher with the unit, said it was known that certain viruses caused cancer - for example, cervical cancer and some liver cancers - in humans.
"If this research proves that cancer in meatworkers is caused by the transmission of viruses from animals to humans, then there are wider public health implications."
Environmental scientists are already urging health authorities to find out why the incidence of some communicable diseases has soared to give New Zealand some of the world's highest rates of infectious diseases.
They have pointed to apparent links between some of the diseases and water quality that have implications not only for public health but for industries that rely on New Zealand's "clean and green" reputation.
Concerns over water quality are closely linked to contamination from New Zealand's huge population of farmed livestock, which produces effluent equivalent to a human population of 150 million.
Health authorities have known for more than a decade - from a study of 19,904 cancer patients between 1980 and 1984 - that meatworkers face an increased risk of lung and laryngeal cancer, as well as soft-tissue sarcoma, non-Hodgkin's lymphoma and all types of leukaemia, with a special risk of acute myeloid leukaemia.
The first results of that study were published in 1988, but some researchers wrongly thought the problem lay in chemicals used to process hides or cure meat.
Mr McLean will attend a meeting of the International Agency for Research on Cancer in Lyon, France, next month to discuss New Zealand's new research, which is financed by the Health Research Council.
The project is part of an international study in 13 countries coordinated by the World Health Organisation agency.
"We have a large, long-established meat export industry. We have a significant workforce of something like 15,000 to 20,000 workers in the wholesale meat-processing sector," said Mr McLean.
"We also have the Ministry of Health's National Cancer Registry, which makes this type of research that much easier."
Mr McLean will use worker records provided by Meat Union Aotearoa and the NZ Meatworkers' Union, and then undertake a follow-up study of those who have worked in the industry over the past 30 years.
Rates of certain diseases within that control group will be compared with rates for the general population, and between groups with different levels of exposure.
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