Female agricultural workers are more at risk of developing leukaemia than all other occupation groups, a Massey University study has found.
Among such workers, market gardeners had the highest risk.
The study, conducted by the university's Centre for Public Health Research, involved interviewing more than 200 cancer patients aged between 25 and 75, as well as nearly 500 people selected from the general population.
It found that the risk of leukaemia among market gardeners and nursery growers was four to five times greater than the public, while crop and vegetable growers also had a higher risk of getting the disease.
Principal researcher Dave McLean says the elevated risks among those groups can probably be attributed to the sorts of agrichemicals they use and which groups of workers have exposure to what.
Mr McLean says a significant proportion of cases are related to exposures at work and therefore could be avoided with better exposure controls.
He has concerns about the health of migrant workers who are often used in the horticulture industry, and whose many problems will not be easily tracked when they return to their home countries.