Canterbury's medical officer of health is calling for research into whether the region's drinking water increases the risk of bowel cancer.
A Danish study has suggested a connection between even very low nitrate levels and colorectal cancer.
Dr Alistair Humphrey has spoken to the researchers and says given Canterbury has high rates of bowel cancer and growing problems with nitrates in the water, it's time for New Zealand to do its own research.
Canterbury has more than 1.3 million dairy cattle making the region one of the densest dairy-agro industrial plants in the world.
Dr Alistair Humphrey talks to Susie Ferguson.