A new study raises concerns around the link between bowel cancer and nitrate in drinking water

The research has been done in collaboration with the universities of Otago, Auckland, Victoria, and Loughborough .

It discovered 800-thousand New Zealanders are exposed to nitrate levels found to be a risk in international studies.

It estimates nitrates could cause 100 cases of bowel cancer each year ... leading to 40 deaths.

Otago University Senior Research Fellow Dr Tim Chambers says it highlights the potential health risks, nitrates create.

He says it's cause for concern given nitrate levels are increasing.