Stacy Squires/Stuff
Christchurch Surgeon and Bowel Cancer NZ medical adviser Frank Frizelle has cautioned against over-interpreting studies that seek to prove a link between nitrates and bowel cancer.
A medical adviser for Bowel Cancer NZ has criticised studies linking lower levels of nitrates in drinking water with an increased risk of bowel cancer. A major Danish study published in 2018 found a significant increase in bowel cancer when nitrate levels were just 0.87 milligrams per litre of water and a 15 per cent increase at 2.1mg per litre. The current safe level in New Zealand, as mandated by the World Health Organisation (WHO), is 11mg per litre.