See article in Stuff (link)
The New Zealand Food Safety Science & Research Centre commissioned its partner, The Institute of Environmental Science and Research (ESR), to assess the levels of nitrates New Zealanders are consuming from both water and food. The Ministry of Business, Innovation and Employment and Fonterra co-funded the research, which was undertaken by Peter Cressey and Dr Belinda Cridge at ESR. Peter will present their findings at a Centre webinar on Wednesday afternoon, 1 September, 1.30pm (register here – it’s free).
A Danish research study in 2018 reported an association between the level of nitrate in drinking water and the occurrence of bowel cancer and a subsequent NZ study also concluded it was a risk factor. These studies caused concern here in New Zealand, where we have high rates of bowel cancer (though these have declined 30% since the peak in 1994), and some private drinking water sources, such as shallow wells, which have elevated nitrate levels.
We believe that it is important to look at nitrate intake from both food and water, as less than 10% of nitrates consumed are in water – the rest is from food, especially green vegetables, which contain antioxidants that cancel out nitrates.
Cressey and Cridge report that, on average, the nitrates New Zealanders take in from food and water add up to about one-quarter of the internationally agreed acceptable daily limit. According to their calculations, only 2.6% of nitrate consumption for adults, and 0.7% for children, is from drinking-water consumed on its own and not in close (less than 1 hour) proximity to eating.
It should be emphasised that the causal link between nitrates and bowel cancer is unproven.