In their Dec 2021 statement, Bowel Cancer NZ clearly agrees that “Nitrate contamination of water is a serious environmental and public health issue.” They mention blue baby syndrome and negative effects on thyroid function and also that nitrate associated freshwater toxins are harmful to humans. They don’t mention recent studies on adverse birth outcomes including a US study showing that nitrate is also a risk for preterm birth in pregnant people.
They also agree that “Nitrates can enter waterways from animal waste [and] the use of nitrogen-based fertilisers,” and acknowledge that “[it] is unsurprising [that unregistered water supplies had higher levels of nitrates] given these supplies are generally in the countryside where farming and fertiliser use is common.”
These are all strong enough reasons alone for political action on the main sources of nitrate contamination of our drinking water by cutting synthetic nitrogen fertiliser and lowering dairy stocking rates.
The ESR study that Bowel Cancer NZ reference saying nitrate is not a bowel cancer risk for New Zealanders was funded by our biggest dairy company Fonterra and has been criticised for its methodology and bias.
The meta-analysis study Bowel Cancer NZ quotes for bowel cancer risk is currently being retracted and corrected by the journal due to major errors. Unfortunately they do not quote the results of the most comprehensive local research – and internationally published work – which warns that 100 cases of colorectal cancer and 40 deaths per year in New Zealand could be attributable to nitrate in drinking water or the peer-reviewed work by leading epidemiologists in New Zealand that clearly articulates there is a plausible biological mechanism for nitrate to increase the risk of bowel cancer published in the Australian and New Zealand Journal of Public Health.
Bowel Cancer NZ do acknowledge the World Health Organisation says that nitrate is probably carcinogenic which is based on the findings from the 2010 International Agency on Cancer Research (IARC) review which concluded that “ingested nitrate or nitrite under conditions that result in endogenous nitrosation is probably carcinogenic to humans.”
Call on the Government to lower the limit for nitrates in drinking water to safe levels