Saturday, December 4

Polluted water can cause 40 deaths a year in New Zealand: study

New research has found that nitrate contamination in our drinking water could lead to 40 deaths a year from bowel cancer.

A glass of water showing a farm

Photo: RNZ / Vinay Ranchhod

Research from the Universities of Otago, Loughborough, Auckland and Victoria found that 800,000 people in New Zealand are exposed to nitrate levels in water that are higher than what is considered a risk in international studies.

The University of Otago Principal Investigator in the Department of Public Health, Dr. Tim Chambers, said it is the first study to assess the level of nitrate exposure in New Zealand and compile a national data set on water quality. potable.

“So we found that around 800,000 people may have water supplies above the thresholds seen in international studies linking nitrate to bowel cancer.

“We also estimate based on that, that potentially in New Zealand there could be around 100 cases and around 40 deaths from bowel cancer attributable to nitrate in drinking water.”

Chambers said it showed that a substantial number of New Zealanders had water supplies with nitrate levels that could increase their risk of bowel cancer.

“This research highlights the possible health burden of nitrate contamination, particularly if more evidence on the link between nitrate and bowel cancer strengthens existing studies.

“The results support the need for a precautionary approach to nitrate contamination in New Zealand.”

Nevertheless the study it did not directly assess the link between nitrate exposure and bowel cancer as some epidemiological studies abroad had done.

It is the first of future research to assess the potential impact of water quality on public health in New Zealand after the 2016 Campylobacter Havelock North outbreak, which caused an estimated 8,320 people to become ill, 42 hospitalizations and four deaths.

Chambers said the results showed the need for water reforms, as recent requests from the Official Information Act showed that some councils had not tested drinking water for key contaminants for years, as the legislation did not require it.

The research was associated with a broader body of evidence linking nitrate in drinking water to premature births, low birth weight and birth defects that are a growing concern, he said.

Other environmental research also shows the negative impact of nitrate pollution on freshwater ecosystems and the environment in general.

“While more research is required in this area, particularly around the biological mechanism and additional epidemiological studies, the potential health and environmental impacts of nitrate contamination provide a compelling case for intervention.”

Nitrate pollution in New Zealand is mainly due to livestock, specifically intensive dairy farming. It has increased substantially since 1990 and many groundwater sites continue to degrade.

The likely biological mechanism for nitrates to increase bowel cancer risk is complicated and is influenced by dietary factors, especially the balance of red meat, fruits, and vegetables, and the intestinal microflora.

New Zealand experiences one of the highest rates of bowel cancer in the world with an average of 3,000 cases per year. It is our second leading cause of cancer death, causing an average of 1,200 deaths per year.

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