Over the past fortnight Breakfast has been looking at nitrate levels in New Zealand’s drinking water.
And the question that keeps being asked is: how much nitrate is too much nitrate in our water supply?
This is particularly relevant in some areas of New Zealand, where there is intensive dairy farming and bore water supplies.
As the Canterbury District Health Board stated , “typical sources of nitrate include: fertilisers and animal wastes, particularly in areas of intensified farming”.
But opinions vary widely on how much nitrate is too much nitrate.
One school of thought is that our current level of what’s considered acceptable, based on World Health Organization standards, is fine. That’s 11.3mg of nitrate per litre of water.
But Greenpeace, Forest & Bird, the Environmental Defence Society, Choose Clean Water and Fish & Game are all arguing for a much lower limit.
They say it should be under 1mg per litre.
Eleven or one? That’s a big difference.
The case for a lower limit is based on a study out of Denmark, which began with 2.7 million people then focused in on 1.7 million of them.
And this morning, Breakfast spoke to one of the scientists who’s used that study to do extensive research on safe nitrate levels in our water.
Dr Jörg Schullehner, from the Department of Public Health at Aarhus University in Denmark, told Breakfast this morning there are statistically measurable increases in rates of colorectal cancer, and other negative health outcomes, in populations where nitrate levels are lower than what is regarded as acceptable in New Zealand.
Schullehner said science should inform a conversation about nitrate levels in our bore water, which he believes are beyond reliably safe limits in some communities.
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