Greenpeace is calling on the Government to take urgent action on nitrate levels in drinking water.
A report out today reinforces known links between intensive dairying, nitrates and bowel cancer.
It says the health of 800,000 New Zealanders could be affected by nitrate water pollution.
"The new study is disturbing, but not entirely unexpected, says Greenpeace campaigner Steve Abel.
He says the report from Victoria and Otago universities confirms what has been long suspected that areas of heavy dairy
farming end up with high nitrate levels in drinking water.
"Where there are too many cows there are high rates of nitrate and where nitrate is high there are higher rates of bowel
Nitrates on dairy farms come from cow urine and nitrogen fertiliser manufactured in Taranaki and sourced from fossil
Greenpeace has been campaigning for several years for a phase out of synthetic nitrogen fertiliser.
"We’ve known for a long time that intensive dairying, driven by synthetic nitrogen fertiliser, is bad for our planet -
causing climate change and contaminating rivers - this new report suggests it could be killing people too."
The link between nitrates in drinking water and bowel cancer was originally established by a Danish study which is
relied on by the New Zealand research.
Last month, Greenpeace delivered a petition signed by 33,000 people calling on the Government to phase out synthetic
nitrogen fertiliser, a key driver of industrial dairying and a known water pollutant.
"Industrial dairy is effectively poisoning public and private water sources for profit and robbing us of something that
belongs to everyone - our most fundamental resource - fresh water.
"The Government must remove dairy’s free-pass to pollute and protect New Zealander’s health. That means phasing out
synthetic nitrogen fertiliser, reducing cow stocking rates and working to ensure everyone has access to clean water."