Abstract
New evidence linking nitrate contamination of drinking water to colorectal cancer has prompted the Danish Government to commit to a substantially lower drinking water limit for nitrate, reducing the allowable concentration by almost ten-fold. The new limit of 1.3 mg/L nitrate-nitrogen is based on an independent international expert assessment that concluded existing evidence indicates an increased risk of colorectal cancer at concentrations well below current guideline values (11.3 mg/L).
This development is highly relevant for Aotearoa New Zealand (NZ), where nitrate contamination of groundwater is widespread and increasing in many regions. Given the growing body of epidemiological evidence and the slow pace of international guideline reviews, NZ agencies should consider whether a dedicated reassessment of the current limit is warranted and whether existing regulatory frameworks are adequate to protect drinking water sources from nitrate contamination.