A new national study suggests that around 120 premature births occur each year in New Zealand as a result of drinking water contaminated with nitrates linked to the country’s agricultural sector.
Scientists at Canterbury, Otago, and Massey universities identified a “significant” link between nitrate levels in drinking water and early births — and notably, the association held even when nitrate concentrations were far below New Zealand’s legal limit of 11.3 milligrams per litre. The researchers also found that as nitrate levels climbed, the risk grew stronger, with “stronger associations for more severe outcomes.”
The findings carry particular weight in New Zealand, where farming is a cornerstone of the national economy and nitrates rank among the most frequently detected contaminants in drinking water supplies.
The dairy industry is New Zealand’s top export earner, projected to generate a record NZ$28.6 billion ($16.56 billion) in revenue for the year ending June 2026, according to government figures. Nitrate contamination is largely traced back to the use of fertilizers and runoff from livestock manure.
Environmental organization Greenpeace called on dairy companies, including Fonterra, to be held accountable for the pollution. Campaigner Will Appelbe released a statement saying, “We need to stop nitrate pollution at the source. That means regulating the intensive dairy industry, and limiting the amount of synthetic nitrogen fertiliser that can be applied to the land.”
Fonterra declined to comment directly, instead pointing reporters to the industry group DairyNZ. That organization responded by saying questions around public health and drinking water standards fall under the jurisdiction of health and regulatory agencies, which are tasked with evaluating scientific evidence. New Zealand’s Ministry of Primary Industries had not responded to requests for comment at the time of publication.
The study examined more than 735,000 births recorded between 2008 and 2021 and is scheduled to appear in the peer-reviewed journal Environmental Research in September. The authors found connections between pre-natal nitrate exposure and premature births across all categories. When the study applied a causal assumption, it determined that nitrate exposure could be responsible for approximately 120 premature births annually — accounting for about 4% of pregnancies that ended between 20 and 37 weeks.
