More than 62 million Americans may be drinking tap water containing nitrate levels linked to cancer and birth defects, according to a report by the Environmental Working Group.
The nonprofit used water quality data from nearly 50,000 public water systems across all 50 states, covering the years 2021 to 2023.
Nitrates enter drinking water when rainfall washes fertiliser from farm fields into rivers and groundwater. The contamination can travel far from its source, reaching reservoirs that supply major cities.
Federal safety limits for nitrates have not been updated since 1962. They are set at 10 milligrams per liter. Peer-reviewed studies now link health harms to levels as low as 2 milligrams per liter.
More than 6,000 water systems tested at or above 3 milligrams per liter — a level tied to childhood cancers. More than 3 million people were exposed to water at or above the legal limit of 10 milligrams per liter.
The worst-affected system serves just 31 people near Dinuba, California, where levels reached 50 milligrams per liter. Larger cities affected include Los Angeles, Phoenix, Philadelphia and Las Vegas.
Christopher Jones, a biologist and former water quality researcher at the University of Iowa, said groundwater levels of 40 milligrams per liter were not unusual in heavily farmed areas.
The Fertiliser Institute said nitrates come from many sources beyond farm fertiliser, including septic systems and vehicle emissions, and argued the report oversimplified the causes of elevated levels.
For households concerned about contamination, Jones recommended a reverse osmosis filter on the kitchen cold-water tap. He said there was no risk from bathing or washing dishes in high-nitrate water.
Sources : CNN
