WHO urged to review drinking water standards amid nitrate health fears

Dozens of global health and environmental organisations called on the World Health Organization on Tuesday to revise decades-old standards for nitrate levels in drinking water, arguing they do not reflect recent scientific evidence about potential health risks.

In an open letter, 85 organisations, including Greenpeace International and the World Organization of Family Doctors (WONCA), called on the United Nations health agency to include nitrate in an upcoming review of its drinking water guidelines.

The toxic effects of nitrates – a residue left behind by intensive farming – are widely recognised as particularly dangerous for children and pregnant women.

But the current WHO guidelines – which set the maximum acceptable nitrate level in drinking water at 50 milligrammes per litre as nitrate or 11.3 milligrammes per litre as nitrate-nitrogen – date back to 1958 and are “outdated”, the organisations warned.

That level was set specifically to prevent so-called “blue-baby syndrome” – a deadly blood disorder in which the blood’s capacity for carrying oxygen is reduced.

But the limit “has not been updated in response to robust epidemiological evidence linking chronic, low-level nitrate exposure to long-term human health risks”, Tuesday’s letter said, pointing in particular to “colorectal cancer and adverse birth outcomes”.

“Studies now link nitrate in drinking water, at levels well below the current WHO limit, to bowel cancer and premature birth,” WONCA chair Pratyush Kumar said in a joint statement.

‘Decisive action’

The letter was sent to coincide with WHO’s annual One Health Day, which aims to raise awareness about the interconnected health of humans, animals, plants and shared ecosystems.

Surface water models indicate that hundreds of millions of people globally are exposed to elevated nitrate levels, the letter warned.

“Water should be life-giving, not life-threatening,” Amanda Larsson, the global project lead for agriculture at Greenpeace, said in the statement.

“We cannot protect human health without protecting the groundwater and rivers that sustain us,” she insisted.

“Governments must take decisive action to curb the growth of intensive livestock farming and actively support producers in transitioning to ecological farming practices – ensuring that clean, safe drinking water isn’t a luxury but a guarantee.”

The organisations pointed to findings published last year by an expert panel commissioned by the Danish government indicating that the current international standard was insufficient to protect public health.

That expert panel recommended reducing the nitrate limit to 6.0 mg/L – nearly 10 times below the current WHO benchmark – something Denmark committed to earlier this year.

But most national governments base their drinking water standards on WHO guidelines, the organisations said, stressing that updating those guidelines was “vital for global policy reform”.

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