7 November 2018

Nitrates in drinking water linked to kidney disease

Renal Research Rural

Research in remote Western Australia has raised suspicions that drinking water loaded with nitrates is a factor in high rates of kidney disease.

Dr Christine Jeffries-Stokes, a paediatrician based in the Goldfields city of Kalgoorlie says nitrates in drinking water pose a risk on their own but could also contribute to renal disease by making heavy metals such as uranium soluble in water.

Toxic metal contamination may also explain findings of blood in urine, indicating irritation or inflammation, in the ten populations studied in the Western Desert Kidney Project, conducted by Dr Jeffries-Stokes and co-chief investigator Annette Stokes, an Aboriginal health worker and medical researcher.

They set out to study the prevalence of kidney disease, type 2 diabetes and risk factors in five remote towns and five communities, in conjunction with an arts project, visiting each location for two to three weeks per year in 2013-16.

The test results from the targeted populations – spread over a wide area from Wiluna in the state’s midwest to Tjuntjuntjara in the southeast – came as a shock.

“When we crunched the numbers, to our surprise we found no difference between the Aboriginal and non-Aboriginal children,” Dr Jeffries-Stokes told The Medical Republic, after presenting her research at the Rural Medicine Australia conference last month in Darwin.

“If anything, the non-Aboriginal children tended to be a bit worse off,” she said, adding that they were too few in number to be statistically significant.

“We found children as young as two were at risk, and some of them were starting to show signs of kidney disease.

“The non-Aboriginal adult rates were also much higher than you would have expected. But nearly 95% of the non-Aboriginal adults had not grown up there; they were teachers, nurses and policemen. Their risk had risen to almost an ‘Aboriginal level’ from an urban level in a very short time.”

She said a large majority of those tested had a very low urine pH, a sign of metabolic acidosis, which is implicated in diabetes.

“Acidosis also shortens cell life, and you concentrate the acidosis in the kidneys, so it is going to shorten your kidney cell life more than the rest of you.  That is going to contribute to kidney failure,” she said.

Dr Jeffries-Stokes said she only considered water as a contributor to kidney disease after looking at known risk factors such as diet, illness, food and diabetes.

In raw ground water at remote communities, nitrates routinely far exceeded recommended levels and could be many times the safe level for infants, she said.

High concentrations of nitrates in ground water can occur naturally from decomposed organic matter and the leaching of fertilisers and septic waste, particularly in shallow or unconfined aquifers.

In step with World Health Organisation standards, the permitted level of nitrates under Australian Drinking Water Guidelines (ADWG) is set at 50mg/L for infants up to three months old and 100mg/L for adults and older children.

Some 11 WA communities supplied by the state’s Water Corporation have exemptions from the 50mg/L requirement, however, and water supply in many others falls outside the corporation’s responsibility.

A WA Health spokesperson told The Medical Republic that the department had reviewed Dr Jeffries-Stokes’ findings and all of the drinking water quality results for the communities referenced in her thesis.

“The thesis does not provide sufficient evidence that the nitrate or uranium levels in drinking water, in the affected communities, are responsible for the specific disease burden apparent in the Western Desert, relating to diabetes or kidney disease.

“All drinking water, supplied to the communities mentioned, complies with the Australian Drinking Water Guidelines in relation to uranium and nitrate.”

The spokesperson said there was “no health issue” posed to community members by uranyl nitrate, a water-soluble compound of uranium and nitrate.

“Drinking water abstracted from any groundwater source in Western Australia can be impacted by the local geology,” the spokesperson said, adding that remote towns and communities usually had to rely on a very small number of sources with limited source options.

WA Health said 11 communities supplied by the Water Corporation had been granted an exemption from complying with the 50mg/L nitrate guideline requirement for more than 20 years “without any ill effects being recorded”.

The exemptions had been granted “on the basis that the potential number of persons at risk (bottle-fed infants under the age of three months) is extremely low and that alternate water supplies are made available by the water service provider when this occurs”.

The department said where nitrate levels exceeded 50mg/L, community health staff must provide bottled water for the preparation of babies’ bottles.

According to Dr Jeffries-Stokes, this does not happen in practice in remote towns and communities.

“In more than 25 years as a paediatrician visiting three towns in this region, I had never heard of it,” she said.