Drinking water containing levels of lead below the threshold level that warrants regulatory action in the US may be associated with worse health in people with advanced kidney disease.
“For individuals with heightened susceptibility to lead exposure, such as those with chronic kidney disease, there is no safe amount of lead contamination of drinking water,” says John Danziger at Beth Israel Deaconess Medical Center in Massachusetts.
Danziger and his colleagues analysed health information from 597,968 patients with chronic kidney disease in the US who started dialysis between 2005 and 2017, as well as official data on lead concentrations in city water systems in the five years leading up to their dialysis initiation.
The team found that those who lived in cities with detectable levels of lead in the water systems had significantly lower concentrations of the oxygen-transporting protein haemoglobin in their blood before starting dialysis and during the first month of the therapy than people who lived where lead wasn’t detectable in the water. Lead is known to interfere with the ability of blood cells to produce haemoglobin, increasing the risk of anaemia.
Every 0.01 milligram per litre increase in lead concentration in the water was associated with a 0.02 gram per decilitre reduction in haemoglobin concentration in people’s blood.
The trend was observed even at lead levels below the US Environmental Protection Agency’s threshold of 0.015 milligrams per litre, which mandates regulatory action that can include public education, water treatment and lead service line replacement. “More comprehensive surveillance of household water is critical,” says Danziger.
He and his team also found that Black people were exposed to higher water lead levels on average than white people, which is consistent with previous research revealing racial disparities in exposure to lead and other contaminants. Danziger says this inequality is compounded by the fact that Black people in the US experience higher rates of kidney disease, which may heighten their susceptibility to the effects of lead exposure.
Journal reference: Journal of the American Society of Nephrology, DOI: 10.1681/ASN.2020091281