Even low lead levels in drinking water tied to worse kidney disease outcomes

Reuters Health - 23/07/2021 - Kidney disease patients may have lower hemoglobin levels and take higher doses of medication to treat anemia when they're exposed to lead in their drinking water, even at low levels permitted by U.S. regulators, a new study suggests.

Researchers examined data on 597,968 patients who initiated dialysis in the U.S. between 2005 and 2017. Overall, 86% of patients lived in cities with detectable 90th percentile lead levels, while 2% of patients lived in cities with lead levels above threshold allowed by the Environmental Protection Agency (EPA) of 0.015 mg/L.

Patients had average pre-end stage kidney disease (ESKD) hemoglobin of 9.77 g/dL, and each 0.01 m/L increase in community water lead levels was associated with a 0.02 g/dL decrease in hemoglobin concentration, the study found. When researchers corrected hemoglobin concentration for erythropoietin stimulating agent (ESA), patients had average hemoglobin of 9.23 g/dL, and each 0.01 m/L increase in lead levels was associated with a 0.03 g/dL decrease in hemoglobin concentration.

Prior to dialysis initiation, 29% of patients were on ESA therapy. The proportion of patients on ESA therapy steadily climbed with rising lead levels in drinking water; each 0.01 mg/L increase in lead concentration was associated with a 0.4% in increase in the absolute prevalence of pre-ESKD ESA therapy, researchers report in the Journal of the American Society of Nephrology.

When researchers restricted their analysis only to the 585,299 individuals living in cities with lead levels below the EPA actionable threshold of 0.015 mg/L, they still found each 0.01 mg/L increase in lead levels associated with a 0.05 g/dL decrease in pre-ESKD hemoglobin and a 0.4% higher prevalence of pre-ESKD ESA usage.

"While the exact mechanisms remain under investigation, people with kidney disease likely accumulate more lead than those with normal kidney function, so that any given level of environmental exposure has greater potential toxicity," said lead study author Dr. John Danziger, an assistant professor at Harvard Medical School and Beth Israel Deaconess Medical Center in Boston.

"What is most surprising is that these adverse effects seem to be apparent at even the lowest amount of levels of contamination, as found commonly in drinking water in the United States," Dr. Danziger said by email.

One limitation of the study is that researchers were unable to account for how much community drinking water individual patients consumed, the study team notes. Researchers were also unable to account for other sources of lead exposure, which may have influenced the outcomes.

Even so, the results underscore the importance of reducing the incidence or severity of iron deficiency anemia by reducing lead exposure as a first-line therapy for kidney disease, said Erika Mitchell, a senior researcher at Better Life Laboratories, a nonprofit scientific research organization in East Calais, Vermont.

"This therapy should begin with first diagnosis of kidney disease, long before the disease reaches end-stage," Mitchell, who wasn't involved in the study, said by email.

SOURCE: https://bit.ly/3zveoWk Journal of the American Society of Nephrology, online July 15, 2021.

By Lisa Rapaport



Posted on 23 July 20213 August 2021