Even low levels of lead in drinking water allowed by the Environmental Protection Agency (EPA) can adversely affect the health of patients with advanced chronic kidney disease (CKD), according to a recent study published in the Journal of the American Society of Nephrology.
Among patients initiating dialysis in the US, those living in places with detectable lead levels in drinking water had significantly lower hemoglobin concentrations prior to development of end-stage kidney disease (ESKD) and increased use of erythropoiesis-stimulating agents compared with individuals living in places without detectable levels.
“Our findings suggest that for patients with kidney disease, there is no safe amount of lead in drinking water,” a team led by John Danziger, MD, of Beth Israel Deaconess Medical Center, Boston, Massachusetts, wrote.
This study is the first nationwide analysis linking EPA water supply records to patient data, according to the investigators.
Dr Danziger and his colleagues analyzed data from 597,968 patients initiating dialysis in the US from January 1, 2005 to December 31, 2017 and who lived in 9566 cities serviced by 21,113 water systems. They merged data from the EPA’s Safe Drinking Water Information System with patient-level data from the US Renal Data System. For their analysis, the investigators used average 90th percentile lead levels in municipal water systems during 5 years prior to dialysis initiation according to city of residence.
Each 0.01 mg/L increase in 90th percentile water lead was significantly associated with 0.02 g/dL lower hemoglobin level and 0.4% increase in ESA use in adjusted analyses. The investigators observed these associations at lead levels below the EPA’s threshold (0.015 mg/L) that mandates regulatory action, according to the investigators.
“The primary finding of our study is that even low levels of lead exposure, as found widely in water systems across the United States, may result in meaningful differences in anemia and ESA utilization for patients with advanced CKD,” Dr Danziger said in an interview.
He also observed, “Low levels of environmental heavy metal contamination remain ubiquitous in the United States, including lead, cadmium, mercury, and others. Given the importance of renal function in heavy metal excretion, better understanding the hazard of such exposure for those with CKD is of great public health urgency.”
Lead toxicity has been linked to neurologic conditions, cardiovascular conditions, and endocrine complications. Dr Danziger and his colleagues concluded that greater efforts to improve the water system infrastructure may be needed to protect individuals with CKD. “Our findings raise broader concerns about the aging water system infrastructure in the United States,” the authors wrote. “The full extent of lead contamination is unknown, in part due to large numbers of lead lines that remain in service and older household plumbing.”
Orlando M. Gutiérrez, MD, professor of nephrology at the University of Alabama at Birmingham, said the new study is important because it addresses an important issue affecting large numbers of patients. “Unfortunately, as with all epidemiologic studies, it’s very hard to know whether the associations described in this study are causally related or just correlations, as the authors acknowledge,” Dr Gutiérrez said.
It may be that communities with higher lead in the water have other characteristics that impact health, such as lower access to health care. For this reason, Dr Gutiérrez said it is premature to draw any definitive conclusions other than it will be important for future studies to disentangle the effects of lead from other potential environmental exposures. “I personally would not make any recommendations about changing drinking habits for my patients based on this study, but it certainly has me worried, and wanting to see further evidence,” Dr Gutiérrez said.
Nephrologist Panduranga Rao, MD, professor of internal medicine at the University of Michigan in Ann Arbor, said a major strength of the study is that it relied on national data from a large number of patients starting dialysis. Additionally, he noted, the findings point to potential approaches that could easily be adopted and result in significant benefits. “It should be pursued further as this is one of the many factors where we can intervene to prevent poor outcomes in chronic kidney disease,” Dr Rao said.
Danziger J, Mukamal KJ, Weinhandl E. Associations of lead concentrations in drinking water with hemoglobin concentrations and erythropoietin stimulating agent use among patients with advanced chronic kidney disease. J Am Soc Nephrol. Published online July 15, 2021. doi:10.1681/ASN.2020091281