Lead levels commonly found in US drinking water may worsen kidney health

Key takeaways:

• Lead levels commonly found in U.S. drinking water were linked to several measures of hematologic toxic effects.
• This is particularly harmful for patients with kidney failure, researchers said.

Low levels of lead contamination were often found in drinking water among United States households and may be particularly harmful for susceptible individuals, researchers reported in JAMA Internal Medicine.

“Individuals with chronic kidney disease (CKD) are disproportionately susceptible to heavy metal accumulation due to increased gastrointestinal absorption and decreased urinary excretion,” John Danziger, MD, MPhil, an academic and clinical nephrologist at Beth Israel Deaconess Medical Center and assistant professor at Harvard Medical School, and colleagues wrote.

Danziger and colleagues conducted a cross-sectional study of 6,404 patients with incident kidney failure — 65% of whom were men — and followed up for the first 90 days of dialysis. Of the participants, 742 — 12% — had measurable lead in their household’s drinking water. The researchers evaluated the hematologic toxic effects, which they defined by monthly erythropoiesis-stimulating agent (ESA) dosing, of lead contamination.

A higher category of lead contamination in a household’s drinking water was most notably linked to a 15% (OR = 1.15; 95% CI, 1.04-1.27) higher risk for maximum monthly ESA dosing. More lead content was also associated with a 0.48% (95% CI, 0.002-0.96) higher monthly resistance index and a 4.5 g (95% CI, 0.8-8.2) higher monthly ESA dose.

“Our findings suggest that lead contamination has detectable, clinically relevant adverse effects in at-risk individuals, even at levels below the current Environmental Protection Agency actionable threshold for U.S. households,” Danziger and colleagues wrote.

The researchers also found that, for the 2,648 patients with pre-kidney failure hemoglobin measures, a higher household lead categorization was associated with a 0.12 g/dL (95% CI, 0.23 to 0.002) lower concentration of hemoglobin. The effects were particularly strong for those with concurrent iron deficiency; their hemoglobin concentrations were 0.25 g/dL (95% CI, 0.47 to 0.04) lower.

“Given the scope of our findings, more rigorous assessment of household water quality in the U.S. and its association with health outcomes in susceptible populations may be warranted,” Danziger and colleagues wrote.

The researchers additionally warned that further consequences — other than “the direct hematologic effects of lead poisoning” like “the morbidity of lower hemoglobin levels” and “the financial burden of higher ESA dosing” — are possible. For example, considering that lead is nephrotoxic, “ongoing exposure may accelerate CKD progression, leading to a feed-forward cycle in which lead exposure drives its own accumulation due to impaired excretion.

“Thus, these findings documenting an association between household water lead contamination and hematologic toxic effects in kidney failure may signal even greater lead-associated morbidity among patients with CKD,” Danziger and colleagues wrote.