Levels of Lead in Residential Drinking Water and Iron Deficiency among Patients with End Stage Kidney Disease.

Abstract

Although those with kidney disease may have heightened susceptibility to heavy metal toxicity, whether low levels of drinking water lead contamination have clinical consequence is unknown. Given that lead toxicity is known to associate with iron deficiency, we merged data from the Environmental Protection Agency (EPA) Safe Drinking Water Information and United States Renal Data Systems to examine whether municipal 90th percentile drinking water lead levels associate with iron deficiency among incident dialysis patients. Iron deficiency was defined across thresholds of transferrin saturation (<10% and 20%) and ferritin (<100 and <200 ng/ml), and simultaneous transferrin saturation <20% and ferritin <200 ng/ml, all obtained within 30 days of dialysis initiation. The average 90th percentile of drinking water lead samples per patient city of residence over a 5-year period before dialysis initiation was examined at the <1 μg/L level of detection, and at the 25th, 50th, and 100th percentile of the EPA's actionable level (15 μg/L). Among 143,754 incident ESKD patients, those in cities with drinking water lead contamination had 1.06 (95% CI, 1.03 to 1.09), 1.06 (95% CI, 1.02 to 1.10), and 1.07 (95% CI, 1.03 to 1.11) higher adjusted odds of a transferrin saturation <20%, ferritin <200 ng/ml, and simultaneous transferrin saturation <20% and ferritin <200 ng/ml, respectively. These associations were apparent across the range of lead levels found commonly in the United States and were significantly greater among Black patients (multiplicative interaction P values between lead and race <0.05). Even exposure to low levels of lead contamination, as commonly found in US drinking water, may have adverse hematologic consequence in patients with advanced kidney disease. These associations are particularly evident among Black people and, although consistent with other environmental injustices facing minorities in the United States, might reflect a greater susceptibility to lead intoxication.