Susceptibility to environmental heavy metal toxicity among Americans with kidney disease Original paper

What was studied?

This original investigation examined heavy metal toxicity in CKD by evaluating how impaired renal function alters the body’s handling of environmental lead and cadmium. Using NHANES 1999–2002 data, the study quantified associations between estimated glomerular filtration rate and circulating versus urinary concentrations of these metals. Because lead and cadmium accumulate in soft tissues and bone and are eliminated primarily through renal pathways, the authors investigated whether reduced kidney function increases susceptibility to environmental exposure even at low levels commonly encountered in the United States. The analysis also assessed racial and ethnic differences in circulating metal levels to determine whether certain groups show disproportionate vulnerability. This included stratified examination of Black, White, Hispanic, and other racial groups to determine whether renal impairment interacts with environmental exposure to elevate toxic burden. Visual data depicts the inverse relationship between eGFR and blood concentrations of lead and cadmium, illustrating higher metal levels among individuals with lower filtration capacity.

Who was studied?

The study population included 5638 NHANES participants with cystatin C measurements, representing a nationally representative civilian, noninstitutionalized US population. Participants ranged from adolescents to older adults, with oversampling of individuals aged ≥60 years. Of these, 17% met criteria for chronic kidney disease (eGFR <60 ml min 1.73 m²). racial diversity was considerable: approximately 43% white, 21% black, and 32% hispanic among those without ckd, with higher proportions of white participants ckd. a subgroup 1852 also had urinary lead cadmium levels measured, allowing assessment excretion patterns. the dataset included detailed demographic, socioeconomic, household characteristics, providing rich covariate control in multivariate modeling. age differences between ckd non-ckd groups were large, averaging 74.6 years. study therefore captures broad cross-section americans exposed to ambient environmental metals.< p>

Most important findings

The study demonstrated that lower eGFR is strongly associated with higher blood concentrations of both lead and cadmium, while simultaneously predicting reduced urinary excretion of lead. Individuals with CKD showed a 0.23 μg/dL higher lead level compared with those with normal kidney function, despite having lower urinary lead concentrations, supporting reduced renal clearance. Page 3’s regression output (Table 2) shows a statistically significant interaction between Black race and eGFR, with Black participants experiencing a markedly larger rise in blood lead per decrement in renal function. Cadmium exhibited weaker racial modification and smaller absolute differences, but still rose with declining eGFR. These findings support the hypothesis that CKD heightens long-term accumulation of toxic metals, particularly lead, increasing systemic burden and potential toxicity.

Key implications

The findings suggest that declining renal function transforms even low-level environmental exposures into a greater systemic hazard by reducing elimination and increasing total body burden. This vulnerability is amplified in Black Americans, reflecting both physiologic interactions and known environmental inequities. Clinically, this indicates that CKD patients may require stricter environmental safeguards and monitoring of cumulative exposure. Public health measures that reduce community lead exposure may disproportionately benefit individuals with impaired kidney function.

Citation

Danziger J, Dodge LE, Hu H, Mukamal KJ. Susceptibility to environmental heavy metal toxicity among Americans with kidney disease. Kidney360. 2022;3(7):1191-1196. doi:10.34067/KID.0006782021