Associations of low-level urine cadmium with kidney function in lead workers.
OBJECTIVE
Low-level cadmium exposure, resulting in, for example, urinary cadmium <2.0 μg/g creatinine, is widespread; recent data suggest nephrotoxicity even at these low levels. Few studies have examined the impact of low-level cadmium exposure in workers who are occupationally exposed to other nephrotoxicants such as lead.


METHODS
We evaluated associations of urine cadmium, a measure of cumulative dose, with four glomerular filtration measures and N-acetyl-β-D-glucosaminidase (NAG) in lead workers. Recent and cumulative lead doses were assessed via blood and tibia lead, respectively.


RESULTS
In 712 lead workers, mean (SD) blood and tibia lead values, urine cadmium values and estimated glomerular filtration rate (eGFR) using the Modification of Diet in Renal Disease equation were 23.1 (14.1) μg/dl, 26.6 (28.9) μg Pb/g bone mineral, 1.15 (0.66) μg/g creatinine and 97.4 (19.2) ml/min/1.73 m(2), respectively. After adjustment for age, sex, body mass index, urine creatinine, smoking, alcohol, education, annual income, diastolic blood pressure, current or former lead worker job status, new or returning study participant, and blood and tibia lead, higher ln-urine cadmium was associated with higher calculated creatinine clearance, eGFR (β = 8.7 ml/min/1.73 m(2); 95% CI 5.4 to 12.1) and ln-NAG but lower serum creatinine.


CONCLUSIONS
Potential explanations for these results include a normal physiological response in which urine cadmium levels reflect renal filtration, the impact of adjustment for urine dilution with creatinine in models of kidney outcomes, and cadmium-related hyperfiltration.
Weaver
Virginia M
VM
Division of Occupational and Environmental Health, Johns Hopkins University Bloomberg School of Public Health, 615 N Wolfe St, Rm 7041, Baltimore, MD 21205, USA. vweaver@jhsph.edu
Kim
Nam-Soo
NS
Jaar
Bernard G
BG
Schwartz
Brian S
BS
Parsons
Patrick J
PJ
Steuerwald
Amy J
AJ
Todd
Andrew C
AC
Simon
David
D
Lee
Byung-Kook
BK
D000328:Adult; D000367:Age Factors; D000368:Aged; D015415:Biomarkers / Q000378:metabolism; D002104:Cadmium / Q000633:toxicity / Q000652:urine*; D003404:Creatinine / Q000652:urine; D004784:Environmental Monitoring / Q000379:methods; D005260:Female; D005919:Glomerular Filtration Rate / Q000187:drug effects; D006801:Humans; D007668:Kidney / Q000187:drug effects* / Q000502:physiology; D007854:Lead / Q000493:pharmacokinetics / Q000633:toxicity*; D008297:Male; D008669:Metallurgy; D008875:Middle Aged; D016273:Occupational Exposure / Q000009:adverse effects* / Q000032:analysis; D013977:Tibia / Q000378:metabolism; D055815:Young Adult
D015415:Biomarkers; D002104:Cadmium; D007854:Lead; D003404:Creatinine