Is Urinary Cadmium a Biomarker of Long-term Exposure in Humans? A Review
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Cadmium is a naturally-occurring element, and humans are exposed from cigarettes, food, and industrial sources. Following exposure, cadmium accumulates in the kidney and is slowly released into the urine, usually proportionally to the levels found in the kidneys. Cadmium levels in a single spot urine sample have been considered indicative of long-term exposure to cadmium; however, such a potentially exceptional biomarker requires careful scrutiny. In this review, we report good to excellent temporal stability of urinary cadmium (intraclass correlation coefficient 0.66–0.81) regardless of spot urine or first morning void sampling. Factors such as changes in smoking habits and diseases characterized by increased excretion of proteins may produce short-term changes in urinary cadmium levels. We recommend that epidemiologists use this powerful biomarker in prospective studies stratified by smoking status, along with thoughtful consideration of additional factors that can influence renal physiology and cadmium excretion.
KeywordsCadmium Urinary-cadmium Creatinine Biomonitoring Heavy metal Biomarker
We wish to thank Scott Adams, Alfred Bernard, Esther Garcia-Esquinas, Meian He, Ana Navas-Acien, Peggy Reynolds, and Maria Tellez-Plaza who kindly provided additional data from their studies in order for us to prepare Fig. 2 of this manuscript.
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Conflict of Interest
Caterina Vacchi-Suzzi, Danielle Kruse, James Harrington, Keith Levine, and Jaymie R. Meliker declare that they have no conflict of interest.
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This article does not contain any studies with human or animal subjects performed by any of the authors.
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