Is Urinary Cadmium a Biomarker of Long-term Exposure in Humans? A Review

Abstract

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.

Copper–zinc imbalance induces kidney tubule damage and oxidative stress in a population exposed to chronic environmental cadmium

“…However, the mean urinary Cd level in the high Cd exposure group (GM 3.63, 95% CI 3.51-3.76 μg/g creatinine) was more than twice of that reported in previous studies on general population (Eom et al 2017;Huang et al 2013;Lim et al 2016). Compared to the low Cd exposure group, the high Cd exposure group had many more women and individuals classified as elderly, both of which are known predictors of an elevated body burden of Cd (Jarup et al 1998;Vacchi-Suzzi et al 2016). In addition, the low Cd exposure group had significantly more current-or ex-smokers than the high Cd exposure group.…”

The Effects of a Workplace Health Promotion Program to Decrease Cadmium Exposure Levels in Nickel-Cadmium Battery Workers

“…Similarly, we only used cadmium urine levels for our analysis, which are considered to be a longterm exposure biomarker. Although some authors prefer blood samples to demonstrate short-term changes better (12,19,20), in our case urine testing was a standard part of the check-up and therefore no additional invasive procedures were needed. Finally, there was no control group from the same village where the factory is located, who would only be exposed environmentally.…”

“…Full automation of the manufacturing processes has led to reduction of cadmium exposure in workers, and some positions have become more favourable for women. Simi- larly, the exposure duration for workers was relatively long, so the variations in exposure factors may be reflected in U-Cd levels (12). The insignificant impact of smoking on cadmium levels can be explained by the strict smoking ban in the factory (13).…”

Benchmark dose estimation of urinary and blood cadmium as biomarkers of renal dysfunction among 40‐75‐year‐old non‐smoking women in rural areas of southwest China

“…Exposure to Cd occurs through intake of contaminated food or water, or by inhalation of polluted air, including cigarette smoke and indoor dust contaminated with Cd (Hogervorst et al, ; Jarup, Berglund, Elinder, Nordberg, & Vahter, ; Nawrot et al, ). Approximately 50% of accumulated Cd is prone to be stored in the kidneys with an estimated half‐life of 10‐30 years, while a small portion of Cd is slowly but continuously excreted in the urine (Johri, Jacquillet, & Unwin, ; Nordberg, ; Vacchi‐Suzzi, Kruse, Harrington, Levine, & Meliker, ). Therefore, urinary Cd (U‐Cd) has the potential to reflect long‐term exposure to Cd, whereas blood Cd (B‐Cd) may reflect a combination of long‐term and more recent exposures (Vacchi‐Suzzi et al, ).…”

“…Approximately 50% of accumulated Cd is prone to be stored in the kidneys with an estimated half‐life of 10‐30 years, while a small portion of Cd is slowly but continuously excreted in the urine (Johri, Jacquillet, & Unwin, ; Nordberg, ; Vacchi‐Suzzi, Kruse, Harrington, Levine, & Meliker, ). Therefore, urinary Cd (U‐Cd) has the potential to reflect long‐term exposure to Cd, whereas blood Cd (B‐Cd) may reflect a combination of long‐term and more recent exposures (Vacchi‐Suzzi et al, ). U‐Cd excretion also reflects cumulative Cd exposure or body burden more accurately than estimated Cd intake (Vacchi‐Suzzi et al, ).…”