Background: Walking speed is a practical measure of physical performance and mobility in older adults and has been considered as an informative “vital sign”. Environmental exposure to cadmium, even at low levels, are associated with neurologic, vascular, and cognitive dysfunction, which may be connected with physical function decline. We aimed to investigate the associations of cadmium concentrations in blood and urine with walking speed in the US general population.
Methods: The present study used data of 3,787 participants aged ≥50 years from the National Health and Nutrition Examination Survey 1999-2002 who had determinations of cadmium concentrations in blood or in urine, and who had measurements of walking speed. Walking speed (ft/sec) was calculated as walked distance (20 ft) divided by time to walk (second).
Results: The weighted geometric means of cadmium concentrations in blood and urine were 0.49 [95% confidence interval (CI): 0.47-0.52] µg/L and 0.37 (95% CI: 0.34-0.42) ng/mL, respectively. The highest (vs. lowest) quintile of blood cadmium was associated with 0.18 (95% CI: 0.10, 0.25) ft/sec reduction in walking speed (P-trend <0.001) after adjusting for sociodemographic, anthropometric, health-related behavioral, and biomarkers for inflammation and clinical health conditions. However, no association was observed for urine cadmium levels with walking speed.
Conclusions: We found that the cadmium concentrations in blood, but not in urine, were associated with a reduced walking speed. Our findings suggest that cadmium exposure even at low levels contribute to physical function decline in the general population.