Low-level cadmium exposure is associated with decreased cortical thickness, cortical area and trabecular bone volume fraction in elderly men: The MrOS Sweden study.

It is well known that high-level exposure to cadmium can cause bone disease such as osteoporosis, osteomalacia and fractures. However, the effect of low-level exposure, as found in the general population (mainly derived from diet and smoking), has only been assessed recently. The aim of this study was to examine if cadmium exposure in the general Swedish population causes other bone changes than decreased areal bone mineral density as measured by traditional DXA technology, e.g. changes in microstructure and geometry, such as cortical thickness or area, cortical porosity and trabecular bone volume. The study population consisted of 444 men, aged 70-81 years at inclusion year 2002-2004, from the Swedish cohort of the Osteoporotic Fractures in Men Study (MrOS). Cadmium was analyzed in baseline urine samples (U-Cd). Different parameters of bone geometry and microstructure were measured at the distal tibia at follow-up in 2009, including examination with high-resolution peripheral quantitative computed tomography (HR-pQCT). Associations between bone parameters and U-Cd in tertiles were estimated in multivariable analyses, including potential confounding factors (age, smoking, BMI, and physical activity). We found significant associations between U-Cd and several bone geometry or microstructure parameters, with 9% lower cortical thickness (p = 0.03), 7% lower cortical area (p = 0.04), and 5% lower trabecular bone volume fraction (p = 0.02) in the third tertile of U-Cd, using the first tertile as the reference. Furthermore, significant negative associations were found between log-transformed U-Cd and cortical thickness, cortical area, trabecular number and trabecular bone volume fraction, and a significant positive association with trabecular separation. The results indicate that low-level Cd exposure in the general population has negative effects on both cortical and trabecular bone.