Occupational cadmium exposure and calcium excretion, bone density, and osteoporosis in men

Exposure to cadmium has been associated with osteoporosis and fracture risk in women and the elderly, but studies in middle-aged men are lacking. In 83 male (ex)workers (mean age 45 years; range 24 to 64 years) in a radiator factory using cadmium-containing solder, we investigated the association between urinary cadmium excretion (as an index of lifetime body burden); bone mineral density (BMD) in the distal forearm, hip, and lumbar spine (by dual-energy X-ray absorptiometry); and urinary calcium excretion. Geometric mean urinary cadmium concentration was 1.02 microg/g of creatinine (5th to 95th percentile 0.17 to 5.51 microg/g). BMD was negatively correlated with urinary exposure to cadmium. The partial correlation coefficients (r) adjusted for age, body-mass index, and current smoking were -0.30 (p = .008) for BMD in the forearm, -0.27 (p = .017) in the hip, and -0.17 (p = .15) in the spine. Urinary calcium correlated positively (r = 0.23, p = .044) with the urinary cadmium excretion. Adjusted for the same covariates, the risk of osteoporosis (defined as a T-score below -2.5 in at least one measured bone site) increased dose dependently. Compared with the lowest tertile of urinary cadmium, the risks were 4.8- and 9.9-fold higher in the middle and highest tertiles, respectively. Only four (5%) men had evidence of renal tubular dysfunction (beta(2)-microglobulin > 300 microg/g of creatinine). Even in the absence of renal tubular dysfunction, occupational exposure to cadmium is associated in men with lower BMD values, a higher risk of having osteoporosis, and a higher urinary calcium excretion, suggesting a direct osteotoxic effect of cadmium.