Environmental exposure to cadmium, forearm bone density, and risk of fractures: prospective population study. Public Health and Environmental Exposure to Cadmium (PheeCad) Study Group.
BACKGROUND
Chronic low-level exposure to cadmium may promote calcium loss via urinary excretion. We undertook a prospective population study to investigate whether environmental exposure to cadmium lowers bone density and increases risk of fractures.


METHODS
We measured urinary cadmium excretion, a biomarker of lifetime exposure, in people from ten districts of Belgium, of which six districts bordered on three zinc smelters. We also measured cadmium in soil and in vegetables from the districts, and collected data on incidence of fractures and height loss. Bone density was measured at the forearm just above the wrist by single photon absorptiometry, and calculated as the mean of six proximal and four distal scans.


RESULTS
Mean cadmium excretion at baseline was 8.7 nmol daily. Across the ten districts, mean cadmium concentration in soil ranged from 0.8 to 14.7 mg/kg, and from 0.1 to 4.0 mg/kg dry weight in vegetables. Median follow-up was 6.6 years. Mean forearm bone density in proximal and distal scans was 0.54 g/cm2 and 0.43 g/cm2 in men, and 0.44 g/cm2 and 0.34 g/cm2 in women. In postmenopausal women, a twofold increase in urinary cadmium correlated with 0.01 g/cm2 decrease in bone density (p<0.02). The relative risks associated with doubled urinary cadmium were 1.73 (95% CI 1.16-2.57; p=0.007) for fractures in women and 1.60 (0.94-2.72, p=0.08) for height loss in men. Cadmium excretion in districts near smelters was 22.8% higher (p=0.001) than in other districts, with fracture rates of 16.0 and 10.3 cases per 1000 person-years, respectively, and a population-attributable risk of 35.0%.


CONCLUSIONS
Even at a low degree of environmental exposure, cadmium may promote skeletal demineralisation, which may lead to increased bone fragility and raised risk of fractures.
Staessen
J A
JA
The Hypertensie en Cardiovasculaire Revalidatie Eenheid, Departement Moleculair en Cardiovasculair Onderzoek, Katholieke Universiteit Leuven, Belgium. jan.staessen@med.kuleuven.ac.be
Roels
H A
HA
Emelianov
D
D
Kuznetsova
T
T
Thijs
L
L
Vangronsveld
J
J
Fagard
R
R
D015502:Absorptiometry, Photon; D000328:Adult; D017677:Age Distribution; D000368:Aged; D001530:Belgium / Q000453:epidemiology; D001827:Body Height / Q000187:drug effects; D015519:Bone Density / Q000187:drug effects*; D002104:Cadmium / Q000009:adverse effects* / Q000032:analysis / Q000652:urine; D004781:Environmental Exposure / Q000009:adverse effects* / Q000032:analysis; D004784:Environmental Monitoring; D062665:Epidemiological Monitoring; D005260:Female; D005542:Forearm; D050723:Fractures, Bone / Q000139:chemically induced* / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D008297:Male; D008669:Metallurgy; D008875:Middle Aged; D011159:Population Surveillance; D011446:Prospective Studies; D012111:Residence Characteristics; D012307:Risk Factors; D017678:Sex Distribution; D012989:Soil Pollutants / Q000032:analysis; D014675:Vegetables / Q000737:chemistry; D015032:Zinc
D012989:Soil Pollutants; D002104:Cadmium; D015032:Zinc