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Cadmium exposure increases osteoporosis risk in Chinese adults
Chinese adults living in areas exposed to cadmium pollution for at least 15 years are more likely to develop osteoporosis and show signs of renal impairment compared with those living in areas that are not polluted with the heavy metal, according to findings published in the Journal of Bone and Mineral Research.
“Recent data indicate that adverse health effects of [cadmium] exposure may occur at lower exposure levels than previously anticipated, and the exposure to [cadmium] from food in many areas is high enough to influence human health,” Xingfen Yang, PhD, of the School of Public Health at Southern Medical University in Guangzhou, China, and colleagues wrote. “Based on a review of the literature, the joint Food and Agriculture Organization/[WHO] Expert Committee on Food Additives has concluded that substantial uncertainty exists regarding the long-term effects of [cadmium] on bone.”
In a cross-sectional study, Yang and colleagues analyzed data from 1,116 Chinese adults (45.8% men) aged at least 40 years living in eight villages randomly selected from seven towns that were polluted with cadmium, based on pilot results of cadmium levels found in rice (n = 832), as well as adults living in nonpolluted areas from two towns (n = 284). Participants lived in their villages for at least 15 years and lived on a subsistence diet of rice and vegetables grown in the investigated areas; those with a history of occupational exposure to cadmium or impaired renal function were excluded. Participants provided urine and blood samples to measure urinary cadmium concentration, serum creatinine and albumin, and urinary levels of N-acetyl-beta-D- glucosaminidase (NAG), alpha-1-microglobulin and beta-2-microglobulin; researchers calculated estimated glomerular filtration rate. Bone mineral density was measured via DXA; osteoporosis was defined as a T-score less than –2.5.
Among adults living in the polluted areas, median urinary cadmium concentration was 5.53 µg/g creatinine vs. a median 1.7 µg/g creatinine among those living in nonpolluted areas.
Researchers stratified participants into quartiles based on urinary cadmium concentrations: low (< 2.05 µg/g creatinine); medium-low (2.05-3.97 µg/g creatinine), medium-high (3.97-8.89 µg/g creatinine) and high ( 8.89 µg/g creatinine). Women made up 66.7% of participants in the highest quartile of cadmium exposure.
Researchers found that the prevalence of osteoporosis rose across quartiles, from 10% in the low quartile to 37.6% in the highest quartile; prevalence of eGFR below 60 mL/min/1.73 m² was also higher in participants in higher quartiles.
In logistic regression analyses, increasing urinary cadmium concentrations were associated with greater odds of developing osteoporosis. Compared with participants in the lowest quartile, those in the highest quartile had an OR of 9.15 (95% CI, 5.25-15.94) after adjusting for factors including age, sex, BMI and serum albumin. When comparing nonsmokers only, those in the highest quartile of exposure had an OR of 9.28 (95% CI, 4.56-18.93) for developing osteoporosis compared with those in the lowest quartile.
Analyses excluding participants with an eGFR less than 60 mL/min/1.73 m² strengthened the magnitude of the associations, according to the researchers.
“The results indicated that [cadmium] might act independently on bone,” the researchers wrote. “The findings support efforts to reduce environmental [cadmium] exposure and reassess the maximum permitted level for foods that are naturally enriched in [cadmium].” – by Regina Schaffer
Disclosures: The researchers report no relevant financial disclosures.