Women aged 50 years and above, with low levels of urinary cadmium concentrations are at an increased risk of developing osteoporosis, says a new study.
Cadmium is a toxic metal found in foods, tobacco, drinking water and air.
According to the U.S. Occupational Safety & Health Administration, the safety standard for urinary cadmium levels to be 3.00 microgram per gram creatinine or lower.
"Our study found that women age 50 years and older with urinary cadmium levels between 0.50 and 1.00 microgram per gram creatinine were at 43 percent greater risk for BMD-defined osteoporosis relative to those with levels at or below 0.50," said Carolyn Gallagher, lead investigator and graduate student in the Graduate Program in Public Health.
"These results show statistically significant associations between cadmium exposure and osteoporosis and between cadmium and BMD in the U.S. population. The findings are consistent with previously reported studies in Swedish, Belgian and Japanese populations," she added.
For the study, researchers analysed two datasets from 1988-1994 National Health and Nutrition Examination Surveys (NHANES).
The survey included 3,207 women age 50 years and older, and the 1999-2004 NHANES included 1,051 women age 50 to 85 years.
In the first dataset, osteoporosis was indicated by hip BMD cutoffs based on the international standard. In the second dataset, osteoporosis was indicated by self-report of physician diagnosis.
The team found that urinary cadmium was not significantly associated with osteoporosis among ever-smokers.
This null finding among smokers leads the researchers to believe that dietary cadmium, rather than from tobacco, is the likely source of cadmium-related osteoporosis risk for the U.S. population of women age 50 and older.
Researchers believe that the study results should prompt further investigation of the relationship between cadmium and osteoporosis, as well as a reexamination of the safety levels of cadmium in food, the most common source of cadmium exposure for the general population.
The study is reported in Environmental Health Perspectives.