Researchers from Stony Brook University Medical Center have found that women in the United States who have urinary cadmium levels that are below the U.S. Occupational Safety & Health Administration safety standard are at risk for breast cancer. While the study design is not sufficient to identify a causal link between cadmium and osteoporosis, the report revealed that women age 50 years and older who had higher levels of urinary cadmium than other women had a much greater risk for osteoporosis.

According to the World Health Organization, osteoporosis poses a disease burden that exceeds that of high blood pressure (hypertension) and breast cancer. The disease causes deterioration of bone tissue and increased fracture risk, particularly among women age 50 and older. Cadmium – a toxic metal found in foods, tobacco, drinking water and air – has been associated with decreased peripheral bone mineral density (BMD) and osteoporosis.

The U.S. Occupational Safety & Health Administration considers 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,” says 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.”

The researchers emphasize, however, that the SBUMC study is unique from the other similar studies because it is the only one that: 1) identified the cadmium/osteoporosis association in the U.S. population, 2) confirms osteoporosis using femoral BMD, the international standard for diagnosing osteoporosis, and 3) shows an association at or below cadmium levels of 1.00 microgram per gram creatinine or lower.

Two datasets were analyzed for the study – the 1988-1994 National Health and Nutrition Examination Surveys (NHANES), which included 3,207 women age 50 years and older, and the 1999-2004 NHANES, wich included 1,051 women age 50 to 85 years. NHANES is a cross-sectional survey that interviews, examines and conducts laboratory tests on sample U.S. civilians that is statistically representative of the U.S. population. 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.

After adjusting factors within the study population, the researchers also 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.

The researchers further suggest that their findings, detailed in “Urinary Cadmium and Osteoporosis in U.S. Women Age 50 and Older, NHANES 1988-1994 and 1999-2004,” 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.

Ms. Gallagher’s colleagues in the study include Jaymie R. Meliker, Ph.D., Assistant Professor, Department of Preventive Medicine and Graduate Program in Public Health, and John S. Kovach, M.D., Professor, Department of Preventive Medicine.

Environmental Health Perspectives is a monthly journal of research and news on the impact of the environment on human health. The journal is published by the National Institute of Environmental Health Sciences and is the top ranked environmental science journal in the nation.

Part of Stony Brook University School of Medicine, the Graduate Program in Public Health seeks to advance the field of public health through application of the population health principles. The program vision is to improve the health of Long Island and regional populations though education, research, and community service.

The study findings are reported in Environmental Health Perspectives, available online at http://www.ehponline.org/docs/2008/11452/abstract.html.

About Osteoporosis

Osteoporosis is a disease where bone breaks down over time. The bones become thin, brittle and break easily.

'Osteo' means bone, and 'porosis' thinning or becoming more porous, so osteoporosis literally means 'thinning of bone.' It is commonly confused with the word osteoarthritis, which is a form of arthritis that results in breakdown of the cartilage covering the ends of bones. In contrast, osteoporosis is a condition where bone itself breaks down.  Bones then become thin, brittle and easily broken.

The bones most commonly affected by osteoporosis are those in the hip, wrist and back (the vertebrae), particularly those in the mid-back.  Hip fractures are also common in people with osteoporosis, and can lead to immobility and hospitalization.

Many people do not have warning signs for osteoporosis until they have had it for a long period of time.   The first warning sign may be a sudden sharp pain in your back that seems to have come on for no reason.  

Some people with osteoporosis have other family members with it, which suggests that heredity may be a factor. Heredity also plays a role in a person's body type; having a small frame and bone structure may increase the chances of getting osteoporosis Other risk factors may include:

• Lack of exercise. Because bone is a living tissue it needs exercise to stay strong. Normally through the activities of daily living such as walking, bending, stretching, and exercising, forces are imposed upon the bones. Bone responds to these forces by restructuring itself and becoming stronger. If you are not active your bones will become weaker over time because there is nothing for them to respond to.
  
• Diet. Bones need nourishment from calcium, vitamin D, and phosphorous. A poor diet lacking foods that contain these vitamins and minerals contributes to bone loss.
• Life style factors such as smoking and alcohol use. Excessive use of alcohol or caffeine-containing products such as tea, coffee or some sodas can stop your body from absorbing calcium. Smoking also contributes to bone loss.
• Hormone changes. Osteoporosis can also be linked to changes in hormones. Hormones are substances produced by the body that help different organs run normally.  Estrogen is also a hormone that is important to maintaining bone strength. Once a woman enters menopause her estrogen levels fall. This affects how her bones process calcium and may lead to a more rapid loss of bone. For the first five or six years following menopause a woman can lose 3% to 5% of her bone density each year. In men, low levels of the hormone testosterone may have the same effect.
• Medication. Some medications, when taken in high doses, can influence how your body deals with calcium and so contribute to bone loss. These medications include cortisone/corticosteroids, anticoagulants, thyroid supplements, and some anti-convulsive drugs.
• Other illnesses. Other illnesses or diseases, such over-active thyroid, diabetes and rheumatoid arthritis may also cause bone loss.