Tobacco smoke most common source of exposure to heavy metal, researchers add
FRIDAY, May 24, 2013 (HealthDay News) -- People with high levels of cadmium in their urine are much more likely to die of liver disease than those with lower levels, a new study finds.
A high level of cadmium in urine is evidence of long-term exposure to the heavy metal that is present in industrial pollution and tobacco smoke, the Johns Hopkins researchers explained.
They also said their findings do not show that cadmium directly causes liver disease but instead suggest an association that requires further investigation.
For this study, the researchers analyzed data from more than 12,700 people who took part in the U.S. National Health and Nutrition Examination Survey. People with the highest levels of cadmium in their urine were nearly three and a half times more likely to die of liver disease than those with the lowest levels.
The link between cadmium and liver disease was much stronger in men than in women, according to the study, which was published online in the Journal of Gastrointestinal Surgery.
This may be due to hormonal differences in women that result in the redistribution of stored cadmium from the liver and kidneys (where it can do more damage) to bones (where it remains more stable), the researchers said.
"We already know about the health hazards of heavy metals like lead and mercury, but we don't know much about what cadmium does to the body," study leader Dr. Omar Hyder, a postdoctoral fellow in the department of surgery at the Johns Hopkins University School of Medicine, said in a university news release.
"In mice, chronic cadmium exposure has been shown to cause liver failure, but we need to understand more about the factors that may cause liver disease in humans, and whether we can do anything to prevent it," Hyder said.
Tobacco smoke is the most common single source of cadmium exposure in the general population. Other sources include the burning of fossil fuels and municipal waste. For many years, most batteries in the United States were made with cadmium, which also is used in pigments and plastics.
The U.S. Environmental Protection Agency has more about cadmium and its levels in drinking water (http://water.epa.gov/drink/contaminants/basicinformation/cadmium.cfm ).
SOURCE: Johns Hopkins Medicine, news release, May 2013