Cadmium Linked to Lung Disease
New research suggests that cadmium is one of the critical ingredients causing emphysema, and even low-level exposure attained through second-hand smoke and other means may also increase the chance of developing lung disease.
The SPH study suggests that higher cadmium levels in the body as much as double the risk of developing a pulmonary disease diagnosis such as emphysema or chronic bronchitis.
Though some studies have linked high levels of cadmium with decreased lung function in occupationally exposed workers, this is only the second known study to show that subjects with even slightly increased levels of cadmium had decreased lung function and the first known study to do so using repeated measures of lung function over time.
"The study suggests that the critical ingredient in smoking that may be causing emphysema is cadmium, a well-known contaminant of cigarette smoke," says Howard Hu, professor and chair of environmental health sciences at SPH and principal investigator in the study. "The worry is if you are exposed to cadmium through other sources you can also be at risk for emphysema." Sung Kyun Park, a research assistant professor in Hu's department, is co–principal investigator; researchers from Harvard and the VA Boston Healthcare System also contributed to the study.
Non-smokers are exposed to cadmium when they eat contaminated foods or inhale second-hand smoke, as well as through a host of occupational exposures. Some consumer groups are concerned about cadmium in sludge and crop fertilizers. It is also widely used in batteries and pigments.
Cadmium is difficult for the body to dispel, Hu says, because kidneys tend to retain the metal, and it recycles into the body.
"The big picture is, we keep learning more about the contributions of environmental toxins to the chronic diseases of aging for which we never suspected an environmental cause," Hu says.
The next step is a much larger, population-based study with more subjects and multiple measurements of cadmium exposure and lung function over time. Hu notes that "with a larger population we will be able to better disentangle the independent effects of cadmium and smoking, and whether dietary cadmium or other non-cigarette sources may also influence lung function."
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