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Industrial Metal Emissions May Increase Parkinsonís Disease Risk
- Nov 11 2010
A new study reports an increased incidence of Parkinson’s disease (PD) among people who live in urban areas and who are exposed to high levels of manganese, and possibly copper, released into the environment by metal processing, chemical and other industries. The results appear in the October 19 online edition of the American Journal of Epidemiology.
Scientists believe that, in most cases, Parkinson's is caused by a combination of genetic susceptibility and environmental factors. The most compelling evidence for environmental exposures that modify the risk of PD have linked pesticide exposure to higher risk for PD and smoking to a lower risk for PD.
A research study published last year, led by Allison W. Willis, M.D., at the Washington University School of Medicine reported that Parkinson's is more common in urban than in rural areas of the United States (US), and that more people are diagnosed with PD in the Midwest and Northeast than in other areas of the country. Most of the country’s metal-emitting industries are located in the metropolitan areas of these two regions.
The same group of scientists also analyzed the records of US Medicare beneficiaries who had been enrolled since 1995, lived in an urban county (population more than 250,000), and had not moved between 1995 and 2003. In this group, more than 35,000 people were diagnosed with Parkinson's.
The scientists used information on industrial chemical releases, available from the US Environmental Protection Agency, to estimate exposure to copper, lead and manganese. They then compared the incidence of Parkinson's among people living in counties with the highest levels of chemical emissions with the incidence among those living in areas where emissions were lowest.
- In urban counties with little or no industrial release of copper, lead or manganese, 274 people in every 100,000 were diagnosed with Parkinson's.
- In urban counties with the highest levels of manganese emissions, about 490 people in every 100,000 were diagnosed with PD.
- In urban counties with the highest levels copper emissions, about 304 people in every 100,000 were diagnosed with Parkinson's.
- The researchers did not find a strong relationship between Parkinson's and lead emissions.
- Parkinson's was substantially more common among whites and Hispanics than among people of black or Asian ethnicity.
- There was little difference in education, income and property values between people who lived in areas with high and low metal emissions.
What Does it Mean?
Research of environmental exposures is very difficult to conduct. This new study suggests that living in an urban area with industries releasing heavy metals into the environment, particularly manganese and maybe even copper, may increase a person’s risk of developing Parkinson's disease.
The scientists focused on exposure to copper, lead and manganese because these metals have been associated with injury to the same brain pathways that deteriorate in people with PD. However, none of these metals have been previously associated with PD. Since few people are exposed to these metals in the workplace, passive, environmental exposure to them may be an important way in which they cause neurological injury.The researchers caution that there might be other risk factors of living in urban areas that the study does not take into account, for example, exposure to other toxins alone or in combination to heavy metals could confound the study’s findings. Additional studies on environmental exposures that may modify the risk for PD, including metal emission exposure, are required in order to confirm these findings.
What do we know about the causes of Parkinson’s? Read PDF’s web page on this topic.
Reference: Allison Wright Willis, Bradley A. Evanoff, Min Lian, Susan R. Criswell, Brad A. Racette. Geographic and Ethnic Variation in Parkinson Disease: A Population-Based Study of US Medicare Beneficiaries. Neuroepidemiology 2010;34:143-151 (DOI:10.1159/000275491) (http://content.karger.com/produktedb/produkte.asp?typ=fulltext&file=000275491).
Source Date: Nov 12 2010