Occup Environ Med doi:10.1136/oem.2010.057448
1. Line Kenborg1,
2. Christina F Lassen1,
3. Beate Ritz2,
4. Eva S Schernhammer3,4,
5. Johnni Hansen1,
6. Nicole M Gatto5,
7. Jørgen H Olsen1
1. 1Institute of Cancer Epidemiology, Danish Cancer Society, Copenhagen, Denmark
2. 2Department of Epidemiology and Environmental Sciences, School of Public Health, University of California, Los Angeles, California, USA
3. 3Channing Laboratory, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
4. 4Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts, USA
5. 5Department of Epidemiology, School of Public Health, University of California, Los Angeles, California, USA
1. Correspondence to Line Kenborg, Institute of Cancer Epidemiology, Danish Cancer Society, Strandboulevarden 49, 2100 Copenhagen, Denmark; kenborg at cancer.dk
* Accepted 28 July 2010; * Published Online First 30 September 2010
Objectives Sunlight is the main contributor to vitamin D in humans. Since inadequate levels of vitamin D have been linked to increased risks for neurodegenerative diseases, we examined whether outdoor work is associated with a reduced risk for Parkinson's disease in a population-based case–control study of Danish men.
Methods We identified 3819 men with a primary diagnosis of Parkinson's disease in the period 1995–2006 in the Danish National Hospital Register and selected 19?282 age- and sex-matched population controls at random from the Central Population Register. Information on work history was ascertained from the Danish Supplementary Pension Fund and the Central Population Register. Based on trade grouping codes and job titles, we evaluated the extent of outdoor work of study subjects as a proxy of exposure to sunlight.
Results Relying on _trade grouping codes_, we estimated ORs for study subjects with
maximal outdoor work
compared with exclusive indoor work of
0.90 (95% CI 0.78 to 1.02),
0.86 (95% CI 0.75 to 0.99) and
0.72 (95% CI 0.63 to 0.82),
respectively, for Parkinson's disease.
Reduced risks were also found for Parkinson's disease among outdoor workers based on study subjects' job titles.
Conclusions Our findings suggest that men working outdoors have a lower risk for Parkinson's disease.
Further studies of measured vitamin D levels in outdoor workers are warranted to clarify a potential inverse association between vitamin D and the risk for Parkinson's disease.
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