Occupational exposure to UV light and mortality from multiple sclerosis

Authors

  • M. Westberg MD,

    Corresponding author
    1. Department of Occupational and Environmental Health, Stockholm Centre for Public Health, Stockholm, Sweden
    2. Division of Occupational Medicine, Department of Public Health Sciences, Karolinska Institutet, Stockholm, Sweden
    • Department of Occupational and Environmental Health, Stockholm Centre for Public Health, Norrbacka, 171 76 Stockholm, Sweden.
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  • M. Feychting PhD,

    1. Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
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  • F. Jonsson MD,

    1. Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
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  • G. Nise PhD,

    1. Division of Occupational Medicine, Department of Public Health Sciences, Karolinska Institutet, Stockholm, Sweden
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  • P. Gustavsson MD, PhD

    1. Department of Occupational and Environmental Health, Stockholm Centre for Public Health, Stockholm, Sweden
    2. Division of Occupational Medicine, Department of Public Health Sciences, Karolinska Institutet, Stockholm, Sweden
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  • Compilation of the Cohort was Funded by the Swedish Council for Working Life and Social Research and Stockholm County Council.

Abstract

Background

The etiology of multiple sclerosis (MS) is largely unknown; low exposure to ultraviolet (UV) light has been a suggested risk factor. The aim of this study was to investigate whether occupational exposure to UV light reduces the risk of death from MS.

Methods

The cohort was based on all individuals in the Swedish census in 1980. All MS-related deaths were identified in the national registry of causes of death. A job-exposure matrix was developed to classify the occupational exposure to UV light.

Results

MS was recorded as a cause of the death for 839 individuals. The risk of MS-related death decreased with increasing occupational exposure to UV light. The relative risk adjusted for age, sex, and socioeconomic status was 0.48 (95% CI 0.28–0.80) in the high-exposure group and 0.88 (95% CI 0.73–1.06) in the intermediate-exposure group.

Conclusions

Occupational exposure to UV light was associated with a reduced risk of MS. Our findings are corroborated by previous observations that UV light has a preventive role in the development of MS, although the possibility of reversed causality cannot be completely ruled out. Am. J. Ind. Med. 52:353–357, 2009. © 2009 Wiley-Liss, Inc

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