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Association of ambient air pollution with age-related macular degeneration and retinal thickness in UK Biobank
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    Could the current link between PM2.5 and NOx and age-related macular degeneration be confounded by historic exposure to traffic-related lead air pollution?
    • Esme Fuller-Thomson, Director of Institute for Life Course & Aging, Full Professor at Factor-Inwentash Faculty of Social Work University of Toronto, Ontario, Canada
    • Other Contributors:
      • ZhiDi Deng, Student

    Dear Editor,

    Chua et al,[1] used the UK Biobank to identify an association between higher levels of air pollution and increased odds of age-related macular degeneration (AMD). We hypothesize that exposure to high levels of the air pollutant, lead, before 2000, while gasoline contained lead, may play a role in this observed relationship.

    Lead is a toxic heavy metal pollutant that can accumulate in various tissues in the body, including the retina and bones.[2] Lead exposure can induce inflammation and oxidative stress, processes that can be harmful for the eye.[2]

    Various studies have indicated a link between lead exposure and AMD. An autopsy study reported 50% higher lead levels in AMD-affected eyes than controls’ eyes.[2] A doubling of blood lead levels (BLL) in the Beaver Dam Offspring Study was associated with 60% greater risk of 5-year incident AMD.[3] Analyses of a nationally representative Korean survey found 25% higher odds of late AMD per 1 μg/dl increase in BLL.[4]

    In the late 1970s, mean BLLs were 12 μg/dl higher than today, primarily due to exposure from leaded gasoline.[5] BLLs were even higher among those living close to major roads. Once inhaled, lead can deposit in bones, with a half-life of up to 49 years.[5] While the concentration of lead in air decreased dramatically after lead was removed from gasoline, the lead that has accumulated in bones is slowly released, resulting in persistent endogenous exposure which may negativel...

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    Conflict of Interest:
    None declared.