Prospective study of ultraviolet radiation exposure and mortality risk in the United States

Geographic variations in mortality rate in the United States could be due to several hypothesized factors, one of which is exposure to solar ultraviolet radiation (UVR). Limited evidence from previous prospective studies has been inconclusive. The association between ambient residential UVR exposure and total and cause-specific mortality risks in a regionally diverse cohort (346,615 white, non-Hispanic subjects, 50-71 years of age, in the National Institutes of Health (NIH)-AARP Diet and Health Study) was assessed, with accounting for individual-level confounders. UVR exposure (averaged for 1978-1993 and 1996-2005) from NASA's Total Ozone Mapping Spectrometer was linked to the US Census Bureau 2000 census tract of participants' baseline residence. Multivariate-adjusted Cox proportional-hazards models were used to estimate hazard ratios and 95% confidence intervals. Over 12 years, UVR exposure was associated with total deaths (n = 41,425; hazard ratio for highest vs. lowest quartiles (HR_{Q4 vs. Q1}) = 1.06, 95% confidence interval (CI): 1.03, 1.09; P_trend < 0.001) and with deaths (all P_trend < 0.05) due to cancer (HR_{Q4 vs. Q1} = 1.06, 95% CI: 1.02, 1.11), cardiovascular disease (HR_{Q4 vs. Q1} = 1.06, 95% CI: 1.00, 1.12), respiratory disease (HR_{Q4 vs. Q1} = 1.37, 95% CI: 1.21, 1.55), and stroke (HR_{Q4 vs. Q1} = 1.16, 95% CI: 1.01, 1.33) but not with deaths due to injury, diabetes, or infectious disease. These results suggest that UVR exposure might not be beneficial for longevity.