title: Self-reported sunscreen use and urinary benzophenone-3 concentrations in the United States: NHANES 2003-2006 and 2009-2012.
abstract: BACKGROUND
  Sunscreens protect against skin cancer and other harmful effects of solar ultraviolet radiation (UVR). Epidemiologic and public health surveys often rely on self-reported sunscreen use to estimate sun exposure and avoidance, but questions remain about the validity of self-reports. Benzophenone-3 (BP-3), a common sunscreen ingredient, can be detected in the urine. Prior studies suggest that BP-3 concentrations increase after application of sunscreen.
  
  
  OBJECTIVE
  The goal of this study was to assess the validity of self-reported frequency of sunscreen use in relation to urinary BP-3 concentrations in a representative sample of the general US population, including in sub-groups defined by age, sex and race/ethnicity.
  
  
  METHODS
  To assess the relationship between categorical self-reported sunscreen use and creatinine-corrected urinary BP-3 concentrations, we conducted a linear regression adjusted for age, sex, race/ethnicity, six-month time period, body mass index, education, and sun avoidance behaviors. We tested for effect modification by age, sex, ethnicity and time period of measurement using multiplicative interaction terms and a F test.
  
  
  RESULTS
  BP-3 was positively associated with self-reported frequency of sunscreen use across all ages, sexes, race/ethnicities, and time periods. Crude and multivariate adjusted models were all statistically significant. R-square was relatively low for all models, ranging from 0.15 to 0.43.
  
  
  CONCLUSIONS
  Urinary BP-3 is positively associated with self-reported frequency of sunscreen use in the general US population, even in groups with overall low sunscreen use. These results suggest that self-report is a valid, although weak, way of assessing relative frequencies of sunscreen usage in a population-based study.
authors: Radiation Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Rockville, MD, United States. Electronic address: rachel.zamoiski@nih.gov.
authors: Rachel D
authors: RD
authors: Zamoiski
authors: Radiation Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Rockville, MD, United States.
authors: Elizabeth K
authors: EK
authors: Cahoon
authors: Radiation Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Rockville, MD, United States.
authors: D
authors: D
authors: Michal Freedman
authors: Radiation Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Rockville, MD, United States.
authors: Martha S
authors: MS
authors: Linet
mesh_terms: D001577:Benzophenones / Q000652:urine*; D015415:Biomarkers / Q000652:urine*; D003430:Cross-Sectional Studies; D049674:History, 21st Century; D009749:Nutrition Surveys; D013473:Sunscreening Agents; D014481:United States
chemical_list: D001577:Benzophenones; D015415:Biomarkers; D013473:Sunscreening Agents; C005290:oxybenzone
keywords: Benzophenone-3; NHANES; Sunscreen