Association of sun-seeking behaviors with indoor tanning behavior in US white females during high school/college in Nurses' Health Study II.

Background: Frequent exposure to ultraviolet light has more detrimental and longer-term effects on the skin in early life than in adulthood. Teenagers with strong sun-seeking behaviors may be more likely to use an indoor tanning bed than those who seek less sun. We aimed to examine associations between sun-seeking behaviors and indoor tanning behavior during high school/college in US females.

Methods: In this cross-sectional study, we used data from The Nurses' Health Study II, a large prospective cohort of US female nurses. We included a total of 81,746 white females who provided responses on the average annual frequency of indoor tanning during high school/college. Our study exposures were number of times/week spent outdoors in a swimsuit and percentage of time wearing sunscreen at the pool/beach as a teenager, weekly hours spent outdoors in direct sunlight during the daytime during high school/college, and number of severe sunburns that blistered between ages 15-20 years. The main outcome was annual frequency of indoor tanning bed usage during high school/college.

Results: In multivariable-adjusted logistic regression, we demonstrated positive associations between sun-seeking behaviors and indoor tanning use. Specifically, teenagers who spent 7 times/week outdoors in a swimsuit (adjusted odds ratio [aOR], 95% confidence interval [CI] for daily vs. <1/week: 2.68, 1.76-4.09) were more likely to use indoor tanning beds ≥ 12 times/year. Teenagers with ≥ 10 sunburns (aOR, 95% CI for ≥ 10 vs. never: 2.18, 1.53-3.10) were more likely to use indoor tanning beds ≥ 12 times/year. Also, teenagers/undergraduates who spent ≥ 5 h/week outdoors in direct sunlight (aOR, 95% CI for ≥ 5 h/week vs. <1 h/week: 2.18, 1.39-3.44) were more likely to use indoor tanning ≥ 12 times/year. However, there was not a significant association between average usage of sunscreen at the pool/beach and average usage of indoor tanning beds. Multivariable-adjusted linear regression models also showed similar results.

Conclusions: Teenagers who spent more time outdoors in a swimsuit/direct sunlight or got more sunburns tended to use indoor tanning more frequently. These findings provide evidence that teenagers with stronger sun-seeking behaviors may have more exposure to artificial ultraviolet radiation as well.