In this study, we sought to better characterize individuals under age 40 who engaged in indoor tanning. Indoor tanning was strikingly common in our population, with approximately three-quarters of females and just over one-third of males having tanned indoors at least once before age 40. Our finding that females were more likely than males to use tanning beds is well supported in the literature [21
]. Our data on indoor tanning across specific age periods indicated that both males and females were most likely to have engaged in this activity under age 30, which is also in line with existing research [21
With unique comprehensive lifetime indoor tanning data, we found that one quarter of female indoor tanners 31 or older were persistent tanners, as they had engaged in indoor tanning throughout the queried age periods. The persistent female indoor tanners tended to be less educated, drank more alcohol, and sunbathed outdoors more frequently than other females who only occasionally tanned indoors. Among these older females, the correlates of persistent indoor tanning were similar to findings among college-age and adolescent females where indoor tanning has been positively associated with both risk taking [25
] and unhealthy lifestyle [26
] behaviors. Since indoor tanning is less common in males there is less descriptive research in this population, yet a recent study in adolescent males found that indoor tanning correlated with binge drinking, unhealthy weight control practices, and steroid use [32
]. The clustering of addictive behaviors, such as smoking and drinking, with indoor tanning may reflect more general risk taking behavior, although it may also correlate with an addictive tendency, since some have posited that indoor tanning may be a biologic dependency [33
]. Additional research on addiction in relation to indoor tanning is needed because interventions aimed at those who persistently tan indoors may need to focus on addiction rather than skin health or cancer prevention messages.
Pigment characteristics such as eye color, skin color, and skin reaction to UV exposure are commonly used to identify individuals at higher risk of skin cancer [4
]. Overall, we found that people with lighter pigment traits who would be more likely to burn with UV exposure were less likely to engage in indoor tanning compared to those with darker phenotypes. Nonetheless, within the most at-risk phenotypes, there was still a large proportion of participants, especially females, engaging in indoor tanning. For example, among the 14 females who said that prolonged sun exposure would yield no tan and just freckling, approximately 30% had tanned indoors at least once in their lifetime. Similarly, among females who reported they would experience at least some burning upon one hour exposure to the summer sun, 68% had tanned indoors at least once.
Strengths of our study include the detailed lifetime indoor tanning history that enabled us to determine not only ever versus never use of indoor tanning beds/booths, but also frequency as well as persistence over time to evaluate potential differences between different types of indoor tanners. From the detailed in-person interview, we also had a wide range of sociodemographic and lifestyle variables to evaluate as potential correlates. A limitation to our study is that our participants were controls with a benign skin biopsy from a case-control study on BCC. It could be argued that this group of participants may be more aware of their skin health or overall health than the general population, as they were seen by a dermatologist. It is unclear what effect, if any, this choice of a study population could have on the applicability of our findings to the general population. If our controls were more aware of their skin health than other persons under age 40 in Connecticut, the true use of indoor tanning in this age group could be higher than what we observed. Alternatively, our population might be enriched in persons focused on their appearance and therefore might be more likely to use indoor tanning. While our control group might affect our prevalence estimates, this has less of an impact on the correlates of tanning. Another limitation to this study was the self-reported nature of all of the measures of interest. Our method of data collection relied on participants' willingness to give complete and true answers and also on their ability to accurately recall behavior at different points in their lives.
Age of intense UV exposure may be particularly relevant in relation to skin cancer, as evidence suggests freckling as a child (due to genetic factors and sun exposure) and sunburns early in life are particularly associated with risk of skin malignancies [2
]. In our population, females had a much earlier age of first use of indoor tanning than males. The incidence of both melanoma and non-melanoma skin cancer is increasing [8
] with a marked increase among young people, especially females [13
]. Indoor tanning may underlie, at least partially, this temporal trend. In addition, with several recent studies finding positive dose-response effects for skin cancer with increasing indoor tanning [18
], frequency and duration of exposure in addition to ever versus never use are important factors to consider for risk. In our own early-onset BCC case-control study, ever indoor tanning was associated with a two-fold (OR = 2.14 95% CI = 1.31-3.47) increased risk of BCC compared to never indoor tanning among all females [18
], yet in females over age 31, the risk associated with persistent indoor tanning versus never indoor tanning was even stronger (OR = 2.76, 95% CI = 1.30-5.86) (data not shown).
While individual-level interventions are one avenue for reducing use of tanning beds/booths, legislation has also been enacted to curtail youth utilization of indoor tanning. A telephone survey of indoor tanning facilities in 116 cities in the United States found that businesses in states with youth access laws to tanning beds were significantly more likely to state they would require written permission from a parent for a minor to use the facility [37
]. However, not all research supports policy level changes as a sole means to curtail youth access. A survey of adolescents in the 100 most populous cities in the United States did not find an association between indoor tanning and residing in a state with youth access laws [38
], and studies which employed face-to-face interactions between an indoor tanning facility and a potential youth client found a lack of compliance with parental consent policies [39