(Reuters Health) More than one-third of indoor tanning salons don’t follow state laws limiting use by children and teens, a U.S. study suggests.

Researchers posing as minors called 427 tanning salons in 42 states and the District of Columbia and said they wanted to tan before an upcoming family vacation. Tanning facility employees were asked about session costs and whether a parent needed to be present to consent to the tanning session.

Overall, 159 salons, or 37%, failed to follow state laws restricting access for minors, the study found. The most common lapse was allowing teens to book appointments without permission from a parent in states that required parental consent.

Complicated laws were linked to higher rates of noncompliance.

“States that have multiple components to their tanning laws based on age of the minors or parental consent ability had worse compliance than states with simple bans for all minors, similar to bans on cigarettes or alcohol,” said senior study author Dr. Erik Stratman, a dermatologist at the Marshfield Clinic and the University of Wisconsin School of Medicine and Public Health in Madison.

“We believe that straightforward banning for all minors would improve compliance with the law,” Stratman said by email.

Most states have enacted laws to prevent or create barriers to tanning establishments for minors, researchers note in JAMA Dermatology online October 25. Still, nearly 2 million high school students in the U.S. use these facilities.

Banning indoor tanning for anyone under 18 could prevent thousands of melanoma diagnoses and deaths, as well as millions of dollars in treatment costs, researchers point out.

“Because the damaging effects of UV are cumulative over a lifetime, when intense UV exposure occurs during childhood, there is greater chance in that person’s life that enough damage to the skin cells will trigger cancer,” Stratman said.

Tanning salons were less likely to follow state laws in rural areas, the South, and in states where laws applied only to younger minors aged 15 or less, the study found.

Independently owned salons were also less likely to comply with state laws than chain establishments.

One limitation of the study is that the phone encounters might not reflect what would happen if young people came to tanning salons in person to book appointments.

Even if salons are following the law, parents should still refuse to give teens permission to use these facilities, said Dr. Elizabeth Martin, president of Pure Dermatology and Aesthetics in Hoover, Alabama.

“The American Academy of Dermatology’s position is that no minor under 18 should be permitted to use sunlamp products, and this is a position I strongly support,” Martin, who wasn’t involved in the study, said by email. “But in those states in which indoor tanning is currently permitted at a younger age with parental consent, I would impress upon parents that if they allow their teen to patronize indoor tanning facilities, they are increasing their child’s risk of developing cancer.”

Part of the problem with giving parents a choice about teen tanning is that many people don’t realize the risk involved, said Dr. Kathleen Cook Suozzi, a researcher at Yale School of Medicine in New Haven, Connecticut, who wasn’t involved in the study.

“Cigarette smoke is readily accepted as a cause of lung cancer; however, the number of skin cancer cases due to tanning is higher than the number of lung cancer cases due to smoking,” Suozzi said by email.

While tanning is also a cancer risk for adults, teens may not have the same ability to make an informed decision about the health effects of tanning when they go to a salon, said Dr. Henry Lim, president of the American Academy of Dermatology.

“The major risk for young people is that their judgment is not yet fully formed, therefore, they are much more easily misled by false or inaccurate statements from tanning booth operators on the lack of side effects of tanning booth exposure,” Lim, who wasn’t involved in the study, said by email. “In addition, peer pressure for this group is also a major factor that leads to overuse of tanning booths.”