Despite mounting evidence about the health risks of tanning beds, a new study shows that more than one-third of teenage girls have gone tanning at least once.

Researchers from Case Western Reserve University School of Medicine and University Hospitals in Cleveland looked at a 1996 survey of more than 6,900 teens. They found that 37 percent of girls have used an indoor tanning facility at least once and almost 30 percent of girls have used a tanning booth three or more times.

And the older the girls got, the more likely they were to tan, according to the study, which is published in the September issue of the Archives of Pediatrics and Adolescent Medicine. Only 11.2 percent of the 13- to 14-year-old girls had been tanning three or more times, compared to 47 percent of 18- to 19-year-olds.

Meanwhile, only 11 percent of teenage boys in the study used a tanning booth at least once and 6.9 percent went to a tanning booth three or more times.

Teens who tanned easily were more likely to visit tanning booths, while girls who participated in routine physical activity were less likely to go tanning, according to the study. The researchers also found a higher percentage of indoor tanners among teens from the Midwest and South, from rural areas, and among dieters, as well as among teens reporting recent use of alcohol and tobacco.

Lead researcher Catherine Demko said the majority of teenagers don't have an appreciation for the dangers of the ultraviolet rays involved in indoor tanning. She said there's evidence that indoor tanning might contribute to the risk for malignant melanoma, the most serious kind of skin cancer. Other studies have linked indoor tanning to premature aging.

An editorial in the journal calls for a $20 tax on teen tan salon use -- which officials from the Indoor Tanning Association challenge.

ITA President Dan Humiston argues that regular and moderate exposure to ultraviolet light has a positive effect on health, and instead of taxing teens, officials should educate them about responsible UV exposure.