By JANE E. BRODY


At risk for skin cancers, even with brief exposure.

Despite dermatologists’ repeated warnings, millions of people continue to abuse the ultraviolet rays that in small doses help maintain health but in larger doses can destroy it.

The widespread belief that people look better with a tan has helped to foster the multibillion-dollar indoor tanning industry .

But an explanation has emerged that offers considerable scientific support: the idea that exposing one’s skin to ultraviolet radiation has addictive potential.

There are enough UV abusers to warrant a new medical diagnostic category: tanning addiction.

In a report in The Skin Cancer Foundation Journal, Dr. Robin L. Hornung and Solmaz Poorsattar of the University of Washington in Seattle wrote that the “continued purposeful exposure to a known cancercausing agent suggests that factors besides lack of knowledge are driving individuals to tan.” In addition to a tanned appearance , “tanners also report mood enhancement, relaxation and socialization” as their reasons, the authors wrote.

And so the incidence of skin cancers, including potentially fatal melanoma, continues to rise. This year, 3.5 million new cases of skin cancers, and an estimated 68,720 melanomas, will be diagnosed among Americans.

Even brief exposure to UV light can cause mutations in the DNA of skin cells, including the host cells for melanoma. With enough mutations a cancer can result.

“As we age, the number of mutations increase and our immunity wanes,” said Richard F. Wagner Jr., a dermatologist at the University of Texas Medical Branch in Galveston .

Dr. Wagner, with Dr. Molly M. Warthan and Tatsuo Uchida, conducted two tests of substance abuse on 145 people at a local beach. One is a modified version of the test often used to root out alcohol addiction : Have you ever felt you needed to cut down on your tanning? Have people annoyed you by criticizing your tanning? Have you ever felt guilty about tanning? Have you ever felt a need to tan first thing in the morning ? as an eye opener?

The authors found that 26 percent of the beachgoers met the criteria for addiction. And in a second test, a modified version of the psychiatric profession’s official diagnostic criteria for a substance abuse disorder, 53 percent of the respondents scored positively.

Research by Dr. Steven R. Feldman and colleagues at Wake Forest University Baptist Medical Center in North Carolina demonstrated that frequent salon tanners experienced withdrawal symptoms when given the drug naltrexone, which blocks the pleasurable effects of narcotics. Frequent tanners reported symptoms like nausea and jitteriness when naltrexone blocked their endorphins.