Consider this familiar storyline: A common, nonessential, human activity is revealed with certainty to harm or kill repeat users. Modest measures get proposed to regulate the activity and protect individual and public health.

The industry that has grown large by promoting the activity, however, is trying to derail the proposed regulation. They say the science isn't conclusive and, besides, individuals should be able to choose for themselves what to do ("Veto tanning bill," Sept. 17).

We could be talking about smoking. Instead, we're talking about the use of indoor tanning beds, which has been conclusively shown to cause melanoma and other cancers. Senate Bill 746 is a common-sense approach to prevent indoor-tanning salons from offering their services to minors.

Under SB 746, anyone 18 and older can absolutely still use tanning beds (and they can buy cigarettes afterward, if they wish). But the principle behind the bill is that the use of indoor tanning beds is risky and the results can be fatal, and so the choice to use them should be — in every sense of the term — an adult decision.

As one might guess, SB 746 is being fought aggressively by the indoor tanning industry, represented by the Indoor Tanning Association. Their claims — that the science is inconclusive and that 15-year-olds know best — could easily have been borrowed from the tobacco industry during the second half of the last century. But their claims need refuting, which is not difficult to do:  The scientific evidence that tanning beds kill is airtight. Multiple studies have specifically confirmed the direct causal connection between indoor tanning beds and deadly skin cancer. These studies have themselves undergone meta-analysis from the International Agency for Research on Cancer, which has classified the radiation from tanning beds as "carcinogenic to humans." A 2004 study in England found that 25 percent of the melanomas found in young women owed to the use of tanning beds.

In 2009 the World Health Organization classified tanning beds as a Level 1 carcinogen, the same as plutonium and cigarettes. The U.S. Department of Health and Human Services and the Food and Drug administration have added tanning beds to their lists of dangerous carcinogens. The house of medicine uniformly agrees tanning beds cause cancer. The American Academy of Pediatrics recommends prohibitions like that in SB 746, which is sponsored by the California Society of Dermatology and Dermatologic Surgery and the Aim at Melanoma Foundation. Health insurers such as Kaiser Permanente and Anthem Blue Cross also support the tanning-bed ban proposed in SB 746. More recently, a Stanford Cancer Institute study in March shows that skin-cancer rates among girls and young women from high-income ZIP codes have doubled in the past 20 years.

* We don't let children smoke cigarettes or buy vodka with parental consent. Current law allows 14- to 17-year-olds to use tanning beds with parental consent, the rationale being that parents can be expected to better understand the risks than do their kids. The parental consent rule, unfortunately, is inadequately enforced. Some forms provide little information beyond space for a signature. In other cases, consent forms can portray "sunburn" as the major health concern rather than malignant cancer. And parents with questions about health and safety are typically on their own, as no specific training in health risks is required of salon employees.

* There is an alternative to tanning beds. There is a safe, effective alternative to tanning beds that many tanning salons already offer: commercial spray tanning. This tanning is growing in popularity, and celebrities such as Snookie of Jersey Shore have switched to spray-tanning. SB 746 is less a threat to tanning salons than an opportunity to serve valued clients in a safer, more responsible way.

Because of the incontrovertible medical evidence linking tanning beds directly to skin cancer, several countries in Europe such as France and England have banned tanning beds for anyone under 18. Brazil has banned tanning beds completely for all ages. In the United States, 30 states have some restrictions on teen UVR tanning. Texas is the most progressive, with a tanning-bed ban for anyone under 16 1/2. New York, Illinois, Ohio and Rhode Island currently have bills in progress similar to SB 746.

It is time we follow where the evidence takes us and urge Gov. Brown to sign a public-health bill that has enjoyed bipartisan support. We in California must act now so that someday we won't have to regret the suffering and loss of life that occurred after we already knew better.

State Sen. Ted W. Lieu, Torrance

Dr. Isaac Neuhaus, San Francisco

Sen. Ted W. Lieu, D-Torrance, represents nearly 1 million Los Angeles-area residents. Dr. Isaac Neuhaus, is a board-certified dermatologist at University of California, San Francisco's School of Medicine and president of the California Society of Dermatology and Dermatologic Surgery. For more, visit http://www.senate.ca.gov/lieu.