Anti-sun critics often refer to ultraviolet light as a carcinogen – an oversimplification that is completely inaccurate. Here’s why:
The U.S. National Toxicology Program in 2000 placed ultraviolet light on the federal government’s list of known human carcinogens. In doing so, ultraviolet light became the first item on that list that humans need to live and would die if they didn’t receive.

Putting UV light on the list without explanation misrepresents the nature of the relationship between ultraviolet light and cancer for several reasons:

1. The listing does not mean that moderate tanning will cause skin cancer. Here is why: The criteria to be on the list do not take into consideration the dosage required for a substance to be harmful. That is the problem. Here is a portion of the listing criteria: “The Report does not present quantitative assessments of carcinogenic risk. Listing of substances in the Report, therefore, does not establish that such substances present carcinogenic risks to individuals in their daily lives.” As it applies to UV light, this exclusion makes the listing of UV meaningless.
2. The lack of exposure criteria in NTP’s report downgrades the listing to mean nothing more than overexposure to sunlight may contribute to your risk of skin cancer. Overexposure is exactly what the professional indoor tanning industry is trying to prevent in tanning facilities by controlling your exposure to UV light.
3. The conclusions to support the listing reached by the NTP – which produces the Report on Carcinogens in the Department of Health and Human Services – are divergent from conclusions reached about UV light by the U.S. Food and Drug Administration, which is also an HHS agency. The government is disagreeing with itself.
4. Perhaps most importantly: The list does not take into account that there are positive effects to ultraviolet light exposure. Many forms of cancer – including breast, colon, prostate and ovarian tumors – now appear to be retarded or even prevented by regular exposure to ultraviolet light, which is the body’s most natural and abundant source of vitamin D. This omission on the NTP list is conspicuous, given that positive effects are listed for other substances in the government’s list of carcinogens that have positive effects.

One thing we know for certain: You would be dead today if you did not receive any ultraviolet light. So to call it a carcinogen without pointing out that sunburn – not regular, moderate exposure – is what’s harmful and, more importantly, that humans need sun exposure in order to be healthy is doing everyone a disservice.