Ten or 20 years ago, people spent more time in the sun. Many of the people who got their sun in the 1970s and 1980s will develop cancer eventually. Unfortunately, there is some anecdotal evidence that sun exposure is having its effects on people earlier in life. Robins reports that the average age of his patients has dropped by seven years, from about 70 in 1965 to the current average age of 63. The younger people who are getting skin cancers commonly have been to tanning beds or have been lifeguards.
Ultraviolet radiation is the offending cause.
The epidemiological evidence of the sun's role in America's skin cancer boom is convincing, perhaps even overwhelming, experts say. But some believe other factors are also playing a role. The thinning of the ozone layer is one suspect. At least two major scientific organizations, however, are on record supporting the thinning ozone theory. In addition, the Skin Cancer Foundation estimates that a 5 percent decrease in the ozone layer will result in a 10 percent increase in biologically effective radiation from the sun, which could increase melanoma rates by 5 to 7 percent, basal cell cancer by 10 percent, and squamous cell cancer by 20 percent for those living in ozone-poor areas.