A mismatch of expectation and realization. That is said to be a reason why sunscreen use is a risk factor in melanoma. Researcher Brian Diffey, of the UK’s Newcastle General Hospital, said the SPF numbering system on sunscreens is misleading people into believing the numbers actually indicate how much longer it takes the skin to burn than unprotected skin. His comments find merit as Americans went from spending $18 million on sunscreen products in 1972 to $500 million in 1996, while risk of melanoma has gone from 1 in 1,500 people in 1930 to an expected 1 in 75 this year. In a Reuters Health January 2000 report, Diffey cites a study which found that “people who say they usually or always use sunscreen with SPF of 15 or higher are more likely to burn than those who rarely or never use sunscreen.” The reason? Diffey believes most people apply less sunscreen than used in manufacturers’ tests, miss areas of their bodies, and overexpose themselves to the sun on the belief of ultimate protection.