The standard, pro-sunscreen explanation is that, like lung cancer, the disease has a long lag time, on the order of 20 years. Americans began sunbathing in earnest in the 1950s, and as a result, the melanoma epidemic hit in the 1970s. But even a cursory look at the history of sunbathing washes this explanation away faster than a sand castle in a hurricane. Ask any elderly person you know. Beaches around the country were jammed on summer weekends in the 1930s.
Sunscreen promoters offer no clue.
Meanwhile, ever since the melanoma rate began soaring, health authorities have exhorted us to use sunscreen. Americans have clearly taken this advice to heart. If melanoma has a 20-year lag time and sunscreen is protective, the melanoma rate should have started to level off by now. Instead, it's climbing. In 1980, an American's lifetime melanoma risk was 1 in 250.