At some point in the 20th century, Americans decided optical white skin and ill-fitting swimsuits were no longer in style. We lost our repulsion to exposed flesh and began jumping into pools, lakes, and rivers with attire more closely resembling strips of cloth than baggy housedresses. And now, we’re suffering the consequences.

New research from New York University reveals our shifting social norms — from covered-up and pale to bare and bronzed — have left lasting impacts on our risks for melanomas, the most common form of skin cancer. It doesn’t help that men already face a greater risk for the disease; lacking an upper body shield, poor application of sunscreen fails to pick up the slack, raising rates ever higher.

Skin Is In

Led by NYU Professor of Dermatologic Oncology Dr. David Polsky, the research team combed through several sources of historical data, including artwork, advertisements, and prior reviews of Sears department store catalogs. To assess skin exposure levels, they relied on the “rule of nines,” an oft-used shortcut for dividing the body’s surface area into nine-percent increments. Each arm makes up roughly nine percent of a person’s total body, each leg about 18 percent.

Their review showed a number of coinciding trends made for a perfect storm of rising skin cancer rates. Around the 1920s, people started tanning for recreation. “With the Industrial Revolution shifting many lower- and middle-class workers indoors, tanned skin emerged as a symbol of travel, leisure, and wealth,” the report noted. And in the decades that followed, skin exposure matched the newfound desire to glow, increasing from 18 percent to 43 percent in women and from 23 percent to 43 percent in men.

As Americans ditched their baggy swimsuits for skin-exposing bikinis and swim trunks, skin exposure rates jumped from as low as 18 percent to as high as 89 percent. American Journal of Public Health. American Journal of Public Health

But it wasn’t until the 1960s when the rates made their largest leap. The 1946 invention of the bikini, by French designer Louis Reard, had taken hold in the States. And women, looking to keep up with celebrities like Ursula Andress — the iconic (and inaugural) Bond girl who emerges from the sea in Dr. No clad in a white bikini — decided skin was most definitely in. Exposure rates leapt from 47 percent to 80 percent. Around the same time, men shirked their tank tops, leaving only their shorts and moving the needle on exposure from 47 percent to 89 percent.

Here Comes Cancer

What we gained in sex appeal, we matched in disease prevalence. While dermatologists were recommending people use a mild sunscreen as early as the 1960s, it wasn’t until the 1970s when companies began introducing water-resistant versions, and the 1980s when Coppertone developed the first sunscreen to shield against both UV-A and UV-B rays. All the while, melanoma rates were on the uptick.

As the report points out, the final two decades of the 20th century saw accelerated incidence rates in the U.S. Between the 1960s and the 1990s, the “all-site” age-standardized cancer rates in men and women went up 30 percent, while melanoma incidence rose 167 percent in women and 244 percent in men. Still, Americans were unfazed. A 1996 survey showed 56 percent of people believed tanned skin indicated better overall health.

These lax attitudes only reinforced our preference for revealing swimsuits, and continued to pay the price. Between 2000 and 2009, incidence rose from 22.8 to 28.9 cases per 100,000 white patients. Today, the Centers for Disease Control and Prevention show 71,000 men and 42,000 women were diagnosed with melanomas of the skin in 2011. In the same year, just over 8,000 men and 4,000 women died as a result. Skin cancer ranks as the most common form of cancer in the United States.

“Attitudes and behaviors shape exposures,” the researchers conclude. The problem is, we’re comfortable with knowing on an intellectual level that ultraviolet radiation is harmful, but equally apt to satisfy our emotional and social cravings to be tan.

Seeming healthy, in other words, often trumps being healthy. And if the logic can be applied to other arenas of personal health, and the researchers argue it can, then bad habits like smoking, alcohol abuse, and overeating can fall as well.

Source: Chang C, Murzaku E, Penn L, et al. More Skin, More Sun, More Tan, More Melanoma. American Journal of Public Health. 2014.