Breasts are getting bigger. In the past 15 years, the average bust size for North American women has gone from 34B to 36C. That may seem cause for celebration for those dreaming of a world with the proportions of Christina Hendricks, the buxom Mad Men star recently named Esquire’s “sexiest woman alive.” But some theories explaining the development (sorry, couldn’t resist) are more sobering, namely one linking the trend to bisphenol A, or BPA.
Puberty is starting earlier in girls, at around 10 years—nearly a year earlier than a 1991 study indicated. This, along with women having children later or not at all, and lifelong exposure to contraceptive pills, could account for increased estrogen levels in women’s bodies, reported the Sydney Morning Herald. (In Australia, average bra size grew from 32B in 1960 to 36C today.) Add to this more estrogen in the environment, which some scientists say comes from pollutants, pesticides and herbicides taken in through food. Professor Susan Davis of Melbourne’s Monash University told the Sydney paper, “We’re also ingesting chemicals in the environment from industry all the time.” Then there’s the chemical BPA, which is notorious for its potential to wreak hormonal havoc and may contribute to increased estrogen levels and breast size. It’s most often found in certain plastics, sales receipts, and the lining of food and beverage cans.
However, it’s also possible that women are bustier because they’re eating better than they did 60 years ago, with more protein, fresh fruits and veggies, reports the Herald. And some women are bigger up top because they’re bigger all over. In 2007-2008, 68 percent of Americans were either overweight or obese, according to the Centers for Disease Control and Prevention.