Are women's breasts getting too big?

That's what one author is saying in a new book Breasts: A Natural and Unnatural History, Medical Daily reported.  According to her research, author Florence Williams found that the average bra size for women in the U.S. has increased from 34 B to 36 C - a trend that Williams says isn't as good as it sounds.

Williams outlines numerous unpleasant reasons that may be contributing to expanding bra sizes, such as women's expanding waistlines - a factor that has been linked with increased risk of breast cancer.

Another culprit behind growing cups is early onset puberty, another precursor for breast cancer, Medical Daily said.  According to a 2010 study in Pediatrics, 15 percent of American girls start to get breast tissue when they're only seven years old.

Once a woman develops large breasts, she's put at a greater risk of pollution exposure.  Bigger breasts have a much higher concentration of fatty tissue, and according to Medical Daily, the body stores toxic chemicals in its fat cells.