I read an article discussing a study that women who are living in urban areas have denser breasts than rural women. Studies have shown that a higher breast density may be a factor in the future development of breast cancer.
http://www.ctv.ca/servlet/ArticleNews/story/CTVNews/20071126/breast_density_071126/20071126?hub=CTVNewsAt11 They're not sure what factors in causing denser breast tissue, but they definitely have found a link between density and cancer.
It's an interesting read. As studies change and more information is available it's interesting to find out what information changed, and what stays consistent throughout the years.
Please share what you think about the article...