Breasts: A Natural and Unnatural History (W.W. Norton, $25.95) is a fine and serious book, even though the title may lead some readers to wonder what it could possibly be about. Far from an x-rated treatment of the subject, it is a highly readable and fascinating documentation of how an essential part of the human anatomy has been altered and harmed by environmental degradation. Florence Williams, a respected environmental reporter, discovered while breast-feeding her child that she had a high percentage of a toxin called perchlorate in her breast milk. This prompted her to do more research (it turns out most women have perchlorate and a lot of other bad stuff in their mammary glands) that explores the history and evolution of breasts, including the early popularity of silicon implants to a frightening rise in breast cancer cases among U.S. servicemen.