Although breast milk is recognized by doctors, public health officials, and scientists as the best first food for an infant, it is not pure. Many synthetic chemicals released into the environment, intentionally or not, can be found in breast milk. Chemicals such as famous "bad actors" like dichlorodiphenyltrichloroethane, commonly known as DDT, and polychlorinated biphenyls (PCBs), as well as less well-known substances such as flame retardants (polybrominated diphenyl ethers, or PBDEs), have been detected in human breast milk around the world. Many of those synthetic chemicals are known or suspected causes of cancer, and they have been linked to other health problems such as diabetes, reproductive disorders, and impaired brain development. The health benefits of breastfeeding far outweigh the possible negative effects of chemical contaminants in breast milk, but the presence of those chemicals remains a cause for concern among health officials, individuals, and the companies whose products or manufacturing process release toxins into our environment.