A Not-So-New Role for Bisphenol A: Mammary Gland Carcinogen

By The Editors

Bisphenol A (BPA) is not just a harmful chemical found in many plastic products — it’s also a news champion, and our guess is we’ll keep hearing about it for a long time. The latest? BPA may act as a complete mammary gland carcinogen.

BPA is a known endocrine disruptor (a chemical able to interfere with the body’s endocrine system and produce adverse developmental, reproductive, neurological, and immune effects in both humans and wildlife) and a potential environmental obesogen (a chemical able to disrupt the normal development and balance of lipid metabolism, which can lead to obesity). Moreover, mounting scientific evidence strongly suggests a link between BPA and cancer.

The Breast Cancer Fund website states: “With regard to mammary development and increased risk for development of breast cancer, several studies using both rat and mouse models have demonstrated that even brief exposures to environmentally relevant doses of BPA during gestation or around the time of birth lead to changes in mammary tissue structure predictive of later development of tumors. Exposure also increased sensitivity to estrogen at puberty. Early exposure to BPA led to abnormalities in mammary tissue development that were observable even during gestation and were maintained into adulthood. Prenatal exposure of rats to BPA resulted in increases in the number of pre-cancerous lesions and in situ tumors (carcinomas), as well as an increased number of mammary tumors following adulthood exposures to subthreshold doses (lower than that needed to induce tumors) of known carcinogens.”

Now, a new study published in the scientific journal Environmental Health Perspectives (Perinatally Administered Bisphenol A Acts as a Mammary Gland Carcinogen in Rats, July 23, 2013) concludes that “Developmental exposure to environmentally relevant levels of BPA during gestation and lactation induces mammary gland neoplasms in the absence of any additional carcinogenic treatment. Thus, BPA may act as a complete mammary gland carcinogen”.

For their study, the authors used Sprague­Dawley rats, a strain used extensively for toxicology and carcinogenesis studies by the National Toxicology Program at the National Institute of Environmental Health Sciences. Pregnant rats were treated with a wide range of BPA doses for different exposure times. The mammary glands from the offspring were then examined for preneoplastic and neoplastic lesions. Unexpectedly, the investigators observed large mammary carcinomas occurring at BPA doses relevant to human exposure. Tumors were found in animals exposed to BPA across all doses and exposure times.

BPA is the building block of polycarbonate plastic. It’s also used in the manufacture of epoxy resins found in many common consumer products as well as in thermal receipts and other paper products.

Polycarbonate plastics have many applications including use in some food and drink packaging, e.g., water and infant bottles, compact discs, impact-resistant safety equipment, and medical devices. Epoxy resins are used as lacquers to coat metal products such as food cans, bottle tops, and water supply pipes. Some dental sealants and composites may also contribute to BPA exposure.

Below are some suggestions from the National Institute of Environmental Health Sciences to limit daily exposure to BPA:

• Don’t microwave polycarbonate plastic food containers. Polycarbonate is strong and durable, but over time it may break down from over use at high temperatures.
• Plastic containers have recycle codes on the bottom. Some, but not all, plastics that are marked with recycle codes 3 or 7 may be made with BPA.
• Reduce your use of canned foods.
• When possible, opt for glass, porcelain or stainless steel containers, particularly for hot food or liquids.
• Use baby bottles that are BPA free.