Exposure to chemicals early in life may alter how breast tissue develops and raise the risks of breast cancer and lactation problems later in life, scientists concluded in a set of reports published Wednesday.

The scientists are urging federal officials to add new tests for industrial chemicals and pesticides to identify ones that might disrupt breast development. In some cases, they said, mammary glands are more sensitive to effects of hormone-disrupting chemicals than any other part of the body, so low levels of exposure may be causing breast changes.

"Few chemicals coming into the marketplace are evaluated for these effects," said one of the reports, based on the findings of more than 60 scientists who convened a workshop in Oakland, Calif., in 2009.

Although many experts have long debated the role of the environment in breast cancer, the possibility that chemicals are changing how and when breasts develop is a relatively new concern for scientists.

Recent animal tests show that when rodents are exposed to some hormonally active chemicals in the womb or as newborns, their mammary glands do not grow normally, and the changes can slow or speed up breast development, impair breastfeeding or cause cancerous tumors later in life. Included are estrogens used as pharmaceuticals, phytoestrogens in plants consumed as foods and synthetic compounds including bisphenol A, flame retardants and pesticides, according  to the report, which was published online in the journal Environmental Health Perspectives.

Whether the same thing happens with human beings is largely unknown, although scientists say that rodent breasts develop much like human breasts, in the same stages.

"Animal studies demonstrate that early life exposure to hormonally active agents can lead to effects on mammary gland development, impaired lactation and increased susceptibility to cancer. However, the influence of environmental exposures on breast development outcomes is poorly understood, as is the relationship between breast development, lactational deficits, and breast cancer," wrote the authors, who are scientists from the National Toxicology Program, the Environmental Protection Agency and the nonprofit Silent Spring Institute.

In a companion report published Wednesday, scientists with three federal agencies who studied mice exposed in the womb to a chemical used to make Teflon found delayed breast development and impaired lactation. The effects were found in the mice at the concentrations detected in the water supply of an Ohio town near a DuPont Co. plant that uses the chemical, known as PFOA. Water supplies are not routinely monitored for it.

"If human exposures in distinct populations are approximating those provided in this study, concern over human breast health and lactational competency are justified," said the authors, led by Suzanne Fenton, a mammary gland expert at the National Toxicology Program.

Traditional animal tests required by federal officials have linked more than 200 chemicals and contaminants to breast cancer. But, in an editorial published with the three reports, Julia Brody and Ruthann Rudel of the Silent Spring Institute and Mhel Kavanaugh-Lynch of University of California said that those tests "may be missing many more" because they look only for tumors and "neglect development effects."

Breast cancer is the leading form of cancer in women, and some experts are concerned that chemicals acting like hormones may raise the risk if exposures come during critical development times. The most critical times are in the womb, and during puberty and pregnancy. During these times, hormones regulate how mammary glands grow, and if they grow abnormally, it may cause cancer and other problems later.

3 Comments

1. 1. TurboKitty 04:14 PM 6/22/11

   When are these "respected and educated scientists" going to tell the truth about growth hormones and anti-biotics? I don't drink milk and neither did my kids because the obvious result is apparent to everyone BUT the scientists ... Milk ... it does a body HARM!

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2. 2. SigmaEyes 08:45 PM 6/22/11

   Of course the article has significant focus on the inadequacy of testing to be able to be a suitable indicator of human safety; but I believe the problem is much broader, and systemic outside of scientific domains.
   
   Corporations have released over 60,000 chemicals into our environment because they were effective in producing profit. Our government only regulates about 250 of those 60,000 in our water supplies.
   
   In the European model, chemicals must be proved safe before being used for widespread human contact. Here in the US, we allow the use of any new concoction, wait for a generation or so go by, and wait for people to get sick. If they do, of course the toxins are so wide spread that it is impossible to prove the the connection between sickness and the cause, and even if so, the originating source can never be identified when it appears so widespread. So the corporations are safe, and it doesn't matter if the people are.
   
   Now there are those who think making the US more European is traitorous, and those who think regulating 250 chemicals out of 60,000 is too onerous and burdensome on the poor corporations that irradiate our meat and dye it pink so we will buy it, even when 20% of the grocers displays are spoiled meat.
   
   The world has known the dangers of genetically modified food, but the laws in the US effectively preclude scientific testing, and in fact, any dissent. There are laws prohibiting labeling food as GM so people cannot make their own choices and vote with their dollars.
   
   We have a political and a legal problem here, it is kind of irrelevant that the science is inadequate. But hey, lets solve the problem by giving tax breaks to the elite corporatists.

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3. 3. PaloPaolo 12:16 AM 6/29/11

   When I lived in Puerto Rico back in the late '60s, the San Juan Star (as I recall... it's a long time ago) ran articles about the increasing incidence of precocious sexual development. They mentioned third-graders who needed bras. The author speculated that the widespread use of hormones in commercial chicken feed might be a contributing factor. In Puerto Rico, people eat a lot of chicken. I believe a spokesperson for that industry said "There's no proof of such a connection."

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