June 22, 2011
By Pat Rizzuto

Reproduced with permission from Daily Environment Report, 120 DEN A-11 (Jun. 22, 2011). Copyright 2011 by The Bureau of National Affairs, Inc. (800-372-1033) http://www.bna.com

Science Policy

Few Chemicals Evaluated for Early Effects On Breast Development, Cancer, Paper Says

Early life exposures to chemicals can alter breast development, potentially increasing susceptibility to cancer, yet few chemicals are evaluated for that potential, according to a paper being published June 22 in Environmental Health Perspectives.

“Early life environmental exposures can alter mammary gland development, disrupt lactation, and increase susceptibility to breast cancer. ... Few chemicals coming into the marketplace are evaluated for these effects,” wrote two Environmental Protection Agency scientists, one researcher from the National Institute of Environmental Health and Science (NIEHS), and two researchers from the Silent Spring Institute, a nonprofit research organization that seeks to identify links between the environment and women's health, especially breast cancer.

Early puberty in girls of all ethnic background is at an all-time high, Suzanne Fenton, an NIEHS toxicologist and a co-author of the paper, told BNA June 21.

Early puberty increases the risk of breast cancer, which is already the most common cancer in U.S. women, Fenton and the other researchers wrote in the paper, Environmental Exposures and Mammary Gland Development: State of the Science, Public Health Implications, and Research Recommendations.

Information Needed on Contribution

“According to recent reports, obesity plays only a small part in contributing to early puberty, the rest is environmental. We have to understand what in the environment is affecting breast development,” Fenton said.

In the paper, the scientists summarized the findings of participants attending a Mammary Gland Evaluation and Risk Assessment Workshop that took place Nov. 16-17, 2009. EPA, NIEHS, the California Breast Cancer Research Program, and the Silent Spring Institute helped fund the workshop.

The paper said that an EPA-sponsored workshop on the timing of puberty concluded in 2008 that U.S. girls were tending to have earlier breast development.

Many details on how chemicals may affect breast development in male and female laboratory animals are provided in the summary of the mammary gland workshop.

In the past, few of the tests used for chemical screening and testing would expose laboratory animals early in life and then examine whether the exposure affected mammary gland development, Fenton told BNA.

The paper described several ways toxicity test protocols could be modified to allow researchers to study
whether chemicals are affecting mammary gland development.

For example, an analysis of mammary glands could be added to pubertal development tests being used as part of EPA's Endocrine Disruptor Screening Program, the team of scientists led by Ruthann Rudel, from the Silent Spring Institute wrote.

EPA's program requires pesticide and some chemical manufacturers to conduct a series of tests to determine whether their products have the potential to mimic, block, or alter the functions of hormones. If they do, the pesticides and chemicals may be further tested.

The workshop summary urged regulatory and other scientists to incorporate an evaluation of mammary gland effects into toxicity tests and to consider the potential effects in risk assessments.

Major Changes Not Needed

“Protocols that already have an early life exposure wouldn't have to be modified all that much. At least, if
mammary glands were collected, we would have some information for that test chemical,” Fenton said.

Studying chemical effects on mammary gland development would help scientists understand if there are some chemicals or groups of chemicals that teen-age girls should stay away from, she said.

The National Toxicology Program, which NIEHS manages, already is revising its toxicity testing protocols to ensure that mammary gland development is examined in many studies, Fenton said.

The Organization for Economic Cooperation and Development also is working to include mammary gland analysis in a test protocol it is developing, she said.

Meanwhile, chemical manufacturers and other researchers studying chemicals could help, she said. Among the other chemical effects they are studying, they could examine breast development.

Environmental Health Perspectives is a peer-reviewed journal published by the National Institute of Environmental Health Sciences.

Environmental Exposures and Mammary Gland Development will be published at http://ehp03.niehs.nih.gov/article/aop.action?catName=Ahead.