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THIRD EDITION 2004 Stateof the Evidence What Is the Connection Between the Environment and Breast Cancer? Edited by Nancy Evans, Health Science Consultant, Breast Cancer Fund Dedicated to our founders, pioneers in breast cancer and environmental health ANDREA RAVINETT MARTIN 1946-2003 Breast Cancer Fund ELENORE G. PRED 1933-1991 Breast Cancer Action Cover Illustration: Book of Flowers IX, by Lynda Fishbourne, 1997, “Art.Rage.Us; Art and Writing by Women with Breast Cancer” After I finished chemotherapy and started radiation treatments every day, I also found a new medium, encaustic (wax). It felt like a rebirth in a way. As a reward to myself for my daily hospitals visits, I painted in encaustic every day before leaving for my appointment. A series of these paintings resulted. The darker side has petals falling, and the background is etched with counting; it shows what I was leaving behind. The lighter, sunnier side contains written thoughts as well as flowers and leaves from my walks in nature. It reflects the more positive feelings I was having. Acknowledgments Breast Cancer Fund and Breast Cancer Action wish to thank the following scientific experts who reviewed and commented on State of the Evidence: Devra Lee Davis, Ph.D., M.P.H., Director, Center for Environmental Oncology, University of Pittsburgh Cancer Institute and Professor, Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh. Philip Randolph Lee, M.D., Professor Emeritus, University of California San Francisco School of Medicine, former Assistant Secretary of Health & Human Services, San Francisco, Calif. Annie J. Sasco, M.D., Dr P.H., Chief of the Unit of Epidemiology for Cancer Prevention, International Agency for Research on Cancer and Director of Research, Institut National de la Santé et de la Recherche Médicale, Lyon, France. Ted Schettler, M.D., M.P.H., Science Director, Science and Environmental Health Network, Boston, Mass. Ana Soto, M.D., Professor, Department of Anatomy and Cell Biology, Tufts University School of Medicine, Boston, Mass. Steven D. Stellman, Ph.D., M.P.H., Professor of Clinical Epidemiology, Mailman School of Public Health, Columbia University, New York, N.Y. Breast Cancer Fund and Breast Cancer Action are solely responsible for the content of this document. Some of the elements included may not reflect the opinions of these experts, nor should their assistance with this document imply endorsement by their institutions. Editorial for Breast Cancer Fund Nancy Evans, Health Science Consultant Jeanne Rizzo, R.N., Executive Director Kevin Donegan, Director of Communications for Breast Cancer Action Barbara Brenner, Executive Director Lisa Wanzor, Associate Director Production and Design Design: Dennis Johnson and Ika Simpson, Dennis Johnson Design Cover Illustration: Lynda Fishbourne Printing: Action Printing Breast Cancer Fund gratefully acknowledges the following foundations, corporation, and individuals supporting the production and printing of this edition of State of the Evidence: Beldon Fund; Columbia Foundation; The Fred Gellert Family Foundation; The San Francisco Foundation; Clif Bar Inc., the makers of LUNA; Ruth Dell; and ChannahOra Meir © 2002, 2003, 2004 by Breast Cancer Fund and Breast Cancer Action THIRD EDITION 2004 Stateof the Evidence What Is the Connection Between the Environment and Breast Cancer? Edited by Nancy Evans, Health Science Consultant, Breast Cancer Fund Executive Summary reast cancer rates have been climbing steadily in the United States and other industrialized countries since the 1940s, amounting to more than one million cases per year worldwide. B In 2004, in the United States alone, an estimated 215,990 women will be diagnosed with invasive breast cancer and more than 55,390 women will be diagnosed with in situ breast cancer, meaning the tumor is confined to its original location in the breast. This year, breast cancer is expected to kill more than 40,000 American women and more than 370,000 women worldwide. Billions of dollars have been spent in an effort to stem this unrelenting tide, yet as many as half of all Less than one out of breast cancers occur in women who have no known risk every 10 cases occurs factors for the disease. Less than one out of every 10 cases occurs in women born with genetic predisposition for in women born with the disease. genetic predisposition Research indicates that breast cancer arises for four for the disease. primary reasons: genetic mutation, altered gene expression, altered cell interaction or from exposure to agents that alter the body’s natural production of estrogen and other hormones. Not everyone exposed to a carcinogen will develop breast cancer, how- ever. In fact, the development of breast cancer and other cancers is a multi-step process that most commonly results from more than one exposure over time. For example, one exposure might occur prenatally, another during childhood and a third during adolescence. Each of these exposures increase the risk of breast cancer in later life. Depending on the individual, cancer might develop after just two exposures, perhaps after dozens more, or may not develop at all. Ionizing radiation is the best-established environmental cause of human breast cancer. A growing body of evidence also implicates non-ionizing radiation (electromagnetic fields and radio-frequency radiation) as a possible contributor to the development of breast cancer. In addition, compelling scientific evidence points to some of the 85,000 synthetic chemicals in use today as contributing to the development of breast cancer, either by altering hormone function or gene expression. As with ionizing radiation, some synthetic chemicals (called mutagens) also can cause gene mutations that lead to breast cancer. While there is no simple method for linking chemical exposures to breast cancer, several types of research—experimental, body burden and epidemiological studies—yield evidence that such a link exists. For women born without genetic predisposition for breast cancer, events during their lifetimes contribute to producing the disease. But genetic predisposition does not cause breast cancer. Rather, it means that women 4 | BREAST CANCER FUND AND BREAST CANCER ACTION with inherited predisposition are more sensitive manufacture and processing of synthetic rubber to the effects of breast carcinogens than those products and some fungicides. without a genetic predisposition. There also is experimental evidence that certain There is broad agreement that exposure over time chemicals can disrupt hormone function and to estrogens that are naturally produced in the thereby may increase the risk of breast cancer. body increases the risk of breast cancer. Thus, the These chemicals include the insecticide heptach- earlier in life a woman’s menstrual cycle begins lor, the herbicide atrazine and ingredients in some and the later it ends, the higher her risk of breast sunscreens. Others include certain phthalates, cancer. Hormones administered as pharmaceuti- which are compounds cals also increase this risk. The Women’s Health used to make plastic Studies by the Initiative study on Hormone Replacement soft and flexible, Therapy (HRT) was halted when it became clear and parabens, which Centers for Disease that women who regularly took HRT had signi- are chemicals that Control and ficantly higher rates of breast cancer (as well as act as preservatives. other potentially life-threatening diseases). The Both phthalates and Prevention (CDC) National Toxicology Program now lists steroidal parabens are widely show that Americans estrogens as known human carcinogens.1 Since used ingredients 1987, the International Agency for Research on in personal care of all ages carry a Cancer (IARC) has categorized nonsteroidal products. estrogens as known human carcinogens. Other body burden of at Body burden studies compounds with estrogenic activity, including measure the presence least 116 chemicals, drugs such as diethylstilbestrol (DES) and pesti- of chemicals in people cides such as dieldrin, are understood to increase some of them banned by analyzing blood, the risk of breast cancer. In addition, plastic urine, body fat or for more than two additives such as bisphenol-A (BPA), polyvinyl breast milk. Also called chloride (PVC, which is found in many consumer decades because of biomonitoring, this products) and gasoline additives such as benzene, type of research is used toxicity. solvents and degreasing agents may be linked to study possible con- with increased risk of breast cancer due to their nections between chemicals and breast cancer. estrogenic activity. These studies cannot establish cause but can reveal Experimental studies have identified a number the internal contamination of women’s bodies. of synthetic chemicals that induce mammary Studies by the Centers for Disease Control and cancer in rodents. These include: organic solvents Prevention (CDC) show that Americans of all ages (used in many manufacturing processes, including carry a body burden of at least 116 chemicals, the manufacture of computer components); some of them banned for more than two decades polycyclic aromatic hydrocarbons (PAHs, pro- because of toxicity.2 duced from combustion of gasoline, diesel, heating Public health studies that have followed the oil, cigarettes and other tobacco products, or by development of breast cancer in women over time grilling meats and fish at high temperature); and have identified a number of other compounds 1,3-butadiene, which is both an

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