EXCELLENT read on the association of increased rates of Breast Cancer with increased synthetic chemicals in our environment:

http://www.breastcancerfund.org/site/pp.asp?c=kwKXLdPaE&b=1370047


State of the Evidence 2008 Executive Summary

Edited by Janet Gray, Ph.D.

Breast cancer strikes more women in the world than any other type of cancer except skin cancer. In the United States, a woman’s lifetime risk of Breast Cancer has increased steadily and dramatically over the decades of the 20th century. Between 1973 and 1998, Breast Cancer incidence rates in the United States increased by more than 40 percent. Today, a woman’s lifetime risk of breast cancer is one in eight.

The increasing incidence of breast cancer over the decades following WorldWar II paralleled the proliferation of synthetic chemicals. An estimated 80,000 synthetic chemicals are used today in the United States; another 1,000 or more are added each year. Complete toxicological screening data are available for just 7 percent of these chemicals. Many of these chemicals persist in the environment, accumulate in body fat and may remain in breast tissue for decades. Many have never been tested for their effects on human health.

The most recent breast cancer incidence data (2003 - 2004) indicate a significant decline in breast cancer incidence for women in the U.S., although this effect may be relevant only for women over the age of 50 with a particular sub-type (estrogen receptor postitive, or ER+) of the disease. The most widely discussed explanation for this decrease is the sharp decline in use of post-menopausal hormone replacement therapy (HRT), especially following the 2002 discovery of HRT’s association with increased risk for breast cancer.

A recent survey conducted at the Massachusetts-based Silent Spring Institute indicated that 216 chemicals and radiation sources have been recognized by national and international regulatory agencies as being implicated in breast cancer causation. Many other chemicals, especially those classified as endocrine-disrupting compounds (EDCs), are not listed by the regulatory agencies, the researchers said; yet the scientific evidence linking EDCs to breast cancer risk is substantial and growing.

In State of the Evidence 2008, we examine the increasingly sophisticated and compelling data linking radiation and myriad chemicals in our environment to the current high rates of breast cancer. While we acknowledge the importance of commonly discussed risk factors for breast cancer — primary genetic mutations, reproductive history and lifestyle factors such as weight gain, alcohol consumption and lack of physical exercise — we assert that these commonly discussed factors alone do not address a large portion of the risk for the disease.

An important body of scientific evidence demonstrates that exposure to common chemicals and radiation may contribute to the staggering incidence of breast cancer. In our daily lives, we are rarely exposed to these substances in isolation; the pervasiveness of many of these substances means we likely have multiple, low-level exposures over the course of weeks, months, even years. There are several examples in recent scientific literature demonstrating that mixtures of environmental chemicals, chemicals and radiation, or complex combinations of chemicals and particular genetic or hormonal profiles may alter biological processes and possibly lead to increases in breast cancer risk. These new data show that we need to begin to think of breast cancer causation as a complex web of often interconnected factors, each exerting direct and interactive effects on cellular processes in mammary tissue.

When examining the effects of lifestyle factors, environmental chemicals and radiation on future breast cancer induction, scientists now know that the timing, duration and pattern of exposure are at least as important as the dose. A growing body of evidence from both human and animal models indicates that exposure of fetuses, young children and adolescents to radiation and environmental chemicals puts them at considerably higher risk for breast cancer in later life. Issues of timing reflect the fact that mammary cells are more susceptible to the carcinogenic effects of hormones, chemicals and radiation during early stages of development, from the prenatal period through puberty, adolescence, and on until the first full-term pregnancy.

Summarizing findings of more than 400 epidemiological and experimental studies, State of the Evidence 2008 demonstrates that a significant body of scientific evidence links exposures to radiation and synthetic chemicals to an increased risk of breast cancer. The report also addresses some of the ongoing methodological complexities in breast cancer research.

The Moving Forward section of the report was written for breast cancer prevention, women’s health and environmental health and justice advocates as well as others interested in developing policy and research agendas at the state and federal levels that call for the identification and elimination of the environmental links to breast cancer.

This report builds on the data suggesting that recent declines in cancer incidence rates are associated with decreases in HRT use. At the same time, it recognizes that over the past 30 years there have been significant improvements in cleaning our environment of some contaminants associated with breast cancer risk. These new data offer real promise for the future that by decreasing exposures to carcinogens, such as exogenous estrogens, estrogen mimics and endocrine disruptors, we may continue to lower breast cancer levels—and actually prevent the devastating disease—in the future.

Hormones and Endocrine Disrupting Compounds Linked to Breast Cancer

There is broad agreement that exposure over time to natural estrogens in the body increases the risk of breast cancer. Hormone replacement therapy (HRT) and hormones in oral contraceptives (OC) and some other pharmaceuticals also increase this risk. The National Toxicology Program now lists steroidal estrogens (the natural chemical forms of estrogen) as known human carcinogens. The International Agency for Research on Cancer (IARC) has listed both steroidal and nonsteroidal estrogens as known human carcinogens since 1987.

Synthetic agents that mimic the actions of estrogens are known as xenoestrogens, and are one type of endocrine- (hormone-) disrupting compound. Other endocrine disrupting compounds (EDCs) may disrupt normal biological processes by disturbing not only the actions of the estrogens, but also those of other hormones including the androgens and thyroid hormone. All of these disruptions may increase the risk for breast cancer. EDCs are present in many pesticides, fuels, plastics, detergents, industrial solvents, tobacco smoke, prescription drugs, food additives and personal care products. Chronic exposure to widespread and persistent xenoestrogens may help explain the increase in breast cancer in industrialized countries around the world. Examples of EDCs that have been shown to affect the risk for breast cancer in humans, or the risk of mammary cancer in animals include:

* Numerous pesticides:

o The banned, but still pervasive, insecticide DDT;
o Dieldrin and aldrin, insecticides that are currently banned but were pervasive from the 1950s to 1980s,when exposure may have affected subsequent risk of breast cancer for exposed women;

o The triazine herbicides, including atrazine, a chemical banned in Europe but widely applied in the U.S. on many major agricultural crops;

o The banned but, until a decade ago, widely applied insecticide heptachlor;

* Bisphenol A: one of the most pervasive chemicals in modern life, used to make polycarbonate plastic, epoxy resins and dental sealants;

* Polyaromatic hydrocarbons (PAHs): ubiquitous byproducts of combustion;

* Tobacco smoke: both active and passive exposures;

* Dioxins: byproducts of incineration, manufacturing processes and vehicle exhaust that have contaminated the food supply (including crops, meat and dairy products);

* Alkylphenols: industrial chemicals used in the production of detergents and other cleaning products;

* Metals: including copper, cobalt, nickel, lead, mercury, cadmium and chromium;

* Phthalates: chemicals used to make plastics more flexible, also found in some cosmetics;

* Parabens: anti-microbials found in some cosmetics and other personal care products;

* food additives : recombinant bovine somatotropin (rBST) and zeranol, compounds administered to cattle and sheep to enhance growth.

Other Chemicals of Concern Linked to Breast Cancer

Not all chemicals exert their cancer-causing effects on mammary tissue through disruption of hormones. Some chemicals that are found widely in our environment exert carcinogenic effects by causing direct damage to mammary cell DNA, or by altering a cell’s ability to respond to internal or environmental challenges that increase the probability of the development of cancer. Examples of some of these other chemicals of concern include:

* Benzene: high-volume petrochemical solvent inhaled from gasoline fumes, vehicle exhaust, tobacco smoke and industrial burning;

* Other organic solvents: including those used in the production of electronics, computer components, textiles, furniture and printing;

* Polyvinyl chloride (PVC): used extensively for medical products, food packaging, appliances, toys, water pipes and many other products;

* 1,3-butadiene: byproduct of petroleum refining and vehicle exhaust, also used in processing of synthetic rubber;

* Ethylene oxide: surgical instrument sterilizer, also found in some cosmetics;

* Aromatic amines: byproducts of manufacturing plastics, pesticides, dyes and polyurethane foams, as well as high-temperature grilling of foods.

Radiation Linked to Breast Cancer

Both ionizing (X-rays and gamma radiation) and non-ionizing radiation (especially electromagnetic fields [EMF]) have been implicated in an increased risk for breast cancer.

* Ionizing radiation: the longest-established environmental cause of human breast cancer. Radiation increases the risk of breast cancer, both by directly damaging DNA and by disrupting normal cellular and intra-cellular processes. Radiation may also enhance the ability of hormones or other chemicals to cause cancer.

* Non-ionizing radiation (EMF): including microwaves, radio waves, radar and artificial light. The mechanisms by which EMF can affect health are not completely understood. However, the most widely studied model is built on the finding that EMF exposure and increased light-at-night (LAN) lower the body’s level of melatonin, a hormone secreted by the pineal gland during darkness. Through complex interactions with estrogens and cell signaling pathways, melatonin appears to have anti-cancer properties.

New Research Included in State of the Evidence 2008

* In studies of both U.S. and European women with BRCA1 or BRCA2 mutations, groups of women with higher incidence of the disease were born in recent decades that parallel increasing exposures to a wide variety of synthetic chemicals shown to increase risk for breast cancer. These data confirm an earlier study reporting this cohort effect.

* Several recent studies have confirmed the results first reported in 2001-02, that use of combined estrogen-progestin hormone replacement therapy (HRT) increases the risk of breast cancer in post-menopausal women. These cancers tend to have low proliferation rates (mitotic indices) and favorable prognostic outcomes.

* Use of oral contraceptives (OC) within the past five years led to significant increases in breast cancer incidence in both Hispanic and non- Hispanic white groups. The effect was magnified for women of both groups when OC use had continued for more than 20 years. In agreement with earlier studies, and again for both Hispanic and non-Hispanic white women, significant increases in estrogen receptor negative (ER-) tumors were observed.

* Scientists interested in the long-term health effects of exposure to the banned pesticide DDT looked at blood DDT levels in young women at the time they gave birth. These blood levels served as markers of DDT exposures during their youth. Researchers then followed the women for two decades after they had given birth, noting cases of non-invasive or invasive breast cancer before the women reached age 50, and deaths from breast cancer before age 50. Exposure to DDT during childhood and early adolescence was associated with a fivefold increase in risk of developing breast cancer before the age of 50.

* Prenatal exposure to the pesticide atrazine delays development of the rat mammary gland in puberty, widening the window of sensitivity to breast carcinogens. Similarly, exposure of rats late in pregnancy to amixture of metabolites of atrazine also leads to persistent changes in mammary gland development in the pups that were exposed during gestation. These abnormalities in prenatally exposed rats persist into adulthood.

* The insecticide heptachlor has been implicated in increased risk for breast cancer. Recent studies of body burdens of its major metabolite, heptachlor epoxide (HE), show that high levels of HE in breast milk and fat tissue from breast biopsies52 are associated with increased incidence of breast cancer.

* An overview of the scientific literature has confirmed that exposure to environmental tobacco smoke increases breast cancer risk in pre-menopausal women.

* Several studies of both rat and mouse models have demonstrated that even brief exposures to environmentally-relevant doses of bisphenol A (BPA), either prenatally 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 prenatal exposure to BPA leads to abnormalities in mammary tissue development that are observable during gestation. Prenatal exposure of rats to BPA also increased the number of pre-tumorous changes in mammary tissue, and an increased number of mammary tumors following adulthood exposures to a sub-threshold dose (lower than that needed to induce tumors) of a known carcinogen.

* Prenatal exposure to the dioxin TCDD alters subsequent mammary gland development in ways that predispose rats to develop mammary cancers as adults.

* Higher accumulations of iron, nickel, chromium, zinc, cadmium, mercury and lead have been found in cancerous breast biopsies as well as in serum samples of women diagnosed with cancer as compared with healthy women.

* A recent laboratory rat study demonstrated that application of octyl-methoxycinnamate (OMC) to the skin enhances the penetration of the endocrine-disrupting herbicide 2,4-D. OMC is a chemical commonly found in sunscreen lotions.

* A case-control study of 128 female Latina agricultural workers newly diagnosed with breast cancer in California identified three pesticides— chlordane,malathion and 2,4-D—associated with an increased risk of breast cancer. Scientists found that the risks associated with use of these chemicals were higher in young women and in those with early-onset breast cancer than in unexposed women.

* Recent studies examining occupational exposures to benzene among enlisted women in the U.S. Army and women in different professions in Israel show significant increases in breast cancer rates among women with the highest benzene exposures.

* Benzene administration to laboratory mice induces mammary tumors. These animals have more mutations of genes that are responsible for suppressing the development of tumors.

* A recent questionnaire study found an association between higher lifetime consumption of grilled meats and fish and increased incidence of post-menopausal breast cancer.68 Heterocyclic aromatic amines (HAAs) are formed, along with polycyclic aromatic hydrocarbons (PAHs), when meats or fish are grilled or otherwise cooked at high temperatures.

* Studies of both breast milk and cells from the ducts of women’s breasts revealed the presence of DNA adducts in association with HAAs. These DNA adducts are indicators of problems in DNA repair in cells, one of the early hallmarks of tumor development.

* Laboratory studies of HAAs in systems using cultured human breast cancer cells demonstrate that these chemicals can mimic estrogen, and can also have direct effects on cell division processes in ways that can enhance the development of tumors.

* Increases in breast cancer have been observed in women living in areas surrounding the Chernobyl nuclear power plant in the former Soviet Union, which exploded in 1986 and caused massive radiation contamination. The most devastating effects have been found in women who were younger at the time of the accident.

* Recent genetic data indicate that women with some gene mutations that may make them more likely to develop breast cancer (e.g., ATM, TP53 and BRCA1/2) may be especially susceptible to the cancer-inducing effects of ionizing radiation exposure.

* Girls and adolescents treated with radiation for non-Hodgkin’s lymphoma or for Acne had an increase in rates of breast cancer several decades later.

* A recent study of female radiology technologists who had sustained daily exposures to ionizing radiation demonstrated an increased risk of breast cancer. The findings hold for those women who began working during their teens or, independent of age, worked in the field earlier than the 1940s, when exposure levels were substantially higher than they have been in more recent decades.

* Post-menopausal women whose earlier breast cancers were treated with radiation therapy have increased risks of radiation-induced secondary cancers of the breast.

* A recent population-based case-control study in the United States looked at breast cancer risk in women who were exposed on the job to low, medium or high levels of EMF in their respective work environments. Small but significant increases in breast cancer incidence were found.

* A major case-control study from Poland found an increased risk for breast cancer in women working in white-collar jobs, such as marketing, advertising, management, engineering, social Science and economics. Increased risk was also found in blue collar workers, such as machine operators in a variety of settings. No single chemical or other exposure can be linked to the occupations with excess risk, leading the authors to conclude that possible associations of these occupations with EMF deserve further attention.

* The BioInitiative Report, a new analysis of Science on the health effects of EMF exposure, summarizes the evidence on breast cancer and other cancers as well as neurodegenerative diseases. This groundbreaking document is based on a review of more than 2,000 studies and calls for strengthening safety standards to avoid future cancers and other diseases and disorders in adults and children.

Moving Forward: Breast Cancer Fund’s Policy and Research Recommendations

Together, we must move forward to identify and eliminate the environmental causes of breast cancer. The Moving Forward section provides a call to action for advocates and policy makers. It offers a menu of different ways, from crafting state and federal policy to research initiatives, that supporters can be active in breast cancer prevention. The evidence is clear and growing. There are actions we can take today to reduce the public’s exposures to toxic chemicals and radiation.