EMFs: Breast Cancer Culprits?
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Danger: power lines! Women who work in electrical jobs may be at greater risk for breast cancer. |
Women who work in electrical jobs, including electricians, telephone installers, power-line workers, and electrical engineers, may run a greater risk of dying from breast cancer, according to new evidence linking breast cancer and electromagnetic fields.
Over the last 10 years, scientists have been researching the possibility that EMFs contribute to the development of cancer. Recent theories have suggested that exposure to low-frequency EMFs (50-60 Hz) reduces the pineal gland's output of melatonin, a hormone that regulates cell growth. Breast cancer is one of many cancers that have been linked to low levels of melatonin.
This link was the basis for a study conducted by Dana Loomis and colleagues at the School of Public Health at the University of North Carolina at Chapel Hill. Their study found that women who work in electrical jobs have a more than twofold risk of breast cancer than other women.
The researchers examined computer files of U.S. mortality data from 1985 to 1989 in 24 states that provided death certification records with occupation and industry codes to the National Center for Health Statistics. They compared data on women over 20 years old who had been employed in jobs associated with EMF exposure to women in other occupations. Loomis and colleagues compared 68 cases of breast cancer and 199 controls among women in electrical jobs with 27,814 cases of breast cancer and 110,750 controls among women in occupations without exposure to EMFs. Results of the study showed that nearly 40% more cases of breast cancer occurred among women in electrical jobs.
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Dana Loomis |
The UNC study does have limitations. Loomis cited two major problems with the use of death certificates in his study. First, the study only examined deceased women. "Intuitively, the theories can't be taken in the same way as if we also had information on the experiences of the living," Loomis said. Second, the use of death certificates limits the amount of information and raises questions about the findings. For example, Loomis noted that there was a lack of information on the womens' risk factors for breast cancer, including reproductive history, which could provide more insight into the issue. Also, the researchers could not determine the exact levels of magnetic field exposure women had experienced by examining their job titles alone.
The study was published in the 15 June 1994 issue of the Journal of the National Cancer Institute along with a critical editorial written by Dimitrios Trichopoulos, an epidemiologist at the Harvard School of Public Health, considered a skeptic of the EMF-cancer connection. Trichopoulos questioned the study's validity, but he did add that the analysis was exemplary and the data are noteworthy. Trichopoulos and Loomis agree that more research is needed in the area.
This study does not prove the theory that lower rates of melatonin occur in the body when it is exposed to EMFs, according to Loomis, but it does provide more evidence. "It's not the strongest support, but the results are consistent with and do support [the theory]," he said.
On the same date that Loomis's study appeared in JNCI, a study was presented at the 16th Annual Meeting of the Bioelectromagnetics Society in Copenhagen, that also links EMFs to breast cancer in females. Tore Tynes of the Cancer Registry of Norway in Olso found that women working as radio and telegraph operators in electromagnetic environments had nearly twice the risk of developing breast cancers as other Norwegian women.
Tynes and his colleagues examined 2,132 female certified radio operators born between 1934 and 1969, most of whom worked on ships. The researchers found that the women who had been licensed for up to nine years were 80% more likely to have had breast cancer than other presumably unexposed women. The risk was the same for those who had licenses for 10-20 years, and for women certified over 20 years, the risk rose to 2.2 times the expected rate.
Tynes cautioned that in interpreting the findings he had not measured individual radiation exposures. He also pointed out that there were several factors that could distort the estimates, such as high-fat diets aboard ships and shift work. Tynes also noted that the number of years of certification did not necessarily indicate that the women had been operators the whole time.
Tynes was among the first to suggest a link between workplace EMF exposures and male breast cancer, a more rare disease than female breast cancer. A study was recently conducted among railway workers in Scandinavia, in which researchers examined rates of male breast cancer. This study, conducted by Birgitta Floderus and other Swedish researchers at the National Institute of Occupational Health in Solna, offered a new analysis of previously published data on leukemia and male breast cancer among railway workers.
In this analysis, Floderus and colleagues found that workers aboard electric-powered trains face a higher risk of leukemia and breast cancer, while track or station workers do not appear to have increased risks of cancer. The researchers found an eightfold increase in male breast cancer among engine drivers and a fivefold increase for drivers and conductors combined. They also observed three times more pituitary gland tumors than expected among drivers and conductors combined. Although the numbers were small, the researchers noted that, together, these results lend support to "the hypothesis of EMF acting on hormonal-dependent organs."
According to Microwave News, the Floderus study is the fifth to link occupational EMF exposure to male breast cancer. The authors of the first study say that there is less data on breast cancer in women who work in electrical jobs, but point out that this is most likely due to the small percentage of women who work these types of occupations.
Tree of Life
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The giving tree. The neem tree may provide answers to some of the toughest environmental and health questions. |
For thousands of years, the people of India have known about the powers of the neem tree. They clean their teeth with neem twigs, heal skin disorders such as ulcers and eczema with neem-leaf juice, drink neem tea as a tonic, place neem leaves in their grain bins and cupboards to ward off insects, and pour neem tea on their plants to repel insects.
Now scientists around the world are researching the possibilities that the neem, a member of the mahogany family, could provide answers to many global problems such as including reforestation, cancer prevention methods, pesticide alternatives, and population control, including a role in the development of a male birth control pill.
"Even some of the most cautious researchers are saying that neem deserves to be called a wonder plant,'" according to Noel Vietmeyer, the study director of a 1992 National Research Council report entitled "Neem: A Tree for Solving Global Problems."
Indian scientists began research on the neem in the 1920s, but their work was little recognized until a German entomologist, Heinrich Schmutterer, witnessed a locust plague in the Sudan in 1959. Schmutterer began researching the neem when he saw that the only plant survivors of the plague were neem trees. Interest in the tree spread, and by 1991, several hundred researchers in over a dozen countries were conducting research on the neem. The U.S. Department of Agriculture has been studying the neem tree since 1972.
One of the most promising benefits of the neem tree may be the use of neem extractions in new organic insecticides. According to the World Health Organization, over 20,000 deaths and a million illnesses each year result from misuse or overuse of pesticides in the Third World alone. Neem insecticides have many advantages over traditional chemical methods: research indicates they are not harmful to humans or animals, insects don't become resistant to them, neem extracts do not accumulate in the environment, and they also spare beneficial insects like butterflies and ladybugs.
Entomologists have found that neem compounds can affect more than 200 insect species, including mosquitoes, fruit flies, head lice, Japanese beetles, Colorado potato beetles, Gypsy moths, fire ants, fleas, cockroaches, and boll weevils. The neem serves as a unique insecticide in that its compounds do not immediately kill insects, but rather alter insects' behavior or life processes in subtle ways as to impair the insect so that it can no longer feed, breed, or metamorphose.
The chemical structure of the neem contains only carbon, hydrogen, and oxygen, in contrast to inorganic, synthetic insecticides. The neem relies on four major compounds which act as antihormones in combating insects, and these are backed up by some 20 or so other minor, less active compounds.
The four major compounds, azadirachtin, salannin, meliantriol, and nimbin, are of the general class of natural products called triterpenes, or more specifically, limonoids. Azadirachtin is the major agent for warding off insects, causing about 90% of the effect on insects. It repels and disrupts the growth and reproduction of insects by interrupting the process of metamorphosis by blocking molting, thus ending the insect's life cycle. Meliantriol and salannin both repel insects by causing them to cease eating. The fourth compound, nimbin or nimbidin, is involved in antiviral activity, affecting potato virus X, vaccinia virus, and fowl pox virus. Other neem ingredients also work as antihormones, including some that are able to paralyze certain insects' swallowing abilities.
It is a fairly simple process to obtain these compounds by extracting them from the seed kernels of the tree. Crushing the kernels and extracting them with water is the most effective way for village peoples to obtain neem insecticides. Scientists have developed more advanced processes and means to convert neem extracts to forms of granules, dust, wettable powders, or emulsifiable concentrates. Scientists have also developed formulations, including the addition of chemicals or chemical modification of the neem ingredients, to increase shelf life of products or to reduce phototoxicity, the damage to sensitive plants.
There are currently four neem-based insecticides available on the U.S. market. AgriDyne Technologies, Inc. manufactures Azatin, Turplex, and Align. Azatin, which was introduced in 1992, is produced for use on ornamental plants, such as greenhouse plants and flowers. Turplex, also introduced in 1992, is used for turf and lawn care, while Align was introduced last year for use on food crops. W.R. Grace manufactures Margosan-O, which is now registered in all 50 states, also for use on food crops. The EPA has approved the use of both Align and Margosan-O for food crops. According to John Cuomo, the director of chemistry research at AgriDyne, the products have been accepted very well by growers, and the company continues to receive many requests for the products.
Although the neem seems to have endless possibilities, there are some disadvantages that need to be overcome. According to the NRC study, "the truth is that despite all its properties and promise, some impediments must be overcome and many uncertainties clarified before neem's potential can be fully realized." For example, neem products sometimes degrade and lose their pest-control properties when exposed to sunlight. This has been mitigated in some U.S. products by the addition of sunscreen. Cuomo said that the AgriDyne products do not contain sunscreen because it is not necessary for them to be effective. On a positive note, he said because of the UV breakdown and the hydrolysis of the neem products, they decompose rapidly, preventing buildup in the environment.
Although there appear to be few adverse human health effects of neem ingredients, further toxicity tests need to be conducted. Toxicity tests on fish and other wildlife also require investigation. Another disadvantage of the use of neem insecticides is that they kill insects by delayed action, so they work slower than synthetic pesticides. Consumers who have become accustomed to instant results may be impatient with the slower action of neem insecticides. Cuomo said that although AgriDyne's products are slow-acting, they are very effective if used for a full season.
Perhaps one of the greatest advantges of the neem is the fact that its fruits may be harvested without destroying the tree, making the neem more profitable standing than felled. As stated in the NRC report, "the use of neem products has the merit of promoting a greening of the earth."
Asthma Gene Is Nothing to Sneeze at
Approximately 5,000 people, many of them children, will die of asthma this year. Scientists have long known that allergic reactions to environmental irritants such as dust, pollen and other allergens, air pollution, and cigarette smoke trigger asthma attacks. They have now identified a gene that may contribute to susceptibility to asthma attacks by telling the body to overproduce a receptor for immunoglobulin E (IgE), an antibody involved in allergies.
Asthma Facts
- Asthma affects as many as 15 million persons in the United States.
- After hay fever, asthma is the most frequent chronic condition in persons under age 18. Nearly 5.1 million Americans under age 18 have asthma.
- Asthma was the underlying cause of 5,106 death in the United States in 1991 and the number is growing.
- Blacks with asthma are about three times as likely to die of asthma as are whites. Inner city black children are more likely to develop asthma than white children in suburban areas, and are less likely to receive treatment.
- The 1991 National Center for Health Statistics National Hospital Discharge Survey indicates that asthma was the first-listed diagnosis in 490,000 hospital admissions.
- In 1990, the cost for treatment of asthma was estimated at $6.2 billion. Forty-three percent of asthma's economic impact was associated with emergency room use, hospitalization, and death.
Source: National Institute of Allergy and Infectious Diseases |
Researchers led by William Cookson of John Radcliffe Hospital and Julian Hopkin of Churchill Hospital, both in Oxford, England, presented the new research in the June issue of Nature Genetics. When IgE binds to a protein receptor in cells lining the airways of the nose and chest, it sets off a series of events leading to an allergy attack. The gene found in the study contains the information for making part of the IgE receptor. The researchers found that people with a particular variant of the gene were likely to have high levels of IgE in their blood, an indicator of a tendency to allergy attacks. The researchers studied 60 families in which 10 had at least one person who had inherited both the variant and the allergic reaction. Of the 12 children who had the variant, all had allergic reactions, compared to only 2 of the children who did not inherit the variant.
The researchers stressed that the association was found only in a minority of the families, and that other genes may be implicated in asthma as well. Still, in an article by the Associated Press, Marshall Plaut, chief of the asthma and allergy branch of the National Institute of Allergy and Infectious Diseases, said, "I think they might have at least a partial answer, and it could be very important."
Any answers as to how and why people develop asthma would be good news to the 12 million Americans who suffer from it. But answers to these questions alone will not stop the increasing rates of asthma, which has become a major environmental health threat, particulary among inner-city children who are more often exposed to allergens and air pollution and may be especially sensitive to them. Misdiagnosis, mismedication or lack of treatment, and lack of the means to remove environmental contibutors to asthma are common in inner cities. Answers to these problems are also needed to prevent the increasing numbers of childhood deaths from asthma.
Recent studies sponsored by NIH and the National Center for Health Statistics (NCHS) show that African-American children who live in urban areas are more likely to develop asthma than white children who live in the suburbs and more likely to die from it due to a lack of diagnosis or treatment. In an article in the Washington Post, epidemiologist Diane Wagener of the NCHS said, "Deaths due to asthma among children should not happen, because it's a preventable situation." Public health officials say that although genetic research may help to identify individuals who may be susceptible to developing asthma, without adequate prevention and treatment measures the information has little worth.
Making Headlines on Health
In a recent statement, David Satcher, director of the Centers for Disease Control, criticized the news media for giving too much coverage to attention-grabbing health-related stories and not enough to less sensational, more substantive issues. In October more than 400 environmental journalists gathered in Utah, in part to examine this and other complaints about their profession.
Speaking at the plenary session of the 1994 Annual Meeting of the Society of Environmental Journalists, Jim Detjen, an editor at The Philadelphia Enquirer and the former president of SEJ, said, "The line is becoming increasingly blurred between what is news and what is entertainment." Detjen cautioned his colleagues that the current focus on "telling stories" erodes the credibility of the press and detracts attention from serious environmental and health issues. Detjen's observations were echoed by other members of the plenary panel including Thomas Winship, chair of the Center for Foreign Journalists and a former editor of The Boston Globe ; Noel J. Brown, special representative of the executive director of the United Nations Environment Programme; and F. Sherwood Rowland, winner of the 1983 Tyler World Prize in Ecology and Energy for his discoveries of the depletion of ozone by chlorofluorocarbons and the 1987 Award for Creative Advance in Environmental Science and Technology. Panelist Erin Hayes, a correspondent for ABC News in Chicago, advised journalists to avoid the danger of overdramatizing stories just to make them sexy enough to get on the air or in the paper. Said Hayes, "Environmental stories need to be told with context and perspective so people know how it affects their lives."
Journalists at the conference were also encouraged to lessen their reliance on anecdotal evidence and pursue more quotes and information from science experts. In an attempt to bring more scientific expertise into the process of environmental reporting, scientists working in many of the "hot" areas of environmental health were brought to the conference to provide journalists with briefings on these topics. Researchers Theodora Colborn, senior scientist at the World Wildlife Fund, Inc., Earl Gray of the EPA's Health Effects Research Laboratory, and Stephen Safe, professor of toxicology at Texas A&M University, presented a seminar on the role of environmental estrogens and endocrine disruptors on reproductive health of humans and animals. A panel including Robert Alvarez, deputy assistant secretary for national security and environmental restoration of the Department of Energy, and Arthur C. Upton, clinical professor of pathology and radiology at the University of New Mexico School of Medicine, explored issues surrounding human health and exposure to radiation. Other sessions discussed topics such as biodiversity, a potential ban on chlorine, and media coverage of population issues.
EPA Administrator Carol Browner and Secretary of Energy Hazel O'Leary were among the government representatives to address the conference. Commenting on her agency's unsuccessful attempt to have Congress pass reforms of the Safe Drinking Water Act and Superfund, Browner said, "What we've run into is gridlock and obstructionism that is truly unprecedented." Actor and environmentalist Robert Redford, who hosted part of the conference at his resort in Sundance, expressed similar frustration with Congress for failing to enact environmental legislation. "[The environment] is continuously abused for short-term and even spurious gain," said Redford. "It makes me sick actually." Redford encouraged journalists to continue to focus citizens' attention on environmental and health issues.
Pesticides and Food Safety
The EPA is formulating plans to regulate pesticides with an emphasis on food safety rather than agricultural use of chemicals. Under new proposed legislation, the agency would regulate the amount of pesticide residue on food, not just crops. Currently, the EPA monitors concentrations of pesticides on crops until just after harvest, while the new regulations would monitor food all the way to the supermarket shelf.
The agency is concerned about the amount of chemicals that are concentrated in food products. The plan aims to monitor food safety by moving backward though the food chain to the farm. New limits may be set based on how foods are likely to be consumed and would take into account that before foods are actually eaten, pesticides may wear off, be washed or peeled off, or diluted during processing. Industry is opposed to the proposed legislation because it would lead to tighter restrictions. |
ER Gene Disruption Is a Knockout
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Motley crew. C57 black founder mice (top), bred with mice with disrupted ER genes (middle), produce mice that are heterozygous for ER disruption (bottom). |
In the last year scientists have developed a new tool for research on the effects of estrogen that is a real knockout . . . literally. Researchers have been able to knock out the estrogen receptor gene in mice to disrupt the expression of estrogen receptor protein in the hopes that experiments on these animals will yield new insights into development, fertility, and the effects of estrogenic drugs and environmental chemicals on the body.
Estrogens bind to the estrogen receptor protein to activate a variety of physiological responses including tissue differentiation, growth, protein synthesis, and hormone secretion. In 1990, researchers in the Laboratory of Reproductive and Developmental Toxicology at the NIEHS and the Department of Pathology at the University of North Carolina at Chapel Hill were able to successfully produce a strain of transgenic mice (called ERKO for estrogen receptor knockout) that are homozygous for disrupted function of the estrogen receptor. The researchers made two important discoveries from this exercise: first, crosses of heterozygous strains produced even sex ratios of homozygous ER-negative mice, indicating that sex determination is not influenced by the absence of a functional estrogen receptor, and second, this absence is not necessarily lethal, although the animals are infertile.
Scientists are excited about the possibilities of using this animal model to study the role of estrogen in a variety of diseases and health effects on humans. Said Kenneth Korach, chief of the receptor biology section of the NIEHS lab, "There is a question of estrogen's exact role and mode of action related to osteoporosis and cardiovascular disease. These ERKO mice should be a useful experimental model for answering the question of whether estrogen plays a direct role."
Because ERKO adult female mice have undeveloped mammary glands, Korach is attempting to cross mice with an increased incidence of mammary cancer with ERKO mice to test whether the estrogen receptor is necessary for development of breast cancer. Studies of the reproductive organs of female and male ERKO mice may provide information on infertility. Female ERKO mice have dysfunctional ovaries and may be useful for studying the effects of estrogen therapy. Studies of male ERKO mice, who appear to have normal male accessory sex organs but produce less than 10% as much sperm as normal mice, may be helpful in evaluating the role of the estrogen receptor in male reproduction.
Future studies in which ERKO mice are exposed to environmental estrogenic chemicals and hormonally active drugs such as tamoxifen and diethystilbestrol may help scientists understand whether these chemicals operate through the estrogen receptor signaling pathway to cause reproductive tract and other target tissue cancers in humans. According to Korach, creation of these animals and the observation of nonlethality led colleagues at the University of Cincinnati Medical School to the clinical identification of the first human patient with an estrogen receptor gene mutation. Said Korach, "Because both males and females are infertile due to loss of function mutations of the estrogen receptor, it brings up the possibility of whether human infertility may have a similar mutational basis. We are currently attempting to evaluate some of these cases."
Last Update: June 4, 1998