Cancer Boom
Plotting cancer progressions. A graph of relative risks shows the incidence of nonsmoking-related cancers in baby boomers is rising.
White male baby boomers in the United States are three times as likely to get cancers unrelated to smoking as their grandfathers were, and female baby boomers are 30% more likely to develop cancers unrelated to smoking than were their grandmothers, a study says. Many researchers speculate that the cause for the increase is the existence of unspecified cancer-causing chemicals in the environment.
The findings "strongly suggest there are preventable causes [of cancer] out there that remain to be identified," said Devra Lee Davis, a senior adviser to the assistant health secretary of the U.S. Department of Health and Human Services, which led the study.
The research also revealed that heart disease deaths in a 15-year period beginning in 1973 dropped 42% in people under the age of 55 and 33% among 55- to 84 year olds. But the incidence of cancer is up among all age groups, and it is not due to smoking alone. "Many people in the cancer world have believed it was only smoking we had to pay attention to," Davis said.
Smoking-related cancer has also drastically increased. Compared with their grandmothers, women have 500% more cancers related to smoking and men have about 15% higher rates of smoking-related cancer than their grandfathers.
Similar findings were reported by researchers in Sweden this past spring. They found that Swedish females born from 1948-1957 have 1.3 times more cancer not related to smoking, and the risk of all cancer has doubled. Swedish men of the same ages have 1.7 times more cancer unrelated to smoking, and the risk of all cancer has tripled.
Researchers say the declines in heart disease and lung cancer, especially in men, are largely due to reductions in smoking and partly due to better medical management of heart disease. Thus, the causes of the increase in cancer cannot stem solely from causes shared with heart disease, such as smoking, but must reflect other environmental factors. However, many scientists who disagree with this conclusion believe that the predominant causes of these increases in cancer are factors such as diet, increased longevity, and lifestyle.
Cancer rates among farmers offer some suggestions as to why unspecified environmental factors may be contributing to these increases, the report says. Farmers smoke less than most people and suffer less heart disease and lung cancer. But farmers die more often of prostate cancer, brain cancer, bone cancer, skin cancer, and non-Hodgkin's lymphoma. This may be due to their chronic exposure to engine exhausts, solvents, animal viruses, sunlight, pesticides, and fuels. "Perhaps widespread workplace and environmental exposures to these same materials account for part of the recently observed population trends," Davis said in the report. In response to these speculations, the National Cancer Institute is beginning a study of disease and environmental exposures in 100,000 American farm families.
This study was the first national analysis of a 10% sample of the U.S. population developed by the National Cancer Institute, the results of which were published in the Journal of the American Medical Association in February. The study only involved whites because statistics and information on other races were thought to be unreliable.
Changing of the Guardians
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Linda Rosenstock-- Occupational and environmental health are overlapping disciplines. |
The spring of 1994 has seen a changing of the guardians of worker health, with new leaders heading the two government agencies dedicated to protecting America's laborers. Linda Rosenstock, head of the University of Washington's occupational and environmental medicine program and an advisor to the World Health Organization, takes command of the National Institute for Occupational Safety and Health, while Joseph A. Dear, former director of the Washington state Department of Labor and Industries, has been named assistant secretary of labor of the Occupational Safety and Health Administration.
Rosenstock moved with NIOSH from its headquarters at the Centers for Disease Control in Atlanta, Georgia, to the CDC's Washington offices. Under its mandate, NIOSH researches occupational disease and injury and develops strategies for promoting worker health. Rosenstock has charged that Congress has failed to provide NIOSH with the resources to protect worker health, and she has pledged to work to ensure that this failure is addressed through health care reform. "There has been an isolation of detecting and treating occupational health conditions from dealing with other medical conditions," said Rosenstock. "We have an opportunity now to change that." Rosenstock said that moving NIOSH to the nation's capitol will enable the agency to better fulfill its legislative mandate and provide collaboration opportunities with OSHA as there is "a need for us to work much more effectively together."
As far as her plans in the area of environmental health are concerned, Rosenstock said she believes that occupational and environmental health are overlapping disciplines where "often we are talking about different doses of the same potential hazard, whether exposure occurs in the workplace or from the environment." Rosenstock has stated that some of the major goals of her directorship will be to increase funding for NIOSH so that it may fulfill its broad mandate; evaluate and revitalize the agency's extramural training program; focus on developing prevention and intervention strategies; and create partnerships with industry and labor to address a changing technology and changing workforce that includes more women and minorities.
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Joseph A. Dear-- A revitalized OSHA will be committed to protecting the lives of working Americans. |
Rosenstock comes to NIOSH with a background in researching occupational diseases, particulary asbestos-related disease and effects of exposure to pesticides. She has taught in developing countries and has written two textbooks on occupational medicine. Rosenstock is credited with founding one of the first occupational medicine clinics in the United States at the University of Washington.
Rosenstock received her M.D. from Johns Hopkins University School of Medicine and her master's degree in public health from its School of Hygiene and Public Health. U.S. Health and Human Services Secretary Donna E. Shalala said in announcing the appointment, "She is a world-class scientist in occupational health, a teacher and mentor in occupational medicine, and a physician with 13 years of experience devoted to treating workers with occupational conditions."
NIOSH's public mandates are enforced by the Occupational Safety and Health Administration, now headed by Dear, whose nomination as assistant secretary of labor was confirmed in November 1993. At the announcement of his confirmation, Dear promised a "revitalized OSHA" with a renewed commitment to the "fundamental mission of saving lives, preventing serious injuries, and protecting the health of American workers." Dear described these goals and the hallmarks of a new OSHA whose "most important contribution to the lives of working Americans will be that they return to their homes and their families safe and secure each and every day."
Dear outlined a three-point program for revitalizing OSHA. First, he plans to more effectively target OSHA's enforcement efforts in areas where the greatest numbers of workers are most at risk, including increased use of the agency's "egregious violations" policy that allows OSHA to levy fines and pursue criminal penalties against companies that repeatedly fail to comply with health and safety standards.
Second, Dear plans to initiate a streamlined standards-setting process to reduce the time OSHA takes to promulgate regulations, based on a system of priorities including number of workers at risk, level of exposure, and the nature of the hazard. Third, Dear intends to promote greater cooperation between workers and management in development and implementation of safety and health programs.
Before assuming his position at OSHA, Dear was recognized for converting a $225-million deficit in Washington's workers' compensation fund into a $350-million surplus. He also instituted a health care cost containment and quality assurance program. Praising the appointment, Secretary of Labor Robert B. Reich said, "[Dear] will bring strong, creative leadership to an agency fundamental in developing safe, healthy, high-performance workplaces."
A former president of the National Association of Government Labor Officials, Dear worked as research director of the Washington State Labor Council before joining the state government. He received a B.A. in political economy from the Evergreen State College in Olympia, Washington, and graduated in 1986 from Harvard University's program for senior executives in state and local government in the John F. Kennedy School of Government.
Biodiversity Protection Treaty
A United Nations treaty with the mission of conserving forms of wildlife worldwide passed into international law at the beginning of the year. The agreement, called the Convention on Biological Diversity, is both a global conservation pact and a guide to help rich and poor nations share in the profits of biotechnology. Biotechnology is a young industry that uses organisms with unique genetic characteristics to create products such as cancer-fighting drugs and improve crops and livestock.
The United States is 1 of 167 nations that have signed the treaty, but a two-thirds vote of the Senate is still needed for ratification. As of April, the agreement is still in the hearing stage, being reviewed by the Senate Foreign Relations Committee.
The treaty was developed approximately 10 years ago in response to research that revealed that the rate of extinction had risen to 25,000 times the natural rate. It was first presented for signatures at the Earth Summit in Brazil in 1992.
If the Senate passes the treaty, the United States will join the other participating countries in creating strategies to conserve plants, animals, microorganisms, and the habitats that sustain them. The treaty also requires that countries adopt laws to protect endangered species, expand protected areas and restore damaged ones, and promote public awareness of the need for conservation and sustainable use of biological resources.
President Bush rejected the treaty when it was presented because he felt that its biotechnology provisions would weaken patent rights for American companies. But President Clinton reversed that decision last year, saying that although he also held reservations, he was confident that the problem areas could be negotiated later.
The treaty is based on three broad political principles. The first is the idea that countries have "the sovereign right to exploit their own resources pursuant to their own environmental policies." Also, affluent countries have an obligation to help their poorer neighbors abide by the pact by offering "new and additional" financial aid and technology. And finally, species-rich but financially poor nations should share in the profits from products developed from their biological resources.
Exactly how the agreement will function has yet to be determined. The treaty signers will meet later this year to discuss this and other problems that have already surfaced. One such problem is that there is considerable scientific uncertainty as to how, or if, many species can even be saved. Another problem is how to balance access to genetic material with biotechnology profits. The treaty signers also face questions about how the treaty will be financed, how the technology will be shared, and how the permanent secretariat will be established.
The treaty became legally binding after the 30th signer, Mongolia, ratified it. Among the other countries that have ratified the treaty are industrialized nations such as Canada, Japan, Norway, and Australia, and a number of developing countries such as Uganda, Nepal, the Philippines, and Ecuador. "I think its worth remarking that the first 30 ratifications came overwhelmingly from the lower-income countries," Angela Cropper of Trinidad and Tobago, executive secretary of the treaty's interim secretariat, told the The New York Times. "Biological diversity--our food and medicines as well as the treasure house of animals and plants--come mainly from the tropical and developing nations. If we want to continue to profit from this wealth, we must make it worthwhile for poor countries to protect this heritage," she said.
No Fun in the Sun
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What's in a name? Sunscreens may not really screen out the most harmful effects of tanning. |
Sunbathers who believe using sunscreens or tanning at indoor salons make tanning safe may soon see a dark cloud on the horizon. In the past, some scientists assured the public that the use of sunscreen would help prevent skin cancers, including melanoma, the deadliest form of skin cancer. It has also been generally accepted that the use of UV-A light in tanning salons is a safe alternative to the shorter wavelength UV-B, which was thought to induce melanoma. But recent studies on how ultraviolet light affects the skin challenge these theories.
A study by Peter Wolf and colleagues at the M. D. Anderson Cancer Center in Houston found that while sunscreen did protect mice from sunburn when they were exposed to ultraviolet light, it did not protect them from developing melanomas. Because sunscreen has been proven to help prevent the development of some forms of skin cancer, the researchers had expected sunscreen to protect against developing melanomas also.
The three sunscreens used in the study contained FDA category I sunscreens with the maximum approved concentration of the single compounds being tested by the researchers. Two of the three were UV-B-absorbing sunscreen preparations with an anti-inflammatory sun protection factor (SPF) of at least eight in mice. The third sunscreen preparation was a UV-A and UV-B absorber with an SPF of at least four. The researchers applied the sunscreens to the ears of mice and then injected them with melanoma cells. When they exposed the mice to ultraviolet light, the melanoma cells grew more aggressively than usual. They also observed that ultraviolet light suppressed the immune system of the mice. "What we found was that the exposure of skin to ultraviolet light will result in a change in the immunological environment," said Cherrie E. Donawho, one of the researchers. The breakdown of the immune system may be a factor in the development of melanomas. Even when sunscreen was applied and no noticeable damage was done to the skin by the ultraviolet light, the immune system was still suppressed. This suggests that even when the skin does not burn, there may be changes below the surface.
According to the researchers, the use of sunscreen may actually contribute to the risk of developing melanomas because protection against sunburn may encourage prolonged exposure to the sun. If melanomas are a result of exposure to ultraviolet light, rather than a result of sunburn, the longer periods of sun exposure may increase the risk of melanoma.
Beliefs about the "safe" light currently used in tanning salons may also be incorrect. In the past, UV-A light has been considered safer than shorter wavelength UV-B because it is not as readily absorbed by DNA and is therefore less likely to damage it. However, recently published research suggests that direct damage to DNA is not the only cancer-causing event caused by UV light, and UV-A light is not as safe as previously thought.
Richard B. Setlow led a study at the Brookhaven National Laboratory on the effect of different wavelengths of light on pigmented hybrid fish that are very sensitive to melanoma. He found that the group of fish exposed to UV-A light developed the same number of melanomas as the group of fish exposed to UV-B light. This suggests that wavelengths of light not directly absorbed by DNA still contribute to the development of melanoma. Setlow believes that the skin pigment melanin absorbs the radiation in UV-A and in turn affects DNA by energy or free radical transfer, thereby inducing melanoma.
The fish used in the experiment are bred to be extremely sensitive to melanoma, more sensitive than even fair-skinned humans, Setlow said. Darker-skinned people do not develop as many melanomas as fairer-skinned people. But he believes the fish can serve as a good model for the effects of UV light on humans. "The sensitivity of the fish versus humans is not important. What is important is the relative effect of wavelengths on the pigment cells," he said.
Setlow's advice to reduce chances of developing melanoma is to slowly tan, rather than expose skin to the sun in fewer, longer episodes. "To go out into the sun and get an episode of lots of light is probably bad," he said.
New R&D Directions
On March 28, a meeting was convened in Washington, DC, to set in motion the Clinton administration's plans for revamping federal scientific research and development. The National Forum on Environment and Natural Resources Research and Development assembled representatives of the scientific community, the private sector, Congress, state and local governments, and nongovernmental organizations to provide their insights to the members of the agencies represented on the Committee on Environment and Natural Resources Research (CENR) of the National Science and Technology Council (NSTC).
The NSTC, chaired by the president, was created by Executive Order 12881 on 23 November 1993 as a cabinet-level body to coordinate science, space, and technology policies throughout the government. Said President Clinton in announcing the NSTC, "Science and technology are essential tools for achieving the administration's goals for strengthening the economy, creating high-quality jobs, protecting the environment, improving our health care and education systems, and maintaining our national security."
The forum, sponsored by the White House Office of Science and Technology Policy, the National Academy of Sciences, and the National Academy of Engineering, in addition to the NSTC, was the first in a series of planning efforts to develop a long-term strategy for the nation's R&D programs. Before the meeting, the agencies of the CENR prepared preliminary strategies for establishing scientific approaches and short-term priorities for seven programmatic and three cross-cutting issue areas in which to address the administration's concerns about federal R&D efforts. The programmatic issues include air quality, biodiversity and ecosystems, global change, natural disasters, resource use and management, toxic substances and hazardous and solid waste, and water resources, coastal, and marine environmental research. The three cross-cutting issues are risk assessment, social and economic sciences, and technology and engineering.
The areas outlined in the preliminary strategic plans will provide the structure for addressing key weaknesses in federal R&D that have been raised in a number of reports over the last two years, including program integration, interagency cooperation, links to the policy formulation process, partnerships with industry and academia, research approaches that address long-term scientific issues as well as short-term management and regulatory requirements, need for expanded federal efforts in the biological and social sciences, and human resource development.
Some of the key administration officials who took part in the forum are John Gibbons, assistant to the president for science and technology; Vice President Al Gore; Secretary of Interior Bruce Babbitt; Robert T. Watson, associate director for environment of OSTP; D. James Baker, under secretary for oceans and atmosphere of the Department of Commerce; EPA Administrator Carol Browner; and Kathleen McGinty, director of the White House Office of Environmental Policy. Interagency cooperation, sustainable development, and effective integration of science and policy were major themes throughout the addresses given during the forum.
Browner offered three suggestions to guide the federal research agenda. First, move away from basing regulations on risks to the average person to protecting those populations who are most at risk, including children, minorities, pregnant women, and the elderly. Second, use an ecosystem approach that recognizes the integration of natural resources; for example, air pollution in water that is eventually consumed by animals and humans. Finally, incorporate industrial incentives for preventing pollution and reducing consumption, rather than devoting increasing resources to the development of better waste disposal technologies.
At the forum, strategic plans in each of the 10 areas were reviewed and finalized. These documents will form the rationale for selecting high-priority research areas for inclusion in budget requests for fiscal year 1996.
Underwater Drugstore
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Cure in Curacao? Curacin A, a substance in algae found off Curacao, may be lethal to cancer cells. |
Always in search of new disease-fighting substances, scientists are now diving into the ocean for new possibilities. According to scientists, the world's oceans are more genetically diverse than tropical rain forests and may contain creatures that could have pharmaceutical uses. Many of the millions of organisms in the ocean have already been found to produce chemicals that have a variety of uses, such as deterring crop predators and checking growth of weeds. Scientists believe these natural compounds could be used in medicine.
The marine environment is "incredibly diverse biologically and is enormously complex," said William Fenical, director of the Marine Research Division at the Scripps Institution of Oceanography in La Jolla, California. "But I think the ocean is 25 to 50 years behind the study of terrestrial environment. We need to turn to the marine environment for the discovery of new drugs."
A research team in Oregon, headed by marine chemist William H. Gerwick, a professor of pharmacy at Oregon State University, is one of the leaders in the field. Gerwick is supported by the Oregon Sea Grant and is working under a five-year, $1 million grant from the National Cancer Institute. NCI is funding three discovery teams consisting of university, government, and corporate researchers exploring marine organisms as sources of new anti-cancer agents.
Gerwick's work has shown some success thus far. He discovered and received a preliminary patent for an anti-cancer compound in a tropical alga, Lyngbya majuscula, found off the island of Curacao near Venezuela. Studies show that the chemical, curacin A, is lethal to cancer cells in a test tube. According to Gerwick, the compound inhibits cells from dividing due to its extreme toxicity; a concentration of one part per billion is enough to kill a cell. Tests involving administration of curacin A to mice are currently being run by NCI. According to Gerwick, the drug shows some selectivity for colon and breast cancer. "It's a long pathway to becoming a clinically useful drug, but the chemical shows all the characteristics of an agent that could go the distance," Gerwick said.
Dale G. Nagle, a doctoral student on Gerwick's team, collected the algae. "You can't really tell from looking at it about what's going on," Nagle said. "This alga is growing like fine little hair out there, and nothing seems to be eating it. That gives a slight hint there's something toxic in there."
Matthew Suffness, program director of NCI's National Cooperative Natural Product Drug Discovery Group in Bethesda, Maryland, said, "The marine natural products area is becoming more and more prominent in science. We're very hopeful that we're going to get quite a number of interesting compounds out of it with potential to be developed into new agents."
Another promising anti-cancer compound that has been discovered is bryostatin 1. This chemical is produced by tiny, spongelike sea creatures called bryozoans, which are usually found in colonies attached to boat bottoms, docks, and seaweed. After preliminary tests in humans, the compound appears to be effective in treating melanoma, lymphomas, leukemias, and ovarian cancers. The chemical is "very mundane-looking and is actually a pest in our harbors," said George R. Petit, director of the Cancer Research Institute at Arizona State University, which discovered the compound.
The promise of these and other possible disease-fighting compounds beneath the ocean's surface emphasizes the importance of protecting biodiversity. Many environmental groups have turned their attention to oceans because human activities are harming the seas. Some of these activities include wetlands destruction, overfishing, discharge of chemical pollutants, and dumping trash into the oceans. Groups such as The Audubon Society's Living Oceans Program aim to reform laws concerning marine and fisheries management for stricter regulations and more protection. One such law, the Magnuson Fisheries Conservation and Management Act, manages living marine resources and is up for reauthorization.
Persian Gulf Puzzle
In addition to its military outcomes, the 1991 Persian Gulf War gave rise to a public health puzzle that may take years to solve. At the end of a workshop in Bethesda, Maryland, on April 27-29, a blue-ribbon panel convened by the NIH Office of Medical Applications Research concluded that more research is needed to unravel the mystery of what is being called "Gulf War illness."
At the workshop on "The Persian Gulf Experience and Health," a multidisciplinary panel compiled by the National Institutes of Health heard evidence from environmental and occupational health scientists, military physicians, epidemiologists, and a number of Persian Gulf veterans and family members on what Major General Ronald R. Blanck of the Walter Reed Army Medical Center described as a "prolonged, nonresolving illness arising in soldiers either during or after deployment to the Persian Gulf . . . ,
The working case definition includes three major criteria--deployment to the Persian Gulf between 8 August 1990 and 31 July 1991; the onset of a persistent, relapsing, debilitating illness severe enough to reduce or impair ordinary activity for at least six months, and the exclusion of other known clinical conditions that could account for symptoms, which include severe fatigue, respiratory symptoms, unremitting diarrhea, sleep disturbances, irritability, and incapacitating joint and muscle pain.
More than two dozen presenters and an often vocal audience discussed the factors that complicate accurate diagnosis of Persian Gulf veterans' illnesses. First, little baseline health data were collected among troops before deployment, and monitoring of their exposures to environmental toxins did not begin until months after the fighting. For example, collection of air quality data started months after many of the oil-field fires had been extinguished, and administration of blood tests to determine types of exposures the soldiers received was erratic at best.
Second, no well-designed epidemiologic studies have been done to link Gulf War exposures with the reported illnesses. The different military branches, the Veterans Administration facilities, and civilian physicians have followed different protocols in evaluating undiagnosed Gulf War illness.
Third, no single or multiple etiology or biological explanation for the reported symptoms has been identified from the data available, although the panel emphasized that many veterans are in fact becoming sick and that the environment of the Gulf War contained many potential causes for these illnesses.
Over 700,000 troops, mostly from the United States, fought on dry terrain in Kuwait and Iraq, where powdery sand, often permeated with pesticides, was constantly being blown and stirred by heavy equipment. The attitude of local oil and chemical industries toward the environment is casual; the Persian Gulf is one of earth's most polluted bodies of water.
In late February 1991, retreating Iraqi forces detonated oil wells, and dense smoke covered much of the area. Crude oil poured from broken pipes, and, with water scarce, troops routinely went two weeks or longer between showers or fresh clothing. To quell the dust, the Army poured thousands of gallons of oil around living quarters, working areas, and even hospitals. When the desert nights turned cold, troops warmed confined spaces by burning diesel oil in commercial heaters designed for kerosene, probably resulting in elevated concentrations of sulfur dioxide, nitrous dioxide, nitric acid, sulfuric acid, ammonium sulfate, carbon monoxide, lead, and respirable particulates.
Investigators also attribute the illnesses to factors ranging from depleted uranium used in tank armor and armor-piercing weapons to the chemical and biological weapons Saddam Hussein boasted about. Botulinus and anthrax vaccinations given to troops on a sometimes accelerated schedule are also suspect, as well as pyridostigmine, a prophylactic drug taken by some troops to block anticipated neurotoxic agents. Some believe American personnel may have been vulnerable to unusual forms of infections endemic in Southwest Asia that are unfamiliar to American clinicians.
The Walter Reed Army Hospital reported 7 of 10 patients with Persian Gulf illness had an unusual, intestinal form of infection by Leishmania tropica, a parasite that usually infects the skin. Alan J. Magill, a physician at Walter Reed, hypothesized that leishmania was spread by the ubiquitous sand flies, and may cause a spectrum of illnesses, including a chronic form caused by reactivation long after exposure. "It is unlikely that our group has diagnosed all or even the majority of potential infections," he said.
Still other researchers are pointing to factors such as fear of chemical, biological, and nuclear weapons as a possible explanation for the illnesses. The panel concluded that Gulf War troops experienced "unprecedented stress" due to anxiety about possible chemical and biological warfare intensified by false alarms from oversensitive detection devices. Although the typical symptoms of post-traumatic stress disorder were not evident, a higher percentage of soldiers in the National Guard and reserves appeared to have acute anxiety expressed as physical symptoms.
The workshop panel urged the Department of Defense to consult outside experts in developing plans to measure environmental health factors in future military actions.
As of February 1994, approximately 16,000 veterans had been enrolled in a Persian Gulf Registry for war-related health problems established by Congress at the Centers for Disease Control. In May, the Pentagon announced that it will begin administering standardized tests on hundreds of veterans to determine if there is a single cause for the reported illnesses. Stephen Joseph, assistant secretary of defense for health affairs announced May 12 that the purpose of the study is to move "as quickly and as intensively as we can to provide a diagnostic explanation, veteran by veteran, for the symptoms they're describing."
Dangerous Dyes
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A need to go natural. New evidence shows chemicals in hair dyes may contribute to miscarriages and cancer. |
Frequent contact with chemicals in various cosmetics and hair dyes may cause serious health problems, according to recent studies. Researchers have found that female cosmetologists who regularly use chemicals while pregnant nearly double their risk of miscarriage. Other studies have also linked the regular use of hair dye with increased risks of cancer.
A survey of 8356 licensed female cosmetologists ages 22-36 was conducted in North Carolina between 1983 and 1988. The main analysis was restricted to 96 cosmetologists who had a spontaneous abortion and 547 cosmetologists who had a single live birth, all of whom worked full-time in cosmetology or in other jobs during the first trimester of pregnancy. The results revealed associations between miscarriages and the number of hours worked per day in cosmetology, the number of chemical services performed per week, the use of formaldehyde-based disinfectants, and work in salons where nail sculpturing was performed by other employees.
The study, conducted by Esther John, an associate professor of epidemiology at Stanford University School of Medicine, and David A. Savitz and Carl M. Shy, professors of epidemiology at the School of Public Health of the University of North Carolina at Chapel Hill, is the first to examine the relationship between specific occupational exposures in cosmetology and the risk of spontaneous abortion. "Cosmetology, a predominantly female occupation comprising over half a million women in the United States, has received little attention with regard to potential adverse reproductive outcomes," stated the researchers in a paper published in the March 1994 issue of Epidemiology.
Because cosmetology involves exposure to chemical mixtures from multiple sources, it is difficult to identify effects associated with specific chemical agents, according to the authors. Exposure to the solvents found in many cosmetics has been linked to spontaneous abortion in occupations other than cosmetology, yet uncertainties remain about the toxic effects of specific solvents on the fetus.
Although chemicals in hair dyes have been found to cause detrimental effects on health, the Stanford study found that the risk of spontaneous abortion did not increase with the number of hair dyes performed per week. Those who use hair dyes, however, do have increased risks of developing cancers. It is estimated that about 30-60% of people in the United States use some kind of permanent or temporary hair dye. Because some dye products contain chemicals that are mutagenic and carcinogenic to animals, there has been concern about the effects on human health, especially because hair dyes are absorbed through the skin during application. Recent studies show that although hair dyes do not pose significant health risks to most users, those who use hair dyes frequently for a long period of time have increased risks of developing certain types of cancer.
The most recent study, conducted by the American Cancer Society, found that women who used black hair dye for more than 20 years had a slightly increased risk of dying from non-Hodgkin's lymphoma and multiple myeloma. Researchers surveyed 573,369 women who completed questionnaires about their use of permanent hair dye. Surprisingly, women who dyed their hair showed a slightly reduced risk overall of dying of cancer than women who never used dyes. This study was published in the 2 February 1994 issue of the Journal of the National Cancer Institute.
A similar study conducted by Anastasia Tzonou and others at the Harvard School of Public Health suggested that the use of hair dyes may increase the risk of ovarian cancer. The study revealed that women who used hair dye five or more times a year had twice the risk of nonusers of developing ovarian cancer. Another study, conducted in the late 1980s by Dale Sandler and colleagues at NIEHS, compared a group of leukemia patients to people without the disease. Sandler found that the use of permanent and semi-permanent dyes for 16 years or more increased people's risk for developing leukemia."We found risks associated with dark and blonde dyes," she said. The results were revealed in a presentation, but the study has not yet been published.
The NCI concludes that because studies of the risks of hair dye are inconclusive, no recommendations to limit use can be made. Further research is needed to establish the safety of hair dyes.
FETAX for Neurotox
Scientists of the National Toxicology Program are looking once again to tadpoles for help in screening chemicals that may be harmful to humans. Although the FETAX (frog embryo teratogenesis assay: Xenopus) system, using the South African clawed frog Xenopus laevis, has been used since the early 1970s to assess morphological defects caused by chemical exposure, researchers now hope to use this system to examine alterations in the developing nervous system.
According to Jean Harry, a toxicologist at NIEHS and project officer of the interagency agreement between NTP and the U.S. Army under which the research is being conducted, a goal of the program is to identify subtle changes in function and interactions between cells that are critical for normal development in response to doses of chemicals too low to cause gross morphological changes. Harry says that the Xenopus frog embryo offers the possibility of using the developing nervous system "to target bad actors" by enabling scientists to identify which chemicals they should evaluate for noncancer endpoints.
Scientists believe several characteristics make these tadpoles ideally suited for this type of research: the system is simple, and a great deal of information is available on the biology of the developmental process; the in vivo preparation allows for repeated measures on the same animal during development, exposure, and recovery; absorption of dilute solutions is prompt, and concentrations of neurotoxicants in the nervous system rise rapidy; and, most importantly, many mechanisms critical in the functioning of the Xenopus nervous system are similar to those for mammals.
Researchers first began considering the Xenopus tadpole as a model system for perturbations to the developing nervous system when it was shown that hexachlorophene toxicity on the myelin of tadpoles is comparable to the pattern of pathology seen in mammalian nervous systems. Hexachlorophene, a chemical present in an antibacterial solution used to wash newborn babies, was shown to cause similar neurological problems in some children. According to Harry, basic components of the nervous system such as myelin are phylogenetically maintained "so a perturbation in the Xenopus may also be a target site in mammals."
The project will use fluorescent dyes in transparent albino embryos to visualize structural components of the nervous system, major nerve tracts and brain regions, and cellular interactions on the basis of membrane potential. NTP scientists plan to conduct assay tests on 14 chemicals that have already been tested under the NTP for teratogenesis, among them pesticides, glycol ethers, and boric acid, of which some have tested positive, some negative, and some inconclusive for morphological effects at high doses. Preliminary results from these studies should be published within the next year.
Last Update: July 30, 1998