I had rather raise up one man to front the world than half a hundred dependents that dare not breathe the outside air. |
| Louis J. Halle, Jr.
Spring in Washington, 1947 |
Turning CFCs into Salt
Following a widespread ban on the production of ozone-destroying chlorofluorocarbons (CFCs), researchers are scrambling to turn massive stockpiles of the substances into useful or at least benign materials. In one example at Yale University, scientists are converting CFCs into table salt and other harmless solids using a chemical found in rhubarb leaves.
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Conversion collaboration. Juan Burdeniuc (left) and Robert H. Crabtree (right) have developed a "hot tube" to turn CFCs into salt.
Photo: Yale University |
Professor Robert H. Crabtree and graduate student Juan Burdeniuc say they've developed an inexpensive system for destroying CFC stockpiles--including an estimated 100 million pounds of Freon, a coolant used in refrigerators and car air conditioners. By passing vaporized CFCs through a packed bed of powdered sodium oxalate at about 550°F, Crabtree reported in the 19 January 1996 issue of Science, it's easy to generate carbon, salt, and sodium fluoride, a toothpaste ingredient. "The apparatus is remarkably simple," he says. "It's a so-called 'hot tube' arrangement."
R. Tom Baker, a project leader and research associate for the DuPont Company of Wilmington, Delaware, once the world's largest CFC maker, says it remains to be seen whether Crabtree's technique will be cost-effective, in part because it generates salt, a low-cost commodity that poses handling and disposal problems. But, Baker adds, Crabtree's process is "intriguing" because at lower temperatures, it reportedly converts CFCs into valuable fluorocompounds--a category that includes mefloquine (an antimalarial drug), ciprofloxacin (an antibiotic), halothane (an anesthetic), and surface coatings such as Teflon.
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Recycled CFCs. New processes turn ozone-destroying chlorofluorocarbons into sodium oxalate used in products such as salt, sodium fluoride, drugs, and surface coatings for cookware.
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Chlorine atoms from CFCs destroy stratospheric ozone, exposing people, plants, and animals to harmful UV radiation, which is linked to skin cancer, cataracts, crop damage, and global climate changes.
At altitudes above 18 miles, sunlight strips chlorine atoms from CFCs, according to an essay prepared for the National Academy of Sciences by Professor F. Sherwood Rowland of the University of California- Irvine. Chlorine atoms react with ozone to form chlorine oxide, a free radical, which sets off an ozone-destroying chain reaction, writes Rowland, co-recipient of the 1995 Nobel Prize in chemistry for ozone research. Because a lone chlorine atom can destroy 100,000 ozone molecules, CFCs annually deplete ozone levels in an area the size of Europe in the earth's gaseous shield above Antartica. People in the Northern Hemi-sphere receive an annual dose of UV radiation that's 5% more potent than it was in the 1980s, Rowland reports, and skin cancer rates are now 10 times higher than in the 1950s. Though scientists haven't found a biological link between ozone loss and cancer, he says, epidemiological evidence is mounting.
Consequently, CFC production was banned in most developed countries beginning in 1996 as part of the international Montreal Protocol. But existing CFC supplies can still be used in older-model cars and refrigeration equipment, explains Sue Stendebach, an acting branch chief in the Stratospheric Protection Division at the EPA. In the future, Stendebach says, the EPA might work to have congress amend the Clean Air Act to require the destruction of CFC stockpiles, "but only when demand starts going down significantly."
Crabtree's invention is one of a dozen CFC conversion technologies now under development, Stendebach says. Two U.S. firms, Commodore CFC Technologies, Inc. of Columbus, Ohio, and Process Technologies, Inc. (PTI) of Boise, Idaho, are getting into the business in a big way.
Like Crabtree's process, the Commodore and PTI techniques generate salts. Using ammonia, Commodore solvates calcium, sodium, and other metals to produce a solution rich in free electrons, which transforms CFCs into salts. The closed system doesn't require heat, and it doesn't pollute the air, Commodore president Jim DeAngelis says.
The PTI system sends gas-phase CFCs through an aluminum box lined with lamps containing mercury, which vaporizes and emits UV light, explains Michael S. Swan, PTI's vice president for business development. Just as sunlight splinters CFCs, the UV lamps release highly reactive molecules known as free radicals. To prevent these promiscuous molecules from bonding with unsuitable partners, Swan says, PTI "mates" them with a solid reagent containing calcium oxide, thereby producing salts such as calcium chloride.
DuPont, meanwhile, is focusing on techniques to convert CFCs into less destructive hydrochlorofluorocarbons (HCFCs), as well as chlorine-free hydrofluorocarbons (HFCs), which may not destroy ozone but may contribute to the greenhouse effect. Baker has patented a process that turns CFC-113a into HCFC-123 using homogeneous catalysis (in which the catalyst and the reactants are in the same phase) without generating salts. When gas-phase CFCs and hydrogen are fed into a reactor, he explains, chlorine atoms are simply replaced by hydrogen. Compared to more traditional heterogeneous catalysis, the homogeneous system is less likely to generate undesirable byproducts, Baker says, and it isn't deactivated by heat.
To be cost-effective, Swan says, CFC conversion technologies must compete with incineration, which can cost up to $15 per pound. Swan claims he can destroy CFCs for $2-$4 per pound. DeAngelis says his system is 30-50% cheaper than incineration. Key Commodore ingredients--sodium and calcium--cost between $2.25 and $2.45 per pound, DeAngelis says. By comparison, laboratory samples of the sodium oxalate used in Crabtree's process may be priced at $40 per pound. But Gregory E. Gardiner, Yale's director of cooperative research, says larger quantities are available for $2.25 per pound.
Cytokine Knockouts
Mice that lack the genes for the cytokines tumor necrosis factor (TNF) and interleukin-6 (IL-6) may soon help scientists at the NIEHS sort out the complex roles these molecules play in modulating inflammatory responses to environmental toxins.
Cytokines are released from a wide variety of cell types and regulate neighboring cells. They exhibit diverse and often seemingly unrelated biological effects. For example, cytokines play key roles in development, immunological disorders, infection, and tissue injury.
Dori Germolec, immunotoxicology group leader in the Systems Toxicology Laboratory of the NIEHS, in collaboration with Michael Luster, chief of the Toxicology and Molecular Biology Branch of the National Institute for Occupational Safety and Health, plans to use the knockout mice to study the effects of toxins on cytokine function in the liver, lung, and kidneys. "There are a number of compounds that we have been investigating in our laboratory whose activity is modulated by TNF-alpha," Germolec said. These compounds include dioxin, cadmium, and acetaminophen. The hepatotoxic effects of each of these compounds depend on TNF-.
"A lot of hepatotoxins are characterized by cellular infiltrations," says Lawrence Schook, chairman of the Department of Veterinary PathoBiology of the University of Minnesota. "TNF, along with IL-1 and IL-6, is associated with inflammation. I think a number of independent observations have shown that TNF is being produced in situ for a wide array of hepatotoxins."
Jean Harry, neurotoxicology group leader in the Systems Toxicology Laboratory, of the NIEHS plans to use the cytokine knockout mice to study TNF- modulation of toxicity of compounds such as triethyl- and trimethyltin in the brain.
TNF- responses are mediated by two distinct receptor subtypes, TNFR1 and TNFR2. The receptors are expressed in specific tissues. Extracellularly, the two receptors are very similar but intracellularly they have distinct signaling pathways that may account for the different effects of TNF- in different types of cells. "One cell might have ten times [more] of one receptor than the other," says Schook. "In another cell, it might be the reverse. They both might be expressed but it seems one is really predominate in one cell type or the other."
The cytokine knockout mice are ideal for studying the role played by TNF- in the body's response to toxins. "We are going to get a TNFR1/R2 knockout which lacks both TNF receptors," Germolec explains. "[Those deletions] will completely abrogate any TNF response. We will also get mice with just the TNFR1 knockout so we should be able to tease out the effects of different receptors and how they function," she said.
The knockout mice were developed by scientists at Immunex, a biotechnology company in Seattle, for use in their drug discovery projects. They are being provided to the NIEHS by Schook, who has a long-term project funded by the NIEHS to study the effects of the hepatotoxin and carcinogen dimethylnitrosamine (DMN). To identify genes that are turned on and off following exposure to DMN, Schook is using differential display libraries--a new, powerful technique analogous to polymerase chain reaction--to identify the transcripts expressed in mice that lack one or more TNF receptors. Preliminary results of the study indicate that DMN does not elicit an inflammatory response in mice lacking the TNFR1 receptor.
"A real question for us is [whether] TNF is a friend or foe," says Schook. "Is it a protective signal or is it really the signal that leads to necrosis and cell death?" Schook suggests it is possible that in the initial stages of chemical exposure, cytokines such as TNF- help to protect tissue, but that prolonged exposure leads to cytokine-mediated toxicity.
The NIEHS researchers will probably experiment with the IL-6 knockout mice in different model systems. Most of the compounds they have studied, though, modulate the effects of TNF-. "[TNF-] is the most important one for us," said Germolec. Schook's long-term goal is to map the genes that are being turned on by toxins via cytokine signaling, perhaps to identify people at greater genetic risk of adverse effects from exposure to specific toxins.
1996 CENR Initiatives
Since its creation in 1993 as part of the National Science and Technology Council, the Committee on Environment and Natural Resources (CENR) has been working to coordinate federal research on environment and natural resources among varying agencies and programs. The CENR has developed its key research initiatives for 1996, which include two new initiatives, three on-going activities at their initial stages of implementation, and two that are in the early stages of discussion.
The CENR is developing a National Ecological Monitoring and Research Program as a new initiative to coordinate current monitoring systems into an integrated, interagency system. Current programs track specific components of the ecosystem but do not provide adequate information on how those components interact. A major goal of the program is to provide insight into how ecosystem health and sustainability are controlled on a regional scale, where policy and management decisions are made.
The second new initiative is the development of a Natural Disaster Information and Mitigation program. In order to reduce the financial burden of natural disasters, which have cost the U.S. economy about $1 billion per week since 1992, the CENR is working on a multi disciplinary research program which will improve national capabilities for risk assessment and risk management. By working with state and local governments to conduct natural hazard risk assessments, the CENR aims to carry out the National Mitigation Strategy, which seeks to cut losses due to natural hazards in half by the year 2020.
The CENR is working to implement the ongoing North American Research Strategy for Tropospheric Ozone (NARSTO) in response to the National Academy of Science's conclusion in 1991 that efforts to control ground-level ozone over the past 20 years had failed, as well as the finding that 53 million people live in areas that exceed the national ambient air quality standard for ozone. This research strategy involves cooperation among the U.S., Canadian, and Mexican governments; industry, and academia.
The CENR is also developing a comprehensive program to study endocrine disrupters, as new information is learned about these chemicals that may cause hormone-related problems such as decreased fertility, cancer, and wildlife population decline. The Endocrine Disrupter Research Strategy will evaluate current data, identify knowledge gaps, and determine what research will be required to fill those gaps.
An international research program to investigate Seasonal to Interannual Climate Change is being funded by the CENR's Global Change Program. This project will examine societal vulnerabilities to climate variation such as floods and droughts, and develop ways to improve scientists' abilities to predict climate changes on a seasonal to interannual time scale.
Finally, activities that the CENR has determined merit additional emphasis but will require more definition to become true initiatives include the proposed Integrated Global Observing System (the CENR plans to develop the U.S. role), and the expansion of economic and social science research to address how human activities affect the environment and how environmental changes impact on society.
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Mexican Brickmaking
The twin cities of El Paso, Texas, and Ciudad Juarez, Mexico, lie in a deep gorge between two mountain ranges. The airshed is often subject to temperature inversions, in which dirty air becomes trapped near the surface. More than 2 million people in the area breathe air pollution labeled "serious" by the EPA. One of the major contributors to the mix is the Cuidad Juarez brickmaking industry. A concerted effort by a number of governmental, environmental, industrial, academic, and health organizations working with the brickmakers holds promise that residents of the two cities may eventually breathe cleaner air.
Bad air at the border. Mexican brickmaking in Ciudad Juarez creates air pollution that knows no borders.
Photos: Environmental Defense Fund
Bricks are made by ladrilleros--about 400 artisans living in the colonias (unzoned shantytowns) outside Ciudad Juarez. The bricks are fired in kilns whose design dates to ancient Egypt. Cramped and makeshift brickyards are sandwiched among squalid houses and shelters. The brickmakers will burn anything available, ranging from old tires and wood scraps to butane and natural gas. These primitive fuels create billows of black smoke containing carbon monoxide, nitrogen oxide, benzene, toluene, and particulates that drift into the airshed and mix with automobile exhaust and road dust to create some of the worst air quality in the United States and Mexico.
The health consequences of air pollution are difficult to trace to any single factor. Researchers now suspect that it's the combination of noxious ingredients that poses the greatest health hazards. Dirty air decreases lung capacity, increases susceptibility to infectious disease, and contributes to the incidence of lung cancer. The groups most at risk are children because their lungs are still developing and they contract more respiratory infections than any other group.
The families of brickmakers are at risk of high exposure to dangerous chemicals. "The health impact is not only of concern to the worker but also the entire family, especially pregnant women and children who, because of their socioeconomic status, tend to be undernourished," says Beatriz Vera, project coordinator for the U.S.-Mexico Border Environment and Health Projects. "Many times the entire family participates in the process. Sometimes children are put directly into the area where the kiln is fired." Because the smoke from the kilns enters the airshed, children in other parts of the metropolitan area are also exposed.
Although Ciudad Juarez is growing faster than El Paso and tends to contribute more to the air pollution problem, the cities are so interlinked geographically, culturally, and economically that any solution must be cooperative. In 1983, the La Paz agreement between the United States and Mexico defined a 100-kilometer-deep environmental corridor along the 2,000-mile border. In 1993, the North American Free Trade Agreement created the Border Environment Cooperation Commission (BECC) to oversee pollution reduction of all kinds--air, water, and solid waste. Groups working specifically on the brickmaking problem include the Environmental Defense Fund (EDF), Physicians for Social Responsibility, the Federacion Mexicana de Asociaciones Privadas de Salud y Desarrollo Comunitario (FEMAP), and El Paso Natural Gas (EPNG). FEMAP and EPNG started a brickmaking school to teach the ladrilleros how to use higher quality fuel. According to EPNG vice president John Somerhalder, the school also helps the brickmakers with safety and business practices as well. "A huge number of brickmakers, not only from Juarez but from all over Mexico, have been through that school," Somerhalder says.
For a time, brickmakers were able to use liquefied petroleum gas (LPG), also known as butane. But in 1994 the Mexican government began to phase out its subsidy of LPG. Around the same time, the peso was also devalued. Consequently, the cost of LPG rose steeply. The brickmakers reverted to the cheaper fuels, especially at night, despite the fact that the Mexican government has made it illegal to burn tires.
A combined amelioration effort by EPNG and New Mexico's Los Alamos National Laboratory (LANL) has shown strong promise. LANL materials scientists Karl Staudhammer and Charles Grigsby experimented with kiln design to improve fuel efficiency. "The big problem is nonuniformity of temperature," Staudhammer says. The LANL design entails building several kilns near each other and transferring the heat that is lost during the firing of one kiln to the next one. Computer modeling enabled Staudhammer and Grigsby to design a furnace that uses 60% less gas.
Somerhalder emphasizes that "as in all environmental problems, there's usually a solution; it's just a very expensive solution." Because the colonias are not equipped with natural gas lines and the cost of LPG remains high, the conversion and increased-efficiency approaches to the problem have limited effectiveness. "It's a classic case of balancing the social and economic and environmental concerns," Somerhalder says. It would be easy, he says, to impose a strictly environmental solution from the top down by banning all dirty fuels, but the brickmakers of Mexico would probably be driven out of business altogether.
According to Michael Cormier of the Solar Energy Association, the pollution problem could easily be solved if builders would return to using traditional adobe instead of bricks. Adobe and bricks use the same raw materials but in different proportions. "The adobe is sun-dried and so it eliminates the kiln," Cormier says. "I know of no other manufactured building material that uses less energy and emits less pollutants. No jobs would be lost. The adobe is easier to build with and has better thermal mass properties for use in solar design." However, there is a snag. "While adobe construction remains steady in the United States, and appeals to people on every budget," Cormier says, "in Juarez the banks will not finance an adobe home."
Staudhammer says the brickmakers are eager to address the pollution problem but are constrained by the economics of their trade. Most of them are trying to support families on annual incomes of less than $2,000. "I've come to appreciate that the problems of the environment are not just the scientific technology alone," he says. "[The way] to deal with this problem isn't just for science to go in and say, 'Do it this way.' You have to deal with the economic factor."
The El Paso-Ciudad Juarez initiatives represent one of the first binational attacks on mutual and inextricably intertwined pollution problems. Both government officials and environmentalists are hopeful that air quality can improve. Roger Frauenfelder, general manager of the BECC says, "Pollution problems are neither created nor solved rapidly. We will make progress in solving the problems as time goes on, but there are no instantaneous solutions." Carlos Rincon, project director for air quality actions at EDF, says, "We cannot do anything about the climate, but we can do a lot about the environment."
The first steps are already underway to do something about the air in El Paso-Ciudad Juarez. Environmental and foreign affairs officials from Mexico and the United States are expected to sign an agreement during an international conference May 6-7 in Mexico City to reduce air pollution in what will be called the Paseo del Norte airshed. The agreement will establish a joint advisory council to recommend prevention and cleanup strategies to each of the governments.
EHPnet
National Center for Human Genome Research
To direct its role in the Human Genome Project--the worldwide research effort to map the human genome--the National Institutes of Health formed the National Center for Human Genome Research (NCHGR) in 1989.
The NCHGR has a home page on the Internet located at http://www.nchgr.nih.gov, which offers the opportunity to learn about the center, its organization, and research. The link to NCHGR's Mission Statement and Organization describes the agenda and different offices of the NCHGR.
There are three main divisions of the NCHGR: the Office of the Director (OD), the Division of Extramural Research (DER), and the Division of Intramural Research (DIR). The home page provides links to these divisions and their respective branches.
The OD provides leadership for the NCHGR and develops scientific, fiscal, and management strategies. The office oversees research, formulates research goals, and promotes international coordination and data exchange. Links are provided to the divisions of the OD including the Office of Administrative Management, the Office of Information Systems Management, the Office of Policy Coordination, and the Office of Scientific Review.
A link to public information within the Office of Policy Coordination offers press releases and informational articles about the NCHGR. This link also provides information about the task force on genetic testing, a committee developed by the NIH-DOE Joint Working Group on the Ethical, Legal, and Social Implications of Human Genome Research to perform a two-year evaluation of the current state of genetic testing technologies in the United States. The committee will examine tests used to assess genetic disease risk for issues such as safety, effectiveness, and accuracy. The task force will also focus on the psychological effects of genetic testing and discuss what individuals with altered genes can do to prevent disease in the future.
The public information link also offers a link to The Human Genome Project: Maps to Medicine, which gives an overview of the Human Genome Project's relevance to society and describes the processes involved in using genome data to prevent and cure genetic diseases. It includes basic information about genetics and an explanation of the Human Genome Project.
The DER funds Human Genome Project research in chromosome mapping, DNA sequencing, database development, technology development for genome research, and studies of the ethical, legal, and social implications of genetics research in laboratories throughout the country.
Links to the divisions of the DER include the Ethical, Legal, and Social Implications Branch; Mammalian Genomics Branch; Mapping Technology Branch; and Sequencing Technology Branch. There are also links to NCHGR grants and funding and NCHGR notices, policy statements and guidelines, and reports.
The DIR focuses on applying genome technologies to finding human disease genes, and developing DNA-based diagnostics and gene therapies. The division serves as a center for NIH-wide human genetics research, complementing the work of investigators in other NIH institutes who are searching for specific genes and studying their function in health and disease. The mission of the DIR is to develop and implement technology for the rapid isolation, analysis, and treatment of genetic diseases.
The site provides links to the various divisions of the DIR including The Breast Cancer Information Core (BIC) Homepage, Clinical Gene Therapy Branch, Diagnostic Development Branch, Genetic Resource Branch, Laboratory of Cancer Genetics, Laboratory of Genetic Disease Research, Medical Genetics Branch, Principal Researchers and Advisors, Technology Transfer, and Visiting Investigator Program.
The home page also offers NCHGR resources, including a site keyword search engine and other sources on the Internet.
Last Update: June 4, 1997