As we constantly become more and more nearly lords of creation, there is nothing so much to be feared as ourselves, yet we know so little about fearsome us.
Howard Zahniser, quoted in John Muir and His Legacy, 1970
Last Supper for Mosquitoes
The same pond scum that nourishes young mosquitoes soon may deliver their death blow. A newfangled version of the common algae chlorella has been bioengineered as a mosquito larvicide. The larvicide's effect comes from a hormone that shuts down digestion. Because the hormone occurs in mosquitoes naturally, researchers believe the new larvicide poses none of the environmental risks of older methods. "It's a natural hormone," explains John Bennett, chairman and CEO of Insect Biotechnology, a Chapel Hill, North Carolina-based corporation that has licensed the larvicide technology from the University of Florida in Gainesville, where it was developed. "This is a green product--safer than chemical pesticides used today."
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Languishing larvae. A new strain of chlorella may prevent mosquito young such as these Aedes aegypti larvae from growing up to become disease carriers.
Source: Leonard E. Munstermann |
Dov Borovsky, a biochemist at the Florida Medical Entomology Laboratory in Vero Beach, discovered that in nature, trypsin modulating oostatic factor (TMOF), a peptide hormone, normally shuts off the production of stomach enzymes in mosquitoes after a blood meal has been digested. Young larvae that were fed the hormone stopped digesting food prematurely and quickly starved to death.
Borovsky and his colleagues packaged his mosquito "diet pill" in the freshwater chlorella algae favored by waterborne larvae. The hormonal protein gene is incorporated in the DNA of the genetically altered chlorella.
Borovsky claims that TMOF is effective against most species of mosquitoes, including those that transmit dengue fever, yellow fever, St. Louis encephalitis, eastern equine encephalitis, and malaria.
TMOF has yet to be tested in the field. Bennett expects to begin small field trials within the next four months and continue until the EPA's requirements for registration are satisfied. But already the new larvicide is creating a stir in the mosquito-control community. Since word of his development hit the Internet, Borovsky has received calls from people as far away as China, India, and Singapore.
"We could sure use alternatives," says Andrew Spielman, a professor of tropical public health at the Harvard University School of Public Health in Cambridge, Massachusetts. "If you could have a transgenic alga that expresses the [TMOF] protein, it would be very attractive."
The most commonly used mosquito larvicides in the United States, according to Spielman, are Bacillus thuringiensis ssp. israelensis (Bti) and the growth hormone methoprene, sold under the brand name Altosid. Both are considered environmentally safe, although studies suggest they kill some nontarget aquatic insects. "We found that with long-term, high-level applications, some midges [gnat-like flies] are affected," says Nancy Read, the technical leader of a study of the effects of larvicides for the Metropolitan Mosquito Control District in St. Paul, Minnesota.
Another possible drawback of Altosid and Bti is resistance. "When you're using only one or two insecticides, the probability of resistance is strong," says entomologist Kelly Johnson of Ohio University in Athens. "An arsenal of more tools is better." Borovsky says he's heard of Altosid resistance problems in several mosquito-control districts in Florida.
In many developing countries, the larvicide temophos, sold as Abate, is often used because it costs considerably less than Bti and Altosid. But the broad-spectrum organophosphate weakens the food chain by killing other waterborne arthropods and copepods.
Borovsky believes his larvicide is a safer choice, not only because the hormone occurs naturally in mosquitoes, but also because its pond life is limited. The genetically altered variety of chlorella is believed to carry the hormone only through a few generations, lasting a total of 3-4 weeks. "The gene we put in is not stable, so eventually the dividing chlorella will kick it out," Borovsky says. "You don't want something [like that] to stay in the water forever." Spielman and Johnson agree. "I think it could be a good delivery system if there's tight control over the chlorella," Johnson says.
Spielman cautions that mosquitoes might develop resistance to TMOF as they apparently have to methoprene. Borovsky points out, however, that methoprene is an analog that binds to a different receptor than does the natural form of the hormone. He doubts mosquitoes will resist his chlorella larvicide because it contains the same hormone they produce naturally.
A significant limitation of Borovsky's larvicide is that chlorella grows only in fresh water. Borovsky is experimenting with other delivery vehicles that can be used in saltwater marshes. He is also investigating the digestion-regulating hormones of budworms, diamondback moths, and other pests. He expects his research to one day greatly lessen the need for chemical insecticides. "Insects are regulating their digestive enzymes," he says. "We are looking at these regulators. I see that in the 21st century we're going to control most of these pest insects through natural hormones."
The Threat of Meth
In January 1996, a large mobile home in Aquanga, California, burst into flames after a home methamphetamine lab exploded. Kathy James, her son Jimmy, and two men managed to scramble out, but trapped inside and suffocating to death were James' three younger children. Then, in September 1997, toxic fumes from a home lab killed little Joseph Carnesi in a Phoenix, Arizona, apartment as he slept on a couch. These are just two of many such incidents graphically illustrating the growing environmental health danger of the home meth labs that have sprung up across the country in recent years.
Meth labs, in fact, have become known in law enforcement as the hazardous waste sites of the drug trade. "Almost every day, people are arrested who are willing to risk their lives and those of their children," says Thomas Abercombie, assistant laboratory director at the Bureau of Forensic Sciences in the California Department of Justice. "They usually don't have a clue what those chemicals can do to them."
In California, where meth manufacturing in the United States is largely centered, hospital admissions due to methamphetamine-related causes rose by 360% between 1986 and 1996. These patients included victims of fires, chemical spills, explosions, and the inhalation of toxic fumes. In December 1997, federal drug agents raided one meth lab in Los Angeles where the combustible and toxic chemicals were still cooking. Across the street was a day care center; nearby were two public schools.
Experts describe meth as the "poor man's cocaine"--a cheaper drug that gives people a longer high. "It's easy to manufacture," says Tom Cashman, a special agent with the United States Drug Enforcement Administration (DEA), who is the agency's leading expert on methamphetamine. "Amateurs can cook it up with a few chemicals in a makeshift lab. You don't need a lot of space or sophisticated equipment either. That's why it's being cooked in a variety of settings: apartments, cheap motels, mobile homes, and isolated farms and ranches."
![Home lab stuff](forumfighomelab2.GIF)
Cottage industry? Home labs (left) freqently use commonly available ingredients (right) in the production of illegal methamphetamine.
Source: Jackson County (Missouri) Drug Task Force
It takes just $4,000 in raw ingredients to make eight pounds of meth, which is worth $50,000 on the street. Most of these ingredients are obtained from drug companies or the black market, or distilled from other substances, depending on the meth "cook"'s contacts and resourcefulness. While most of the chemicals needed are not dangerous by themselves and can thus be easily obtained and manufactured, they create numerous environmental health hazards during the production process and afterwards, when the chemicals are discarded.
Hydriodic acid and red phosphorus, the most dangerous chemicals used in meth production, can produce toxic phosphine gas and hydriodic acid vapors, while exposure to or inhalation of ether can cause respiratory damage, chemical burns, and even death. Red phosphorus poses additional problems because it's unstable and flammable, and can cause explosions and chemical fires if exposed to a flame or spark.
The fact that the meth-making process is getting easier has encouraged more people to get into the illegal activity. A recently unclassified DEA report reveals that phenyl-2-propanone (P2P) has been the primary precursor for meth manufacture. Since 1990, however, it has been increasingly replaced by the ephredine reduction method, a simpler procedure that involves fewer chemicals.
Rod Oswalt, a forensic scientist with the California Department of Justice, points out that the information for making meth is widely accessible. "The Internet contains thousands of recipes and discussions on how to make meth," he explains. "This, no doubt, has been a big factor in the rising popularity of meth."
The post-manufacturing phase poses the additional problem of what to do with the hazardous waste generated in making meth. One pound of finished meth normally produces 5-6 pounds of waste that includes corrosive sodium hydroxide solution, sealed cans containing residual freon and other hazardous fluids, and even pillow cases and bed sheets--used for filters--that hold large traces of red phosphorus and hydriodic acid, which can remain an environmental threat for years.
Cleaning up such hazardous waste sites is expensive, too. "It costs the taxpayers $5,000-7,000 every time we clean up a [meth lab] site," reveals Mike McCorson, an Arcadia, California-based hazardous waste coordinator for the Angeles National Forest.
Removing the containers, contaminated apparatus, and other typical waste is only a part of the cleanup cost. Cleaning a building, for example, can involve removing carpet, washing the walls, and removing or cleaning the drywall and the wood stud framing. In one incident, the Los Angeles police found that meth manufacturers had used a garage adjoining a private residence. Due to the proximity of the lab, the contamination extended to the house. The final cost of cleanup was more than $45,000. Responsibility for cleanup costs is one of the biggest issues regarding methamphetamine, and varies from case to case, and state to state.
Law enforcement officials nationwide foresee no letup in the meth lab environmental problem. Says Rodney Pickel, an antinarcotics officer with the Rock Hill, South Carolina, police department, "Right now, meth is the drug of choice in mainly California, but that state usually sets the trend for the rest of the country when it comes to drug abuse." And where there is demand for drugs, supply follows, creating even more opportunities for environmental disasters.
A New Side of the Nicotinic Receptor
As the "decade of the brain" approaches an end, that wrinkly organ remains largely uncharted territory. But recent studies by two NIEHS researchers may lay important groundwork toward understanding the molecular mechanisms behind such neurological disorders as Alzheimer's disease, depression, epilepsy, and Parkinson's disease. Jerrel L. Yakel, a scientist in the Laboratory of Signal Transduction at the NIEHS, and Susan Jones, formerly of the NIEHS and now a postdoctoral fellow in the department of neurobiology at Duke University in Durham, North Carolina, have reported a study in the 1 November 1997 issue of the Journal of Physiology that reveals a previously unsuspected location and role for the brain's receptor for nicotine. By gaining a clearer understanding of the function of this receptor, it may be possible to devise more accurate methods for treating neurological disease.
The nicotinic receptor, one of two main categories of acetylcholine receptor, is a specialized ion channel that plays an important role in learning, memory, and survival- and stress-related responses. Ion channels function as "portholes" in the membranes of cells, opening or closing in response to chemical signals from outside, and therefore regulating the flow of electrical current through the cells. Says Yakel, "Our data provide a new mechanism to be considered about how the function of these ion channels, gated by the endogenous neurotransmitter acetylcholine or an exogenous activator [such as] nicotine, can act to regulate neuronal activity in a region of the brain--the hippocampus--that is believed to be a very important center for learning and memory."
Yakel's earlier work includes research on the role of the serotonin receptor in the brain. The Yakel-Jones study sought to build upon that work by determining whether the nicotinic receptor would exhibit characteristics similar to those of the serotonin receptor. The scientists made an important discovery: nicotinic receptors, which had previously been thought to exist only on the presynaptic terminals of excitatory cells in the hippocampus, were also found on interneuronal (probably inhibitory) cells. The nicotinic receptor was thus found to act in a way previously unsuspected, possibly suggesting a novel mechanism by which acetylcholine may regulate neuronal activity in the hippocampus. This may further indicate that nicotinic ligands--the substances that bind to the nicotinic receptor--could be used as preventive measures against diseases associated with functions regulated by the receptor.
Unlocking the gateway. The nicotinic receptor subunit (left) includes carboxy (C) and amino (N) termini; nicotinic ligands bind to the N terminus. The complete channel is thought to comprise five subunits clustered around a central ion "passageway" (right) that opens and closes like a camera shutter.
Neurological disease is a mysterious realm, with scientists' understanding limited to a few tantalizing bits of knowledge. It is known, for instance, that a mutation in one of the subunits of the nicotinic receptor is associated with the rare autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE), although whether this particular mutation actually causes this form of epilepsy has not been conclusively shown. It is also known that Alzheimer's patients have fewer nicotinic receptors in their cerebral cortex, the portion of the brain that is ravaged by the irreversible disease. But the relationships between the various components that make up the electrical circuit that powers the brain are largely undefined. Scientists such as Yakel and Jones are beginning to look at more specialized groups of cells in order to tease apart these relationships.
Theoretically, Yakel says, the ligands that bind with the nicotinic receptor could be used to treat diseases such as Alzheimer's disease. Nicotine has been observed to improve memory, including that of some Alzheimer's patients. Little is known, though, about how nicotine actually works in the brain.
Some Alzheimer's patients are currently treated with a drug called tacrine that works by blocking the enzyme acetylcholinesterase, which breaks down acetylcholine, therefore prolonging the period of time that neurons are exposed to the neurotransmitter. While the cellular activity of the drug appears clear, it is uncertain exactly why or how the drug works, and to what degree the nicotinic receptor is involved. Yakel says that further work with the nicotinic receptor will focus on ascertaining whether it has a direct link with Alzheimer's disease.
EDF Launches "3,000 by 2000" Project
Last year, the Environmental Defense Fund (EDF) released a study called Toxic Ignorance that found that the U.S. public does not have access to data on the basic health effects of 71% of high production volume chemicals. High production volume chemicals are defined by the EPA as those that are imported into or produced in the United States annually in quantities greater than 1 million pounds.
According to the Toxic Substances Control Act (TSCA) of 1976, the responsibility for testing chemicals for effects on health and the environment lies with the manufacturers of the chemicals. However, the EDF study asserts, up to this point, few efforts have been made by the chemical manufacturers to comply, and the government has not been effective in enforcing the mandates of the act. The EDF study states that this is due to the "self-defeating" language and structure of the TSCA, which cause it to be vulnerable to legal attacks by chemical manufacturers, thereby foiling the EPA's efforts to require chemical testing.
The EDF has begun a campaign to contact the chemical manufacturers directly, and challenge them to take responsibility and commit to testing chemicals. The goal of the campaign, called "3,000 by 2000," is to have health effects data available to the public for the top 3,000 high production volume chemicals by the year 2000.
The EDF sent letters to the top 100 chemical producers and challenged them to commit to completing a preliminary health screening on all chemicals that are produced in excess of 10 million pounds per year by 1 March 1999, and to screen all chemicals produced in excess of 1 million pounds per year by 1 January 2000. The EDF requested that the chemical manufacturers perform tests based on the human health hazard elements of the Screening Information Data Set (SIDS), developed in 1990 by the international Organisation for Economic Co-operation and Development (OECD) and the chemical manufacturing industry. SIDS is now considered the international standard for chemical testing. The six categories of potential adverse human health impacts are acute toxicity, repeated dose toxicity, in vitro genetic toxicity, in vivo genetic toxicity, developmental toxicity (including teratogenicity), and reproductive toxicity.
Source: Toxic Ignorance. New York:Environmental Defense Fund, 1997.
Eleven companies agreed to comply with the EDF's request, while six refused. Many others cited their current efforts to test chemicals. The EDF placed an advertisement in the 3 December 1997 issue of USA Today listing the companies that committed to the project, as well as those that refused.
By widely publicizing the campaign, the EDF has thrust the issue of chemical testing into the international spotlight, helping it gain priority with government and industry groups. Thus far, response to the campaign has been generally positive, with government agencies and industry agreeing on the importance of the issue and cooperating to determine what steps need to be taken to test chemicals and make the data available to the public.
The Chemical Manufacturers Association (CMA), an industry organization that represents most of the 100 companies that were contacted by the EDF, has been active in discussions with the EDF and the EPA. The EDF actions were "favorably received," says Mort Mullins, vice president for regulatory affairs at the CMA. "We agreed with EDF that progress toward getting the OECD/SIDS data [on the chemicals] has not been achieved."
However, Mullins says that a CMA study conducted after the EDF released its findings indicates that there are data available for 47% of the chemicals, rather than the 29% that the EDF found. The CMA included information in its study that was not accessible by the EDF because certain databases containing such information are not currently available to the public.
Mullins says the CMA is conducting another in-depth audit of its databases to determine what chemicals have been tested. The group will then determine which steps need to be taken to compile existing information and put it into a format that will be accessible by the public. For chemicals that have not been tested for health effects, the CMA plans to oversee a testing process, divvying up the chemicals between different companies, Mullins says.
The EPA has also been auditing its databases to determine what data are available. Once chemicals that need to be tested have been identified, the EPA will work to ensure that they are tested, perhaps through regulation. "We have the authority under TSCA to require testing," says Charlie Auer, director of the chemical control division of the EPA. "We haven't written a rule, but we've been thinking about that. In the past, we've relied on voluntary efforts by companies. The problem in the U.S. is that we need to get more companies involved. One way to do that is through regulation."
Meanwhile, the OECD is examining the issue from a global perspective. So far, there has been a lot of action in a short period of time. "The key is going to be to go from the talk stage to the action stage," says David Roe, senior attorney for the EDF. He says the EDF plans to serve as a watchdog on the issue, adding, "We're in it for the long haul."
Doing a World of Good
Cooperation is crucial to meeting the environmental, resource, and development challenges of global significance for the future. The World Resources Institute (WRI) is an independent center dedicated to working with governments and private organizations to face these challenges.
The mission of the WRI, which celebrated its 15-year anniversary last year, is to teach and inspire human society to live in ways that protect the earth's environment and its capacity to provide for the needs and aspirations of current and future generations. The WRI conducts policy research and technical assistance on global environmental and development issues.
The WRI is accessible on-line through its site located at http://www.wri.org. The home page contains links that provide general information about the WRI, as well as information about its programs.
A link to Business and Technology provides information about two programs through which the WRI is working with industry on environmental issues. The WRI's Program in Technology and the Environment works with industry to develop environmentally efficient technologies, while the Management Institute for Environment and Business (MEB) works with universities, graduate schools, and corporations to integrate environmental issues into their educational programs. A link to the Business-Environment Learning and Leadership Program (BELL) tells how the MEB works with professors to enhance curricula, host seminars and conferences, and develop partnerships between universities and communities.
Another WRI program that works to involve businesses in environmental issues is the Climate Protection Initiative. Through this program, the WRI partners with businesses to identify "safe, climate-sound" government policies and corporate strategies. The What's New link on the home page offers an example of a partnership--the "Safe Climate, Sound Business" project--which is described under the WRI and General Motors Dialogue on Climate Change link. This collaboration between the WRI and General Motors will identify ways to reduce greenhouse gas emissions while protecting the economy.
The WRI also has an active division that works to protect human health, called the Program in Health, Environment, and Development (HED), which can be found via the Health and Environment link on the home page. HED investigates the impact of factors such as climate change and pollution on human health and seeks to develop policies to reduce human risk. Found on the HED page is information about a report, The Hidden Benefits of Climate Policy: Reducing Fossil Fuel Use Saves Lives Now, which is the first study to look at the global short-term health impact of fossil fuel consumption projects. The study says that by implementing climate policies now, approximately 8 million deaths resulting from particulate air pollution and the buildup of greenhouse gases could be avoided in the next two decades.
The WRI is also active in education through the Environmental Education Project, which is found under the link to Environment and Education. This program works with educational groups in the United States, Mexico, India, Europe, Australia, Vietnam, and Japan to develop and implement teaching materials about the environment including videos, teachers' guides, slide presentation sets, and computer software.
Information about programs in Africa and Asia can be found via links to the Policy Consultative Group for Africa and the Resources Policy Support Initiative, which works with Southeast Asia. These groups supply information about sustainable development and management of natural resources. The Forest Resources link provides information about the Forest Frontiers Initiative (FFI), a project that works to promote stewardship of forests. From this page, a link to Frontier News provides information such as news stories and statistics about forests around the world. A link from the FFI page to Business News contains information about another business/WRI partnership called the MacArthur Foundation-MEB/WRI Forestry Project, which works to expand the number of companies engaged in sustainable forestry, and to increase investment in sustainable forestry.
Other links from the WRI home page provide comprehensive information about issues such as biodiversity, sustainable agriculture, climate change, and global warming.
Last Update: March 25, 1998