The world's environmental problems are greater
than the sum of those in each country.
Tom McMillan
hearing, World Commission on Environment and Development
26-27 May 1986
Pesticide Use in Developing Countries
A World Health Organization/United Nations working group estimated in a 1990 report, Public Health Impact of Pesticides Used in Agriculture, that 3 million people worldwide suffer acute pesticide poisonings each year, and that a disproportionate burden of such poisonings is shouldered by people of the developing world. The conclusions of this working group's report sparked a collaborative agreement between the Pesticide Program of Universidad Nacional of Costa Rica (PPUNA) and the Swedish International Development Agency (SIDA), which culminated in the International Conference on Pesticide Use in Developing Countries: Impact on Health and Environment. The conference, which was held in San José, Costa Rica, 23 February-1 March 1998, investigated the causes of this disparity and what can be done to change it. Conference participants also toured nearby organic and cooperative farms.
PPUNA and SIDA have supported several studies on pesticides in the developing world, particularly in Costa Rica. One study, coauthored by Catharina Wesseling and Luisa Castillo of PPUNA and published in the August 1993 issue of the Scandinavian Journal of Work, Environment and Health, estimated the usage of pesticides in Costa Rica during the last decade to be 4 kg per capita annually in the last decade, eight times the estimate for the world population. Today, there are indications that the use of pesticides in Costa Rica is declining through the change from an agricultural exports-based economy to one based on ecotourism and increased organic farming.
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People at risk. Toxic exposures from unprotected application of pesticides is a major health concern in the developing world. |
Over half the pesticides used in Costa Rica are used on plantations that raise bananas, a major agricultural export. One effort towards reduction of pesticide use is Ecos del Agro, an organic banana farm located in Guapiles. The farm is currently the only commercial enterprise in the world producing a particular variety of pest-resistant banana developed by the Honduran Foundation for Agricultural Research. Exportation of organic bananas to North America will begin this year. Refuse from surplus bananas--bark and leaves, for instance--is used to make paper products. In fact, materials for the International Conference on Pesticide Use in Developing Countries were printed on paper made through this process.
Another example of sustainable agricultural practices in Costa Rica is Jugar del Valle, an organic agriculture training center near the town of Zarcero. The center was founded by local farmers to reduce pesticide-related disease in their community by sharing knowledge of alternatives to chemical pesticides. They started by gathering the knowledge of community elders about farming practices used prior to the widespread availability of pesticides. After years of producing only subsistence products, this cooperative farm is now a supplier for Costa Rica's main supermarket chain. To date, over 350 people have completed the training program, 20% of them from other countries. The centerpiece of the program is innovative approaches to producing fermented fertilizers. Felicia Echevarria, director of the training center, explains, "[Our] motivation is to leave in the earth what is in it that is good, so that it gives us things that are even better."
The conference highlighted these successes and pointed out areas in need of more research. David Pimentel, a professor of entomology at Cornell University's College of Agriculture and Life Sciences in Ithaca, New York, estimated the economic impact of pesticides on nontarget species (including humans) at approximately $8 billion annually in developing countries. Although only 20% of pesticides produced worldwide are used in developing countries, these countries experience more than half the pesticide poisonings, Pimentel said.
Rob McConnell, former director of the Pan American Health Organization and now an associate professor of environmental and occupational medicine at the University of Southern California in Los Angeles, stated that outbreaks of pesticide poisonings can be used to support changes in policy around the world. To achieve this goal, he proposed that universities establish surveillance mechanisms to monitor poisoning outbreaks and provide scientific literature and epidemiological results to government agencies. McConnell gave examples of outbreak epidemiology used as a tool to develop protective pesticide policies in Latin America, such as the case of an epidemic of carbofuran and methamidophos poisoning in Nicaragua in the mid-1980s that led the country's Ministry of Labor to list pesticide poisoning among the five priority preventable diseases for the subsequent triennial plan.
However, Carina Salazar, coordinator of research projects for La Era Agricola, an educational program for Venezuelan farmers located in Merida, pointed out that the results of many studies of outbreaks of human pesticide poisonings had not been shared directly with affected communities. She argued that identifying a direct benefit to affected communities must be an integral part of such research.
Community outreach, effective environmental health monitoring, preventive strategies, implementation of practices that reduce pesticide usage, and health promotion measures were identified as areas that need more extensive international attention. A complete conference report is slated for publication in the May 1998 issue of AMBIO, the journal of the Royal Swedish Academy of Sciences (due out in mid-August).
The Relentless Flu Drug
Just as it is always morning somewhere in the world, so also is it always flu season. But hope may be dawning for the thousands of people worldwide who suffer the misery of the flu each year. The Australian influenza drug GG167, also known as Relenza or zanamivir, began regulatory and commercial testing in early April, with sales to the public anticipated for the 1998-1999 flu season. Relenza, the result of three decades' worth of research, is what Tom Spurling, chief of the division of molecular science at the Commonwealth Scientific and Industrial Research Organisation (CSIRO), headquartered in Melbourne, Australia, calls "the world's first antiviral drug for the treatment of all strains of flu."
The development of the new drug is the result of a collaboration between Graeme Laver, a visiting fellow at the John Curtin School of Medical Research at Canberra's Australian National University, CSIRO scientist Peter Colman (now head of the Biomolecular Research Institute [BRI] in Melbourne), and a team of investigators led by Mark von Itzstein, head of the medicinal chemistry department at Monash University's Victorian College of Pharmacy in Parkville, Australia. The scientists, backed by the pharmaceutical companies Biota Holdings and Glaxo Wellcome Australia, have created a treatment that appears to offer effective relief against the annual scourge.
Relenza works by blocking the catalytic activity of the enzyme neuraminidase--also known as sialidase--on the influenza virus. Neuraminidase helps in the spread of infection by releasing the flu virus from an infected cell and allowing it to pass to adjacent healthy cells.
Laver's early work with the enzyme includes a paper published in the May 1969 issue of Virology that first described the morphology of the neuraminidase subunit within the influenza virus. This led to using the process of X-ray crystallography to delineate the crystal structure of the enzyme. Explains Colman, "X-ray crystallography gives a hundred million-fold magnification of the virus. It is a complex procedure, requiring sophisticated instrumentation and computational facilities. And to determine the crystal structure of a protein, first you need to isolate it, purify it, and then crystallize it. None of these are trivial tasks." In 1978, Laver successfully grew neuraminidase crystals of a high enough quality to begin the X-ray crystallography process, and joined forces with Colman and colleagues to map out the structure of the enzyme. By 1987, Colman and colleagues had fully identified the crystal structure of neuraminidase.
At this point, Colman and colleague Jose Varghese noticed a feature that they came to realize is common to all flu strains: a small "pocket" on the surface of the protein that is actually the active site of neuraminidase. The scientists realized that the strain-invariant neuraminidase receptor site might serve as a weak link that could be exploited in order to treat influenza. Working from Colman's lead, von Itzstein's team was able to design and subsequently synthesize the neuraminidase inhibitor that is used in Relenza. Relenza works by plugging the receptor pocket, thereby blocking the catalytic activity of neuraminidase, which prevents the flu from reproducing and spreading.
At first, many researchers were doubtful that the inhibitor would work, believing that the incredibly fast rate at which flu viruses can mutate and adapt to new hosts meant it would be impossible to target all strains of flu with one drug. But these doubts have been allayed by the performance of Relenza and other experimental neuraminidase inhibitors being developed around the world, such as GS4104, an orally administered drug developed jointly by Gilead Sciences of Foster City, California, and Hoffmann-La Roche of Nutley, New Jersey, that has been shown to be effective against influenza strains A and B in in vitro clinical trials.
Relenza is delivered to the primary site of infection, the lungs, as either a nasal spray or a sniffable powder. The medication appears to work best when administered within 30-36 hours of infection. When taken soon after infection with influenza, test subjects demonstrated a much shorter duration of infection and blunted symptoms. Even high-risk patients in the studies, such as the elderly and the immune-compromised, benefited from using Relenza.
Because the drug acts by stopping the spread of the flu virus, it is less effective if administered after flu symptoms begin to appear. To counter this potential dilemma, laboratories around the world are working to develop simple, rapid diagnostic tests for influenza that people can use at the doctor's office or at home to determine whether they have been infected with the flu. Laver estimates that some type of home rapid-detection kit may be available by the time Relenza hits pharmacy shelves.
Given the flu's capacity for rapid shifting, the question arises whether flu viruses might mutate in such a way that the neuraminidase inhibitor would no longer be effective. von Itzstein doesn't think so. "It is possible that the virus can mutate upon exposure to high doses of the drug [and] work has been published on this already in nonclinical studies," he says. "However, the clinical relevance of this result is yet to be determined. It is clear that if the virus significantly alters its active site pocket, it may well reduce its own infectivity." Colman adds, "[Selection for mutation is] always a possibility with any antiviral drug. Our drug looks promising in the sense that resistance is less likely than usual."
EPA's PM2.5 Program Criticized
In May, the National Research Council (NRC), the research arm of the National Academy of Sciences, entered the debate over the EPA's new air quality standard for particulate matter smaller than 2.5 microns in diameter (PM2.5) by issuing a report that strongly criticizes how the EPA has allocated funds to study these air pollutants. The report, which was requested by Congress, states that the EPA is directing too many of its resources toward monitoring concentrations of the fine particles in air and toward determining the sources of the pollution. On the other hand, the report says, the EPA is not doing enough to investigate human exposures, and its efforts to determine which types of particulate matter are likely to harm human health are "crucially inadequate."
The new National Ambient Air Quality Standard for PM2.5 was set by the EPA in July 1997, despite heavy opposition from many industry groups. The goal of the law, which supplements the EPA's standard for particles less than 10 microns in diameter (issued in 1987), is to protect the public from the very small particles that can be inhaled most deeply into the lungs. Several epidemiological studies have found an association between exposure to PM2.5 and serious health problems including exacerbation of asthma, decreased lung function, respiratory diseases, and premature death.
The debate over the new PM2.5 standard, however, centers on the fact that particulate matter, the visible component of smoke and haze, includes a wide variety of both solid and liquid particles from diverse sources including forest fires, wind erosion, road construction, and fossil fuel combustion. Little is known about exactly which of these particles cause health problems or by what biological mechanisms they act. Business groups argued to the EPA and Congress that the new PM2.5 standard was unfair because industries would likely bear the economic brunt of the regulation despite a lack of evidence linking specific sources or industries to the particles that affect health.
Congress responded to the argument by putting extra money in the EPA's 1998 budget for filling the gaps in the science supporting the PM2.5 standard. Part of this money was earmarked to fund a study of the EPA's PM2.5 research and monitoring program, to be completed by the NRC. Congress mandated that the NRC produce four reports on PM2.5 research needs, of which the May report, Research Priorities for Airborne Particulate Matter, is the first.
In the report, the NRC criticizes the EPA for allocating nearly one-third of its particulate matter budget for PM2.5 monitors that will be used mostly to judge if areas are in compliance with the new standard. Without more information on how actual human exposures relate to PM2.5 levels, and what constituents or characteristics of PM2.5 cause health effects, the monitoring program may fail to protect public health, the report says. Noting that the EPA monitoring methods are known to miss some types of particles in their measurements, the report states that the NRC "recommends that EPA consider more fully the possibility that the expensive monitoring program is not measuring the most biologically important aspects of particulate matter."
Officials within the EPA's particulate matter program call the NRC report useful, but say that some of its criticisms are more the result of incomplete information than shortcomings on the EPA's part. "I would say that from the comments in the report, there was some confusion as to the magnitude of some of our projects," says John Vandenberg, assistant director of the EPA's National Health and Environmental Effects Research Laboratory and the chief coordinator of EPA particulate matter research. "When they looked at our resource allocations, they did not take into account that we had been holding onto some resources in anticipation of this report. Congress gave us around $23 million above and beyond what we had requested for particulate matter research. . . . Most of this money we have held onto while we waited for [the NRC's] recommendation on where to spend it." In the meantime, the EPA continued work on its monitoring program, says Vandenberg, making it appear that monitoring was being disproportionately funded.
As for the usefulness of the particulate matter monitoring program, John Bachman, the associate director for science policy with the EPA's Office of Air Quality Standards and Planning, says that, though it is well known that the monitors may miss some particulates, it is also well known that the mass measurements that they do take seem to be related to health effects. "EPA's mandate is to protect public health," says Bachman, "so we would rather regulate something that we know causes health problems, though we may not know which constituents are the problem, rather than wait until we have identified the [health] effects of 10,000 different particles." However, he also emphasizes that the EPA is setting up more highly sensitive monitors that will give the agency information on the constituents of PM2.5.
Both Bachman and Vandenberg say that the report will be helpful in plotting a course for the EPA's particulate matter program. "We are trying to be very responsive to the [NRC]," says Vandenberg. "For example, they said we were not researching exposures enough, so we are now redirecting some resources toward exposure assessment issues."
Industry groups that fought the EPA over the new PM2.5 standard are not as satisfied with the report, though it affirms some of their accusations that the standard was based on incomplete science. Theresa Larson, director of environmental quality for the National Association of Manufacturers, one of the industry groups that sued the EPA over the standard, says that while the report makes some good points, it will do little to help industry. "The basic comment [from industry groups] is 'too little, too late,'" she says. "The report sort of hit with a thud. Things are really too far along now for it to do any good. The standards have already been set."
Besides pointing to immediate research needs and suggesting that the EPA redirect funding, the NRC report also recommends a 13-year, $444-million research program to answer the remaining questions about PM2.5. For the next few years, the NRC will work with the EPA to help it define its particulate matter research priorities, and the NRC committee that prepared the May report will meet regularly with EPA scientists. The next such meeting will take place June 22-23.
Not Breathing Easier
Preservatives used in certain asthma medications may be doing more harm than good in some patients. Researchers say that the stabilizer edetate disodium (EDTA) and the preservative benzalkonium chloride (BAC), which are commonly used in nebulizer solutions for the treatment of asthma and chronic pulmonary disease, actually counteract the effects of the medications in many patients.
Approximately 15 million people in the United States are affected by asthma, 5 million of whom are children, according to the Department of Health and Human Services. There was an overall increase of 75% in the number of cases of asthma between 1980 and 1994, with an increase of 160% among preschool children for the same period. Many researchers feel there is a strong link between environmental conditions and the development of asthma.
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Bad breath? New research shows that preservatives used in asthma nebulizers may present a health risk to some people. |
The treatment of asthma usually involves two medication options, according to Phillip Korenblat, a professor of clinical medicine at Washington University in St. Louis, Missouri, and a spokesman for the American College of Allergy, Asthma, and Immunology--rapid relievers, or bronchodilators, and long-term controllers. Korenblat says that asthma patients should keep a rapid reliever available at all times in the case of an asthma attack, but they should not rely on such a medication for long-term treatment. There are two types of bronchodilators--multidose inhalers, which administer medicine by means of a propellant or dry powder, and nebulizer solutions, which are delivered by an air compressor in the form of a spray designed to be inhaled. Korenblat says a very small minority of asthma patients use the nebulizer solutions. However, they are often administered to patients in hospitals and in emergency situations.
An article by asthma researchers at the Wellington College of Medicine in New Zealand and the University of Florida in Gainesville, published in the January-February 1998 issue of Pharmacotherapy, offers a review of studies conducted on nebulizer solutions both with and without the preservatives. The preservatives BAC and EDTA are added to nebulizer solutions that are dispensed in multidose dropper bottles and unit-dose screw-cap products in order to keep them sterile. The medications contained in nebulizer solutions are designed to open the bronchial tubes leading to the lungs, but the authors contend that at standard doses BAC constricts these airways, working against the medications and sometimes worsening the lung function in patients. They say EDTA causes the same effects in higher doses.
The authors also state that the addition of the preservatives was not preceded by safety studies, and they cite evidence that, indeed, the preservatives do not prevent bacterial contamination. Leslie Hendeles, a professor of pharmacy and pediatrics at the University of Florida who coauthored the study, says, "The preservatives don't prevent bacterial contamination, so they don't appear to have any benefits, and can actually cause harm."
The authors recommend that patients avoid the preservatives by using nebulizer solutions that are dispensed in preservative-free, sterile, single-dose vials, which have been shown to remain free of significant bacterial contamination. They point out that these single-dose vials are either the preferred product or the only nebulizer solutions available in most Western countries.
Current U.S. regulations do not require manufacturers to list on the label the concentration of preservatives contained in a product, and the amount of preservatives varies greatly between products. Also, it is legal for pharmacists to substitute these medications for one another so that even when a doctor has prescribed a preservative-free product, one containing high concentrations of BAC may be dispensed. The authors of the Pharmacotherapy study recommend that U.S. regulatory agencies ban the use of preservatives. In the meantime, Hendeles says he hopes the risks associated with the preservatives are communicated to pharmacists. He has worked with the Florida State Board of Pharmacy to issue a warning about the preservatives in its newsletter.
Even though a small number of patients use nebulizer solutions, Korenblat says the new information is cause for concern, and the medications should be studied further. He also says that patients should be aware of this information. "This should not raise alarm for people who have been doing well," Korenblat says, "but it is significant enough that asthma patients should know about it."
At this time, the FDA is not planning to take action on the issue, according to Robert Meyer, a medical team leader in the Division of Pulmonary Drug Products at the FDA. He says, "This is an issue that we had already been familiar with for quite a while." Because there is concern, he says the FDA recommends that the use of preservatives be avoided wherever possible, and if preservatives are necessary, they should be used in the lowest amounts possible. "We don't feel like this is a major public health problem," Meyer says. "The bottom line is that an individual who has been known to have adverse reactions should be careful to avoid the preservatives."
At the top of the U.S. Geological Survey's (USGS) home page is the motto "science for a changing world." The USGS--charged in its mission statement with providing reliable, impartial information to describe and understand the earth--is keeping close track of the geologic, climatologic, and environmental changes the planet faces today. The USGS home page, located at http://www.usgs.gov, offers Web users the opportunity to explore much of this carefully gathered information.
The Featured Pages link on the home page leads to a list of browsing options. The Earthshots: Satellite Images of Environmental Change link lets users choose from a number of satellite photographs and accompanying narratives that demonstrate the effects of desertification, air pollution, and other environmental threats. The USGS Water Resources Applications Software link leads to an array of software applications that can be downloaded off the site, such as HST3D, a three-dimensional model for simulating heat and solute transport within groundwater.
The Biology link on the home page takes users to the USGS Biological Resources Division home page. From here, users can read about the structure of the division and its current programs, projects, strategies, and partnerships, as well as browse a library of fact sheets, FAQs, and news releases. This page also boasts a Features link that leads to a photo image gallery, a children's page, education and special interest links, and even a link to a site that tracks the migratory progress of individual snow geese.
The Geology link on the home page goes to a page devoted to such geographical resources as a log of data on the latest earthquakes, a library of geological research activities searchable by state or region, and Ask-a-Geologist, in which users can have their questions about geology, geophysics, or geochemistry answered by a USGS geologist. The Geology page also contains links, under the Research link, to ongoing environment-related studies. For instance, the Global Change Research Program seeks to ensure the future availability of such human necessities as clean water and adequate food; by understanding how human activities affect environmental systems, it may be easier to formulate methods of ensuring that availability.
The Mapping link on the home page leads to information about the USGS National Mapping Program, which is responsible for providing the cartographic and remote sensing information and maps used by the USGS. This page provides links to mapping products and services such as the Geographic Names Information System--a searchable encyclopedia of nearly 2 million geographic features and cultural landmarks in the United States--and an online version of the National Atlas of the United States.
The Water link on the home page takes users to the home page for the USGS Water Resources Division, which is responsible for providing the hydrologic information used by the USGS in its mission of stewardship. The Water Data link on this page accesses a sea of information for those interested in the state of the nation's water supply. For instance, the Water Use link leads to online documentation and graphic depictions of water use data and trends in the United States by county and watershed. The Acid Rain link allows users to view levels of atmospheric depositions of various compounds by year, unit of measure, and compound.
Back at the USGS home page, the NAWQA Publications link takes users to a listing of publications--generated by 20 different water-quality studies conducted across the United States within the past decade by the USGS National Water-Quality Assessment--which document the major issues and findings, water quality conditions, and a summary of compound detections and concentrations for each sample. The USGS News and Information on El Niño link takes users to press releases, news items, and graphics documenting the latest developments in El Niño's global onslaught. And the link labeled President Clinton Announces the Clean Water Action Plan-Clean Water Initiative: Restoring and Protecting America's Waters lets users browse an outline of the initiative that includes the text of the action plan, budget information, fact sheets, planned strategies, and more.
Last Updated: July 23, 1998