Methyl Bromide under Fire
|
Warning signs. Methyl bromide may be dangerous to ozone as well. |
Methyl bromide is one of the most widely used pesticides in the world, a broad-spectrum fumigant effective in controlling insects, nematodes, fungi, and bacteria. Methyl bromide is also highly toxic to humans. In December 1993, the EPA listed methyl bromide as a stratospheric ozone-depleting substance subject to phase-out. The final rule, issued 1 January 1994, freezes U.S. production and importation of methyl bromide at 1991 levels, with a phase-out of production and consumption by the year 2001. The ban has been loudly protested by industry and agriculture, who say it will impose severe hardship on farmers without yielding a significant benefit to the global environment.
Roughly 59 million pounds of methyl bromide were used in the United States last year--43% of worldwide use--with Florida and California accounting for nearly two-thirds of domestic consumption. Methyl bromide is a preemergent pesticide: it is applied to soil before planting fruit and vegetable crops. It is also applied after harvest to numerous commodities such as grains, raisins, and walnuts.
Humans are mainly exposed to methyl bromide by inhaling it and absorbing it through the skin. The EPA classifies methyl bromide as a category 1 acute toxin, the most deadly category of substances. From 1982 to 1990, 15 deaths and 216 illnesses related to eye, skin, and throat irritation were attributed to methyl bromide exposure in California alone, according to the California Department of Pesticide Regulation. Long-term health effects from chronic exposure to methyl bromide include permanent neurological damage, muscle aches, impaired motor coordination, and abnormal kidney and liver function.
In addition to its immediate toxicity, methyl bromide is a potent destroyer of stratospheric ozone. A 1992 assessment by the United Nations Environmental Program (UNEP) attributes 5-10% of the current loss of atmospheric ozone to methyl bromide. Destruction of the ozone layer leads to increased exposure to ultra-violet radiation (UV-B), which in turn may result in far-reaching adverse effects on human health and the environment, including increased incidence of nonmelanoma skin cancer, cataracts, blindness, and possible effects on both cutaneous and systemic immune function.
Industry, however, is not satisfied with the available data on methyl bromide. "Given how little we know about the sources and sinks of methyl bromide, we feel the ban was premature," says Tom Duafala, director of research for Trical, Inc., a California-based applicator of methyl bromide. "Estimates of the contribution of agricultural use of methyl bromide to total ozone destruction are small and appear to be shrinking. Further, the lifetime of methyl bromide in the atmosphere is at most two years. So why not wait for more definitive information before imposing a severe hardship on agriculture?"
Methyl bromide in the atmosphere comes from both natural and anthropogenic sources. Total source strength is estimated to be between 75-210 gigagrams per year (Gg/year). Thirty-three gigagrams (109) per year, or between 16 and 44%, is estimated to come from direct application as a pesticide, according to the UNEP report.
Scientists have recently focused on methyl bromide resulting from the burning of biomass (the dry weight of living organisms) as a potential major source of ozone depletion. Wildfires of African savannas, chapparals, and boreal forests, as well as agricultural fires to clear land for planting or to burn off post-harvest residues, emit high concentrations of methyl bromide. A recent study by Stein Mano and Meinrat O. Andreae of the Max Planck Institute for Chemistry in Germany, published in Science, estimates that emissions of methyl bromide from such fires range from 10 to 50 Gg/year, with a best estimate of 30 Gg/year. The high degree of uncertainty reflects the limited data set available on this source; however, this amount is comparable to that produced by ocean emissions and pesticide use and may equal as much as 30% of stratospheric bromine.
Some scientists believe a primary natural source of methyl bromide is production by marine plankton. One study by M.A.K. Khalil and colleagues, published in the Journal of Geophysical Research, estimates oceanic contribution to be about 35 Gg/year, with an uncertainty of ±50%. However, it has also been proposed that the oceans serve as a sink as well as a source for methyl bromide, and that a reduction in anthropogenic emissions might result in a corresponding flux from the ocean to the atmosphere. This effect might lessen or negate the benefits to stratospheric ozone from a reduction in anthropogenic emissions of methyl bromide.
In terms of costs to society from the ban, the California Department of Pesticide Regulation estimates growers in its state stand to lose $340 million per year in crop damage. Duafala says no single alternative exists that will replicate the range of uses of methyl bromide. He says there are nematicides (1,3-dichloropropene) and fungicides (methyl isothiocyanate) that effectively perform some of the functions but that these are not as versatile as methyl bromide.
Bill Thomas, methyl bromide program coordinator for the EPA, agrees that there is no single alternative for methyl bromide, but asserts that the ban--phased in over a period of seven years--will allow for the development of alternatives. "The cost of finding alternatives is an issue, but not a monumental barrier," Thomas says.
Vets May Be Compensated
|
Payment prescription. Persian Gulf veterans may soon be compensated for environmental war wounds. |
U.S. veterans suffering from Persian Gulf syndrome may soon be able to receive disability payments. The Clinton administration has endorsed a bill introduced by Congressman G.V. "Sonny" Montgomery (D-Mississippi) that would authorize payments to afflicted veterans for a three-year period.
"Persian Gulf syndrome" is the name given to an illness of unknown etiology that includes a broad range of symptoms such as diarrhea, muscle aches, and fatigue and affects perhaps thousands of Gulf War veterans (see Focus, p. 747). So far, researchers have not been able to pinpoint the cause of Persian Gulf syndrome, although many suspect chemical and biological warfare agents.
Veterans Affairs Secretary Jesse Brown called the proposal to compensate these veterans "unprecedented" because the government usually requires that payments be based on clearly defined illnesses that can be directly linked to active military service. "We left veterans of Vietnam hanging out there for 10 years," said Montgomery. "We cannot always wait on research."
Objections to the bill have already been raised. Senator John D. Rockefeller IV (D-West Virginia) said in a letter to Brown that the VA already has authority to compensate veterans for any "disability resulting from personal injury suffered or disease contracted in the line of duty." Proponents of the bill say that the VA has refused to invoke this authority.
"We simply have different interpretations," said VA spokesperson Jim Holley. "It is our position that we need legislation to award compensation and that is a firm position."
To qualify for any disability benefits, a veteran has to be examined by the VA and found to be at least 10% disabled by the illness or injury. Montgomery's bill would set a one-year claim period. Compensation would depend on the extent of disability. According to Brown, a typical payment would be about $166 per month, based on a veteran who is 20% disabled. The annual cost of compensation is estimated at $45 million.
Congressman Lane Evans (D-Illinois) objects to the bill's three-year limit on benefits. Evans noted that the VA had never offered new benefits to veterans on a short-term basis. Brown said that if the government is unable to define Persian Gulf syndrome by the end of the third year, Congress should extend the benefits.
The United States is not the only country debating the health effects of the Gulf War. The Czechoslovakian military has claimed evidence of chemical discharges during the war. However, Great Britain's Surgeon General, Sir Peter Beale, said in a letter to the British Medical Journal, "We have no evidence to support the claim that a medical condition exists that is peculiar to those who served in the gulf conflict." Whatever the verdict, it is certain, as Brown said, that "The Persian Gulf was a dirty war, environmentally speaking."
Poland's Environmental Docs
|
Mining for doctors. A new environmental physicians program in Poland puts theory into practice by training doctors to treat environmental health problems. |
|
One of the most important issues that has emerged during recent years in Poland is the shortage of sufficiently trained health professionals to deal with environmental health problems. In 1993, the Polish Ministry of Health and Social Welfare, in conjunction with the WHO European Centre for Environment and Health in Bilthoven, launched the Environmental Physician Scheme (EPS) to address this shortage.
The ultimate objective of the EPS is to create a network of environmental physicians that can provide public health facilities, government agencies, and scientific institutes in Poland with expertise on the health effects of pollution. The EPS is centered at the Institute of Occupational Medicine and Environmental Health in Sosnowiec, Upper Silesia, where industrialization and urbanization have led to serious deterioration of the environment.
Recruitment of trainees began in spring 1993. From 102 applicants, 15 were selected to participate in the EPS. Trainees are enrolled in a three-year curriculum which began in January consisting of theory, practice, and individual research. The main body of the course is provided through the Institute of Occupational Medicine and Environmental Health, and lecturers have been invited from research institutes, universities, and government agencies in Poland and the Netherlands.
Courses in environmental health theory form the foundation of the curriculum. The theory portion of the curriculum was developed by Dutch experts on the basis of experience gained through environmental physician training in the Netherlands, where an environmental physician network has been in place for a number of years.
The practical segment is designed to gradually build skills in handling typical environmental health problems. An important aspect of this portion of the curriculum is training abroad. The goal of international training is to familiarize physicians with the methods other countries use to address environmental illnesses as well as to gain knowledge of the organization and legislation of environmental health services around the world.
The third part of training, individual research, is concentrated in the last semesters of the curriculum. The research will be based on practical application and guided by individual mentors. The individual research portion of the program gives trainees an opportunity to produce a doctoral thesis. According to Jerzy A. Sokal, director of the Institute of Occupational Medicine and Environmental Health, the planners of the program are hoping that it will help to establish the environmental physician as an official medical specialization in Poland. A decision on this is expected this year.
The entire EPS is managed by an operational course director and evaluated regularly by the International Steering Committee, composed of representatives from WHO, the National Institute of Public Health and Environmental Protection in Bilthoven, the Institute of Preventive Medicine in Leiden, the Polish Ministry of Health and Social Welfare, local authorities of the Katowice Province, the Silesian Medical University, and other institutions. The program is funded by the Polish government and the WHO European Centre for Environment and Health.
The EPS, as the first post-graduate course in environmental health in Central and Eastern Europe, will provide the experience and knowledge necessary for future training not only in Poland but in other countries in the region. Said Sokal, "We are convinced that our fruitful cooperation with the WHO-ECEH within this project, as well as the assistance and guidance provided by our Dutch colleagues, will lead to successful accomplishment of this important activity."
Cigarette Secrets
As the confrontation between Congress and the nation's tobacco companies heats up over alleged manipulation of addictive nicotine in cigarettes, the issue of possibly toxic chemical additives simmers alongside. Tobacco companies have used additives to enhance cigarette flavor lost when tar has been lowered.
This spring, the tobacco companies made public, for the first time, some 599 chemicals used to process or flavor cigarettes. Tobacco smoke, which contains about 4000 components, is known to contain at least 50 carcinogens, according to the International Agency for Research on Cancer. Cigarette additives may add to this list.
The additives list made public is "essentially the same" as the secret list of approximately 700 ingredients that tobacco companies annually report to the government, according to the Office on Smoking and Health (OSH). The list is kept secret under the Comprehensive Smoking Education Act, which stipulates that ingredient information provided to the Department of Health and Human Services be treated as trade secret or confidential information. But no list specifies any quantities. "What you've got is a witches' brew," explains Michele Chang, special assistant for policy at the OSH. "You've thrown me a list of chemicals. So what? We don't know at what point they're added, in what quantity, in what combination. We don't know how it reacts when it's burned or how it reacts when it's smoked, and those are two different chemical reactions."
Since February, the OSH, which believes that many of the ingredients added to tobacco could cause disease or other adverse health effects, has convened an additives working group that taps the expertise of toxicologists and chemists. "Everyone agrees on one thing," said Chang, "it would take an incredible amount of resources to do actual laboratory studies to figure out what is the effect of X chemical with Y chemical in X cigarette, and then relate these products to a specific health effect. And then you still have to worry about how many cigarettes are they smoking."
Chemicals on the list that are of concern to researchers include, for example, ammonia, angelica root extract, cocoa, pesticides, and other agricultural products.
In addition to being an irritant, ammonia raises the pH of the smoke of American cigarettes from the typical pH 6, explains Dietrich Hoffmann, associate director of the American Health Foundation. "At pH 6, all of the nicotine is present as a salt. When the pH is increased beyond 6.5, going up to pH 8 or 8.5, one obtains a greater portion of the nicotine in the unprotonated, the most toxic form. Unprotonated nicotine is much more quickly absorbed through the mucous membranes of the oral cavity. In other words, one gets a much greater nicotine kick than if one inhales the protonated nicotine in the acidic smoke. So there comes the added toxicity," Hoffmann says. In the list of ingredients added to cigarettes compiled by the six major American cigarette manufacturers, ammonia is listed only as a naturally occurring substance that plays a vital role in protein metabolism in animals and man.
Hoffmann's main concerns, however, are plant extracts, among them angelica root extract, which imparts a sweet aroma to cigarettes but contains coumarin, a carcinogen in rats. While angelica root extract remains on the Food and Drug Administration's Generally Recognized As Safe (GRAS) list, Hoffmann says, the FDA removed one additive, deer tongue extract, many years ago because it contained coumarin. Other plant extracts also contain coumarin, he warns. "About most of these other components [on the list], we know very, very little."
Even additives such as cocoa, long used to flavor cigarettes, can be harmful. "Studies have indicated that when it's burned, it [produces] a co-carcinogen [a substance that in the presence of a carcinogen increases the risk of cancer]," says Scott Ballin, vice president and legislative counsel for public affairs at the American Heart Association and chairman of the anti-smoking Coalition on Smoking OR Health.
Of substantial concern is what happens to additives when a cigarette burns. "When they're burned in conjunction with tobacco and other substances, are they potentially making the product more dangerous than it already is, and what are those dangers?" Ballin asks. "The industry is using as a defense that [some additives] are on the GRAS list for foods and therefore they're nontoxic. But it's very different to put something in the food supply in its raw state and have it safe, as opposed to having something burned."
In particular, 13 ingredients on the industry's list have been questioned by the Congressional Subcommittee on Health and the Environment, chaired by Congressman Henry Waxman (D-California), because they do not appear on the FDA's Everything Added to Food in the U.S. list. Last March, in a memo to Waxman from David Satcher, director of the Centers for Disease Control, the OSH responded to Congress's query with information from a literature review of the 13 chemicals. The CDC's literature search failed to find reproductive, developmental, or carcinogenicity data for a majority of the substances. Some of the data did indicate, however, that further research is warranted on these additives. For example:
- Methoprene, a pesticide, was found to be acutely nontoxic to rodents via the oral or inhalation routes, but it is moderately toxic to dogs.
- Ethyl furoate was found to be severely toxic when parenterally administered to rats. Some recent news articles have reported that ethyl furoate is in the same family as ethyl furoid, which causes liver damage when tested on animals.
- Sclareol, an essential oil extracted from the plant Salvia scalerea, is used to control powdery mildew on crops and by the perfume industry as an odorant. Some reports indicate that sclareol causes convulsions in laboratory rats.
- Trichlorofluoromethane is only slightly toxic when inhaled. Progressive effects from acute inhalation can include rapid and irregular respiration, increased activity, tremors, uncoordinated body movements, and loss of consciousness.
- Tobacco leaf aqueous extract caused joint curvature deformities in offspring of pregnant pigs who consumed it. In studies of rats who received the extract for 21 months, some animals developed lung adenomas (10%) and gastric papillomas (10%), although equal numbers of controls did not develop these tumors.
In June, the OSH asked industry to voluntarily submit additional information. The working group is awaiting a reply.
The tobacco companies have released their own safety assessment of additives, noting that "approximately 98% of all ingredients . . . are approved as food additives by the FDA or have been given the GRAS status, adding that "many of the ingredients are identical or essentially similar in composition to natural leaf tobacco components." The remaining 2% of the list, however, leaves approximately 80 ingredients which have not been approved. The report said the 28 ingredients present at the highest levels in cigarettes occur at levels ranging from 0.05% to 9.28% by weight, the latter being sugars. The remaining ingredients occur at levels below 500 ppm, and over one-third occur at levels below 1 ppm. The industry's report states, "Based upon analyses of all the toxicological data reviewed by the authors, it was concluded that there was no evidence that any ingredient added to cigarette tobacco produces harmful effects under the conditions of use in cigarettes."
"Congress has always asked us, 'Can't you do an analysis' to find out what the health effects are of these additives in cigarettes? That's not something we can do because toxicology requires more information as to quantity and combination. And our answer has always been the same: without brand and quantity, we are so severely limited we can't do anything," Chang says. "Even when we looked at toxicology studies of chemical X and chemical Y, through a literature search, it's in a vacuum. If you don't tell us how much you're being exposed to, we can't easily relate it to a health hazard. What you have is a general characteristic about a chemical. It's a maze, and you've hit another dead end."
World Wildlife Funds for Russia and Asia
In pursuit of protecting biodiversity, the World Wildlife Fund announced two projects this spring that will aid Russia and Southeast Asia in environmental conservation. The organization has launched global campaigns to raise money for the projects.
The WWF says Russia has been one of the last places on earth to conserve true wilderness. Since the collapse of communism, however, Russia's conservation program has been neglected. Due to the economic problems of the country, conservation efforts have been bankrupted. According to the WWF, these economic changes have resulted in activities such as uncontrolled logging in the eastern region, unchecked air, land, and water pollution, widespread poaching, and attempts to destroy at least six strict nature reserves.
Therefore, the WWF has outlined a plan to rebuild conservation programs. This past January, the WWF released a report entitled, "Conserving Russia's Biological Diversity," that divides Russia into 14 ecological regions and identifies their biological value, the threats they face, and opportunities for their conservation. The plans include a program to build on Russia's system of strict nature preserves called zapovedniks. Of the zapovedniks, 17 exceed 2000 square miles; the largest is 15,000 square miles. Russia is one of the few countries able to conserve large, intact ecosystems such as these areas. The WWF plans also include protecting animals such as Siberian tigers, Amur leopards, Siberian cranes, golden eagles, Baikal seals, and saiga antelope. The organization also plans to promote environmental awareness in Russia and introduce community-based approaches to conservation, such as ecotourism.
Investing in conservation of Russia will be a good value, the WWF says, because of the inflated value of the U.S. dollar against the fallen ruble. "When looking at the incredible amount of land that can be conserved, the myriad of species that exist on that land, and how relatively little it would cost to protect it all, Russia is the best conservation bargain on the map today," said Eric Dinerstein, WWF director of conservation science. "The United States has pledged $400 million to assist Russia's space program over four years. For less than a twentieth of that, we can safeguard some of the earth's last true wilderness."
The WWF estimates that $17 million is needed to fund the project. An appeal has been launched to the World Bank, the U.S. government, several European governments, and private groups to raise the funds. The WWF has designated $500,000 of its own funds for the project, to begin next year.
Southeast Asia is also an area of environmental concern to the WWF. Denmark has signed a two-year agreement with the WWF to contribute $75 million to help fund environmental conservation projects in Thailand, Malaysia, Laos, Vietnam, and Cambodia. The WWF international branches will work with the WWF Denmark and the Danish Environment Ministry to choose projects.
Denmark is the first country to sign such an agreement with the WWF. According to the WWF, Denmark is one of the few rich nations which has responded to the call for funds for less prosperous countries. The money is part of Danish funds for global environment and disaster assistance, which will reach 0.5% of Denmark's gross national product by the year 2000.
Last Update: July 10, 1998