We've got a program to invent a new name for ecology, so we can keep it alive after it's been talked to death. We're thinking of calling it politics.
Harvey Wheeler
Newsweek, 26 January 1970
Cataract Development: It's Cumulative
Cumulative exposure to UV-B radiation in sunlight increases the risk of cataracts, even among a population with relatively low exposure throughout their lifetimes. This is the finding of a recent study by researchers at The Johns Hopkins University in Baltimore, Maryland, that was published in the 26 August 1998 issue of the Journal of the American Medical Association. Earlier studies had linked the risk of cataract development to high levels of sunlight exposure.
The Salisbury Eye Evaluation (SEE) project was a two-year study funded by the National Institute on Aging. The SEE project is the first to demonstrate that high levels of sunlight exposure are not necessary for cataract development, but that cumulative exposure over many years is a risk factor. The study also indicates a difference in risk for cataracts among whites and blacks.
The study was conducted in Salisbury, Maryland. Salisbury was selected as the study site for a number of reasons. The moderate size of the town gave the researchers a manageable study cohort. In addition, the Johns Hopkins staff had already established a working relationship with Salisbury's ophthalmologists and optometrists, and the single local hospital allowed ready access to medical records if needed.
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Don't stare into the sun. A new study shows that cumulative exposure to UV-B radiation in sunlight increases the risk of cataracts.
Source: Lester V. Bergman/Corbis |
The researchers obtained a list of 3,821 individuals in Salisbury who were aged 65 and older. This list included 100% of Salisbury's black residents in that age group, 56% of the whites aged 65-74 years, and 62% of the whites aged 75 and older. Females made up 58% of the list. These potential subjects were first visited in their homes and asked to take a screening questionnaire. The questionnaire asked the participants about their sunlight exposure since the age of 30, both at work and during leisure activities, the geographic locations of their work and leisure activities, and whether they used glasses or hats while outside. They also were asked to assess their current level of vision on a scale of 1 (poor) to 10 (excellent).
Those participants who met study criteria were then asked to report to the SEE clinic to undergo dilation of the pupil and photographing of the lens. The researchers used an algorithm that considered the amount of sunlight exposure per day at a given time of day, the month of exposure, the fraction of time spent outdoors, and the use of hats and eyeglasses to calculate each subject's annual UV-B exposure. Exposure units were in Maryland sun-years (MSY), the equivalent of 75.9 joules of radiant energy per square centimeter of tissue. Of the 2,520 individuals who reported to the clinic, no differences were found in their average annual sunlight exposure, though women as a group tended to have less exposure (median 0.007 MSY) than men (median 0.019 MSY).
Blacks exhibited a significantly greater number of cortical cataracts than whites, even though sunlight exposure did not differ between the two groups. "There is a racial factor of some sort demonstrated here," says Sheila K. West, a professor at the Wilmer Eye Institute at Johns Hopkins and coauthor of the study. "We thought it might be associated with the greater prevalence of hypertension or diabetes among the black population, but after controlling for those factors the difference remained." She also notes that eye color, education, smoking, and alcohol use were not found to account for the difference. "Nevertheless," she says, "ours is the first study to document the relationship between ocular exposure to UV-B and risk of cortical opacity in African Americans."
Overall, for the older population of Salisbury, the risk for cortical cataracts resulting from cumulative exposure to UV-B was found to be 13%. This level of risk may well be unique to Salisbury, says West. One might expect the prevalence of such cataracts to be higher among a population living in areas of more intense sunlight occurring over longer periods of time. However, West notes, "People living in areas of intense sunlight may not stay out in the sun for long periods of time and are more accustomed to wearing sunglasses when they are out."
Robert Sperduto, chief of the Epidemiology Branch of the National Eye Institute, agrees. "It is likely that individual levels of exposure differ even in areas with greater amounts of sunlight, though earlier studies indicate a higher prevalence of cataracts in areas with more sunlight," he says.
No association was found between UV-B exposure and other types of cataracts, such as nuclear or posterior subcapsular opacities. Extrapolation of these test results is moot, however, inasmuch as no similar studies have been carried out in other areas.
Fortunately, cortical lens opacities are easily preventable, the researchers say. Simply wearing plastic lenses, tinted or not, or a wide-brimmed hat can significantly reduce the incidence of these cataracts. Some manufacturers are now treating contact lenses to block UV-B radiation.
The study is now in its second phase. The Johns Hopkins team plans to assess whether continued exposure over two years will cause existing cataracts to grow, and whether the use of preventive measures will arrest growth.
New Rules for Feedlots
For livestock and poultry producers across the United States, the manure is hitting the fan. A September 1998 report entitled Draft Unified National Strategy for Animal Feeding Operations, prepared jointly by the EPA and the U.S. Department of Agriculture (USDA), proposes an aggressive strategy to improve water quality and reduce public health risks associated with animal feeding operations (AFOs). The strategy is well timed. Approximately 35,000 river miles in the United States are currently polluted by runoff from livestock operations. Livestock wastes are flowing down the Mississippi River and contributing to an oxygen-depleted dead zone the size of New Jersey in the Gulf of Mexico. Poultry wastes have been implicated in toxic Pfiesteria piscicida infestations off the mid-Atlantic states. These infestations have killed millions of fish, and have been linked to human neurological effects including memory loss.
The draft strategy targets AFOs, which are defined as agricultural enterprises where animals are kept and raised in confined situations. Specifically, it establishes a "national expectation" that all AFOs will develop site-specific comprehensive nutrient management plans (CNMPs) by the year 2008. CNMPs prescribe measures such as feed management, as well as manure storage and land application procedures that AFO operators would be expected to follow to ensure that their feedlots meet clearly defined nutrient management goals. Operators looking for technical guidance in developing a CNMP will be able to turn to sources that include the Natural Resources Conservation Service of the USDA, the EPA, and certified specialists in the private sector. An additional source of information is the National Dialogue on Pork Production, a multiparty coalition of producers and state and federal regulatory agencies (including the EPA) that released a separate set of waste management guidelines entitled Comprehensive Environmental Framework for Pork Production Operations in December 1997.
According to Jeff Lape, the AFO cochair representing the EPA in development of the strategy, smaller AFOs will develop CNMPs on a voluntary basis. However, concentrated AFOs, which are loosely defined as containing more than 1,000 animal units (the equivalent of 1,000 beef cattle, 700 dairy cows, 2,500 hogs, or 30,000 chickens), and other high-risk facilities will be required by regulation to develop CNMPs. "We estimate that there are 450,000 AFOs in the United States," says Lape. "Ninety-five percent of these are going to fall under voluntary programs. The rest will fall within a regulatory program."
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Cleaner critters? The EPA and the USDA have proposed a strategy to reduce public health risks associated with animal feeding operations. |
Although the regulatory component of the strategy is still being developed, it is likely that the AFOs that fall into this category will be required to prepare a CNMP in order to qualify for a National Pollutant Discharge Elimination System permit, to be issued by individual states and the EPA under the Clean Water Act. Currently, around 2,000 facilities have been issued such permits under the Clean Water Act. However, according to Lape, the new strategy will likely raise that number to an estimated 20,000.
Susan Heathcote, research director for the Des Moines-based Iowa Environmental Council, is encouraged by the EPA and USDA's collaboration on the strategy, but adds that much of its success will be determined by actual environmental improvements, whether through voluntary or regulatory means. "Hopefully, if we're doing our job right," she says, "then we're going to see some improvement."
International Lab Established in Chornobyl
Early on the morning of 26 April 1986, two nearly simultaneous explosions at the V.I. Lenin Atomic Power Plant--soon to be known around the world as the Chernobyl nuclear power plant--released what the World Health Organization has estimated to be 200 times the combined radioactivity of the atom bombs dropped on Hiroshima and Nagasaki. Twelve years later, on 22 July 1998, Ukrainian and U.S. leaders signed an agreement to establish the International Radioecology Laboratory in Chornobyl (the city's recently adapted Ukrainian spelling).
The agreement developed from the ongoing work of Ron Chesser, a senior ecologist at the Savannah River Ecology Laboratory (SREL). The SREL is administered by the University of Georgia in Athens and funded by a cooperative agreement with the Department of Energy (DOE). The SREL performs ecological research at the DOE's Savannah River Site, a nuclear weapons materials processing facility in Aiken, South Carolina.
The new laboratory will be devoted to studying the effects of ionizing radiation on the plants and animals of the area surrounding the Chornobyl reactor. According to a 1996 International Atomic Energy Association/World Health Organization publication, Ten Years after Chernobyl: What Do We Really Know?, the only major public health effect of the Chornobyl accident noted to date has been an increase in thyroid cancer among children--up to 800 cases by the end of 1995. But the long-term human health effects of the accident are yet to be seen. By studying the wildlife of Chornobyl, scientists hope to assess the multigenerational effects of high doses of ionizing radiation, and to establish how organisms cope with the genetic damage sustained from such radiation.
The lab will enable scientists to perform, for the first time, long-term studies on the biological and genetic effects of varying amounts of radiation. "The lab is [unique] in the sense that we can study organisms that have lived through many life cycles in varying degrees of radiation," says Chesser. Other studies will look at how much of a given dose of radiation is absorbed by an organism, and at the mobility of radionuclides through soil, water, and biological systems. Chesser says, "It's a diverse set of topics we're addressing. There will be perhaps a dozen different studies looking at different aspects of genetics alone."
The lab's scientists will also evaluate the effectiveness of current cleanup strategies, such as the 800-plus radioactive waste burial pits surrounding the Chornobyl plant, and investigate new remediation techniques. Finally, the new lab will also enable scientists from around the world to consolidate and coordinate their efforts, and launch new studies or expand current ones.
Since 1992, SREL scientists have made numerous expeditions to Ukraine to study the genetic effects of radiation on the flora and fauna within the Chornobyl Exclusion Zone, which extends 30 km from the plant in all directions. Chesser himself has made some 15 expeditions to Chornobyl. The idea for the laboratory was first raised in the summer of 1993. "During my work [at Chornobyl] that summer and since," says Chesser, "I found that many of the samples were too high in radioactivity to transport, and that several important analyses and experimental designs could not be performed because of lack of nearby equipment and [the short-term nature of the] expeditions."
Talks with the Ukrainian government ensued, and in 1996, the Savannah River Operations Office decided to provide further equipment to aid the research efforts at Chornobyl. Since then, through the efforts of the DOE Office of Nonproliferation and National Security, political and logistical arrangements were made that culminated in the agreement signed by U.S. Vice President Al Gore and Ukrainian President Leonid Kuchma.
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A new chapter for Chornobyl. A new international laboratory may help answer questions about long-term environmental effects from the nuclear disaster.
Source: Paul Khrarntsov |
Chesser will serve as director of science programs for the laboratory, and will sit on its governing board. The lab will also employ a director, lab technicians, and field crews. The full-time staff will be Ukrainian, but scientists, professors, and students from other countries are expected to visit. The lab should be at least initially operational by the end of summer 1999. As with all other DOE contracts, the new lab will be reviewed after five years to determine whether it will continue as is, continue with modifications, or be eliminated.
In addition to laboratory space, the new facility will also contain offices and lodging for visitors. The Ukrainian government will provide updated, renovated buildings and utilities for the project, while the DOE will pay for the lab's equipment and operating costs.
Says Chesser, "We're trying to make this a truly interdisciplinary effort." Already, institutions such as Texas Tech University (Lubbock), the Illinois State Museum (Springfield), Oklahoma State University (Stillwater), and Texas A&M University (College Station) have research programs in place that are expected to eventually lend complementary expertise to the lab's research efforts.
Is It Safe to Drive SUVs?
The California Air Resources Board (CARB), often a bellwether of national regulatory trends, voted on November 5 to apply passenger car tailpipe emission standards to light trucks. The proposal to cut pollution from pickups, sport utility vehicles (SUVs), and minivans by the year 2007 is part of a broader effort to bring Southern California's air into compliance with the Clean Air Act.
The issue of light truck emissions is gaining importance because sales of such vehicles currently account for about 45% of total new vehicle sales. Between 1970 and 1995, the total miles driven by passenger cars grew 168%, while the mileage driven by two-axle, four-wheel trucks exploded by 558%, according to the American Automobile Manufacturers Association report AAMA Motor Vehicle Facts and Figures, 1997. Although light trucks, particularly SUVs and minivans, are increasingly used as passenger vehicles, they can create far more pollution than cars.
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Not so sporting. Sport utility vehicles are popular with drivers, but not with air regulators who plan to tighten emission standards on SUVs. |
Federal pollution and fuel efficiency regulations are significantly looser for light trucks (with loaded vehicle weights above 3,750 pounds) than passenger cars. In California, light trucks with loaded vehicle weights between 3,750 and 5,750 pounds can emit 33% more nonmethane hydrocarbons (an ozone precursor) than passenger cars, 100% more nitrogen oxides (NOx), and 30% more carbon monoxide (CO). EPA figures show that motor vehicles overall account for 35% of NOx, 64% of the national output of CO, and 27% of volatile organic compounds.
The auto industry opposes further regulation, saying trucks pollute more than cars because they're heavier and designed for hauling. "The higher standard is a reflection of the fact that they do more work," says Sam Leonard, director of mobile emissions and fuel economy at General Motors. "The controls we have are virtually identical to what's on passenger cars. It's not that we've scrimped on cost or hardware or engineering to make them as clean as possible."
Leonard also says most of the benefits of tightening emissions standards have already been realized. Today's cars and trucks, he says, are 97-99% cleaner than models sold during the 1960s, and each further increment of cleanup will incur ever greater cost.
Environmentalists see matters differently. Roland Hwang, a transportation analyst with the Union of Concerned Scientists, says the 97% claim is "exaggerated, and not relevant to whether cars are still a problem." Hwang says in the real world cars and trucks pollute much more than under laboratory conditions due to aggressive driving, poor maintenance, and the fact that pollution measurements are made with air conditioners shut off. Hwang also says the share of smog-forming pollutants (hydrocarbons and NOx) attributable to light trucks more than doubled between 1965 and 1995, making them a target ripe for control.
And while auto manufacturers complain they'll have trouble meeting the tighter standards, California's air regulators assert that they have conducted tests in which they changed the nature and location of the catalytic converter on a heavy SUV and "met the standard we're proposing," says Richard Varenchik, an information officer for the CARB.
As often happens, California's light truck rule foreruns a national effort to regulate the environmental effects of the increasingly popular vehicles. A draft of the EPA's Tier II auto pollution regulations is due in December 1998, with a regulation due one year later. How the regulation will treat light trucks is still uncertain.
Both the EPA and CARB are focused on emissions, not fuel efficiency, where light trucks again enjoy a significant regulatory advantage. While the Corporate Average Fuel Economy (CAFE) system requires each manufacturer's fleet of cars to average 27.5 miles per gallon, light trucks must average only 20.7 miles per gallon. Yet with the rising popularity of the heaviest SUVs, all three U.S. automakers failed to meet that standard for the 1997 model year. (Because several years' averages can be lumped together, one year's average does not violate the Clean Air Act.)
To Leonard, that difficulty is a good indication of the futility of tighter mileage requirements. "Judging by the difficulty that we and other domestic manufacturers of full lines of trucks and SUVs have had in meeting CAFE, there's very little ability to improve at a reasonable price," he says. But environmentalists argue that 6,000-pound vehicles with V-8 engines are not necessary to haul groceries from the supermarket. "All the improvements [in fuel economy] are getting eaten by increases in performance [such as more horsepower, bigger engines, and faster driving speeds] and rising vehicle weight," says Martin Thomas of the American Council for an Energy Efficient Economy in Washington, DC. "If we held performance constant, there could be improvements in fuel economy."
SUVs also have an outsized appetite for other raw materials. The auto industry already consumes 27% of aluminum, 35% of iron, and 14.5% of steel used in the United States. As increasing sales of ever larger trucks boost the average vehicle size, rising materials consumption will raise the environmental toll of mining, processing, and discarding or recycling these materials.
The issue of size also plays a role in safety. SUVs and light pickups are not only more massive than cars, they also have high, stiff frames that override the protective component of cars. When one car strikes another, 6 people die in the struck vehicle for every 1 in the striking vehicle, according to Julie Rochman, communications director of the Insurance Institute for Highway Safety, an industry group in Arlington, Virginia. But when SUVs strike cars, the ratio is 27 to 1.
That doesn't mean that SUVs are any safer than cars, however. Rochman points out that since SUVs have high centers of gravity, they roll over easily. Indeed, the institute recently analyzed car and truck accidents and, Rochman says, found that "in each weight class, if a crash takes place, your chances of survival are better in a car."
Taking herbs is one of the oldest and most enduring ways of treating human maladies. By one World Health Organization estimate, nearly 80% of the world's population, some 4 billion people, use herbal medicine for some aspect of their primary health care. The U.S. Congress acted in 1994 to reduce FDA control over herbs and other dietary supplements, making them more accessible to a thriving market in this country.
Though no longer evaluating the safety of new herbal supplements before they reach the market, the FDA continues to warn consumers of dangers that may be associated with taking them. An important part of this effort, and a valuable resource for anyone using dietary supplements, is the FDA Center for Food Safety and Applied Nutrition's (CFSAN) dietary supplements Web site at http://vm.cfsan.fda.gov/~dms/supplmnt.html. Here, the FDA warns consumers about the possible risks involved in taking herbal supplements with names like Sleeping Buddha, Herbal Fen-Phen, and Chomper.
In some cases, risk information is based on the testimony of consumers and doctors who have noticed disturbing side effects from using an herbal product. The CFSAN Web site allows users to alert the FDA in such cases and also to find out if anyone else has reported problems with a particular supplement. Both can be done easily by following the Special Nutritionals Adverse Event Monitoring System link on the CFSAN dietary supplement page. For example, entering the term Hypericum perforatum (St. John's wort) will return two reports of adverse side effects observed in people using this popular herb.
For researchers who want to investigate the health benefits and risks of taking
herbal supplements such as St. John's wort, another informative resource is
the Web site of the NIH National Center for Complementary and Alternative Medicine
(NCCAM), located at http://nccam.nih.gov/about/advisory/capcam.
This office collects and organizes a tremendous amount of information and research
on a broad range of alternative treatments, from herbs and acupuncture to prayer
and diet (click first on What Is CAM? and then on Classification of Alternative
Medicine Practices to view the whole list).
The Information Resources link on the NCCAM home page routes users to references such as the CAM Citation Index, a searchable database of over 90,000 alternative medicine citations from the National Library of Medicine. The citations can also be browsed by disease, treatment method, and symptom by following the Browse link on the CAM Citation Index page. Most herbal supplement citations can be found by following the CAM Methods link to the Phytomedicine page. Information about the NCCAM's programs and publications can also be accessed by following the NCCAM Clearinghouse link from the Information Resources page.
Besides organizing information, the NCCAM also sponsors research on alternative treatments. The Research Grants link connects users to information on what projects the NCCAM has funded in the past, while the Research Funding Opportunities link connects to the types of investigations that the NCCAM plans to support in the future. For example, by following the Request for Proposals link, users can see that the NCCAM would like to coordinate a multicenter clinical study of the efficacy of St. John's wort in fighting depression. Information about submitting grant applications to the NCCAM is available via the Grant Preparation link, and information about student, postdoctoral, and clinical training opportunities at the NCCAM is available under the Research Training link. Through the CFSAN site and the NCCAM site, medical professionals, researchers, and consumers can accesss important information on a growing variety of herbal products.
Last Update: November 23, 1998