Taking the Ocean's Temp
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Sound of the sea. A network of underwater speakers will allow scientitsts to measure the ocean's temperature. |
In an experiment proposed by the Scripps Institution of Oceanography in La Jolla, California, scientists are now attempting to listen to the ocean's temperature to provide information about global warming, but some environmentalists would rather they listen to concerns about the project's effect on whales and other marine mammals.
In the study, underwater speakers would emit sound blasts across the Pacific Ocean once a day for two years. The speakers would send low-frequency noises for 20 minutes from a depth of about 3,000 feet off the coasts of California and Hawaii. Receivers would be located throughout the Pacific and operated by Australia, Canada, France, Russia, New Zealand, South Africa, and the United States. Because sound travels faster in warm water than in cold, scientists hypothesize that they could detect temperature shifts by monitoring the sound's speed through the ocean. The project has been protested by some biologists and environmentalists who claim the sounds could deafen whales and other marine mammals, making them unable to navigate or find food.
The project would provide unique information because of its span across thousands of miles of ocean. The ocean is one of the best indicators of climate change because it slowly stores up heat caused by a buildup of greenhouse gases in the atmosphere. The project, called Acoustic Thermometry of Ocean Climate (ATOC), would run for a two-year test period and, if successful, a long-term program may be established, because global warming of the ocean would only be measurable over a long period of time. Scripps hopes the experiment will validate concerns about climate change. "It would eventually give credibility to predictions of climate change," said Walter Munk, the principal investigator for the project. "In the past, no one has been able to test them."
Although the experiment would provide valuable information to research on global warming, biologists point to research that has shown that sharp underwater sounds can harm marine mammals. Protests are also stemming from the fact that the California speaker is to be placed in the Monterey Bay National Marine Sanctuary, which is home to whales, squids, seals, and sea otters, as well as other marine animals.
The scientists at Scripps Institution say these accusations are exaggerated and claim that, at worst, the sounds proposed in the experiment are equivalent to those emitted from a large merchant or cruise ship. But the institute has responded to the protests by expanding the work of its Marine Mammal Research Program, a task within the ATOC program. According to Cindy Rogers, a member of the ATOC Project Office, the research program has been studying the potential effects on mammals from the onset of the development of the project. "We've always been concerned about what the potential impacts might be," Rogers said. The program is made up of some of the leading marine biologists in the world, who are conducting rigorous studies about the mammals, including aerial and boat surveys, sight and sound observations, and some tagging, she said. As concerns about different species develop, the species have been incorporated into the studies.
The expansion of mammal research has mitigated the protests. Scripps has also made efforts to meet with concerned environmentalists and marine mammologists and incorporate their concerns into the project, Rogers said. A watchdog group of marine biologists not affiliated with the ATOC project has been developed to oversee the work of the Marine Mammal Research Program. The scientists in the group were selected by the National Marine Fisheries Service, a branch of the National Oceanographic and Atmospheric Association that enforces the Marine Mammal Protection Act of 1972 and must approve of the project.
Scripps expects to have the experiment approved by the end of January 1995. If the program is approved, Scripps would immediately begin installing the speakers, and transmissions could begin that spring, Rogers said.
A Move for the Better
A change in where they live may change the outcome of a second pregnancy for women whose first child was born with a birth defect, according to a recent study published in the July 7 New England Journal of Medicine.
The odds of having a second child with a birth defect are small to begin with--about 2.2% in the Norwegian sample. However, the study, conducted by epidemiologists Rolv Terje and Rolv Skjaerven in Norway and Allen Wilcox at the NIEHS, revealed that among women who had given birth to one baby with a defect, those who continued to live in the same town had almost 12 times the risk of giving birth to a second baby with the same defect. However, if these women moved to a new town, the risk dropped to five times the normal risk. The study also showed a slightly increased risk of delivering a second child with a different defect from the first for women who remained in the same town.
The study examined birth records of first and second infants born to almost 400,000 women in Norway between 1967 and 1989. Twenty-three categories of isolated defects and a category of multiple defects including, for example, cleft lip and palate, limb defects, genital defects, anencephaly, respiratory system defects, and central nervous system defects were studied. One surprising finding of the study is that moving to a new town correlated with a decreased risk of birth defects more than the second child being fathered by a different man. With a different father the risk of defects in the second child fell to 7.3.
The authors say the study does not cast light on any causes for decreased risk, but when you move, said Wilcox, "you've changed some things: where you work, the house you live in. . . ." Wilcox said that the study is more promising for guiding future research rather than for suggesting preventive measures. The researchers concluded that there is strong indirect evidence that environmental factors contribute to the familial risk of birth defects and that "important environmental teratogens have yet to be discovered."
A Gray Area of Environmental Justice
The issue of environmental justice is hardly black and white, especially in the realm of research. Several studies surfaced in the late 1970s and 1980s providing evidence that polluting and waste facilities are more likely to be located in low-income and minority neighborhoods. This information has prompted widespread political action, but the methodologies used in these studies are now being challenged.
President Clinton issued an executive order on environmental justice, and Congress is also focusing on this issue, debating several bills that would guarantee environmental equity. But some researchers are questioning whether such political attention to the issue is warranted. Two recent studies cast doubt on the empirical evidence supporting the arguments of environmental justice advocates.
One of the studies, conducted at the Center for the Study of American Business at Washington University, examined environmental justice policy. "Our study is an overview of the issue from a policy perspective," said Christopher Boerner, who worked with Thomas Lambert on the study. Their findings indicate that further research should be conducted on the issue.
Boerner and Lambert, research interns at the center, analyzed the studies that provide evidence of environmental racism and detected several flaws in the research. These included inadequacies in how minority communities were defined and in population densities. The researchers said that defining minority communities as areas where the percentage of nonwhite residents exceeds the percentage of minorities in the entire population means that a community could be considered minority even if the majority of its residents are white. They also pointed out that most of the studies are based on ZIP-code data, which are not necessarily accurate when examined on a smaller geographic unit.
Boerner and Lambert also argued that environmental justice studies imply rather than state actual risks posed by polluting and waste facilities since there is a lack of significant scientific data linking negative health effects with proximity to polluting and waste facilities. And finally, the study says that the research on environmental justice fails to establish that discriminatory siting and permitting practices caused current environmental inequities. The studies identify current economic and race characteristics of communities located around industrial and waste facilities, but they do not consider community conditions when the facilities were sited.
Boerner and Lambert's research supports one of their major concerns in regard to environmental justice: that policymakers may be acting too quickly on a subject that needs further research and evaluation.
Boerner and Lambert also examined alternative ways of approaching environmental justice as an issue, as opposed to current suggested solutions. Most of these current remedies include legislation that would prohibit or discourage construction of polluting and waste facilities in certain low-income and minority neighborhoods. Boerner and Lambert recommended that policymakers explore remedies such as compensation approaches, in which those who share the benefits of the undesirable facility provide compensation to those who host the facility. The compensation could be in the form of direct payment to individuals in the community, or through investments to improve the community. Boerner and Lambert also detailed benefits that communities could reap by supporting the construction of polluting and waste facilities in their areas. Among these are the economic benefits a facility could bring to a disadvantaged neighborhood, such as the creation of jobs. This type of compensation approach would allow communities to be involved in the negotiating process.
Early results of an ongoing empirical study at the University of Massachusetts also cast doubt on claims that hazardous waste facilities are more likely to be located in low-income and minority neighborhoods. The researchers, Douglas Anderton and Andy Anderson, both sociology professors, released a preliminary study revealing that commercial, off-site treatment, storage, and disposal facilities (TSDFs) are actually more likely to be located in white, working-class, industrial neighborhoods. The two-year study examined census bureau tracts, groupings of 4,000 people, rather than ZIP-code data, which had been used in many of the previous studies. Tracts containing commercial hazardous waste TSDFs were compared to tracts without TSDFs.
The researchers had expected to find results similar to previous studies on environmental justice. "We were all pretty surprised, including the waste industry," Anderton said. "In retrospect we shouldn't have been, because what we found was that these facilities were not much different than any other industrial facilities." They found that the neighborhoods surrounding TSDFs were made up of white, working-class people, similar to most communities located around other types of industrial facilities.
The study has been criticized by environmental justice advocates because the pre-1990 census tract data that was analyzed excludes rural areas. They claim that if rural areas were assessed, the results could be different. However, Anderton says ongoing research involves 1990 census data that includes rural areas, and the results appear to be similar.
Anderton and Anderson do admit that there are limitations to this study. For example, only commercial, off-site TSDFs were studied; Superfund sites, closed TSDFs, and on-site storage were excluded. They also cited other sources of environmental risk not studied that could unfairly burden minority and poor populations, including lead paint, soil contamination, and air pollution.
"Some of the limitations of this research should be noted so the results of this particular study will not be used to undermine the general cause of environmental justice and equity," the authors said. They summarized the study by saying, "a great deal of work remains to be done."
Anderton said they will continue to research the issue, and future studies will include Toxic Release Inventory data, Superfund sites, comparisons of public and private facilities, and analyses of how sites change over time.
A Nice Cup of Tea
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Reading tea leaves. Scientists studying green tea believe it may help ensure a healthier future. |
Animal studies prove it. Folklore heralds it. And now the first large human study shows that green tea may be more than just an aromatic brew loved by millions of Asians who claim it purifies the body.
A report published in the June issue of the Journal of the National Cancer Institute concluded that green tea is associated with a reduced rate of esophageal cancer in residents of Shanghai. Studying 1552 healthy people and 902 others who had esophageal cancer, NCI researchers found the risk of contracting this cancer was reduced by 57% for men and 60% for women who didn't smoke or drink alcohol but who consumed lots of green tea.
The researchers undertook the study because of compelling animal experiments that demonstrated green tea reduces the incidence of cancer and even the growth rate of tumors. Tea is among the most widely consumed beverages in the world, and a finding that 20% of that tea, an unfermented green, naturally protects against cancer would be good public health news.
The report comes on the heels of a smattering of studies worldwide that suggest green tea has a myriad of benefits. In Japan, scientists have found that green tea lowers rates of cancers of the lung, skin, and stomach, and even reduces cholesterol.
But no one is yet ready to say that green tea protects humans against any disease, including cancer. The NCI's lead tea investigator, epidemiologist Joseph McLaughlin, cautions that no conclusions can yet be made. "This is the first study that shows an association, but as to whether green tea does definitively protect against esophageal cancer, I can't say."
The problem is that although at least 100 studies have been published in the last two years, mostly in Asia, there are too few substantive case-control studies, says McLaughlin. The NCI survey is the largest to date, "but further investigations are definitely needed," he said.
Chung Yang, a biochemist and professor at Rutgers University, said that recent reports of the effect of tea on human health have been "mixed; innately controversial." Yang said that one-fourth of the studies argue for a protective effect, one-fourth find tea increases health risks, and one-half of the studies found no correlation between consumption and disease. And although the Shanghai study "is interesting and encouraging," Yang said that it did not present any clear conclusions.
On the other hand, animal data testing the effect of both black and green tea on cancer has shown a consistent benefit, said Yang, who has had a role in many of those studies, collaborating with investigators from Cornell University and Case Western Reserve University.
In these experiments, Yang gave a group of mice only tea to drink, and he also gave them, as well as a control group, chemicals known to produce different cancers. Among the animal "tea" models he has developed are those for lung, esophageal, and forestomach. He found that mice fed tea developed fewer tumors than the control group and that their tumors were smaller. His latest study on tea's protective effect on skin cancer was published in July in Cancer Research.
Although there are numerous theories as to why tea may offer protection, most scientists think it is due to polyphenols, such as flavanols, which make up 30% of the dry weight of the tea. These chemicals not only possess strong antioxidant activities, but they can also inhibit nitrosation reactions, modulate carcinogen-metabolizing enzymes, trap carcinogens, and inhibit cell proliferation.
Yang said that he can demonstrate that tea scavenges free radicals produced by oxidation reactions in the body, "but whether that is at the heart of the anticancer action remains to be studied." He co-authored a major review discussing the contradictions in the study of tea and cancer, published last July in the Journal of the National Cancer Institute. "It will be very difficult to pinpoint how it works in humans," said Yang. "The protective effects may be small in humans; it may just get lost in a host of other mechanisms."
To help point to an answer, Yang is working with the Beijing Cancer Institute to design an intervention study in China. It will follow thousands of people who will take capsules of tea powder daily to see if the rate of stomach cancer that develops in this population is reduced.
Bernard Goldstein, director of the Environmental and Occupational Health Sciences Center in New Jersey, welcomed a renewed interest in tea, which he first studied 20 years ago. "The studies in animals are very encouraging," he said, "and there is enough information about the effect of tea in humans that it makes one want to do careful and thorough epidemiological evaluation."
Browner v. Bush
In July, EPA Administrator Carol M. Browner proposed to overturn a decision by the Bush administration which eased regulations on industries under the 1990 Clean Air Act in the name of industrial growth. Browner's proposal would grant environmentalists a rule that would require a period of public comment on potential increases in emissions when industries attempt to gain permits to expand their operations.
In 1992, Bush handed down a decision that allowed industries to expand their operations even if the expansion would cause higher levels of emissions than allowed by the permits they had obtained. Environmentalists protested, fighting for a provision that would allow public input on changes in emissions before expansion could take place, but the White House Competitiveness Council argued that such a provision would slow the permitting process and restrict attempts to bring the country out of recession.
The proposed rule is to take effect after a 90-day comment period. Browner's decision stems from negotiations with environmentalists mobilized by the Natural Resources Defense Council, who sued the EPA following Bush's decision. The environmentalists and EPA officials have agreed to reach an out-of-court compromise. |
A Breath of Fresh Air
Flight attendants and passengers may soon be breathing easier if a bill called the Safe Cabin Air Quality Act is passed. The bill (HR 2985), introduced in August 1993 by Congressman Jerrold Nadler (D-New York) in response to health complaints associated with reduced fresh air, would increase the amount of fresh air pumped into airline cabins.
In response to concerns over anticipated increases in the cost of fuel in the late 1970s, airlines studied ways to conserve fuel. It was discovered that energy could be saved by reducing the amounts of fresh air pumped into airplane cabins. For example, a McDonnell-Douglas study in 1980 found that if the amount of fresh air was cut by 50% on a DC-10 trip of 1,050 miles, the airline could save 0.8%, or 42 gallons, of fuel. Since the 1980s, the volume of fresh air circulated in most airline cabins has been cut by about half from 100% fresh air pumped in every 3 minutes to half fresh and half recirculated air every 6-7 minutes. This drastic reduction has been blamed for headaches, nausea, dizziness, and other health problems experienced by flight attendants and passengers. Chris Witkowski, director of air safety and health for the Association of Flight Attendants, says that there are some asthmatics who will not fly now because of difficulties with breathing. "It's going to be a growing health problem," he said.
In 1993, using the current domestic cost of $0.59 per gallon for jet fuel, Witkowski divided the average number of passengers on a 1,050 mile trip on a DC-10 into the price per gallon, multiplied by 42, the number of estimated gallons of fuel saved, and found that the airlines were saving $0.13 per passenger. "The average passenger would pay that much to double the amount of fresh air they get on a flight," Witkowski said.
At such a small percentage of savings, many wonder why airlines would reduce the amounts of fresh air. Because the Federal Aviation Administration has failed to impose guidelines on cabin air quality standards, airlines have had no disincentive to save some money. "There is a tendency for airlines to want to reduce fresh air as much as possible to squeeze every nickel out of the cost of fuel," Witkowski said.
The FAA does regulate the maximum amount of carbon dioxide in airline cabins at a standard of 30,000 parts per million. But Witkowski called the figure "absurd," and said it is "virtually meaningless at that level." The level that the American Society of Heating, Refrigeration, and Air Conditioning Engineers associates with satisfaction or comfort is 1,000 ppm. And the Occupational Safety and Health Association is considering setting a standard of 800 ppm in workplaces.
Several studies have been done that link recirculated air to transmission of viruses and bacteria. Studies by the U.S. Centers for Disease Control have not been able to rule out the possibility that tuberculosis could be transmitted among passengers. Last year a report said that a flight attendant with active tuberculosis infected 13 fellow workers before being diagnosed and treated. Airlines argue that their filtration systems mitigate potential exposures, but a recent study conducted by researchers at the Harvard University School of Public Health questioned the adequacy and effectiveness of strategies used by airlines. The researchers recommended further studies be done before conclusions are made.
Despite these findings, the Air Transport Association recently concluded that reducing fresh air in cabins is safe for passengers and airline crews, outraging airline flight attendants who want the levels of fresh air raised. "We feel it is critical for the federal government to set some standards for cabin air quality. Until this is done, the quality of air is going to get worse," Witkowski said.
Flight attendants are also urging the government to take into account the range of people that travel. Not all airplane passengers are able-bodied workers; among those who fly are asthmatics, the elderly, people with allergies, and people whose immune systems have been impaired by chemotherapy or HIV. Therefore, flight attendants and others say that airplane cabin air should be held to higher standards than workplaces.
Pressure from passengers may be a major contributing factor in encouraging airlines to increase fresh air. In the August issue of Consumer Reports, airlines were ranked according to levels of carbon dioxide in airplane cabins and criticized for the low amounts of fresh air. Consumer Reports recommended that passengers choose airlines according to the amounts of fresh air they circulate. They also recommended that the FAA set a comfort standard of 1,000 ppm.
Double-Edged Sword?
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Cut and paste. Retroviral vectors are made by transferring a modified retrovirus into a packaging cell which produces the desired protein in a target cell. |
Although individuals with genetic disorders and diseases such as cancer, AIDS, diabetes, or Alzheimer's may view the potential of gene therapy as just the weapon they're looking for, other people perceive the "slicing and dicing" of genetic material as a potential double-edged sword. Scientists are attempting to estimate the real risks associated with gene therapy.
Most current gene therapies use retroviral vectors to transfer a therapeutic gene into the cells of a patient who lacks a normally functioning copy of the gene. Retroviral vectors are made by deleting portions of a retroviral genome and replacing the deleted viral genes with the therapeutic gene. The resulting vector integrates a DNA copy of its genome, containing the therapeutic gene, into the genome of a host cell, but because of the missing viral genes the vector cannot be replicated like a normal retrovirus.
Typically, bone marrow cells are removed and exposed to the vector in culture. The cells containing the therapeutic gene are then infused back into the patient. The fear is that the vector may integrate its DNA copy near a gene involved in regulation of growth or development of the cell and interfere with the normal regulatory processes, causing the cell to become cancerous. Although, says toxicologist Richard Irwin of NIEHS, "there is absolutely a finite probability that it will occur," the risk of insertional mutagenesis is believed to be very low. The difficulty comes in trying to determine exactly what "very low" means in terms of absolute risk to humans from gene therapy.
Scientists are concerned about other potential side effects of the process of gene therapy. First, it is not currently possible to target a vector carrying a therapeutic gene to a specific cell population. Expression of the gene in nontargeted cells may interfere with regulation of cell processes or metabolic pathways. Second, the transduced cells may contain a selective growth advantage, enabling their progeny to predominate in the host. When such cells are introduced into a patient during gene therapy, they represent a population carrying a "first hit" insertional event that may put the patient at increased risk for additional mutational events leading potentially to tumor formation. Third, retroviral vector preparations may be contaminated by virions containing packaging cell RNA. In theory, this RNA could be reverse-transcribed, integrate in the genome of the recipient cells, and express a product that could disrupt normal cell functioning.
The risk posed by insertional mutagenesis is a particular concern for extending gene therapy to the treatment of conditions such as diabetes or hemophilia where substantial numbers of people would be candidates for the therapy and might be treated early in their lives. A population of cells carrying a first hit insertional event would put such people at an increased risk throughout the remainder of their lives.
As gene therapies are expanded for the treatment of more diseases, the sheer numbers of people involved makes it more likely that even a relatively infrequent event may result in an unacceptably high risk. Irwin and his colleagues at the NIEHS are developing studies to attempt to evaluate the extent of this risk. In these studies, researchers will expose mice and rats to retroviral vectors in a number of ways. These vectors contain marker genes which allow the researchers to determine the most effective method of integration of the vector into the new cell genome. The animals are allowed to live out their life spans, and researchers then examine them to see if they developed tumors, and if so, if the tumors contained DNA from the retroviral vector. The information from these studies will be used to estimate gene therapy's risk and may help regulators evaluate the safety of cutting edge technology.
Last Update: June 20, 1998