Everything about microscopic life is terribly upsetting.
How can things so small be so important?
Isaac Asimov
Surfers Against Sewage
A ground swell of public concern about water pollution has undulated through Britain, thanks to Surfers Against Sewage (SAS). The organization, founded in 1990 by a group of Cornish surfers to protest local water pollution, now has over 20,000 members, including windsurfers, swimmers, and beach users, who lobby in protest of the 300 million gallons of sewage that are dumped daily and the 2 million tons of toxic waste that are dumped annually into the seas around Britain. Over half of the sewage dumped into the ocean is either raw or has received only preliminary treatment. Many beaches are littered with human excrement, tampons, condoms, and other sewage debris.
Not only is the pollution visually unpleasant, it also poses health risks to water users. High levels of pathogenic viruses and bacteria are contained within the sewage. SAS has developed a medical database that contains over 800 cases of individuals who have experienced adverse health effects stemming from activities in the ocean. The most common illnesses include gastrointestinalproblems and infections of the ear, nose, throat, eye, and skin. However, more serious illnesses such as hepatitis have also been attributed to water pollution. Over 68% of these cases have occurred at "Government Passed Beaches," says SAS. A study entitled Health Risks Associated with Bathing in Sea Water, which was commissioned by the Department of the Environment and published in the British Medical Journal in December 1991, found that there are increased health risks for those who enter British sea water. Surfers are 80% more likely to experience health problems than nonswimmers, while the risks for swimmers and waders are 31% and 25% higher, respectively, than for nonswimmers.
Trash warriors. A coalition of surfers, windsurfers, and beach users is fighting the dumping of sewage and trash into the seas around Britain.
Photos: Angela Maynard (Right), Chris Power (Left)
SAS has gained respect as a political pressure group from the organization's ability to blend the use of sound science, legal work, and media attention. The group has been described by the BBC as "some of government's most sophisticated environmental critics."
"Surfers Against Sewage is waging an effective and important campaign against senseless pollution of the seas. In their campaigns, SAS makes science accessible and relevant to people's experiences and, therefore, makes it matter," said Sue Mayer in the 1996 SAS annual report. Mayer is the former director of science at Greenpeace UK and currently works as a consultant on environmental science and policy issues. "By challenging the questionable assumptions in standard-setting, SAS makes politicians and institutions face up to their abuse of science in legalizing pollution," she said.
SAS is urging the reform of water quality regulations. The European Bathing Water Directive currently provides water quality standards for Europe. However, according to SAS, the United Kingdom enforces only the minimum legal standard, which meets only two out of 19 criteria set by the directive.
Standard practice for treating sewage involves administering a primary treatment and then sending the sewage through a long pipe out to sea. The idea is that harmful microorganisms will die as the sewage disperses throughout the water, and the sewage will not be harmful by the time it reaches shore. However, according to SAS, the current government system for measuring pathogens in the water is inadequate. And water users such as surfers and windsurfers, who venture farther from the shore, encounter sewage at the point of outfall, where it is most harmful.
SAS also pressures industry to change sewage treatment methods. The group is working to mandate that all sewage be fully treated before it is discharged into the sea and that both the liquid and sludge content be used as fertilizer. SAS also aims for the complete cessation of dumping of toxic waste into the oceans.
The SAS campaign has involved protesting, demonstrating, lobbying, and publicly pressuring the water industry. Demonstrators wearing wetsuits and gas masks have carried bags of toilet paper and panty liners collected from the beaches to the House of Commons, the European Commission in Brussels, and water industry conventions.
So far, SAS has experienced several major victories. In 1993, Welsh Water, a water company in Wales, agreed to a new policy of fully treating sewage before discharging it into the ocean. Company representatives credit SAS with persuading them to treat sewage with ultraviolet light to kill viruses and bacteria. "One of the things we liked about SAS was that even though they had colorful demonstrations . . . they were quite willing to explain to us what they wanted, like rational human beings," spokeswoman Margaret Abbett told the Associated Press.
This past April, two women won a case against their local council, which failed to require that sewage be removed from the nearby beaches. The women's lawyer argued that the council had failed to protect the community from a statutory nuisance, as required under the 1990 Environmental Protection Act. SAS members are hoping this case will set a precedent for other local governments to enforce sewage cleanup.
Carcinogens in Food
Labeled a "finding sure to appeal to anyone tired of washing vegetables in detergent to remove pesticides" by a New York Times health columnist, the National Academy of Sciences National Research Council's February report, Carcinogens and Anticarcinogens in the Human Diet, found little to be alarmed about concerning links between chemicals in food and cancer. "I've really been surprised at the great interest that has resulted from the study, and from the message that if you use common sense when you eat, you're alright," says Ronald Estabrook, a biochemistry professor at Southwestern Medical Center in Dallas who headed the 20-member panel that issued the report.
Specifically, the report found that, based on existing data, the great majority of naturally occurring and synthetic chemicals in the diet appear to be present at levels below which "any significant adverse biologic effect is likely, and [are] so low that they are unlikely to pose an appreciable cancer risk." Conversely, the varied and balanced diet needed for good nutrition "also provides significant protection from natural toxicants," the report says. The real cancer culprits in diet, the committee suggests--as other NRC reports have concluded--are excess fat and calories.
But others say there is much more to the story than appears beneath the "sigh-of-relief" headlines. Although the NRC committee made much of the fact that little scientific evidence exists on which to base their conclusions, this point was not adequately communicated to the public, according to committee member Bernard Weinstein, director of the Columbia-Presbyterian Cancer Center in New York. "I would have started the report emphasizing that we need much more intensive research in this area. There are a lot of open questions here and I wouldn't give a clean bill of health to these trace amounts of chemicals yet." As an example, Weinstein cited findings made public in April, after the report's release, that a gene known as Shinga can be transferred into bacteria and spread a toxin to humans from ground meat. "This is a minor compound, a natural chemical in beef. We should not be lulled into false security," he said.
There is also criticism of the committee's composition. According to Samuel Epstein, a professor of occupational and environmental medicine at the University of Illinois at Chicago, the group is "disproportionately weighted with industry consultants and others who trivialize the significance of avoidable exposures to industrial carcinogens in air, water, food, and the workplace, and who exaggerate the role of lifestyle risk factors and of naturally occurring carcinogens, particularly 'natural pesticides' in food." Epstein voiced such concerns to the NAS as far back as 1993 in his role as chairman of the Cancer Prevention Coalition, Inc., which bills itself as a coalition of independent experts in public health and cancer prevention. Al Meyerhoff, senior attorney with the Natural Resources Defense Council, agrees, saying that the conclusions suffer from "serious data gaps on toxins and exposures that make the report a dubious exercise. Increasingly, when dealing with cancer risk, 'science' is in the eye of the beholder," he says. "Different scientists reach fundamentally different conclusions."
Estabrook argues that the committee was unbiased and unanimous in its conclusions. But he concedes that the "database is shallow. We looked at what exposure data was available and we put it all into perspective. This is by no means the final word."
New Laws on Landfills
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Getting tough on dumps? A new EPA rule includes stricter air pollution controls for large landfills, while a new law may exempt smaller dumps from ground water monitoring. |
New environmental rules for landfills seem to be moving in opposite directions: more stringent for larger landfills and less burdensome for smaller ones. On one hand, the EPA has determined that landfills are a source of air pollution and has issued a new rule requiring large municipal solid waste landfills to control their emissions of certain gases. On the other hand, President Clinton has signed into law legislation allowing states to ease certain environmental requirements for small landfills, as long as human health and the environment remain protected.
The new EPA rule, promulgated under the Clean Air Act, aims to reduce landfill emissions of smog-creating volatile organic compounds (VOCs), some of which are also known or suspected carcinogens such as benzene, vinyl chloride, and chloroform. The rule will also cut methane emissions in half which, in terms of reducing greenhouse gases, is the equivalent of taking 20 million cars off the road, according to a statement issued by EPA Administrator Carol Browner. Methane is about 25 times more powerful than carbon dioxide (the primary greenhouse gas) in trapping heat in the earth's atmosphere, according to the EPA.
The rule applies to landfills for household waste--not hazardous waste--with a capacity of 2.5 million cubic meters or greater. Those landfills that are found to emit more than 50 megagrams per year of VOCs will be required to drill collection wells to contain the gas. In turn, the gas may be routed to either an energy recovery system, where it can be captured for use, or to a combustion device, where it can be safely burned.
Although the rule is an important step in reducing ozone-forming VOCs, its primary benefit will be in methane reduction, said Dan Lashof, a senior scientist for the Natural Resources Defense Council (NRDC). "Landfills are an important, but relatively small, source of ozone-forming compounds," Lashof said. "But they are one of--if not the--biggest sources of methane." The process of capturing the VOC emissions will also net significant amounts of methane, Lashof said. In addition, the rule requires landfills to monitor surface methane on a quarterly basis and expand their collection wells if these emissions exceed 500 parts per million.
Of 7,000 landfills nationwide, the EPA estimates the rule will affect up to 280. Total costs nationwide are estimated at $778 million in one-time capital costs and $93 million annually, which the EPA estimates will translate into customer costs between $0.20 and $0.40 monthly. These customer costs could be offset by landfills selling the energy generated through the recovery systems.
Industry representatives are generally supportive of the new rule. "Lots of private landfills are already collecting methane, and this will just require more fine-tuning," said Ed Repa, director of environmental programs for the National Solid Waste Management Association.
"It's a workable rule," said Chris Voell, director of technical services for the Solid Waste Association of North America, "though, as a direct public health concern, we don't think EPA had all the data they needed to say methane has an impact on health."
For small landfills, defined as those that accept 20 tons of solid waste or less per day, amendments to the Solid Waste Disposal Act, signed into law on March 26, could mean less stringent regulations. One provision, authored by Senator Pete Domenici (R-New Mexico), requires the EPA to develop guidelines that afford states flexibility in regulating small landfills while still protecting human health and the environment.
The guidelines, which must be developed within two years, will address four areas: frequency of cover application, frequency of monitoring, infiltration layers for final cover, and means of demonstrating financial assurance. Domenici's office said that, while states currently have a good deal of flexibility to design solid waste regulations to fit local needs, the rules in these four areas are too rigid. According to EPA staff, the current rules require landfill operators to cover solid waste with dirt every day, monitor methane on a quarterly basis, install a final cover of 24 inches of earthen material, and be able to demonstrate they have the money to provide closure and post-closure care for the landfill. The amendments will likely only apply to landfills in dry, remote areas, according to the EPA, where groundwater contamination is less of a potential problem.
Another provision in the amendments exempts small landfills from groundwater monitoring requirements if they are located in an area that receives less than 25 inches of precipitation annually, unless the state finds such monitoring necessary to protect groundwater resources. An earlier EPA attempt to create this exemption by regulation was overturned by the U.S. Circuit Court of Appeals for the District of Columbia, which found the agency did not have authority to issue the exemption.
"The irony is, a landfill's not eligible for the exemption if you have evidence of groundwater contamination, but without groundwater monitoring you can only prove the contamination if it shows up in someone's well," said David Lennett, an attorney who has represented the NRDC.
Proponents of the small-landfill measures say they are necessary because the stringent requirements for large landfills in some cases are simply unnecessary--and unaffordable--for small landfills in arid climates. For example, the New Mexico Environment Department estimates Domenici's provision could save the state $50 million over the next 10 years.
"It's just adding some common sense to the process," said Tom Kennedy, executive director of the Association of State and Territorial Solid Waste Management Officials. If an area doesn't get enough rainfall to create leachate, measures aimed at reducing and monitoring leachate are not needed, he said.
However, other industry groups remain skeptical. "It doesn't make sense from a public health perspective," Repa said. "It is in arid, remote areas where people are drinking groundwater from wells, rather than municipal treatment systems," he said. "So it makes sense to require monitoring wells there." Repa estimated the cost of installing a monitoring well to be about $4,000, plus an annual $1,000 to monitor it. "If you look at the cost, it's small compared to remediation," he said.
"Subtitle D [of the Resource Conservation and Recovery Act] was supposed to close down the small landfills, and create larger ones with more environmental protections through economy of scale," Repa said. "This [exemption] would allow the status quo at those smaller facilities." However, according to Domenici's office, in large states like New Mexico, consolidation of small landfills may not always be a cost-effective option.
Using BRCA1 to Treat Cancer
In the two years since the gene for inherited breast cancer, BRCA1, was identified, researchers have been trying to understand how the gene normally works. A team from Vanderbilt University and the University of Washington has now shown that BRCA1 suppresses the formation and growth of breast tumors in mice. Their results, published in the March issue of Nature Genetics, suggest that the gene or drugs that mimic its protein product might someday be used to treat human breast and ovarian cancer.
"This is what everybody had hoped--that there would be a gene found that actually would retard the development of breast tumors--and it seems to do that," said Anne Bowcock, a breast cancer researcher and associate professor of pediatrics at the University of Texas Southwestern Medical Center in Dallas. "I think it's a significant step toward the treatment of at least some breast cancers." Most of the 184,000 new breast cancer cases diagnosed annually are not the inherited type. But the new research suggests that the protein produced by normal BRCA1 genes may be effective against the more common noninherited forms of breast cancer.
Researchers led by Jeffrey Holt of Vanderbilt first implanted normal BRCA1 genes into human breast and ovarian cancer cells and found that cell growth was inhibited in vitro. Next, the researchers stably transferred either normal or mutant BRCA1 genes into breast cancer cells and injected the cells into mice. Tumors developed in all 15 mice given mutant BRCA1, but in none of the 20 mice given normal BRCA1. Finally, the researchers injected viruses carrying the BRCA1 gene into the abdomens of 10 mice with established breast cancer tumors; half the mice got normal BRCA1, the others got mutated BRCA1. The mice with mutant BRCA1 all died of cancer within two weeks. Those with normal BRCA1 survived 15 to 41 days, and their tumors either shrank or disappeared.
Working outside the cell? Micrographs (A, B, and C in successively higher magnifications) showing granules apparently secreting BRCA1 protein outside the cell suggest that it may be possible to design drugs to mimic the protein's effects. Source: Jensen RA et. al., BRCA1 is secreted and exhibits properties of a granin. Nature Genetics, 12:303-308, (1996).
All the experiments used a cell line derived from noninherited breast cancer, suggesting that the treatment might work against the more common types of the disease. Against hereditary breast and ovarian cancer, "presumably it would have an even more dramatic effect--at least that's what we hope," said Roy Jensen, an assistant professor of pathology and cell biology at Vanderbilt.
Translating the results into treatments for human cancers will take time. "It's going to be a long time before this is taken to the bedside," said Bowcock. "The problem is actually getting BRCA1 into breast cells--it's not going to be easy."
It's easier to get BRCA1 into ovarian tumor cells, and Vanderbilt researchers recently began clinical trials using BRCA1 on about 20 ovarian cancer patients, a move that concerns some of their colleagues. While he finds the results of the mouse and cell culture experiments "intriguing" and "encouraging," Roger Wiseman, head of the Comparative Carcinogenesis Group of the NIEHS Laboratory of Molecular Carcinogenesis (part of the team that identified BRCA1) feels the human gene therapy trials are "premature, based on the data that have been presented so far." Wiseman would like to see more animal studies performed before BRCA1 is used in patients.
A related study led by Jensen found evidence that the BRCA1 protein may be secreted and do its work outside the cell. If this is true, it would be much easier to design and deliver drugs that mimic the protein's effects. However, this finding is controverted, and other research groups are convinced that the BRCA1 protein works from inside cells.
"What we need to do to confirm our theory is purify recombinant BRCA1 and put it onto cells and see if it actually has a growth inhibitory action," said Jensen. If it does, and if it works only on breast and ovarian cancer cells and not other cells, "then that's pretty good evidence that there are specific receptors for this protein. Our efforts then would be focusing on trying to find those receptors."
EHPnet
Genetics and Biosafety
With the pounding pace at which research in genetics and biotechnology is progressing, it has become increasingly difficult for scientists to stay abreast of all the advances and ensure that the new technology is being used in a safe and cautious manner. In an effort to improve communications among scientists and promote the safe use of biotechnology, the United Nations established the International Centre for Genetic Engineering and Biotechnology (ICGEB).
The center maintains two main research laboratories, one in Trieste, Italy, and another in New Delhi, India, with several other smaller labs scattered around the world. These laboratories distribute their findings along with other biology-related information over the Internet via the ICGEB home page and ICGEBnet, an information resource network for molecular biologists.
The ICGEB home page, located at http://www.icgeb.trieste.it/,
provides information on ICGEB-sponsored meetings and symposia, access to biology-related
databases and newsgroups, and information on accessing ICGEBnet. A second biology-related
network available from the home page called BIN21 is still being developed by
the ICGEB and will focus on issues of biodiversity.
Among the databases accessible from the ICGEB's home page is one relating to P450 proteins and P450-containing systems, an on-line directory of biologists around the world, and SBASE (a sequence database of protein domains). An extensive library of biosafety-related rules and regulations from various nations, organizations, and research institutions is also available, along with lists of experts and databases that can be contacted to help researchers in dealing with biology-related legal issues. For further assistance on biosafety and legal questions, a link is provided to the Stockholm Environment Institute's Biotechnology Advisory Board home page. This international board of scientists will answer questions and give advice on any issue relating to ecology, biochemistry, genetics, biotechnology, pathology, environmental law, or economics.
Access to ICGEBnet and BIN21 will be free of charge but generally limited to scientists and policymakers with a pertinent interest in biology. Currently, ICGEBnet gives scientists around the world access to a variety of databases and provides a computer environment that allows molecular biologists to analyze nucleotide and protein sequences. Analysis software, including three major program packages, is distributed over ICGEBnet. In addition, information services such as electronic mail and bulletin boards are also available. The center's goal is to distribute these services to areas of the developing world where they are not yet widely available.
Fueling the Gas Debate
New findings continue to fuel the debate over the safety and effectiveness of gasoline additives, such as methyl tertiary butyl ether (MTBE) and ethanol, being used to reduce air pollution. The Clean Air Act Amendments of 1990 required that, beginning in 1992, areas that fail to meet air quality standards must use oxygenated fuels. Not only has the effectiveness of the oxygenates in reducing carbon monoxide (CO) emissions been questioned, the additives have also been accused of causing health problems including headaches, dizziness, nausea, and rashes. However, a recent study has found that the additives are successful in reducing CO emissions and do not appear likely to substantially increase health risks when compared to normal gasoline. The report emphasizes that further research is needed, but recommends that the use of the additives should not be abandoned at this time.
The Potential Health Effects of Oxygenates Added to Gasoline: A Review of the Current Literature was released in April by the Cambridge, Massachusetts-based Health Effects Institute, a cooperative effort of the EPA and the auto industry created to examine the health effects of motor vehicle emissions. HEI conducted a review of existing research, public complaints, and occupational exposures concerning gasoline additives.
According to the report, potential health effects from exposure to gasoline containing MTBE include headaches, nausea, and sensory irritation; acute, reversible neurotoxic effects (based on studies with rats at high exposure levels); and cancer (based on increased frequency of tumors in rats and mice at high exposure levels). Exposure to ethanol by ingestion of moderate to large quantities has been found to increase the risk of cancer, adversely affect embryos, and produce neurotoxicity. However, the report points out that these effects are unlikely to occur at low levels of inhalation.
The report concludes that possible short-term and cancer-causing effects of exposure to gasoline without oxygenates are similar to those from exposure to gasoline with oxygenates. Adding oxygenates to gasoline reduces the emission of carbon monoxide and benzene from motor vehicles, which may lower health risks for some people, the report stated. However, the process may increase exposure to oxygenates and aldehydes, which may have other health risks. The report concluded that an immediate reduction in oxygenate use is not warranted at this time because adding oxygenates is unlikely to significantly increase health risks associated with fuel use.
The report recommends that further research be conducted and outlines several priorities, including comprehensive assessments of personal exposure to oxygenates, human environmental chamber studies to evaluate the health effects of MTBE and MTBE-gasoline mixtures, epidemiologic and animal studies to evaluate cancer risks of MTBE, and comprehensive assessments of other oxygenates.
The study was commissioned by the EPA and the Centers for Disease Control and Prevention (CDC) as part of a broad review of oxygenated fuels being conducted by the White House Office of Science and Technology Policy, which will examine air quality benefits, engine performance, fuel economy, and costs of the fuels. The HEI study's conclusions are similar to those of a recent National Science and Technology Council report conducted by an interagency panel, says Mary White, an epidemiologist with the CDC. "Both reports clearly state that the information available on the additives is very limited." White emphasized the need for additional research. "There are some troubling and unanswered questions about the acute health effects [of the oxygenates]. These are a real concern, which no one dismisses, but we're talking about acute headaches, not acute mortality," White said.
Representatives of the oil industry who support the use of oxygenates were satisfied with the report's conclusions. "HEI did a good job of reviewing the information. I found the report to be favorable, although it overemphasized the carcinogenesis [of the oxygenates]," said Robert Drew, director of health and environmental research for the American Petroleum Institute. "Even though the results highlighted the carcinogenic and neurotoxic endpoints, [HEI] was not concerned enough for the materials to be taken off the market in the short term," he said.
However, the HEI report findings have angered opponents of oxygenate use, including Myron Mehlman, a staff scientist at the Environmental and Occupational Health Sciences Institute at Rutgers University. Mehlman, who feels that the additives should be immediately removed from the market, says the HEI report does not accurately address the acute effects of the oxygenates, and he criticized the studies cited in the report. "I don't know of any studies that have been conducted [on oxygenates] that are adequate," he said. Mehlman also says there are not sufficient data to show that the additives reduce carbon monoxide emissions; therefore, using the oxygenates is causing unnecessary health risks. Drew counters, "MTBE at this point is a thoroughly studied chemical. We concur with the conclusion that MTBE is certainly no more harmful than gasoline itself."
Although HEI acknowledges that it is not possible to have complete information about a substance before it is used, the report said that, in the future, more research--including a comprehensive testing program, rigorous exposure assessment, and epidemiologic studies--should be conducted before introducing a substance into widespread use.
IARC on Tamoxifen
Tamoxifen, an antiestrogenic compound that has been recognized by the World Health Organization as an essential drug for the treatment of breast cancer, is itself carcinogenic, according to the International Agency for Research on Cancer. IARC researchers, who met in February in Lyon, France, reviewed evidence on the potential carcinogenicity of 13 pharmaceuticals. Though they found evidence that tamoxifen increases a woman's risk of developing endometrial cancer, they emphasized that this does not abate the drug's benefits.
"No woman being treated for breast cancer should have [her] treatment stopped because of the conclusions of the [IARC] working group," the researchers concluded. "The risk of endometrial cancer is far lower than the benefits women with breast cancer receive from tamoxifen."
Tamoxifen has been prescribed to women with metastatic breast cancer for over 20 years and it is registered for use in nearly 100 countries. It has been used as both a curative agent and a secondary cancer-preventive agent, and it is also being evaluated for use as a primary preventive agent for healthy women at an increased risk of developing breast cancer, IARC director Paul Kleihues said in a 17 February 1996 article in The Lancet.
The IARC group, which consisted of 19 scientists from 8 countries, reviewed all the published scientific data on second primary tumors reported in patients who were given tamoxifen as treatment for breast cancer. In a draft of the study results, the group concluded that there was "sufficient evidence in humans for the carcinogenicity of tamoxifen in increasing the risk of endometrial cancer." However, the group also recognized that "there is conclusive evidence that tamoxifen reduces the risk of contralateral breast cancers" (second cancers in the other breast), and that "there is inadequate evidence tamoxifen affects the risk of other cancers." The results of the study will be published in volume 66 of the IARC Monographs on the Evaluation of Carcinogenic Risks to Humans.
Though statements on a drug's benefits are not normally included in the Monographs series, Kleihues told The Lancet that the working group would probably make an exception for tamoxifen. Such a statement may help quell the concerns of those worried that an overzealous reaction to IARC's findings could stop the use of a very beneficial medication. Criticism of the agency's decision to evaluate the carcinogenicity of tamoxifen began late last year when the state of California, in response, considered listing tamoxifen as a carcinogen under its Proposition 65. Critics point out that IARC's report could cause tamoxifen to be quickly replaced by any of a number of new antiestrogens currently being introduced. With comparatively little human data available on the new drugs, the danger exists that tamoxifen will be uncritically replaced by a less effective or more toxic medicine.
Kleihues said that IARC received many letters concerning its study on tamoxifen, but that the agency did not cancel or reschedule the evaluation as a matter of principle. "It is important that women have access to scientific opinion on the low risks of endometrial cancer," Kleihues and working group chairman George Lucier stated in a press release, "so that they can make informed decisions on the treatment they will accept."
Tamoxifen is one of three triphenylethylene antiestrogenic compounds that will be reviewed in volume 66. The other two, droloxifene, a drug also used in the treatment of breast cancer, and toremifene, which is just being introduced, were found to be "not classifiable" as to their carcinogenicity to humans due to inadequate data.
Similar results were found for six of a group of seven benzodiazepines and benzodiazepine analogues that are used in the treatment of insomnia, anxiety disorders, and alcohol withdrawal. One, oxazepam, was found to be "possibly carcinogenic to humans."
Two cholesterol-lowering drugs, clofibrate and gemfibrozil, were also found to be "not classifiable" as to their carcinogenicity to humans. Phenytoin, which is used to treat epilepsy and certain cardiac arrhythmias, was found to be "possibly carcinogenic to humans."
IARC has evaluated the carcinogenicity of more than 800 agents. Of these, 70 have been deemed human carcinogens and about a half dozen of these are still in use. |
Last Update: June 23, 1997