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Science Tuesday - Colds, Mosquitos, Plastic Bags and TB
A lot of you are having summer colds, so these two are for you:
Vital Signs: Resistance: Vitamin C Is Not Much Help Fighting Colds, Study Shows
By NICHOLAS BAKALAR, The New York Times, July 24, 2007
A large review of placebo-controlled trials of vitamin C for cold prevention and treatment has concluded that it is largely ineffective.
In 30 trials involving 11,350 participants who took at least 200 milligrams of vitamin C a day, researchers found no reduction in the incidence of common colds. Vitamin C did reduce the duration and severity of cold symptoms slightly, but the effect was so small as to be clinically insignificant. The review was published last week in The Cochrane Database of Systematic Reviews. [Another large review suggests that echinacea may be effective against colds.]
But vitamin C is apparently effective under certain circumstances. In six trials in people exposed to extreme physical stress — including ultramarathon runners and Canadian soldiers during sub-Arctic winter exercises — vitamin C reduced cold incidence by about half.
“We did find an 8 percent reduction in length of colds in adults and a 13 percent reduction in children,” said Dr. Harri Hemila of the University of Helsinki, a co-author of the review, “so there may be greater effect with higher doses.”
Even in very large doses, vitamin C appears to do little harm. In 2,490 people who took more than 1,000 milligrams a day, only 5.8 percent reported any adverse symptoms (none serious), compared with 6 percent of those taking a placebo. The recommended daily allowance for vitamin C is 90 milligrams for men and 75 milligrams for women.
“Vitamin C is very safe,” Dr. Hemila said. “The main question is whether it’s useful at all and in what conditions.”
BUT...
Echinacea Helps Colds, Major Review Shows
By NICHOLAS BAKALAR, The New York Times, July 24, 2007
Echinacea helps banish colds. Echinacea has no effect on colds. The verdict seems to shift with each new scientific study of the herbal remedy.
In the latest twist, a review of more than 700 studies has concluded that echinacea has a substantial effect in preventing colds and in limiting their duration.
The paper, published in the July issue of The Lancet Infectious Diseases, used statistical techniques to combine the results of existing studies and reach conclusions based on the larger sample that resulted. The researchers selected only those trials that used randomized and placebo-controlled techniques: 14 studies involving 1,356 participants for the number of colds and 1,630 for the prevention of colds. The studies varied in the dosages of the herb, the duration it was taken and the species of echinacea used, and the number of participants ranged from 40 to more than 300.
The analysis concluded that echinacea reduced the risk of catching a cold by 58 percent. It also found that the herb significantly shortened the duration of a cold, but there was no general agreement about the magnitude of this effect.
“Our analysis doesn’t say that the stuff works without question,” said Dr. Craig I. Coleman, an assistant professor of pharmacy practice at the University of Connecticut, and the senior author of the paper. “But the preponderance of evidence suggests that it does.”
The authors acknowledged certain weaknesses in their study. For example, they did not examine the safety of the herbal remedy, only its effectiveness.
Dr. Bruce P. Barrett, an associate professor of family medicine at the University of Wisconsin who was not involved with the review, said he was not convinced of the value of combining the studies in a single analysis.
“If you’re testing the same intervention on the same population using the same outcome measures, then meta-analysis is a very good technique,” Dr. Barrett said. “But here every one of those things fails.” One of Dr. Barrett’s papers on echinacea was included in the analysis.
Other experts also expressed skepticism. J. David Gangemi, director of the Institute for Neutraceutical Research at Clemson University, said he found the study interesting, but added, “I think that many of the people who have dedicated their careers to clinical trials in studying these effects are not at all convinced from this analysis that there is this large reduction in incidence and duration of disease.”
Dr. Gangemi is the senior author of a 2005 study, published in The New England Journal of Medicine and included in the review, that found no benefit in the herb.
There are several possible reasons that even a carefully devised single study might fail to show an effect that actually exists. There are more than 200 species of virus that cause colds, Dr. Coleman said, and a study could test one species against which echinacea proves ineffective, while leaving open the question of whether it works for others.
In addition, some studies might not use large enough doses of the herb; others might use a species of echinacea that is less effective. Some might not have a large enough sample to find a small but statistically significant effect.
Dr. Barrett said there was probably little harm in using echinacea, and he was cautiously optimistic that the herb does have a very small positive effect.
“There’s some danger of kids getting a rash, and it would be inadvisable to give it to women in the early stages of pregnancy,” he said. “But if adults believe in echinacea, they’re going to get benefits — maybe from placebo — but they’ll get benefits.”
Dr. Coleman, who described himself as “not much of a pill taker,” hedged a bit when asked if he planned to use echinacea himself. “I’ll probably consider taking it if I feel a cold coming on,” he said. “These results have pushed me toward the idea. Whether I’m actually going to take it, well, we’ll see.”
And while we are dispelling myths...
Really? The Claim: Eating Garlic Helps Repel Mosquitoes
By ANAHAD O’CONNOR, The New York Times, July 24, 2007
THE FACTS
How nice it would be if eating one simple food could bring relief to all those Americans who become walking bait for mosquitoes each summer.
Garlic, perhaps because of its strong odor, has long been said to be that magic food. But studies so far have found that claim to be little more than wishful thinking. Eating it may repel other humans, but apparently not mosquitoes.
One study illustrating this was published in 2005 by a group of researchers at the University of Connecticut Health Center. The scientists asked groups of subjects to consume large amounts of garlic on some days and a placebo on others and exposed them to mosquitoes on each day. The number of mosquitoes that fed on them and the number of bites they suffered did not seem to differ under the two conditions.
Just about the only food or beverage that has been shown to have an effect on mosquitoes when ingested by humans is alcohol: it attracts them.
In a 2002 study in The Journal of the American Mosquito Control Association, a group of 14 subjects drank 350 milliliters of beer on various occasions. Ingesting beer significantly increased the percentage of mosquitoes that landed on the subjects, though precisely why was unclear.
Typically, mosquitoes locate their victims by seeking out body heat, lactic acid and carbon dioxide. People who are attacked less, studies show, appear to have genes that make them better able to disguise themselves. So far, the substance known to block mosquitoes’ powers of detection the best is DEET, which acts by blinding their senses.
THE BOTTOM LINE
Eating garlic has not been shown to either attract or ward off mosquitoes.
And two extra for good measure...
Pressure Builds to Ban Plastic Bags in Stores
By IAN URBINA, The New York Times, July 24, 2007
ANNAPOLIS, Md., July 23 — Paper or plastic? It is a question that has long dogged grocery shoppers. But the debate may soon be settled for this maritime city, where a bill aimed at protecting marine life would ban plastic bags from all retail stores.
San Francisco enacted a ban in April, but it applies just to larger groceries and drugstores. Similar measures are being considered in Boston; Baltimore; Oakland, Calif.; Portland, Ore.; Santa Monica, Calif.; and Steamboat Springs, Colo.
Alexandra Cousteau, granddaughter of Jacques Cousteau and director of EarthEcho, an environmental education group in Washington, said, “Banning plastic makes sense for the simple reason that it takes more than 1,000 years to biodegrade, which means that every single piece of plastic we’ve ever manufactured is still around, and much of it ends up in the oceans killing animals.”
Ms. Cousteau attended a public meeting here on Monday to support the measure. More than 70 people attended the meeting.
The bill aims to help protect Chesapeake Bay and its tributaries, whose fish and birds often die after ingesting discarded plastic bags. Stores would be required to offer paper bags made from recycled material under the bill, which goes to a final City Council vote in October.
Critics say the ban would be expensive and counterproductive.
“It sounds good until you consider the cost,” said Barry F. Scher, a spokesman for Giant Food, the grocery chain based in Landover, Md.
Instead of taking away plastic bags, which cost 2 cents each compared with 5 cents for paper bags, Annapolis should enforce its litter laws, Mr. Scher said.
He added that Giant already offered a 3-cent credit for every plastic bag that customers return to the store and that 2,200 tons of bags a year were recycled and turned into backyard decks and park benches.
Paper bags are bulkier to transport than plastic bags, Mr. Scher added, and more trucks, fuel and pollution are involved in delivering them to stores.
“That may be true,” said Alderman Sam Shropshire, the sponsor of the bill here. “But what they don’t tell you is that to make 100 billion plastic checkout bags per year, which is how many we use in the U.S. each year, it takes 12 million barrels of oil. No oil is used to produce recycled paper checkout bags.”
Jeffrie Zellmer, legislative director of the Maryland Retailers Association, said it took far less energy to recycle plastic than to recycle paper. Mr. Zellmer added that 90 percent of retailers used plastic bags and that costs could increase threefold or sixfold, eventually reaching consumers.
The commercial recycling coordinator for the City and County of San Francisco, Jack Macy, said that nationally 1 percent of all plastic checkout bags were recycled. “That means the rest end up in landfill,” Mr. Macy said. “And so the argument about plastic recycling being energy efficient isn’t a strong one.”
“Look,” Mr. Shropshire said, “in the end, the best option is for people to bring their own reusable bags. But if they fail to do that, then they can use paper bags that biodegrade faster than plastic and yet do not require any trees to be cut down.”
At the hearing, a lobbyist for Safeway called the bill un-American, saying it would take choices away from consumers.
For now, Mayor Ellen O. Moyer of Annapolis, a Democrat, remains undecided on the measure.
A spokesman for Ms. Moyer, Ray Weaver, said the city planned to distribute reusable bags to residents by the fall. To accomplish that, Mr. Weaver said, the city is considering teaming with sail makers to use excess material that teenagers in a jobs program may sew into sacks.
“I think it’s a smart move,” said Jim Martin, owner of the Free State Press, a small printing and copy store several blocks from the State Capitol, as he ordered business cards for a City Council member to be delivered in a plastic bag.
Mr. Martin said he was more than willing to phase out the plastic bags because he was tired of the litter in the streets, trees and bay.
Brian Cahalan, owner of 49 West, a coffeehouse about two blocks from the Capitol, said that regardless of whether the measure passed, the debate had compelled him to act.
Though his store uses plastic bags, Mr. Cahalan said, he plans to encourage customers to use their own bags or none by adding a fee of 25 cents for each store bag used.
“That way,” he said, “we won’t have to figure out which of these two types of litter is worse.”
The Doctor’s World: TB Tests Show Promise, but Flaws Limit Progress
By LAWRENCE K. ALTMAN, M.D., The New York Times, July 24, 2007
In the escalating battle against extensively drug-resistant tuberculosis, conflicting findings from laboratory tests have hampered efforts to control the spread of the disease.
Some of the conflicts come from a lack of standardized testing methods and others from subtle but critical differences in the way the tests are performed.
The most celebrated example of such discordant findings involved Andrew Speaker, the Atlanta lawyer who caused an international health scare after traveling to Europe in May with what was believed to be extensively drug-resistant tuberculosis, known as XDR.
This month, Mr. Speaker’s doctors downgraded his type of tuberculosis to multidrug-resistant, or MDR, after repeating tests that initially gave a different result.
The reclassification drew widespread publicity partly because conflicting findings came from tests performed at two of the country’s main reference laboratories for tuberculosis — the Centers for Disease Control and Prevention in Atlanta and the National Jewish Medical and Research Center in Denver.
Full details of Mr. Speaker’s case are not known. But the problems go beyond one case. Last week, as Mr. Speaker underwent surgery in Denver to remove the diseased upper lobe of his right lung, a panel of experts met in Geneva at the World Health Organization’s headquarters to discuss resistant tuberculosis testing. The discussion focused on updating the recommendations for such procedures made by a similar agency panel in 2001.
The overwhelming majority of tuberculosis cases are caused by bacterial strains that yield to the standard, or first-line, anti-TB drugs. Newer, second-line drugs are used if a strain of tuberculosis is MDR or XDR, which are resistant to the first-line drugs. If tuberculosis strains are not tested for drug resistance as soon as they are found in a patient, the problem may be detected too late to permit a cure.
Tuberculosis resistance develops when drugs are misused or mismanaged. For example, patients may fail to complete their full course of treatment. Health care providers may prescribe the wrong treatment, the wrong dose or the wrong length of time for taking the drugs. Another problem occurs when drugs are not available, or when the drugs are of poor quality.
What alarms health officials is the potential for outbreaks of MDR to evolve into large XDR ones, creating the specter of an uncontrollable health menace. Officials are trying to control an outbreak in South Africa, in which XDR killed 52 of 53 infected people, all of whom were also infected with the AIDS virus.
Reliable tests to determine resistance to first-line drugs were developed when the drugs were first marketed about a half-century ago. Fewer resistance tests exist for the newer, second-line drugs needed to treat MDR and XDR tuberculosis, and many of them are difficult to perform for a number of reasons.
One reason is that some can become unstable under conditions of laboratory testing. Laboratories do not grind up pills for resistance testing because they contain substances that could lead to unreliable results. Instead, laboratories use pure powders of an antituberculosis drug’s active ingredient. But even such powders can be affected by heat and other factors, leading to inconsistent findings.
Another reason is that the many steps involved in the laboratory process increase chances for human error.
In 2001, the World Health Organization panel said that the latest knowledge was “very incomplete regarding how to best perform” resistance tests of second-line drugs and the usefulness of the tests in treating such cases.
Since then, experience with newer laboratory techniques and a review of published scientific papers show their usefulness, participants said in interviews.
But countries have neglected investments in tuberculosis research and care for many years, and now they need to make greater efforts to improve testing for resistance, said Abigail Wright, a tuberculosis expert at W.H.O.
The panel also relied on quality-control checks of a number of laboratories, which showed their ability to correctly detect resistant strains.
“But no laboratory test for any disease is 100 percent,” said one member of the panel, Dr. Karin Weyer of the South African Medical Research Council. “Labs often have problems and can and do make mistakes,” Dr. Weyer said.
Drug-resistant tuberculosis is not new. In 1962, Eleanor Roosevelt died from a strain of tuberculosis resistant to isoniazid and streptomycin, according to published research by Dr. Barron Lerner of Columbia University, where she was treated.
As more tuberculosis strains have become resistant to more drugs in recent years, health officials have come up with the MDR and XDR designations. Such forms are much costlier to control than standard tuberculosis. In the 1990s, New York spent more than $1 billion to control an outbreak of MDR tuberculosis.
In 2006, the Centers for Disease Control and the World Health Organization revised the definition of XDR in part because of a lack of standardization of the tests for certain antibiotics needed to treat it.
Under current definitions, MDR means that the strain of TB is caused by bacteria resistant to two or more of the most important drugs, isoniazid and rifampicin. XDR strains are resistant to both isoniazid and rifampicin as well as to any member of the fluoroquinolone antibiotic class of second-line drugs and to at least one of three injectable second-line drugs like amikacin, capreomycin and kanamycin.
The World Health Organization says that of the 424,000 MDR tuberculosis cases that occur in the world each year, 25,000 are XDR, but the organization believes that fewer than 5 percent of resistant cases are detected. The agency bases its opinion in part on the high prevalence of multidrug resistance found in an expanding number of provinces surveyed in China and Russia, indicating a larger epidemic than previously suspected.
The W.H.O. plans to publish a technical manual this year detailing the steps that the panel believes are needed to ensure that all laboratories get the same results on the same specimen concerning resistance to second-line drugs.
A key step involves the proper way to prepare the media used to grow tuberculosis bacteria. Another step is determining the precise amounts of bacteria and antibiotics used in testing.
The panel endorsed use of certain new methods like a liquid culture medium that can facilitate faster growth of tuberculosis bacteria, Dr. Weyer said.
The panel also recommended using molecular tests to detect rifampicin resistance as a proxy for MDR tuberculosis. Use of such tests could reliably determine XDR in less than two months, compared with the several months that are often needed now, Dr. Weyer said. Standard tests take weeks to complete because tuberculosis bacteria grow slowly.
Speedier detection of resistant tuberculosis would allow patients to receive appropriate treatment sooner and benefit the public by breaking the chain of transmission more quickly.
Molecular tests are available only for first-line antituberculosis drugs. Such tests require identification of all the genes involved in drug resistance in the microbe. “For second-line drugs, we know very little about which genes are involved,” Dr. Weyer said.
The cost of antituberculosis drugs is dropping, increasing chances for creating resistant strains, the W.H.O. said, making it more imperative for countries where the disease is most rampant to create and expand laboratory capabilities to detect them.
The panel emphasized that laboratory workers needed more experience in interpreting results of the tests. As new laboratories are created in the many countries where drug-resistant tuberculosis exists but testing facilities do not, technicians will need to learn how to do the testing. Refresher training is also needed even in the best laboratories because they are mainly in countries with a low incidence of resistant tuberculosis.
Some countries that believe they are free of MDR and XDR tuberculosis have prohibited shipment of such strains to prevent accidental spread. Airline regulations also prohibit shipment of certain strains.
The panel decided that XDR strains should not be sent anywhere for proficiency testing but that MDR strains could be sent to countries that approve their entry and that have proper safety equipment. For countries banning MDR specimens, certain other strains with predetermined resistance to antibiotics can be sent for proficiency testing.
Resistance tests for the most powerful drugs against MDR and XDR — the fluoroquinolones and aminoglycosides — are reliable, the panel said. But it also said that resistance tests for second-line drugs like cycloserine and para-aminosalicylic acid should not be performed for lack of reliability.
Ethical considerations limit the type of research that can be done to improve resistance testing. For example, scientists cannot carry out studies in which they would give only one antituberculosis drug to a patient to correlate laboratory findings of susceptibility test because it would mean withholding effective drugs, said Dr. Mario C. Raviglione, director of the tuberculosis department at the World Health Organization.
Vital Signs: Resistance: Vitamin C Is Not Much Help Fighting Colds, Study Shows
By NICHOLAS BAKALAR, The New York Times, July 24, 2007
A large review of placebo-controlled trials of vitamin C for cold prevention and treatment has concluded that it is largely ineffective.
In 30 trials involving 11,350 participants who took at least 200 milligrams of vitamin C a day, researchers found no reduction in the incidence of common colds. Vitamin C did reduce the duration and severity of cold symptoms slightly, but the effect was so small as to be clinically insignificant. The review was published last week in The Cochrane Database of Systematic Reviews. [Another large review suggests that echinacea may be effective against colds.]
But vitamin C is apparently effective under certain circumstances. In six trials in people exposed to extreme physical stress — including ultramarathon runners and Canadian soldiers during sub-Arctic winter exercises — vitamin C reduced cold incidence by about half.
“We did find an 8 percent reduction in length of colds in adults and a 13 percent reduction in children,” said Dr. Harri Hemila of the University of Helsinki, a co-author of the review, “so there may be greater effect with higher doses.”
Even in very large doses, vitamin C appears to do little harm. In 2,490 people who took more than 1,000 milligrams a day, only 5.8 percent reported any adverse symptoms (none serious), compared with 6 percent of those taking a placebo. The recommended daily allowance for vitamin C is 90 milligrams for men and 75 milligrams for women.
“Vitamin C is very safe,” Dr. Hemila said. “The main question is whether it’s useful at all and in what conditions.”
BUT...
Echinacea Helps Colds, Major Review Shows
By NICHOLAS BAKALAR, The New York Times, July 24, 2007
Echinacea helps banish colds. Echinacea has no effect on colds. The verdict seems to shift with each new scientific study of the herbal remedy.
In the latest twist, a review of more than 700 studies has concluded that echinacea has a substantial effect in preventing colds and in limiting their duration.
The paper, published in the July issue of The Lancet Infectious Diseases, used statistical techniques to combine the results of existing studies and reach conclusions based on the larger sample that resulted. The researchers selected only those trials that used randomized and placebo-controlled techniques: 14 studies involving 1,356 participants for the number of colds and 1,630 for the prevention of colds. The studies varied in the dosages of the herb, the duration it was taken and the species of echinacea used, and the number of participants ranged from 40 to more than 300.
The analysis concluded that echinacea reduced the risk of catching a cold by 58 percent. It also found that the herb significantly shortened the duration of a cold, but there was no general agreement about the magnitude of this effect.
“Our analysis doesn’t say that the stuff works without question,” said Dr. Craig I. Coleman, an assistant professor of pharmacy practice at the University of Connecticut, and the senior author of the paper. “But the preponderance of evidence suggests that it does.”
The authors acknowledged certain weaknesses in their study. For example, they did not examine the safety of the herbal remedy, only its effectiveness.
Dr. Bruce P. Barrett, an associate professor of family medicine at the University of Wisconsin who was not involved with the review, said he was not convinced of the value of combining the studies in a single analysis.
“If you’re testing the same intervention on the same population using the same outcome measures, then meta-analysis is a very good technique,” Dr. Barrett said. “But here every one of those things fails.” One of Dr. Barrett’s papers on echinacea was included in the analysis.
Other experts also expressed skepticism. J. David Gangemi, director of the Institute for Neutraceutical Research at Clemson University, said he found the study interesting, but added, “I think that many of the people who have dedicated their careers to clinical trials in studying these effects are not at all convinced from this analysis that there is this large reduction in incidence and duration of disease.”
Dr. Gangemi is the senior author of a 2005 study, published in The New England Journal of Medicine and included in the review, that found no benefit in the herb.
There are several possible reasons that even a carefully devised single study might fail to show an effect that actually exists. There are more than 200 species of virus that cause colds, Dr. Coleman said, and a study could test one species against which echinacea proves ineffective, while leaving open the question of whether it works for others.
In addition, some studies might not use large enough doses of the herb; others might use a species of echinacea that is less effective. Some might not have a large enough sample to find a small but statistically significant effect.
Dr. Barrett said there was probably little harm in using echinacea, and he was cautiously optimistic that the herb does have a very small positive effect.
“There’s some danger of kids getting a rash, and it would be inadvisable to give it to women in the early stages of pregnancy,” he said. “But if adults believe in echinacea, they’re going to get benefits — maybe from placebo — but they’ll get benefits.”
Dr. Coleman, who described himself as “not much of a pill taker,” hedged a bit when asked if he planned to use echinacea himself. “I’ll probably consider taking it if I feel a cold coming on,” he said. “These results have pushed me toward the idea. Whether I’m actually going to take it, well, we’ll see.”
And while we are dispelling myths...
Really? The Claim: Eating Garlic Helps Repel Mosquitoes
By ANAHAD O’CONNOR, The New York Times, July 24, 2007
THE FACTS
How nice it would be if eating one simple food could bring relief to all those Americans who become walking bait for mosquitoes each summer.
Garlic, perhaps because of its strong odor, has long been said to be that magic food. But studies so far have found that claim to be little more than wishful thinking. Eating it may repel other humans, but apparently not mosquitoes.
One study illustrating this was published in 2005 by a group of researchers at the University of Connecticut Health Center. The scientists asked groups of subjects to consume large amounts of garlic on some days and a placebo on others and exposed them to mosquitoes on each day. The number of mosquitoes that fed on them and the number of bites they suffered did not seem to differ under the two conditions.
Just about the only food or beverage that has been shown to have an effect on mosquitoes when ingested by humans is alcohol: it attracts them.
In a 2002 study in The Journal of the American Mosquito Control Association, a group of 14 subjects drank 350 milliliters of beer on various occasions. Ingesting beer significantly increased the percentage of mosquitoes that landed on the subjects, though precisely why was unclear.
Typically, mosquitoes locate their victims by seeking out body heat, lactic acid and carbon dioxide. People who are attacked less, studies show, appear to have genes that make them better able to disguise themselves. So far, the substance known to block mosquitoes’ powers of detection the best is DEET, which acts by blinding their senses.
THE BOTTOM LINE
Eating garlic has not been shown to either attract or ward off mosquitoes.
And two extra for good measure...
Pressure Builds to Ban Plastic Bags in Stores
By IAN URBINA, The New York Times, July 24, 2007
ANNAPOLIS, Md., July 23 — Paper or plastic? It is a question that has long dogged grocery shoppers. But the debate may soon be settled for this maritime city, where a bill aimed at protecting marine life would ban plastic bags from all retail stores.
San Francisco enacted a ban in April, but it applies just to larger groceries and drugstores. Similar measures are being considered in Boston; Baltimore; Oakland, Calif.; Portland, Ore.; Santa Monica, Calif.; and Steamboat Springs, Colo.
Alexandra Cousteau, granddaughter of Jacques Cousteau and director of EarthEcho, an environmental education group in Washington, said, “Banning plastic makes sense for the simple reason that it takes more than 1,000 years to biodegrade, which means that every single piece of plastic we’ve ever manufactured is still around, and much of it ends up in the oceans killing animals.”
Ms. Cousteau attended a public meeting here on Monday to support the measure. More than 70 people attended the meeting.
The bill aims to help protect Chesapeake Bay and its tributaries, whose fish and birds often die after ingesting discarded plastic bags. Stores would be required to offer paper bags made from recycled material under the bill, which goes to a final City Council vote in October.
Critics say the ban would be expensive and counterproductive.
“It sounds good until you consider the cost,” said Barry F. Scher, a spokesman for Giant Food, the grocery chain based in Landover, Md.
Instead of taking away plastic bags, which cost 2 cents each compared with 5 cents for paper bags, Annapolis should enforce its litter laws, Mr. Scher said.
He added that Giant already offered a 3-cent credit for every plastic bag that customers return to the store and that 2,200 tons of bags a year were recycled and turned into backyard decks and park benches.
Paper bags are bulkier to transport than plastic bags, Mr. Scher added, and more trucks, fuel and pollution are involved in delivering them to stores.
“That may be true,” said Alderman Sam Shropshire, the sponsor of the bill here. “But what they don’t tell you is that to make 100 billion plastic checkout bags per year, which is how many we use in the U.S. each year, it takes 12 million barrels of oil. No oil is used to produce recycled paper checkout bags.”
Jeffrie Zellmer, legislative director of the Maryland Retailers Association, said it took far less energy to recycle plastic than to recycle paper. Mr. Zellmer added that 90 percent of retailers used plastic bags and that costs could increase threefold or sixfold, eventually reaching consumers.
The commercial recycling coordinator for the City and County of San Francisco, Jack Macy, said that nationally 1 percent of all plastic checkout bags were recycled. “That means the rest end up in landfill,” Mr. Macy said. “And so the argument about plastic recycling being energy efficient isn’t a strong one.”
“Look,” Mr. Shropshire said, “in the end, the best option is for people to bring their own reusable bags. But if they fail to do that, then they can use paper bags that biodegrade faster than plastic and yet do not require any trees to be cut down.”
At the hearing, a lobbyist for Safeway called the bill un-American, saying it would take choices away from consumers.
For now, Mayor Ellen O. Moyer of Annapolis, a Democrat, remains undecided on the measure.
A spokesman for Ms. Moyer, Ray Weaver, said the city planned to distribute reusable bags to residents by the fall. To accomplish that, Mr. Weaver said, the city is considering teaming with sail makers to use excess material that teenagers in a jobs program may sew into sacks.
“I think it’s a smart move,” said Jim Martin, owner of the Free State Press, a small printing and copy store several blocks from the State Capitol, as he ordered business cards for a City Council member to be delivered in a plastic bag.
Mr. Martin said he was more than willing to phase out the plastic bags because he was tired of the litter in the streets, trees and bay.
Brian Cahalan, owner of 49 West, a coffeehouse about two blocks from the Capitol, said that regardless of whether the measure passed, the debate had compelled him to act.
Though his store uses plastic bags, Mr. Cahalan said, he plans to encourage customers to use their own bags or none by adding a fee of 25 cents for each store bag used.
“That way,” he said, “we won’t have to figure out which of these two types of litter is worse.”
The Doctor’s World: TB Tests Show Promise, but Flaws Limit Progress
By LAWRENCE K. ALTMAN, M.D., The New York Times, July 24, 2007
In the escalating battle against extensively drug-resistant tuberculosis, conflicting findings from laboratory tests have hampered efforts to control the spread of the disease.
Some of the conflicts come from a lack of standardized testing methods and others from subtle but critical differences in the way the tests are performed.
The most celebrated example of such discordant findings involved Andrew Speaker, the Atlanta lawyer who caused an international health scare after traveling to Europe in May with what was believed to be extensively drug-resistant tuberculosis, known as XDR.
This month, Mr. Speaker’s doctors downgraded his type of tuberculosis to multidrug-resistant, or MDR, after repeating tests that initially gave a different result.
The reclassification drew widespread publicity partly because conflicting findings came from tests performed at two of the country’s main reference laboratories for tuberculosis — the Centers for Disease Control and Prevention in Atlanta and the National Jewish Medical and Research Center in Denver.
Full details of Mr. Speaker’s case are not known. But the problems go beyond one case. Last week, as Mr. Speaker underwent surgery in Denver to remove the diseased upper lobe of his right lung, a panel of experts met in Geneva at the World Health Organization’s headquarters to discuss resistant tuberculosis testing. The discussion focused on updating the recommendations for such procedures made by a similar agency panel in 2001.
The overwhelming majority of tuberculosis cases are caused by bacterial strains that yield to the standard, or first-line, anti-TB drugs. Newer, second-line drugs are used if a strain of tuberculosis is MDR or XDR, which are resistant to the first-line drugs. If tuberculosis strains are not tested for drug resistance as soon as they are found in a patient, the problem may be detected too late to permit a cure.
Tuberculosis resistance develops when drugs are misused or mismanaged. For example, patients may fail to complete their full course of treatment. Health care providers may prescribe the wrong treatment, the wrong dose or the wrong length of time for taking the drugs. Another problem occurs when drugs are not available, or when the drugs are of poor quality.
What alarms health officials is the potential for outbreaks of MDR to evolve into large XDR ones, creating the specter of an uncontrollable health menace. Officials are trying to control an outbreak in South Africa, in which XDR killed 52 of 53 infected people, all of whom were also infected with the AIDS virus.
Reliable tests to determine resistance to first-line drugs were developed when the drugs were first marketed about a half-century ago. Fewer resistance tests exist for the newer, second-line drugs needed to treat MDR and XDR tuberculosis, and many of them are difficult to perform for a number of reasons.
One reason is that some can become unstable under conditions of laboratory testing. Laboratories do not grind up pills for resistance testing because they contain substances that could lead to unreliable results. Instead, laboratories use pure powders of an antituberculosis drug’s active ingredient. But even such powders can be affected by heat and other factors, leading to inconsistent findings.
Another reason is that the many steps involved in the laboratory process increase chances for human error.
In 2001, the World Health Organization panel said that the latest knowledge was “very incomplete regarding how to best perform” resistance tests of second-line drugs and the usefulness of the tests in treating such cases.
Since then, experience with newer laboratory techniques and a review of published scientific papers show their usefulness, participants said in interviews.
But countries have neglected investments in tuberculosis research and care for many years, and now they need to make greater efforts to improve testing for resistance, said Abigail Wright, a tuberculosis expert at W.H.O.
The panel also relied on quality-control checks of a number of laboratories, which showed their ability to correctly detect resistant strains.
“But no laboratory test for any disease is 100 percent,” said one member of the panel, Dr. Karin Weyer of the South African Medical Research Council. “Labs often have problems and can and do make mistakes,” Dr. Weyer said.
Drug-resistant tuberculosis is not new. In 1962, Eleanor Roosevelt died from a strain of tuberculosis resistant to isoniazid and streptomycin, according to published research by Dr. Barron Lerner of Columbia University, where she was treated.
As more tuberculosis strains have become resistant to more drugs in recent years, health officials have come up with the MDR and XDR designations. Such forms are much costlier to control than standard tuberculosis. In the 1990s, New York spent more than $1 billion to control an outbreak of MDR tuberculosis.
In 2006, the Centers for Disease Control and the World Health Organization revised the definition of XDR in part because of a lack of standardization of the tests for certain antibiotics needed to treat it.
Under current definitions, MDR means that the strain of TB is caused by bacteria resistant to two or more of the most important drugs, isoniazid and rifampicin. XDR strains are resistant to both isoniazid and rifampicin as well as to any member of the fluoroquinolone antibiotic class of second-line drugs and to at least one of three injectable second-line drugs like amikacin, capreomycin and kanamycin.
The World Health Organization says that of the 424,000 MDR tuberculosis cases that occur in the world each year, 25,000 are XDR, but the organization believes that fewer than 5 percent of resistant cases are detected. The agency bases its opinion in part on the high prevalence of multidrug resistance found in an expanding number of provinces surveyed in China and Russia, indicating a larger epidemic than previously suspected.
The W.H.O. plans to publish a technical manual this year detailing the steps that the panel believes are needed to ensure that all laboratories get the same results on the same specimen concerning resistance to second-line drugs.
A key step involves the proper way to prepare the media used to grow tuberculosis bacteria. Another step is determining the precise amounts of bacteria and antibiotics used in testing.
The panel endorsed use of certain new methods like a liquid culture medium that can facilitate faster growth of tuberculosis bacteria, Dr. Weyer said.
The panel also recommended using molecular tests to detect rifampicin resistance as a proxy for MDR tuberculosis. Use of such tests could reliably determine XDR in less than two months, compared with the several months that are often needed now, Dr. Weyer said. Standard tests take weeks to complete because tuberculosis bacteria grow slowly.
Speedier detection of resistant tuberculosis would allow patients to receive appropriate treatment sooner and benefit the public by breaking the chain of transmission more quickly.
Molecular tests are available only for first-line antituberculosis drugs. Such tests require identification of all the genes involved in drug resistance in the microbe. “For second-line drugs, we know very little about which genes are involved,” Dr. Weyer said.
The cost of antituberculosis drugs is dropping, increasing chances for creating resistant strains, the W.H.O. said, making it more imperative for countries where the disease is most rampant to create and expand laboratory capabilities to detect them.
The panel emphasized that laboratory workers needed more experience in interpreting results of the tests. As new laboratories are created in the many countries where drug-resistant tuberculosis exists but testing facilities do not, technicians will need to learn how to do the testing. Refresher training is also needed even in the best laboratories because they are mainly in countries with a low incidence of resistant tuberculosis.
Some countries that believe they are free of MDR and XDR tuberculosis have prohibited shipment of such strains to prevent accidental spread. Airline regulations also prohibit shipment of certain strains.
The panel decided that XDR strains should not be sent anywhere for proficiency testing but that MDR strains could be sent to countries that approve their entry and that have proper safety equipment. For countries banning MDR specimens, certain other strains with predetermined resistance to antibiotics can be sent for proficiency testing.
Resistance tests for the most powerful drugs against MDR and XDR — the fluoroquinolones and aminoglycosides — are reliable, the panel said. But it also said that resistance tests for second-line drugs like cycloserine and para-aminosalicylic acid should not be performed for lack of reliability.
Ethical considerations limit the type of research that can be done to improve resistance testing. For example, scientists cannot carry out studies in which they would give only one antituberculosis drug to a patient to correlate laboratory findings of susceptibility test because it would mean withholding effective drugs, said Dr. Mario C. Raviglione, director of the tuberculosis department at the World Health Organization.