http://www.nytimes.com/2009/01/27/health/27brod.html?_r=1&em

 

January 27, 2009

Personal Health

Babies Know: A Little Dirt Is Good for You

By JANE E. BRODY

Ask mothers why babies are constantly picking things up from the floor or ground and putting them in their mouths, and chances are they'll say that it's instinctive -- that that's how babies explore the world. But why the mouth, when sight, hearing, touch and even scent are far better at identifying things?

When my young sons were exploring the streets of Brooklyn, I couldn't help but wonder how good crushed rock or dried dog droppings could taste when delicious mashed potatoes were routinely rejected.

Since all instinctive behaviors have an evolutionary advantage or they would not have been retained for millions of years, chances are that this one too has helped us survive as a species. And, indeed, accumulating evidence strongly suggests that eating dirt is good for you.

In studies of what is called the hygiene hypothesis, researchers are concluding that organisms like the millions of bacteria, viruses and especially worms that enter the body along with "dirt" spur the development of a healthy immune system. Several continuing studies suggest that worms may help to redirect an immune system that has gone awry and resulted in autoimmune disorders, allergies and asthma.

These studies, along with epidemiological observations, seem to explain why immune system disorders like multiple sclerosis, Type 1 diabetes, inflammatory bowel disease, asthma and allergies have risen significantly in the United States and other developed countries.

Training the Immune System

"What a child is doing when he puts things in his mouth is allowing his immune response to explore his environment," Mary Ruebush, a microbiology and immunology instructor, wrote in her new book, "Why Dirt Is Good" (Kaplan). "Not only does this allow for 'practice' of immune responses, which will be necessary for protection, but it also plays a critical role in teaching the immature immune response what is best ignored."

One leading researcher, Dr. Joel V. Weinstock, the director of gastroenterology and hepatology at Tufts Medical Center in Boston, said in an interview that the immune system at birth "is like an unprogrammed computer. It needs instruction."

He said that public health measures like cleaning up contaminated water and food have saved the lives of countless children, but they "also eliminated exposure to many organisms that are probably good for us."

"Children raised in an ultraclean environment," he added, "are not being exposed to organisms that help them develop appropriate immune regulatory circuits."

Studies he has conducted with Dr. David Elliott, a gastroenterologist and immunologist at the University of Iowa, indicate that intestinal worms, which have been all but eliminated in developed countries, are "likely to be the biggest player" in regulating the immune system to respond appropriately, Dr. Elliott said in an interview. He added that bacterial and viral infections seem to influence the immune system in the same way, but not as forcefully.

Most worms are harmless, especially in well-nourished people, Dr. Weinstock said.

"There are very few diseases that people get from worms," he said. "Humans have adapted to the presence of most of them."

Worms for Health

In studies in mice, Dr. Weinstock and Dr. Elliott have used worms to both prevent and reverse autoimmune disease. Dr. Elliott said that in Argentina, researchers found that patients with multiple sclerosis who were infected with the human whipworm had milder cases and fewer flare-ups of their disease over a period of four and a half years. At the University of Wisconsin, Madison, Dr. John Fleming, a neurologist, is testing whether the pig whipworm can temper the effects of multiple sclerosis.

In Gambia, the eradication of worms in some villages led to children's having increased skin reactions to allergens, Dr. Elliott said. And pig whipworms, which reside only briefly in the human intestinal tract, have had "good effects" in treating the inflammatory bowel diseases, Crohn's disease and ulcerative colitis, he said.

How may worms affect the immune system? Dr. Elliott explained that immune regulation is now known to be more complex than scientists thought when the hygiene hypothesis was first introduced by a British epidemiologist, David P. Strachan, in 1989. Dr. Strachan noted an association between large family size and reduced rates of asthma and allergies. Immunologists now recognize a four-point response system of helper T cells: Th 1, Th 2, Th 17 and regulatory T cells. Th 1 inhibits Th 2 and Th 17; Th 2 inhibits Th 1 and Th 17; and regulatory T cells inhibit all three, Dr. Elliott said.

"A lot of inflammatory diseases -- multiple sclerosis, Crohn's disease, ulcerative colitis and asthma -- are due to the activity of Th 17," he explained. "If you infect mice with worms, Th 17 drops dramatically, and the activity of regulatory T cells is augmented."

In answer to the question, "Are we too clean?" Dr. Elliott said: "Dirtiness comes with a price. But cleanliness comes with a price, too. We're not proposing a return to the germ-filled environment of the 1850s. But if we properly understand how organisms in the environment protect us, maybe we can give a vaccine or mimic their effects with some innocuous stimulus."

Wash in Moderation

Dr. Ruebush, the "Why Dirt Is Good" author, does not suggest a return to filth, either. But she correctly points out that bacteria are everywhere: on us, in us and all around us. Most of these micro-organisms cause no problem, and many, like the ones that normally live in the digestive tract and produce life-sustaining nutrients, are essential to good health.

"The typical human probably harbors some 90 trillion microbes," she wrote. "The very fact that you have so many microbes of so many different kinds is what keeps you healthy most of the time."

Dr. Ruebush deplores the current fetish for the hundreds of antibacterial products that convey a false sense of security and may actually foster the development of antibiotic-resistant, disease-causing bacteria. Plain soap and water are all that are needed to become clean, she noted.

"I certainly recommend washing your hands after using the bathroom, before eating, after changing a diaper, before and after handling food," and whenever they're visibly soiled, she wrote. When no running water is available and cleaning hands is essential, she suggests an alcohol-based hand sanitizer.

Dr. Weinstock goes even further. "Children should be allowed to go barefoot in the dirt, play in the dirt, and not have to wash their hands when they come in to eat," he said. He and Dr. Elliott pointed out that children who grow up on farms and are frequently exposed to worms and other organisms from farm animals are much less likely to develop allergies and autoimmune diseases.

Also helpful, he said, is to "let kids have two dogs and a cat," which will expose them to intestinal worms that can promote a healthy immune system.

 

For a bit more info on this topic:

Why You Don't Need Antibacterial Soap

By Tabitha Alterman

If you choose "antibacterial" products because you trust them to kill germs, think again. According to recent studies, antiseptic ingredients added to numerous products are not effective and may actually be harmful.

In 2005, a U.S. Food and Drug Administration (FDA) panel concluded that there is "no added benefit" from using antimicrobial products over plain soap and water. There's also toxicity to consider. Researchers at Johns Hopkins Bloomberg School of Public Health discovered that one of the most popular antimicrobials, the pesticide triclocarban (TCC), defies water treatment methods after we wash our hands of it. Once it's flushed down drains, about 75 percent of TCC makes it through treatments meant to break it down, and it ends up in our surface water and in municipal sludge. This sludge is regularly applied to U.S. crop fields as a fertilizer, meaning the chemical could potentially accumulate in our food, too.

According to Rolf Halden, assistant professor in the Department of Environmental Health Sciences at Johns Hopkins and lead author of the most recent study, TCC contaminates 60 percent of U.S. streams. In addition, he says it is known to cause cancer and reproductive problems in mammals, and blue-baby syndrome in human infants.

Introducing an antimicrobial into the environment in this way also has the unwanted effect of increasing pathogens' resistance to clinically important antibiotics. The antiseptic triclosan -- another popular antimicrobial added to numerous products -- is known to promote the growth of resistant bacteria, including E. coli. In fact, the American Medical Association (AMA) took an official stance in 2000 against adding antimicrobials to consumer products. The AMA has repeatedly urged the FDA to better regulate these chemicals, advising that they should be avoided "until the data emerge to show antimicrobials in consumer products are effective at preventing infection."

Currently, there is no mandatory monitoring of TCC, but approximately 1 million pounds of it are released annually in the United States. Since 2000, about 1,500 new antibacterial products have hit store shelves.

Halden says the irony of his research is two-fold: "First, to protect our health, we mass-produce and use a toxic chemical which the FDA has determined has no scientifically proven benefit. Second, when we try to do the right thing by recycling biosolids, we end up spreading a known reproductive toxicant on the soil where we grow our food." He emphasizes the importance of considering the full life cycle of the chemicals we manufacture.

Antimicrobial Products: Who Needs Them?

Antimicrobial Products: Who Needs Them?

by Philip Dickey

Turn on the TV or read any home-oriented magazine and you'll see them. Ads for all kinds of household products containing germ-killing ingredients are everywhere. Hand soap, dishwashing liquid, underwear, kitchen sponges, toothbrushes, toothpaste, mattresses, cutting boards, window cleaner, socks, cycling shorts, chop sticks, pencils, and now facial tissues are all being marketed for their ability to kill germs. It's been estimated that more than 700 antimicrobial-infused products are now available, including 76% of all liquid soaps. Consumers, driven by frightening stories of E. coli outbreaks, bizarre viruses, and drug-resistant germs are buying this stuff in the hopes that it will keep them safe (or their gym clothes from smelling). Do these products work or not? Does overuse of antimicrobial ingredients help breed super-germs? It's one of the most controversial topics in public health these days. Still, there are some common-sense approaches that most experts agree on.

Disinfectants, Antiseptics, and Antimicrobials
If you are confused by all the names and labels, you're not alone. Antimicrobial is the general term for any product or ingredient that kills or inhibits bacteria, viruses, or molds. Antibacterials, on the other hand, are only effective against bacteria. Until recently, the main kinds of home antimicrobial products were disinfectants and antiseptics. Disinfectants are products that kill micro-organisms (usually both bacteria and viruses) on surfaces like countertops or toilet seats. Antiseptics are products for use on the skin for cuts and scrapes. Now a third class of products is emerging as companies race to put antimicrobial ingredients into all sorts of products that did not used to have them. Most of the soaps and other household objects that boast germ-killing powers contain triclosan, an antibacterial agent that kills bacteria but has little or no effect on viruses. This distinction is important because most common household illnesses like colds and the flu are caused by viruses, so antibacterial ingredients will not prevent them from spreading.

Disinfectants, such as Lysol™ or chlorine bleach, are considered pesticides and are regulated by the EPA. EPA registration is beneficial because it ensures that the product actually does what it claims to do (if used properly). An ineffective disinfectant can be dangerous, since you cannot tell by looking if it is really working.

Personal-care products like hand soaps, toothpaste, and deodorants are regulated fairly loosely by the FDA. Antibacterial cutting boards, socks, sponges, and other goods are regulated by the Consumer Product Safety Commission but the EPA must grant permission for the use of an antimicrobial agent in these products. This chapter does not cover antiseptics or other antimicrobials used for medical purposes. Specific advice on medications should come from your health care provider, but the FDA recommends that homes should have an antiseptic handy just in case.

Antimicrobial Ingredients

Profiles of common ingredients used in antimicrobial products are shown in the sidebar on page 10. Most household disinfectants contain either chlorine bleach, alcohol, quaternary ammonium chlorides (called "quats"), pine oil, or phenolic compounds.    All of these ingredients can cause some health effects, and a disinfectant product is almost always more hazardous than a similar cleaner without the antimicrobial ingredient. Triclosan (5-chloro-2(2,4-dichlorophenoxy)phenol) is the ingredient used in hand soaps and many other household items. Triclosan appears to be low in toxicity, but some people are alarmed by its structural similarities to the herbicide 2,4-D (2,4-dichlorohenoxyacetic acid) and 2,3,7,8-TCDD, the most toxic form of dioxin. They fear that this similarity could give rise to contamination of triclosan with dioxins, since dioxin contamination of 2,4-D and other chlorinated phenolic compounds has occurred. One recent study found that when triclosan in water was exposed to ultraviolet light, a type of dioxin was formed, though not the most toxic form. Concerns have also been raised over the discovery of triclosan in breast milk and the aquatic environment and the possibility that it may be an endocrine disruptor. 

Good Bugs, Bad Bugs
To make sensible decisions about how to control micro-organisms, you need to know something about them. Some very nasty diseases are caused by bacteria and viruses, but most of the microbes around us are harmless and some are beneficial or necessary. Beneficial microbes found in the soil release nutrients for plants. Without the useful bacteria in our digestive tract, we wouldn't have the vitamin K that is needed for our blood to clot and stop bleeding when we are cut. Without bacteria, we wouldn't have wine, yogurt, blue cheese, soy sauce, or sourdough bread. What kind of world would that be?

What we need to do is protect the beneficial microbes and kill the bad ones when they threaten to spread disease. As Dr. Stuart Levy from the Tufts University School of Medicine has pointed out, this doesn't mean that we need to be at war with the microbial world. In fact, there is considerable evidence that some exposure to bacteria in the environment is actually beneficial because it helps the immune system develop. Some studies have shown an increase in allergies and asthma in people who were raised in an overly sterile environment. At this point it's only a hypothesis, but it may be that too much hygiene in the form of indiscriminant disinfection is harmful.

Where are the bad bugs most likely to be found? In the kitchen, it turns out. Surprisingly, kitchens often harbor more nasty germs than bathrooms do. That doesn't mean you should eat your meals in the bathroom, but you should give some thought to your kitchen practices. More about that later.

Super Bugs
Many public-health professionals fear that too much use of antimicrobials, especially in the uncontrolled home environment, may result in germs resistant to these chemicals. Resistance is a serious problem with antibiotics (drugs) that has arisen in part because of improper use of antibiotics by patients. Triclosan is thought  to cause a similar resistance to develop because its mechanism of action is very specific and its use is becoming so widespread. In fact, resistance to triclosan has already been observed in the laboratory. (Chlorine bleach and alcohol do not cause resistance because they are so destructive to the cells.)

The concept is easy to understand. If a product doesn't kill all the germs, it's the susceptible ones that get killed first, leaving the hardier ones behind. These can multiply and eventually outnumber the susceptible bugs. The Council on Scientific Affairs of the American Medical Association concluded in 2000 that the use in consumer products of antimicrobials in which resistance has been seen should be discontinued unless data can conclusively show that this resistance has no impact on public health and that such products actually prevent infection.

Do You Really Need an Antimicrobial?
As a consumer, this is the question you need to ask. First of all, let's begin by dispelling the myth that you can have a germ-free home. You cannot maintain a sterile home environment with normal efforts. Disinfectants kill germs on surfaces temporarily, but cannot provide long-lasting disinfection. There are a few situations where disinfectants may occasionally be needed, but there are many others where they aren't. Disinfecting the toilet bowl is surely an exercise in futility. Another one is using a spray disinfectant as a room deodorizer. You can't disinfect the air this way. If something smells funny, find the source and clean it up. Some people use pine oil or other disinfectants just because the smell makes them feel comfortable that things are clean. It's hard to change old habits, but if you spend much time outdoors, you know that clean air doesn't smell like a disinfectant.

Disinfectants used to be routinely recommended for cleaning up mold or mildew. However, thinking on this is changing, and many experts no longer recommend disinfecting for this purpose. Bleach requires a long contact time and usually makes materials wetter, which can actually encourage mold growth. The most important thing is to find and correct the source of that problem, usually a leak or ventilation problem, and replace damaged materials. Wet building materials and furnishings must be dried within 24-48 hours. Once surfaces are kept dry, the mold cannot grow.

When might you really need a disinfectant? One example is to clean up a sewer overflow in the basement. Another case is special health problems in the home that involve highly susceptible individuals or require cleaning up contaminated material. If such conditions exist, consult your physician for advice. For most other home uses, simple cleaning with soap or detergent and clean water should suffice if done frequently and thoroughly. In the kitchen, however, there is no margin for error.

If you cut meat, poultry, or fish, you must address the issue of possible contamination of the cutting board. Whether you use a disinfectant to do that is a personal choice. Another method is to use a separate cutting board for these foods and clean it thoroughly after each use, preferably in a dishwasher. Never use that cutting board for foods that will be eaten raw, and never use the same knife without first washing it. Can a treated cutting board or a dishwashing liquid with triclosan protect you? Treated cutting boards (and other kitchen objects) are required to carry a warning stating "This product does not protect users or others against food-born bacteria." Doesn't exactly inspire confidence. It's better to have two cutting boards. Plastic or other non-wood boards can go in the dishwasher, and can also be disinfected with a bleach solution, but microwaving them does nothing. Wooden boards, on the other hand, can be microwaved (if they are small enough), but they cannot be disinfected with bleach because the bleach reacts with the wood and loses its potency. My choice: wood for vegetables, non-wood for meat, and the kitchen sponge never touches the board used for meat.

Speaking of sponges, kitchen sponges and dishrags are among the most bacteria-laden places in your whole house. An alternative to treated sponges is to replace sponges often, wring them out after use, and avoid cross-contamination. I like the idea someone suggested to me of using a new sponge in the kitchen for a week, then cutting off one corner and relegating it to non-food use. Finally, when two corners have been cut off, you can clean the toilet seat with it. Another common suggestion is to microwave sponges for a minute or two to disinfect them. Good idea, but avoid any cold spots in your oven. Cook's Illustrated magazine (Jan/Feb 2003) found that boiling a sponge for three minutes followed by microwaving  reduced the bacteria count the most and was twice as effective as soaking in a bleach solution. Surprisingly, putting the sponge through the dishwasher was much less effective. Any of these practices was far better than simply washing the sponge in soap and hot water.

Triclosan is an antibacterial agent only and has little effect against virus-borne illness, so don't expect your treated hand soap to protect you from colds or the flu any more than ordinary soap does. A study of 238 households in Manhattan found that there was no significant difference between routine health symptoms in households using antibacterial products for cleaning, laundry, and hand washing and households using nonantibacterial products.

Use of triclosan in toothpaste is primarily intended to control gingivitis, swollen or bleeding gums resulting from bacteria and tartar. I'd suggest talking to your dentist. And treated socks or underwear? The idea here is to prevent (actually delay is closer to the truth) the formation of odors. You can wear them for weeks. Give me a break--even if it works it's still disgusting. Throw them in the wash.

All antimicrobials require a certain concentration and contact time to be effective.  If directions are not followed exactly, the product may not function as intended. For example, chlorine bleach requires about 30 minutes of contact time to kill bacteria and is not effective if the surface is dirty--it must be cleaned first, then disinfected. The worst possible situation is to have consumers using disinfectants and antimicrobials when they aren't really needed, and then using them incorrectly on top of that. The proliferation of germicidal products can foster a false sense of security based on unrealistic expectations, such as thinking that antibacterials kill viruses.

Scientists are divided as to the extent that disinfectants and antimicrobial products are routinely needed in the home, as well as whether the huge increase in triclosan use represents a threat of bacterial resistance. I prefer to trust the conclusions of government or independent researchers who don't have a financial interest in the results. If you are interested, look at the articles listed in the box below entitled "For More Information." A more complete list of references is available on request.

Alternative Antimicrobials
A number of common household substances like vinegar and borax are often suggested in books and articles as "alternative" disinfectants, "non-toxic" disinfectants, or "mild" (do they mean ineffective?) disinfectants. Beware. Neither of these substances is registered as a disinfectant with the EPA. Although I have seen vague references to proof of their effectiveness, I have never been able to track these references down, and there are a number of published studies indicating the contrary. Use them as cleaners if you like, but don't depend on them to disinfect.

Similarly, several plant oils (tea tree oil, grapefruit seed extract) are often described as disinfectants, and there are some commercial products based on these ingredients. Unless you find an EPA registration number on the bottle, do not assume that these products can disinfect household surfaces. There is a registered product based on thymol (from thyme oil) as an active ingredient: Sol-U-Guard™ by Melaleuca.

Hydrogen peroxide actually can be a disinfectant, and a number of products based on it exist, though most are not available to consumers. One that you can buy is H2Orange2, a combination of hydrogen peroxide and orange oil. H2Orange2 is a low-toxicity product, but citrus oils may not be acceptable to some people with chemical sensitivities. I believe that hydrogen peroxide is one of the safest disinfectants available, provided the concentration is not more than about 3%, what you can buy as an over-the-counter antiseptic. (Note: concentrated hydrogen peroxide is a potent oxidizer and is extremely dangerous!) Can you use ordinary hydrogen peroxide from the medicine cabinet as a disinfectant? I'd advise against it, since you don't have any label instructions for that use. Better to stick with a registered product.

 

Is Our Fear of Germs Bad for Our Health?

By Stan Cox, AlterNet
Posted on February 2, 2008, Printed on February 2, 2008
http://www.alternet.org/story/75333/

The "vomiting virus" now sweeping across Britain may be headed our way. At the same time, San Francisco is being hit with a new strain of the nasty bacterium known as MRSA (methicillin resistant Staphylococcus aureus) -- this one responsible for "flesh-eating pneumonia."

Meanwhile, four patients were recently isolated in the University of Maryland Medical Center, infected with a multidrug resistant bacterium called Acinetobacter baumannii, which has attacked a number of Afghanistan war veterans. As one doctor said of the that bug, "When these people get infected ... you sort of say this is the last straw."

Those new menaces, and more, are joining the usual biological villains that lurk everywhere in midwinter.

Even more than in past years, we're turning to the chemical industry for help in fortifying the American home against microbial invasion. Few go as far as Jacques Niemand, a reclusive Briton who was killed last May by fumes rising from vast quantities of disinfectant that he kept in open buckets around his house to ward off infection. But lower-intensity chemical warfare on our invisible housemates is in full swing.

Many hospital patients and people with compromised immune systems depend for their very survival on large quantities of not-entirely-benign antimicrobial products. However, there appears to be widespread scientific consensus that for most routine home uses, thorough washing with soap provides sufficient protection.

In domestic use, there's the possibility that some antimicrobial products could induce disease-causing bacteria to evolve antibiotic resistance. Then, as they flow down the drain into sewers and beyond, significant tonnages can accumulate in the tissues of wildlife and people with potentially toxic consequences. And it could be that dramatic increases in asthma and allergy rates are related to immune-system distortion that comes from living in microbe-poor bubbles.

Homeland sterility enforcement

Brian Sansoni, vice president for communication and membership with the Soap and Detergent Association, cites a body of research showing that antibacterial soaps reduce the numbers of harmful bacteria on the skin or other surfaces and are especially useful when you're caring for elderly or immunosuppressed people, dealing with an infectious illness in the house, or preparing food.

"The bottom line," says Sansoni, "is that consumers can continue to safely use antibacterial soaps and hygiene products with confidence - as they already do in homes, schools, offices, hospitals and health care centers, day care centers and nursing homes - every single day."

Among family members who do most of the housecleaning, 71 percent say they prefer to use antibacterial products when available. And germ-killing products are more widely available than ever. As of 2001, 76 percent of liquid hand soaps and 29 percent of bar soaps contained antibacterial chemicals. Mintel's Global New Products Database has seen introductions of new antimicrobial products grow from fewer than 200 in 2003 to more than 1600 last year.

Once you've strategically placed chemical hand cleaners in the kitchen, bedroom, car, and office, you can stock up on antimicrobial toothpaste, cosmetics, kitchen counter wipes, cutting boards, knives, chopsticks, dishrags, gloves, underwear, bath towels, computer keyboards, toys, dog ear wipes, laundry detergent, and paint. The Amana Corporation is promoting a washing machine whose drum is impregnated with an antimicrobial chemical, and several manufacturers offer vacuum cleaners that are chemically resistant to bacteria or bathe your carpet in germ-killing ultraviolet light. And, if you're intent on leaving no bug unturned, you can subscribe to an antibacterial garbage can-cleaning service.

The Environmental Protection Agency (EPA) has registered 8,000 disinfectant products to date. That's required, because the law says they're pesticides. Whether it's referred to as "disinfectant" or "antibacterial" or "antimicrobial" or even the somewhat disturbing term "biocidal," each compound kills a range or organisms -- bacteria, fungi, yeast, or even the viruses that cause colds and flu -- but none fully eradicates them.

The most popular of these weapons are still products of pre-1970 "better living through chemistry." There are standbys like ammonia, pine oil, and chlorine bleach, as well as types of germ-killing super-detergents called quaternary ammonium compounds; most prominent in that latter class is benzalkonium chloride, the active ingredient in many disinfectant wipes and sprays.

The compound drawing the most recent attention has been triclosan, along with its cousin triclocarban. Those chemicals, 1960s-era spinoffs from weed-killer research, are considered safe enough to come into very close contact with the human body: in food preparation, bathing, and even for cleaning sex toys.

Chemical weapons can backfire

Triclosan regularly makes the news because of suspicions that it might select for populations of bacteria resistant to pharmaceutical antibiotics. That's because triclosan and some antibiotic drugs attack bacteria through similar mechanisms, and resistant bacteria use similar means to rid themselves of both types of (what are to them) toxins.

A 2003 study funded by Proctor & Gamble Company allayed concerns about washing dishes with antibacterial detergent, finding that genetic resistance did not increase in bacterial cultures exposed to triclosan for several months. At the time the paper was published, one of its authors, a scientist at a British university, told the press that Proctor & Gamble "does not produce a liquid dishwashing detergent that contains triclosan" -- implying that the company therefore had no conflict of interest. P&G did, however, make a range of other products containing the chemical, and soon after, began marketing triclosan-fortified dishwashing liquids as well.

An independent 2004 evaluation of bacterial cultures collected from hands in more than 200 upper-Manhattan households did not find a relationship between resistance to triclosan and resistance to antibiotics (pdf). The lead author on that study was Dr. Allison Aiello, now assistant professor of epidemiology at the University of Michigan. She believes too little research that has been done to date, and much of what has been done was funded by industry.

Says Aiello, "There is still a big gap in surveillance and research on the ground." Now that lab research has made clearer the potential mechanisms by which triclosan might help breed bacteria resistant to clinical antibiotics, she says, "We need rigorous, independent, long-term studies on household use to fill the gaps in our knowledge."

Brian Sansoni also welcomes more research, but he says it shouldn't matter who pays for it: "The fact is, it's industry's responsibility to undertake and/or fund research on the ingredients they produce or are used in their products. It's a part of good product stewardship."

Back in the laboratory, there are hints of trouble. Research has shown, for example, that lab-selected strains of the disease-causing bacteria Salmonella enterica and Escherichia coli O157 resistant to triclosan or benzalkonium chloride also showed increased resistance to antibiotic drugs. Such "cross resistance" has been associated with use of other disinfectants as well, including pine oil, which is the natural active ingredient of Pine Sol.

Aiello points to another potential worry: "The triclosan concentrations used in medical settings are quite high, and are effective. But my work shows that the concentration in household soaps and detergents [only a tenth to a half of one percent, which is diluted further in cleaning] is too low to be very effective in reducing illness." On the other hand, she says, that lighter exposure may be just right for leaving behind genetically adapted bacteria.

To Sansoni, the threat of bacterial resistance is "suburban mythology." Pointing to the research of Aiello and others, he says, "The studies and the research to-date have shown there is no real world evidence linking the use of antibacterial products to antibiotic resistance."

"It is a shame," he adds, "that a few loud voices are trying to equate use of antibacterial products in the same breath with the known contributor to the antibiotic resistance problem: the over-prescription of antibiotic drugs by the medical community. It's like trying to compare an anthill to Mount Everest."

The associate director of the Clinical Microbiology Laboratory at the University of Nebraska Medical Center in Omaha, Dr. Paul Fey, says he would be concerned if, as some studies indicate, the molecular "pumps" that resistant bacteria use to rid themselves of triclosan could also flush out medically important antibiotics. "That's another good reason why triclosan and other antibiotics should not be used in soaps, plastics, etc. And it's unnecessary. Plain soap itself is one of the best antimicrobials there is."

Sansoni cites an issue brief his group provided a US Food and Drug Administration (FDA) advisory committee in 2005, describing the benefits of antimicrobial bars, liquids, gels and wipes. In the end, that committee issued a nonbinding statement saying that in routine use, antibacterial soaps are no better at fending off illness than is regular soap, and that they might contribute to antibiotic resistance in bacteria. FDA took no action in response to the panel's recommendation.

Beyond the kitchen sink

Proctor & Gamble Company scientists have published studies showing that sewage treatment can break down triclosan. But, says Dr. Rebecca Sutton, staff scientist at the Oakland, Calif. office of the Environmental Working Group (EWG), "Our current water-treatment processes are not designed to deal with it, and they aren't dealing with it." She points to numerous studies finding triclosan and triclocarban througout the environment, including the waters of San Francisco Bay.

The US Geological Survey reported in 2002 on a wide range of potential pollutants found in stream across the country. Triclosan was identified in 58 percent of the samples. Out of 95 chemicals surveyed, triclosan was one of the most commonly detected, outstripped by only three others: caffeine, cholesterol, and a metabolite of nicotine.

As far back as 1998, the people of Sweden were spitting out two tons of triclosan per year in their antibacterial toothpastes alone. In 2002, the chemical was detected in the country's municipal wastewaters, fish, and human breast milk.

Triclocarban, of which 1.7 million pounds are produced in the US each year -- check that rusty orange label on your bar soap -- was found at high levels downstream from three sewage-treatment plants out of nine surveyed across nine states. But it was in the treated solids -- sludge -- where the chemical built up to more than a million times the concentration flowing into the plants.

Triclosan behaves similarly. Speaking to Scientific American, Rolf Halden of the Johns Hopkins Bloomberg School of Public Health explained that their buildup in bacteria-laden sewage solids is of particular concern because sludge is used to fertilize food crops. That, he said, "could be a recipe for breeding antimicrobial resistance."

And along with resistant bacteria, there are the prospects of dead algae, ailing fish and amphibians, and even sick humans. In a 2003 Japanese study, triclosan was acutely toxic to very young fish and caused liver damage in older males. And triclocarban can amplify the action of testosterone in humans and rats.

In other recent experiments, triclosan disrupted the functioning of frogs' thyroid glands. That is especially worrisome, says Sutton, because "the effects occurred even at concentrations less that are found in many of the country's streams, and the human and frog thyroid systems are very similar."

The Fear Factor

To declare war on household bacteria is to lose -- inevitably. You've probably seen the slogan many times on Lysol products (manufactured by Reckitt Benckiser PLC): "Kills 99.9% of germs in 30 seconds." And who's to doubt it? But under good conditions, the much-feared bacterium Staphylococcus aureus, for example, doubles its numbers every 30 minutes through cell division. So once the Lysol has worn off and the surviving bacteria go back to multiplying, the population could grow to its pre-Lysol size in as little as 5 hours.

Rather than stockpile buckets of disinfectant and spray every surface in the house every few hours, most independent researchers recommend that we settle for a stalemate in the war on microbes. But the home-products industry has other ideas.

Along with nursing and family groups, Clorox cosponsors a "Say Boo to the Flu" campaign, which, along with videos on handwashing and vaccination, features microbiologist Dr. Kelly Reynolds of the University of Arizona advising parents to be sure the cleaning products they buy are labeled "disinfecting" or that they contain chlorine bleach or quaternary ammonium compounds -- both of which are made by Clorox.

(A well-publicized 2002 study conducted by Dr. Reynolds's Arizona colleagues -- and funded by Clorox -- found that the average office desk is populated with 400 times as many bacteria as the average toilet seat. That sounds terrifying until you remember that neither desks nor toilet seats are significant causes of any kind of illness.)

WebMD's Flu Prevention page, sponsored by Lysol, features straightforward articles like one on the universally recommended practice of handwashing with plain soap and water. Alongside that are "Flu tips for parents," in which a Dr. Jim Sears recommends that "one of the most important ways to protect your family and stop viruses dead in their tracks is to disinfect commonly touched surfaces with a disinfectant spray or wipe, such as those made by Lysol®."

The Dial Corporation, which kicked off combat against skin-borne microbes with a deodorant in the 1940s, boosted sales of its antibacterial soaps in 2003 with a series of less-than-subtle TV ads. Featuring a range of scenarios -- a kid urinating in a swimming pool, a man using someone else's sweat-drenched towel in a gym, a nudist group riding a bus -- the commercials fed buyers' germ-phobia.

One of the company's vice presidents told USA Today, "We had been talking to focus groups, and consumers were coming back and saying, 'I'm clean enough.' We were stuck with this dilemma. But we turned it around and came up with [the ads'] premise: 'You're not as clean as you think you are.'"

Antibacterial compounds in bar soap or shoe insoles are there to make you smell better, not to keep you healthy. Used in mop handles, computer mouses, or telephones, they are intended to protect the object, not you, against degradation by run-of-the-mill bacteria and fungi. And bathing with antibacterial soap offers no protection when you swallow pee-laced pool-water.

But paranoia sells.

The Reactionary Principle

A commentary last year in the journal Occupational and Environmental Medicine urged adoption of the well-known "Precautionary Principle" -- that when a substance or technology is suspected of being harmful, "precautionary measures should be taken even if some cause and effect relationships are not fully established scientifically." Instead, said the article, current research operates under the "Reactionary Principle." The author explained:

Under this system, anyone is free to introduce a new hazard into the environment, and governments must wait until an overwhelming body of evidence is accumulated before intervening. Each new regulatory action is challenged with the objective of slowing down or stopping public oversight ... We can see reactionary principle inaction in the unconscionable delays in regulating a long list of hazards whose risks were clear long before effective actions were taken to control them: asbestos, benzene, dioxins and PCBs. While these are "old" hazards, a reactionary approach is evident as well in many current controversies in our field, including the potential health risks from hexavalent chromium, artificial butter flavouring, and the antimicrobial agent triclosan.

Even if, displaying full trust in the safety of antimicrobials, you could manage to eliminate those 99.9 perecent of bacteria and viruses from your doorknobs, your computer keyboard, and the change in your pocket, you would still be carrying in and on yourself a community of microorganisms outnumbering -- ten times over -- the cells of your own body. Almost all of those creatures are either neutral or beneficial to you.

But the modern arsenal of purifying products, including not only disinfectants but also regular detergents, medications, vegetable washes, ozone blowers, ultraviolet gizmos, filtered and bottled drinking water, air conditioning, and year-round-sealed windows may be reducing contact between people -- especially children -- and organisms with which we've evolved and which our bodies need for healthy development. Not being "smart weapons", antimicrobial products can wreak collateral damage on harmless and friendly microbes.

The now 30-year-old "hygiene hypothesis" says that skyrocketing rates of allergy and asthma in Western societies may result from human immune systems being driven haywire by excessively sterile home environments. It's a hard thing to demonstrate, the biological mechanisms are highly complex, and there are still plenty of doubters, but patterns continue to fit fairly well. (For an excellent discussion of the hypothesis, see Garry Hamilton's 2005 article in the British magazine New Scientist. Unfortunately, it's not free online).

"We have to find a healthy balance in hygiene," says Allison Aiello. "For example, right now on your hands there are millions of beneficial Staphylococcus bacteria that help maintain the health of your skin." In fact, in her work she has seen disease-conscious people scrub their hands too enthusiastically, creating dry-skin cracks that other, more dangerous bacterial species can infect.

To Paul Fey, putting antimicrobial chemicals into cleaners and toys is "just crazy -- The only reason it's there is to keep parents from worrying." But, he thinks, maybe it's the products themselves they should be worrying about: "This constant search for a totally sterile environment may be hurting our health, and especially children's health."

Stan Cox is a plant breeder and writer in Salina, Kansas. His book, Sick Planet: Corporate Food and Medicine, will be published by Pluto Press in April.

Posted by Saor Stetler on January 27