Anti-bacterial Cleaners

November 1, 2001

Killing germs at what cost?

By Susana Hsu
shsu@uwo.ca

E vil disease causing bacteria are lurking everywhere in your home just waiting to infect you. That's the message many advertisers are sending us. It seems like everyday there is a new product that will save your family from sickness. Everything from hand lotions, to kitchen cleaners, and even toys and mattresses come in anti-bacterial forms.

But there are those in the scientific community who think that anti-bacterial products are ineffective and may even be doing more harm than good.

Photo by Susana Hsu

Widespread use of antibacterial products may lead to emergence of bacteria resistant to antibiotics.

In a world of E. coli outbreaks and anthrax scares, Canadians are worried, especially about their food supply. In a recent survey, 74 per cent of Canadians said that they are concerned about food safety and manufacturers have been cashing in on our fears of germs and infection. Anti-bacterial soaps account for 75 per cent of all liquid hand soaps and 29 per cent of all bar soaps available on the market, according to a 2000 American survey.

It all looks so easy, just spray on the new anti-bacterial cleaner and wipe away the germs. But such germ killers may not be as effective as they claim. Many anti-bacterial cleaners advertise that they kill 99.99 per cent of bacteria but according to Dr. Gavin Clark, professor of microbiology at the University of Toronto, that figure is not as remarkable as it seems.

"The figure looks really impressive but bacterial numbers are always so high, it's not a great reduction," he said.

It is not unusual to have bacterial concentrations of 100 million per square centimetre, and a 99.99 per cent kill would still leave 10,000 bacteria per square centimetre. Since bacteria can reproduce in as little as 20 minutes, depending on the environment, the population could recover in a very short period of time. Moreover, the fine print on many of these products says that in order to disinfect the surface as advertised, these cleaners must have contact with the surface for 10 minutes.

"The efficiency of kill depends on the concentration used and the time of exposure," said Clark. But a 1998 survey by the Soap and Detergent Association, a non-profit trade association representing more than 100 North American manufacturers, found that two-thirds of adults do not understand that disinfectants must stand for a certain period of time to work.

Dr. Gregor Reid, a professor of Microbiology and Immunology at the University of Western Ontario, thinks that the marketing campaigns for anti-bacterial products have caused people to acquire the wrong attitude towards bacteria. "We have developed this idea that all bacteria are bad when in fact that is not at all the case. There is only a small proportion of bacteria that are bad. People should not equate bacteria with things that are harmful to us," he said.

Clark believes that the public's fears about bacteria have contributed to the current paranoia over anthrax. "The anti-microbial kitchen stuff has just set a groundwork for the present anthrax scare to get worse than it should be. Everyone has been hyper sensitized to bacteria because of this kind of thing and it's unnecessary," he said.

Apart from not being very effective, the cleaners may also contribute to the development of bacteria resistant to existing antibiotics. One of the most common anti-bacterial agents used in such products is a compound called triclosan. Researchers have found that it is possible for E. coli bacteria to develop resistance to triclosan and once bacteria are resistant to triclosan they also become resistant to other antibiotics. "It does increase the resistance of the organism to a number of antibiotics and that is the danger of this perpetual exposure to low levels of antibiotics," said Clark.

However, the industry denies that anti-bacterial products contribute to antibiotic resistance. "It is the over-prescription of drugs - and their misuse by patients - that are the key reasons for the emergence of antibiotic resistance," the Soap and Detergent Association's web site states.

Photo by Susana Hsu

Soap and hot water are enough to kill bacteria and keep homes clean.

The American Academy of Dermatology has also expressed concerns over the use of antibiotic soaps by people with sensitive skin. If used on sensitive skin or overused, these soaps can over-dry the hands and cause cracks to form in the skin, creating a space where micro-organisms can invade and cause infection, eventually leading to a skin condition called dermatitis.

Some of the largest consumers of anti-bacterial products are parents who worry about the health of their children. "My daughter who's five goes to kindergarten and I find that she catches a lot of colds and things, so when she comes home I wash her hands with anti-bacterial soap," said Tracey Sirois, a London mother of two. However, most parents don't realize that anti-bacterial soaps and cleaners are useless against the flu and the common cold since they are caused by viruses and not bacteria.

In fact, the widespread use of anti-bacterial products may actually be doing their children more harm than good. At the 2000 International Conference on Emerging Infectious Diseases, scientists revealed that children who do not get enough exposure to bacteria have higher frequencies of allergies, asthma, and eczema (a skin condition). Dr. Stuart Levy, a microbiologist at Tufts University, cited a study that showed that children who grew up on farms had fewer allergies than their urban counterparts. According to Levy, the immune system needs to be exercised to develop properly and excessive hygiene prevents the child's immune system from having enough stimulation to mature properly.

According to Reid many people's fears about bacteria are unfounded. "They're taking this concept of killing bacteria to totally ridiculous levels. I mean I've seen an ad on television where this person sprays their bed sheets to kill all the bacteria on it. It's totally over the top in my view. What bacteria are they killing and why are they killing it?" he asked.

So if anti-bacterial cleaners are unnecessary in our homes, what is the best way to keep our homes clean while still leaving enough naturally beneficial bacteria behind? Clark has this advice: "Soap and hot water are as good as anything else."

More information on keeping homes clean can be found at
Council of American Pathologists