Too Much of a Good Thing?
n our complex world, the solution to one challenge may inadvertently lead to the creation of another. Scientists have long been pursuing less toxic alternatives to many traditional biocidal chemicals. For example, glutaraldehyde has now largely replaced the more toxic formaldehyde, chlorhexidine is generally used in place of hexachlorophene, and gaseous alternatives to ethylene oxide are now being sought. Meanwhile, ozone and hydrogen peroxide, which are both readily biodegradable, may eventually replace glutaraldehyde. While these less toxic alternatives are better for human health and the environment, their widespread acceptance and use may be unwittingly contributing to an additional problem—the overuse and misuse of germicidal chemicals. Many products, including soaps, toothbrushes, and even clothing and toys are marketed with the claim of containing antimicrobial ingredients. Already there are reports of bacterial resistance to some of the chemicals included in these products.
The issues surrounding the excessive use of antimicrobial chemicals are complicated. On the one hand, there is no question that some microorganisms cause disease. Even those that are not harmful to human health can be troublesome because they produce metabolic end products that ruin the quality of perishable products. Based on that information, it seems prudent to destroy or inhibit the growth of microorganisms whenever possible. The role
of microorganisms in our life, however, is not that simple. Our bodies actually harbor a greater number of microbial cells than human cells, and this normal microbial flora plays an important role in maintaining our health. Excessive use of antiseptics or other antimicrobials may actually predispose a person to infection by damaging the normal flora.
An even more worrisome concern is that overuse of disinfectants and other germicidal chemicals will select for microorganisms that are more resistant to those chemicals, a situation analogous to our current problems with antibiotic resistance. By using antimicrobial chemicals indiscriminately, we may eventually make these useful tools obsolete. Excessive use of disinfectants may even be contributing to the problems of antibiotic resistance. Early indications suggest that disinfectant-resistant bacteria overproduce efflux pumps that expel otherwise damaging chemicals, including antibiotics, from the cell. Thus, by overusing disinfectants, we may be inadvertently increasing antibiotic resistance.
Another concern is over the misguided belief that "nontoxic" or "biodegradable" chemicals cause no harm, and the common notion that "if a little is good, more is even better." For example, concentrated solutions of hydrogen peroxide, though biodegradable, can cause serious damage, even death, when used improperly. Other chemicals, such as chlorhexidine, can elicit severe allergic reactions in some people.
As less toxic germicidal chemicals are developed, people must be educated on the appropriate use of these alternatives.
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