Be warned! The food, cosmetic, and pharmaceutical industries commonly use an industrial solvent that remains in the final product. Used as a fire retardant, stain remover, and antifreeze ingredient, it cannot be removed from fruits or vegetables by washing. It is always found in malignant tumors, and is responsible for thousands of deaths every year through inhalation. Surveys show that people become quite indignant when informed of the widespread use of this chemical, and are quite willing to sign petitions to have it banned. But banning dihydrogen monoxide would certainly not improve our life. Water is hardly a poison! Yet everything I said is true, including the thousands of deaths every year through inhalation, perhaps better described as “drowning.”
It is obviously easy to conjure up scary scenarios that will alarm people by using scientific lingo selectively and inappropriately. Numerous publications and Web sites do this as they warn us about hazardous chemicals found in our foods, cosmetics, and cleaning agents. We’re told that parabens, commonly used preservatives in cosmetics, are “estrogen mimics,” that polyethylene glycol, used as a thickener in shaving cream and as an emollient in skin lotions, may be contaminated by 1,4-dioxane, a known carcinogen, and that all perfumes contain toluene, which can cause liver, kidney, and brain damage.
All of these statements are technically correct, but their practical relevance is highly suspect. Remember that the pivotal credo of toxicology, first voiced by Paracelsus in the sixteenth century, is that “only the dose makes the poison!” Yes, perfumes do contain toluene, but in amounts that are way below levels that cause any effect. Evidence for the presence of a substance is not evidence of harm. After all, we don’t avoid apples even though their seeds harbor the deadly toxin cyanide, we happily eat strawberries although they contain acetone, a known neurotoxin, and we are not deterred from toast by the presence of 3,4-benzopyrene, an established carcinogen. The toxic properties of these chemicals are indeed real. When test animals are exposed to high doses of acetone or 1,4-dioxane, they certainly do show neurological damage and tumor growth. But that doesn’t mean small doses in humans over a longer time will have a similar effect. In fact, they may have a significantly different effect.
Buckle your seatbelts, because we are going on a bumpy ride. We are going to rattle some of the basic tenets of toxicology. Not only may tiny doses of toxins not be dangerous, they may actually be good for us! Admittedly, that sounds outrageous. So let’s set the stage for an exploration of a revolutionary concept known as “hormesis,” the notion that small doses of toxins can be healthful. Actually, this may not be quite as surprising as it first appears. Vitamin D is certainly healthy in small doses, but large doses can be lethal. A glass of red wine a day may prolong health, but a bottle a day increases the risk of various cancers. Is it possible, then, that exposure to tiny doses of really toxic substances, such as dioxins or pesticides, may actually lead to a better-functioning immune system? Ed Calabrese, professor of toxicology at the University of Massachusetts, thinks this is a real possibility. And he is no academic slouch. Dr. Calabrese has published over 500 research papers and is recognized as the world authority on exposure to trace chemicals.
Calabrese originally got interested in low-dose toxins when, as an undergraduate, he became involved in a project to investigate the amount of herbicide needed to stunt the growth of peppermint plants. Much to his surprise, the plants grew taller when sprayed with the chemical. It turned out that the solution had been improperly prepared and was far more dilute than intended. Years later, at a conference on radiation, Calabrese was reminded of his peppermint plants when he learned that studies had shown people exposed to low-level radiation lived longer and had lower cancer rates. He then began to scour the scientific literature for other such effects and came up with almost 6,000 publications that had documented dramatically different effects at very low concentrations of toxins when compared with those seen at higher doses. Rats exposed to traces of the insecticide DDT, or the treacherous pollutant dioxin, developed fewer liver tumors than unexposed rats. Bacteria frolicked when treated with trace amounts of antibiotics.
Hormesis (from the Greek “to excite”) is still controversial, because if such effects are real, we may have to reevaluate our exposure standards for contamination of air, water, food, and soil by certain chemicals. It does, however, make biological sense. When attacked by poisons, an organism responds by unleashing a variety of molecules, mostly enzymes, which attempt to repair the damage. If the amount of toxin is minute, there may be an overreaction, with more defense chemicals being churned out than are needed, leaving an excess to deal with the molecular insults of everyday life. It may yet turn out that the apocalyptics who warn us of the perils of exposure to parts per trillion of “toxic” chemicals are on the wrong track. Of course, nobody is suggesting doping our bodies with traces of DDT or dioxin, but accumulating information suggests that the paranoia about trace amounts of toxins in our environment is unjustified.
And just to show you how far irrational chemophobia can spread, the city of Aliso Viejo, California, nearly banned Styrofoam cups when a paralegal working for the City Council chanced upon a “professional looking” Web site that listed the evils of dihydrogen monoxide and described its use in the production of Styrofoam. The council was ready to ban Styrofoam—that is, until someone pointed out that the evil chemical was just water.