This news ought to delight all the five-year-olds who hate taking baths: it looks like we're too clean.
Scientists are puzzled by the sudden rise in the incidence of allergies and asthma in developed countries. Their list of possible culprits reads like a litany of modern ills: pollution, tobacco smoke, household cleaning products, too much junk food, too few siblings, too many vaccines, and on and on. They haven't yet blamed too much television, but that's probably next on the list of suspects. And it's not only children who are having problems; adults are suddenly becoming allergic to substances that they've lived with or eaten all their lives.
Dirt, Dirt, Dirt
One recent study looked at medical records for nearly 25,000 children born in Britain between 1988 and 1999. It showed that if a woman used antibiotics, the chances of her child having asthma rose by 31 percent. If she took two or more courses of antibiotics, her child had a 60 percent greater chance of being asthmatic. Of course the study doesn't tell us whether the increased risk of asthma was due to taking antibiotics or due to the infection that led to antibiotic use. And because the most common ailments among the group were respiratory, it's also possible that heredity may have played a role. The antibiotic users themselves may have had a greater than normal incidence of asthma and passed their susceptibility on to their children.
Some scientists think that children are becoming asthmatic because they no longer get the measles. Nowadays childhood illnesses such as chicken pox, mumps, measles, and rubella are going the way of polio and are being eradicated by vaccine. But the scientists say that our immune systems are strengthened by having to fight off diseases and that children who escaped the fate of their unvaccinated parents are now prey to other ills.
Yet another theory holds our clean-livin' lifestyles partly to blame. Improved public health and hygiene have eliminated and curbed many diseases, but they may have inadvertently increased the prevalence of allergies and other immune system disorders. Studies have found fewer allergies among pet owners and rural farm dwellers, who presumably are exposed to a host of animal cooties1. Scientists think that living with critters and their messes boosts the immune system, thereby making a person less susceptible to allergies.
John Wesley2 must be rolling in his grave. In the United States we're bombarded with advertisements for a host of products, all designed to clean up and improve the unwashed masses. If you took the ads seriously, you'd think that a human being is a walking plague that smells bad and is morally suspect, not to mention unappealing to the opposite sex. Cleanliness, both spiritual and physical, is equated with virtue, rectitude, and a distinct attitude of social superiority3.
The notion of dirt being good for us is downright alarming to those of us brought up to associate cleanliness with all things right and proper. On the other hand, it's welcome news to those who are allergic to housework and think that a little clutter is good for the soul.
'Cleanliness is not next to godliness. In my house, it's next to impossible.'
Which is just as well because all that cleanliness apparently is making us sick. Praise the Lord and put away the mop and pail.
But wait: it gets worse. Now they're telling us that poison is good for us.
One Man's Meat
There is a word for this. No, not that word; the one I'm looking for is 'hormesis'4. Hormesis says that substances that harm or kill at high doses can have the opposite effect at low doses: thousands of studies confirm that at super-low levels, toxins like radiation, arsenic and mercury have beneficial effects on plants, people and other living things.
I suppose this isn't news. Remember the Count of Monte Christo, who foiled his enemies' attempts to poison him through the simple ruse of poisoning himself a little at a time? I never thought of Alexandre Dumas as a scientist, but there you go.
So what's going on here? In short, a toxin mobilizes the body in complicated ways. Given too much of the substance, the body is overwhelmed, but given very low dosages the body gears up to meet the challenge and is the stronger for it. During the past decade, Dr Edward Calabrese, Professor of Toxicology at the University of Massachusetts, has searched through tens of thousands of studies for examples of the effect, and he has found them in large numbers. Worms exposed to excessive heat, rats dosed with dioxin, mice exposed to low-level radiation have all lived longer than they would have without the toxins.
For example, the Centers for Disease Control in the US have data from more than 100,000 infants who received vaccines preserved with thimerosal, an organic compound of mercury. The researchers worried that giving the infants too many vaccines might harm them, but they found that limited exposure to mercury actually lessened the children's chances of developing neurological tics, delayed speech, and other pathologies.
In contrast, an article in the current issue of 'Health' magazine describes the dangers posed by mercury in our fish. People with mercury poisoning as a result of eating too much fish display exactly the kinds of neurological damage that low doses of mercury are shown to protect against. Ain't science great?
Not surprisingly, the whole idea of hormesis gives a lot of folks the heebie-jeebies5. The notion sounds suspiciously like homeopathy, which is considered quackery by many. It goes against all our intuition that tells us poison is bad for us. And many worry that the concept of hormesis could give industries a license to pollute. At the very least, we can't do much with the information. How do you define a 'therapeutic dose' of something like mercury? What's beneficial for one person may well harm another. And toxins aren't the kinds of substances that lend themselves to trial and error.
One thing does suggest itself. Perhaps the observed rise in asthma and allergies points to the hormetic properties of good ol' fashioned dirt and germs. I'm not sure I'd want to forego vaccines for serious illnesses, but I plan to lighten up on the housework, and the next time I have a head cold, I'll just tell myself that it's protecting me from worse. As our friend the Count of Monte Christo noted, vengeance is a dish best served cold, and news from the frontiers of science is best taken in small doses and served up with a grain or two of salt. So fix me a margarita, unleaded please, and don't stint on the tequila. Better make it two.