One of the more interesting medical questions of the last 20 years is why asthma is becoming so much more common among kids. And why cancer seems to be getting more common.

As to cancer, some of that is simply that people are living longer because they're no longer dying from smallpox and cholera and the other big killers of centuries past, but that doesn't completely explain it.

There's a strange idea that's been floating around for a while now. It's known as the "Hygiene hypothesis". What it says is that the real problem is overuse of sanitizers and bactericides. Kids aren't being exposed to enough hostile pathogens, and as a result their immune systems don't develop properly. When the time comes that they do get challenged by something, they either overreact (hence asthma) or don't react properly (hence increased cancer).

Another hypothesis says that the disease "cancer" isn't really the development of tumors. Development of tumors is normal, but in most people they don't represent a threat because the immune system destroys them. The disease "cancer" is actually an immune system failure, a case where the immune system doesn't recognize a tumor in time and take care of it.

An interesting news story: turns out that dairy farmers have only 1/5th the risk of lung cancer of the population as a whole. Isn't that odd? It seems that they breathe in a lot of dried, powdered manure, loaded up with coliform bacteria and other nasty things, and thus their immune systems are better equipped to cope with odd things in their lungs -- like tumors.

The hygiene hypothesis seemed an odd one, but it's been gaining credibility over the years. It seems paradoxical, but it also seems to be true: the reason we're getting sick more is because we're living too clean of lives. Clutter and dirt are good for you. (I keep telling myself, when I procrastinate about using my vacuum cleaner.)

I do sometimes wonder about that kind of thing. I was born in 1953. When I was a kid, it was routine for everyone to get measles (all four kinds, including Rubella), mumps, and chickenpox. Those are diseases you can only get once per lifetime, and I've had them all.

Rubella in particular. Because of its potential to cause birth defects when caught by pregnant women, it was seen as being important that kids get it. I remember one time my mom took me and my sister to spend an afternoon playing with a kid who had Rubella, in hopes that we'd catch it. (We didn't, that particular time.)

Kids today don't get those diseases, because there are vaccines for them now. That's obviously good, because once in a while those diseases turned really nasty. There are people my age with scarring from extreme cases of chickenpox. Some people my age didn't make it this far because they died as kids from those diseases. (When I was about 3 I almost almost died from a norovirus.)

But maybe those vaccines are mixed blessings. I never even heard of asthma when I was a kid, let alone knew anyone who had it. I never heard of anyone having a peanut allergy. Those things just didn't happen in those days, but they're increasingly common now. Have we really done our kids a favor by preventing them from getting those diseases? Have we just exchanged one problem for another? If you survive measles*4 + mumps + chickenpox, they're done and gone. But a malfunctioning immune system is a lifetime problem.

UPDATE: Shamus comments.

Posted by: Steven Den Beste in Weird World at 12:25 PM | Comments (5) | Add Comment
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