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Scientists Say a Dirty Child Is a Healthy Child
Researchers from the School of Medicine at the University of California have shown that the more germs a child is exposed to, the better their immune system in later life. Their study found that keeping a child's skin too clean impaired the skin's ability to heal itself. From the article: "'These germs are actually good for us,' said Professor Richard Gallo, who led the research. Common bacterial species, known as staphylococci, which can cause inflammation when under the skin, are 'good bacteria' when on the surface, where they can reduce inflammation."
Same basic theme as the "hygeine hypothesis" that exposure to soil bacteria plays an important role in causing the immune system to deemphasize inflammatory responses and rely more on cell-mediated immunity. In particular, it's been invoked to account for ectopic disease and asthma.
Lacking <sarcasm> tags,
It could be that the process of cleansing is itself stressful to the skin when carried to excess.
This has been understood for at least several decades.
When I was in college, back in the late 60s and early 70s, a doctor diagnosed my dry, cracked skin and ongoing rashes as the result of too many showers. He recommended only one or two showers a week, with the qualification that any heavy exercise that produced sweating could probably be followed by a shower. I tried following his advice, and the problems cleared up. His explanation is that soap doesn't just clear away dirt and micro-organisms; it also removes surface skin cells and destroys oils, and this isn't too good for the skin.
This whole story is basically just reaffirming what has been understood in the medical community for a long time. As with most other biological topics, extremes in cleanliness aren't especially good for your health. You're better off being mostly clean, but with a small surface sprinkling of the sort of stuff that we evolved with. Soapy water does the same thing to your skin cells as it does to the bacteria. Your skin cells to have mechanisms (proteins) that bind them together, so they don't wash away all that easily. But your skin does succumb eventually to the same chemical attacks that remove the bacteria, if you hit it with too strong an attack.
Those who do study history are doomed to stand helplessly by while everyone else repeats it.
As far as autism goes, the accepted explanation in the medical community is that the rates are increasing because the categories are being redefined to include more symptoms, and because more patients are being checked for it than in the past. It's only the anti-vaccine nutters who are latching on to they hypothesis that the actual incidence rates are going up.