This great article from SLATE beg the questions:
How much of the sanitization science is driven by ‘germaphobia’ rather than good, hard evidence? Could it be more a case of finding evidence because that is all the Public Health Scientists are looking for, or as someone noted to me recently, “If you are a hammer, everything looks like a nail.”
How much of the sanitization drive is a marketing push by manufacturers of sanitization products?
There are other secondary questions of course. Asthma seems worse in cleaner countries. Some experts think there may be particular types of dirt that are good to stimulate the immune system. Allergy is not so clear cut. My brother and sister had bad asthma as children growing up on a farm. My brother gets ‘hayfever’ as soon as he returns to the area. Allergy has a strong genetic component in which the immune system is sensitive to the allergen (a protein). However there is the obvious question why do more predisposed people get allergy in the modern world.
On a similar line of enquiry, the western epidemics of dreaded disease, poliomyelitis, is thought to have been an outcome of using cleaner water which may have reduced the immunity that may have developed in breastfeeding or young children exposed to the virus.
On a lighter note, a doctor once told me that the best cure for Giardia is a few doses. I remember being in India with my wife who lived there for 11 years from early teenager. Every restaurant we visited provided a fresh salad hat I wasn’t allowed to eat, while my wife just bid away at it. One night I subconsciously took one small piece of salad from the bowl and spend a day (well detailed description not necessary)
Cleanliness does seem to be a virtue with health and social benefits. But, do we need a whole new understanding about dirt and the germs it harbours.