From the ‘Science proves mum right’ and ‘Obvious, but still needs to be stated’ file comes the news that children who are exposed to bacteria, viruses, worms, and dirt have healthier immune systems.

Public health measures like cleaning up contaminated water and food have saved the lives of countless children, but they “also eliminated exposure to many organisms that are probably good for us.”

“Children raised in an ultraclean environment, […] are not being exposed to organisms that help them develop appropriate immune regulatory circuits.”

Of course there are caveats, or at least common sense rules (although even the researchers in this field are debating exactly how far to take this):

“I certainly recommend washing your hands after using the bathroom, before eating, after changing a diaper, before and after handling food,” and whenever they’re visibly soiled, [one researcher] wrote.

Dr. Weinstock goes even further. “Children should be allowed to go barefoot in the dirt, play in the dirt, and not have to wash their hands when they come in to eat.”

via Kottke