OMG breaking news! Though Lewis Thomas dicussed this at length in Lives of a Cell (1974). Of course the plan is now continue encouraging the use of antibacterial everything and then the pharmaceutical companies can sell us contaminants to boost our immune system artificially.Gritty rats and mice living in sewers and farms seem to have healthier immune systems than their squeaky clean cousins that frolic in cushy antiseptic labs, two studies indicate. The lesson for humans: Clean living may make us sick.
FFS if you have kids let them get dirty...