Every morning I trundle my daughter onto my bicycle and up the hill to her public day-care center in central Tokyo before heading off to work.

There she spends her day with 14 other 1-year-old tots and her four teachers in "Tampopo gumi," the "Dandelion Class." In a large sunny room, she plays games, sings, snacks and naps as well as does the usual pooping, drooling and babbling that are central to a toddler's day.

If a rash of recent U.S. and U.K. studies are to be believed, however, I may be placing her at risk.