USA Today reports with alarm that researchers have found cotinine, a nicotine metabolite, in the urine and hair of babies who live with smokers—even when their parents did not smoke in their presence. It seems components of tobacco smoke cling to smokers and to household surfaces and get picked up by babies who come into contact with these intermediaries, a phenomenon "some doctors are calling 'thirdhand' smoke." Even something as seemingly benign as a mother's hug may be passing along deadly toxins and carcinogens!
Not until the second-to-last paragraph do we get this caveat, courtesy of "Brett Singer, a scientist at California's Lawrence Berkeley Laboratory": "The million-dollar question is: How dangerous is this?…We can't say for sure this is a health hazard."
No kidding. Since measuring the hazards of secondhand smoke, which delivers doses of toxins and carcinogens that are tiny compared to what smokers absorb, presents a daunting, probably insurmountable challenge to epidemiology, what reason is there to believe we will ever be able to confirm the imagined dangers of "thirdhand smoke," which delivers doses that are even tinier?
Notice where the logic of "thirdhand smoke" leads us. Not only are parents who smoke around their children, or in the same house as their children, or even outside that house, guilty of child abuse; anyone who smokes is potentially guilty as well, since the contaminants may be passed along via residue in a room later occupied by children, physical contact with children, or physical contact with some third party who later interacts with children (although that would be "fourthhand smoke," I guess). To err on the side of caution—which is where we always should err when it comes to the welfare of children, of course—everyone should just stop smoking right now. Then there won't be any need to call the cops.