It’s a very lame argument, and one that happens all too frequently in the news media. The prominent recent example was the recent news that a bread-additive (azodicarbonamide) was being removed from a fast-food chain’s bread, because (gasp (though, literally; see below)) that same chemical is used in yoga mats.
Don’t get me wrong, they should remove it. Because of what the chemical does (contributes to asthma). Not because of guilt-by-association, though.
The mentioning of yoga mats is clearly a foolish association on the part of journalists. It is as if to say, “you wouldn’t eat yoga mats, would you? Are you some kind of sicko?” So of course, nobody wants to be attached to the yoga mat eating stigma.
Another common example that pops up is propylene glycol (PG; found in Electronic Nicotine Delivery Systems (ENDS) aka e-cigarettes, nicotine vaporizers (or other such terms as e-hookahs, vape pens, and probably, at this point, anti-child diol/polyol ordnance)). Quoting Wikipedia: Propylene glycol: “Applications” (references removed for readability):
Like ethylene glycol, propylene glycol is able to lower the freezing point of water, and so it is used as aircraft de-icing fluid. Water-propylene glycol mixtures dyed pink to indicate the mixture is relatively nontoxic are sold under the name of RV or marine antifreeze. It is also used to winterize a vacant structure. […]
Propylene glycol is a minor ingredient in the oil dispersant Corexit, used in great quantities during the Deepwater Horizon oil spill.
No, the fact that PG is a minor ingredient in Corexit does not make it toxic (though Corexit certainly is nasty stuff).
Chemistry just doesn’t work in a way that fits the sensationalist agenda, fortunately. You don’t hear of that vile chemical, nicotine, being present in things as benign and tasty as potatoes and tomatoes. But it’s there (only about a microgram for hundred grams, or less; for eggplant apparently as few as ten grams may contain a microgram of nicotine).
Nor do you often hear that other peoples’ breathing (much less your own) may be killing you: we exhale formaldehyde at several parts per billion, and it’s a known carcinogen. Formaldehyde has long been used as an embalming agent. You’re breathing out an embalming agent (and a constituent of adhesives used in carpeting and plywood). Sicko.
Formaldehyde is toxic, and exposure should be limited. But in minute quantities it is not something to lose sleep over. We should keep in mind that chemical interactions and dangers are always a matter of what the chemical is/does, and how much of it there is.
But you won’t hear sensationalist articles try to keep things in perspective. They’re more likely to invite us to over-dose on fear, uncertainty, and doubt. Even so-called top-tier journalists, publications, and venues fall into this ugly racket.
To understand why we get stuck with a tirade of yoga mat-related dreck, we must follow the path of the story backwards. Undoubtedly the chemical’s use in the bread of the fast-food chain came up. And the reporter did not know anything about that chemical, so they asked an expert, “where’s that chemical used?” The expert listed some examples, and the one that seemed the most imagistic turned out to be yoga mats (though some did mention shoe rubber).
It would be like meeting aliens, and they say, “oh, earthlings, we know about them. They’re the same species as [insert any infamous historical person you want].” And then they would surely blast it across their equivalent of news media.