As part of describing the poor working conditions of salon employees, a link in the NYT article pointed to a study done in 2012 on 3(+)-free nail polishes that showed that many of them still included the chemicals that they were supposedly free from (including formaldehyde, DBP, and toulene). In fact:
You know that I am not overly concerned about "chemicals," but if these particular ingredients, which do pose potential health risks when used frequently or in the wrong way, are a concern for you, well . . . maybe you should still be concerned. Or you should be extra careful to paint your nail in a very well-ventilated space.
"Toluene was found more frequently, and in higher concentrations in products with toxic-trio related claims than in traditional products. Ten of the twelve products with “toluene-free” claims did, in fact, contain toluene."
It was nice to see that the Zoya they tested in that study did turn out to actually be 3-free, so I can blissfully go on loving my Zoyas.