I'm not convinced labeling regulations work. Producers don't label accurately, and consumers aren't realistically in a position to make the choice being described. I live in California, where we have Prop 65 warnings on everything. The motivation there was quite similar -- people should be aware if a product or space is exposing them to substances which can cause serious harm. But I have never met a single person who refuses to enter a space with a Prop 65 warning because you basically couldn't function in society that way. When you buy a product with a Prop 65 warning, it's generally not actually feasible to know which chemical(s) (if any) prompted the warning. (Some companies may put the warning on all of their products even if only some of them actually contain such a substance.) Further, labeling for the nominal presence of some substance is not enough to make decisions -- you need to know what your actual exposure is likely to be. The system ends up being pretty useless.

In addition to what others have said, note that companies already voluntarily label their products as "phthalate free", so the market is already positioned to decide.

In the absence of concrete evidence of harm from phthalates I'm not convinced mandating yet another label would do more good than harm—it would potentially just further reduce the signal that labels provide by watering it down with yet another mandatory compliance label.

Labeling isn't bad, but it doesn't scale. It works for e.g. allergens because people who are allergic are aware of the rather rapid harm done if/when they consume allergens.