Hum, almost all of my t-shirts are 100% cotton, or at least that's what the label says. I use mostly the same clothes from 15 years ago so maybe synthetic is more common nowadays? I think the only t-shirts I own that are not 100% cotton are those I've got for free on things like marathons and hackathons. Does it contain phthalate? I have no idea, there is no label saying what they are made of. Probably polyester. Does it have phthalates in any meaningful concentration? This review says basically that "it varies a lot" and "needs further study". https://www.sciencedirect.com/science/article/pii/S138266892...