[resoluteteeth]

Interestingly Table 4 in that link shows "Plain weave cotton" and "polyster" having similar levels of phthalates.

I don't think phtalates are needed as plasticizers in polyster, so I guess they are coming from the dyes or something else used to treat the fabrics, meaning that the choice of cotton or polyster may not matter for phthalates specifically?

[s1artibartfast]

100% cotton is usually treated with plasticizers, even without dyes