Even most cotton shirts and jeans tend to be a blend with synthetic plastic fibers because it stretches and breaths better.
That said, phthalates are used in tons of stuff, and it's not fully clear to me which sources are the most important. I've replaced my soap/shampoo/shaving creams with phthalate free versions. It's also present though in basically all plastic tubing, which is known to leach phthalates and is used very extensively in food production machinery.
How do you identify these? You mean there are products that advertise themselves to be phtalate free? Or that you are actively looking for phtalate composition in the products you buy?
In general, the problem will be worse with smaller diameter pipes/tubes due to surface area/volume ratio, worse if the water has been standing in the pipe/tube, and worse if the water is hot.
These chemicals are extremely difficult to get away from. I saw a study where they tried to get volunteers to take a reasonably large set of actions to reduce their levels of BPA and Phthalates, and they were able to get them down to about half the original levels, but not lower.
The first is that I recall the shower curtain problem was related to the heat / steam floating around in the shower which facilitated shedding of particles and also ingestion. Having the "plastic" clothing just on the body may be less bad.
Also, and more importantly, I think people who are conscious about those things tend to wear less plastic fibers but won't necessarily think about the shower curtain.
For example, except for full on technical sportswear (think biking shorts), I never wear polyester or other synthetic fibers in clothing that goes directly on my skin. I used to avoid it because, for the most part, I've found that polyester is less breathable, tends to stick a lot, etc. I try as much as possible (I check the labels) to stick to cotton / linen (for the summer) / wool (for the winter). Now, the whole "plastics are bad" thing doesn't really push me to reevaluate my choice.
Just look at the labels...