What to take care of when buying cheap clothes?

So, the wall was selling shirts for insanely cheap prices and I do not understand where they are making a profit.

I got a shirt which should cost 8 dollars for 2.5 and I don't know if I can just wear them without concern.

Are cheap shirts safe to wear? Idk do they use chemicals which are bad for me? They made this insanely cheap and I don't know what gives! It all says 100% cotton and its from a trusted brand but the mystery of the price still remains. I need to know before loading up on these things.

Also, bonus question, is white coloring agent more or less harmful than other colors? (Assume the most frequently used coloring agents)