According to Rod Dreher, the United States Congress wants to ban clothes bought from "thrift stores" because of the apparent problem of poisoning by lead affecting children. (It seems odd given that the United States was the first country to stop new cars from running on petrol containing tetraethyl lead that it should still have problems with lead poisoning!)
The main point, according to the article, relates to the fact that many American children have had their health threatened by paints containing either white lead or red lead, which were known for centuries to be very effective at protecting iron against corrosion.
Although my mass is far too great for me to be able to buy clothes so cheaply, the very fact that I have in the past donated clothes that are anything but cheap to charities makes me guess at least that Dreher is right that it will be very bad for parents to not be able to buy thrift store clothes for their children. With fertility rates as low as they are, thrift stores are undoubtedly a boon for people seeking to have children, and this law could in the long run be disastrous financially even if well-intentioned.