It's a law up here too.
You can't buy or market children's sleep wear if it is NOT flame retardant.
The non treated ones are polyester. The treated ones are cotton. Even form fitting has to be treated up here.
Sure you can sew your own, but if you sell it, you can face some serious fines/jail time.
We have VERY strict product laws up here.
It's a safety thing. seriously call me brainwashed but I do see the safety issue. I've seen a video of how quick an untreated cotton nightgown can catch fire. It's scary. 8 seconds. That's all it takes is 8 seconds.
http://www.hc-sc.gc.ca/cps-spc/child...etement_e.html
Health Canada's statement on the fact. We have stricter regulations and more testing because we can. so please read it....