I wouldn't count on trusting the 'rules' of the U.S. The U.S. requires all mattresses to be sprayed with flame retardants before they can legally be sold (ie. bromide). America is also the behind the brilliance of putting bromide in our bread. IMHO, the U.S. is more toxic than most anywhere else you'd go. Look at the health of our citizens to prove it...
And being someone who's ultrasensitive to chemicals, barriers have never stopped me from reacting to them. I'm suspecting an improvement in symptoms just from swapping out my mattress alone. But I will report after purchase ;)