BPA is Bisphenol-A, a chemical that has created lots of controversy especially with canned products which get heated, and baby products, which involve the baby sucking on a plastic toy or pacifier. Presently it is VERY difficult to find a replacement due to exchanging BPA with another chemical in the new plastic or even glass.
Regarding using a container with BPA exposure on supplements, I could not find any study or research that showed even the slightest danger or negative effect of consuming supplements in bottles make from plastics having BPA. Maybe if you chewed on the bottle there may be a problem, but taking the supplements IN the bottle doesn't seem to create any problems. If you find such a study please send it to me and I want to know about it.