Highly probable -- it's my understanding that most commercial emulsions did prior to the 1970s (cadmium is chemically similar to silver, but slightly less reactive, which makes it useful for controlling crystal growth, reaction rates, etc.). Unlike emulsions such as Plus-X and Tri-X that were reformulated without the cadmium at some point, there was little enough market for Pan-X by the time that reformulation was necessary to make it uneconomical to do so -- faster films had gotten enough finer grain that they could replace Pan-X for most applications, and Tech Pan was available as well by that time.