I have no idea what changes were made to the Biogon, nor what glasses are and were used in it. There were a great many different additives used in glass, and there are a great many still in use. If anyone is particularly interested, I have heard that the Schott glass catalogue is an amazing source of information!
I used the APO-Lanthar as an example because I know that my old 150mm is radioactive (checked with Geiger counter), and that the new 90mm's are not. I also know that the optical formula has been changed a little bit, so that the new ones are even better.