Cadmium can be added at either of 2 points in making an emulsion (Cl/Br). It can be added during precipitation or after precipitation, just before coating. The amount used is different for each case. In any event, its use has been superceded by organic compounds with low toxicity and low environmental impact.

Liquid Light still lists Cd in the MSDS and a number of European and Asian companies still use Cd (last I looked).