Generally, treatment of herbs and spices will be through high pressure steam, ethylene oxide fumigation (not in EU and only for whole spices in USA) or irradiation. None of these processes should cause formation of acrylamide to the best of my knowledge.
Some companies will have some sort of heat treatment process, for instance we have a supplier that produces roasted dried garlic and also applies heat treatment to some chili powders in order to obtain a darker color.
Acrylamide did not come up on our 1st BRC audit a couple of weeks ago, but now that you have mentioned it I suppose I had better have a think about it before the next audit!