It's definitely an interesting dilemma. When it comes to the medical detachment, I can find no information on the members having any kind of white uniform and it would seem that they wore was pretty much what other members of the unit wore. Here's an informative page about WW2 Hospitals and medical personnel:
The jackets that they wear seem more like lab or work coats and they are not wearing ties as all others are. The trousers seem to be white (although that could be from over exposure due to the white shirts) and the headgear seems to be the same as the other soldiers. It seems as though they are wearing some kind of work uniform so could this be a KP uniform or maybe an Orderly uniform for a hospital? Questions, questions...
Gary
I read on Wikipedia today that WW2 army companies all had 1 mess sergeant and 4 cooks so that might explain our 5 men dressed in white......Ralph