noise in batch processing-

System

I have a friend who is batch processing from raw to jpeg and is having noise issues (she does portrait and picking up noise on the white background, mostly)-

all that I could find on here and google alluded to noise being generated by the conversion and quite a few are using noise ninja as a matter of course in their batch processing to deal with any noise issues-

any corrections to the above and any comments, please?-

thanks
george