I don't have an answer for you, Van_Isle. I was commenting to DD yesterday, as we drove by front-end loaders moving big piles of grain, that when I worked for a farmer with a grain elevator, a fungicide was used on stored grain. It is likely that it's use was approved without the requirement that it be noted as an "ingredient" in any finished product. We rely on government regulation and science everywhere.
Homegrown ginger is still in the fridge. My harvest wasn't quite as much as I thought it might be, so I didn't make use of the freeze-drying as I otherwise intended.
A quick and significant use came this fall after I caught a cold in mid-September. A lingering cough was a result so throughout the ordeal, DW made ginger tea for me with fresh, grated ginger. It really helped with the cough and might have lessened the incident of sinus headaches, as well.
I have used a slice of ginger rubbed on the face before, also. I'm not sure if that helps with the sinuses or just acts as a distraction from the discomfort. If you try this, better plan on keeping your eyes closed for an hour or so ...