It is FDs simple grouping mechanic. Biowaste should be in the food category (as it also has the description of being "sterile") or in another category like "chemicals" which furthers boom upon delivery.
Waste causes outbreak and in case of Scrap Metal (can be contaminated) or actual toxic waste, there it is fine. Blame FDs simple grouping mechanics.
If FD requires a method of producing outbreak, passengers would be a far better method of doing this. Passengers from an outbreak system should have a chance of carrying a disease, or even infecting other passengers.
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If it is in the medicine category and a demand... reduce outbreak. Hey TEA prevents famine just because it is in the "food" category. Better not question the logic. It works in groups.
Except the blood bores are usually illegal. So it may actually have the reverse effect. I am only guessing though. I might test this at some stage. Of course it would just be trade, and not missions, as there are no missions for rare goods.