system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why Are You Allowed To Sell Plasma But Only Donate Blood?
gpt
It's because donated blood is used directly on patients and therefore the kind of people you attract when you pay for blood are more likely to be ones that engage in at risk behaviors. Plasma on the other hand is often not used whole and more often used for research, not human application, so the risk of contamination by blood borne pathogens is worth it.