Long-term effects? A little scarring, perhaps.
I used to sell plasma until I learned that the $10 per unit the gave me for my plasma was nothing compared to the $400 to $500 per unit they charged patients in the hospital. Why couldn't I just donate directly, cut out the middle-men, and pocket the difference? But no, that was not permitted, even though exploiting me for someone else's personal gain was. So the long-term effects for me include not selling my plasma any more.
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The mere fact that science may not yet adequately explain an object, event, or experience does not mean the immediate explanation should automatically default to a conspiratorial, extraterrestrial, paranormal, or supernatural cause.