Donating blood for pay

Igros Moshe  (CM I #103) Question Is it permitted to donate blood to a blood bank for pay which is used later when there is need?  Answer  There is a dispute if a person is allowed to hurt himself. Tosfos says that those who prohibit this is even when there is a need. This would include getting paid.  Others say it is permitted if there is a benefit. However donating blood, there is a basis not to prohibit it. Previous generations commonly used bleeding as is stated in the gemora (Shabbos 139) so even that today when it is not common there probably is some inherent benefit and it is done in a way that doesn’t cause so much pain therefore it is possible that it is not prohibited as wounding. If someone wants to be lenient there is no need to protest against it.