Your question is pretty general. How do you feel that organ transplants has an impact upon the environment?
The whole institution of organ transplants are about to take on a new look sometime in the near future. So, whatever the environmental impact, its not likely to be an issue for long.
See: Humans 2.0: Replacing the mind and body
http://www.msnbc.msn.com/id/32269817/ns/health-more_health_news/