What is the biblical basis to claim that masturbation is a sin? There's definitely two sides to this coin, some people say that masturbation is not a sin that leads to death, others say that it's a sin because Jesus commands us to deny the desires of our flesh.

So my question to you, is multi-faceted: What biblical basis for claiming that masturbation is a sin; and what is the biblical basis to claim it leads to death?
The root of the matter is lust.


  Matthew 5:28 But I say to you that everyone who looks at a woman with
  lustful intent has already committed adultery with her in his heart.


I would say that the act itself is not the sin, it's the intent of the act.