[Curve Ball Dave]

Pitching, regardless of the type of pitch, is a danger to your arm. Few pitchers can straighten their arm all the way by the time their done. I can't, and I have permanent nerve damage in my elbow simply from the decades of throwing.

Having said that, all things being equal, a fastball is less likely to damage something. Breaking balls of any kind mean snapping wrists sideways and that puts terrible strain on the tendons that start in your fingers and run the length of your arm. Elbows in particular are at high risk with breaking pitches because that wrist snap will be felt in the elbow and that's were the ulnar nerve damage and bone chips/spurs happen. It was the horrific tendonitis/bursitis in my elbow that caused me change from a traditional curve ball to a knuckle/spike/one finger whatever you want to call it curve as this kind does not require a sideways wrist snap.

I personally think today's pitchers are blowing out their arms because they don't use their lower body ala Seaver, Ryan, Lolich, and many others who pitched three hundred innings a year without arm trouble. Legs are far stronger than arms, and better to use those big leg muscles to generate power than those small arm muscles.