Impossible to say. But if I had to dreate something similar, I might start with a scan of an old slide or negative using a clear area like the sky. Try Google Images with 'Old slide texture' or 'old negative texture'. You'll find a tone of hits that look very like the above background. Use layer blend modes and a solid colour layer to complete the effect.
This image looks a lot like a photo of a plastic binder.
In fact the entire image could very well be nothing more than exactly that Bruce. The text and graphics are as distressed looking as the background.
Occam's razor... If it looks like a duck, swims like a duck, and quacks like a duck, then just possibly, those webbed feet, and that beak, might not have been Photoshopped onto that — now you come to mention it — suspiciously duck like body.