The new paper is avalable at arXiv:1409.4036 [quant-ph]
Entanglement degradation in open quantum systems is reviewed in the Choi-Jamiolkowski representation of linear maps. In addition to physical processes of entanglement dissociation and entanglement annihilation, we consider quantum dynamics transforming arbitrary input states into those that remain positive under partial transpose (PPT-inducing channels). Such evolutions form a convex subset of distillation-prohibiting channels. A relation between the above channels and entanglement-binding ones is clarified. An example of the distillation-prohibiting map Ф(х)Ф is given, where Ф is not entanglement binding.