[en] The concentration of defects produced by irradiation can be measured by several independent methods such as longitudinal and transverse conductivity measurements at room temperature, spin susceptibility at low temperature, volume or lattice parameters change. The physical consequences of this kind of disorder are as follows. The superconductivy in (TMTSF)₂PF₆ is destroyed by a molecular concentration of 10-4. The concentration of 2.10^-3 corresponds to the full pinning of charge density waves in monoclinic TaS₃, 1T-TaS₂, TTF-TCNQ, TMTSF-DMTCNQ ... Microdiffraction experiments demonstrate some structural aspects of this pinning and conductivity, Hall effect and thermoelectric power measurements demonstrate the consequence of the pinning on the electronic properties of several low temperature charge density wave insulators. In most of the cases the metallic state is stabilized by a weak disorder. The problem of the charge density wave motion in presence of defects is discussed in connection with the electric field depinning experiments. Concentrations of the order of 10^-2 or more correspond to a concentration range of localization by disorder