Two Free Electron Laser sources have been developed at ENEA-Frascati and are available for a variety of applications: a Compact Free Electron Laser (C-FEL) that provides coherent radiation in the frequency range between 90 and 150 GHz, and a second source, FEL-CATS, which utilizes a peculiar radio-frequency structure to generate coherent emission in the range 0.4 to 0.7 THz without the use of an optical resonator. The high peak power of several kW in 15 to 50 ps pulses, makes these sources particularly suitable for the assessment of exposure limits in biological systems and for long range detection. In particular the C-FEL has been used to systematically investigate the effects of high peak power millimeter wave radiation on model membranes, human lymphocytes and other living specimens.