Risks of occupational exposure to optical radiation.

During the past 40 years a wide body of biomedical research has been conducted to understand the factors which influence injury to optical radiation-particularly with respect to the eye. A primary motivation for much of this research has been the advent of lasers, since focal damage of the retina from a collimated beam exposure is possible at some distance. A wide range of research studies provided the basis for establishing human exposure limits for ultraviolet and infrared radiation as well as for intense visible light. The International Commission on Non-Ionizing Radiation Protection (ICNIRP) has published guidelines for human exposure, and these are available at no cost from the ICNIRP website (http://www. icnirp.org). Laser Maximum Permissible Exposure (MPE) limits used in international safety standards, such as those of the International Electrotechnical Commission (IEC) are based upon ICNIRP guidelines. Practical laser safety standards and regulations have evolved to promote the safe design and use of laser products. As a result of newer laser applications and increased knowledge of the biological effects, MPEs have been revised a number of times. Despite the existence of safety standards and regulations, accidental eye injuries from lasers still occur. Accidental exposure to welding arcs and intense lights occur more fequently, but the consequential loss of vision is much less, with permanent effects rare. Accidental human exposure information also adds to our understanding of ultraviolet, blue-light and laser induced retinal injury. Accidents are most frequently attributed to the lack of understanding of hazards and a failure to follow established safe work practices.