Concern over the hazards of exposure to laser radiation has resulted in the establishment of guidelines for human exposure by several agencies. Owing to the incompleteness of knowledge concerning biological effects, particularly long-term ones, it is not possible to set firm protection standards at this time. Current guides are based upon the minimum dose required to produce a visible lesion. These threshold values may vary depending upon the criteria by which they are measured. For the eye, threshold damage has been determined by such varying means as ophthalmoscopy, light microscopic histology, histochemical study, and electroretinography. In histochemical studies, impairment of enzyme activity was apparent when the energy level of the light beam had been reduced by 10 to 15% below threshold for ophthalmoscopically visible or histologically detectable lesions. This raises the question of how damage in the human might be demonstrated below levels that are clinically apparent. (Author)

At head of title: U.S. Dept. of Health, Education and Welfare. Public Health Service. Consumer Protection and Environmental Health Service. Environmental Control Administration." "P.B. 184 0003." Includes bibliographical references (pages 12-15). Microfiche.