Chapter

The IRPA/INIRC Guidelines on Limits of Exposure to Laser Radiation

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  • USA Ctr for Health Promotion and Prev Med
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Abstract

The International Non-ionizing Radiation Committee (INIRC) of the International Radiation Protection Association (IRPA) first published Guidelines on Limits of Exposure to Laser Radiation in 1985 [1]. Since that time, as a result of an expanded laser database, the Guidelines were revised in 1988 [2]. Prior to presenting the guidelines on laser exposure, it is worthwhile to explain the process by which IRPA/INIRC develops guidelines on non-ionizing radiation (NIR).

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... [107] bzw. H# = 40 mJ/cm2 über eine Zeitdauer von acht Stunden [108]. Da diese Grenzen im freilaufenden Laserstrahl und in reflektierten Anteilen überschritten werden, ist der gesamte op tische Aufbau, die Strahlführung, durch UV-undurchlässige Plexiglasscheiben abge schirmt worden [109], siehe Bild ...
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Article
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If laser radiation strikes biological tissue, various effects can be observed. All are caused primarily by the interaction of photons with the molecules and the molecular compounds of the tissue. The resulting actions depend mainly on the application parameters, which, in turn, can be characterized by the wavelength of the applied laser, the exposure time and the power density. The action mechanisms may be divided approximately into photochemical actions, thermal processes and non-linear responses.
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Chapter
Before describing the material contained in this chapter, I shall try to explain the general character of eye movements during the perception of stationary objects. Let us consider Fig. 52, which shows a recording of the movements of a subject’s two eyes when examining a flat picture with one eye. During the experiment one of the subject’s eyes was covered by a P2 cap and the other with a P1 cap. The black dots in Fig. 52 show the points of fixation during perception of the picture, and the thin lines show movement of each eye from point to point. During the recording, the picture was in a frontal plane. In this case, change in the points of fixation was, roughly speaking, accomplished by movements of a single type—identical and simultaneous very rapid rotation of the eyes, hereinafter conventionally termed “saccades.”
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Few generally accepted standards for personnel exposure to ultraviolet radiation presently exist. Values which have been used as guide-lines were based either on a single-wavelength effect (253.7 nm) which may be emitted from an essentially monochromatic source, or on data which is somewhat at variance with that obtained in more recent investigations. The Committee on Physical Agents of ACGIH has proposed a tentative TLV for ultraviolet which assumes that a single spectral-effects weighting curve can be made applicable for exposure to both the eyes and the skim. The advantages of this aproach are: (1) Calculations and measurements are simplified. (2) It favors the development of a single direct-readout hazard instrument. It also makes an assumption that the eye is the critical organ and that distinction between eye and skin exposure is not essential; that it is acceptable to apply a large factor of safety to the skin in order to protect the eyes. The biological data which support this synthesized approach, and the limitations of this type of standard, and other possible ultraviolet radiation standards are discussed.
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A quantitative study of the cumulative effects of near-UV laser radiation in the primate cornea has been carried out. An effective tissue repair rate was obtained by determining corneal thresholds for sub-threshold exposures spaced at varying intervals from 1 hr to 10 days. The data are fitted by a single exponential term yielding a repair rate constant of 0.022 hr -1. A possible formulation of safe exposure limits for long exposures to low levels of UV radiation and for repeated sub-threshold exposures is suggested based on the observed cumulative effects. (C)1980Health Physics Society
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Wavelengths between 400–1400 nm are transmitted by the mammalian ocular media to the retina. There are at least three types of retinal injury in this waveband. They are mechanical, thermal and actinic in nature. Each type of damage is described briefly and it is suggested that melanin plays a key role in all three types of damage. Some of the peculiar properties of melanin are discussed briefly.
International Non-Ionizing Radiation Committee Recommendations for minor updates to the IRPA 1985 Guidelines for Limits of Exposure to Laser Radiation
  • Irpa
A Proposal for a New Method to Determine EL Values for Repetitive Pulse Trains, US Army Environmental Hygiene Agency
  • W J Marshall
Ocular Hazards of Picosecond and Repetitive Pulse Argon Laser Exposures
  • H W Hemstreet
  • W R Bruce
  • K K Altobelli
  • C C Stevens
  • J S Connolly
Repetitive Pulse Laser Data and Permissible Exposure Limits Institute Report No. 58, Letterman Army Institute of Research, Division of Non-Ionizing Radiation, Changes in the Maximum Permissible Exposures
  • B E Stuck
  • D J Lund
  • E S Beatrice
Guidelines for Limits of Human Exposure to Laser Radiation
  • IRPA, International Non-Ionizing Radiation Committee
Recommendations for minor updates to the IRPA 1985 Guidelines for Limits of Exposure to Laser Radiation
  • IRPA, International Non-Ionizing Radiation Committee