Risk assessment radiation exposure

EPA, Radiation Exposure and Risks Assessment Manual (RERAM) Risk Assessment Using Radionuclide Slope Factors, EPA 402-R-96-016, U.S. Environmental Protection Agency, Washington, D.C., 1996. 

Fatalities. In the second option, the common measure of stochastic response from exposure to radionuclides and hazardous chemicals would be fatalities, without any modifications to account for such factors as differences in lethality fractions for responses in different organs or tissues or expected years of life lost per fatality. This option is particularly advantageous for radionuclides, because fatalities is the measure of response provided by the most scientifically defensible database on stochastic radiation effects in humans. Fatalities is the measure of response normally emphasized in radiation risk assessments. 

Conduct a risk assessment to any employee and other persons to identify measures needed to restrict exposure to ionizing radiation and to assess magnitude of risk including identifiable accidents. 

The reader should note tliat since many risk assessments have been conducted on the basis of fatal effects, there are also uncertainties on precisely what constitutes a fatal dose of thennal radiation, blast effect, or a toxic chemical. Where it is desired to estimate injuries as well as fatalities, tlie consequence calculation can be repeated using lower intensities of exposure leading to injury rather titan dcatli. In addition, if the adverse healtli effect (e.g. associated with a chemical release) is delayed, the cause may not be obvious. Tliis applies to both chronic and acute emissions and exposures. 

Generally, the phenotype that predisposes an individual to an increased risk of skin cancer is red or blond hair, blue eyes, and fair skin. These characteristics are surrogate measure of the sensitivity of the skin to sun exposure and the tendency to develop nevi, freckles, and sunburns based on the skin type. Freckles, which may appear abruptly after the first high dose of UV radiation sun exposure, represent clones of mutated melanocytes, and their presence is associated with an increased risk of melanoma.12 The Fitzpatrick classification of skin type is used to determine the response pattern of the skin to UV radiation and assess the risk for melanoma. There are six Fitzpatrick skin types Type I skin always burns and never tans, type II skin burns easily and tans rarely, type III skin burns sometimes and tans usually, type IV skin burns rarely and always tans, type V skin always tans and is moderately pigmented (brown), and type VI skin always tans and is darkly pigmented (black). Fitzpatrick I and II skin types are commonly affected by NMSC and MM. The susceptibility to skin cancer, both NMSC and MM, is related to the melanin content of the skin and the skin s response to UV radiation. 

The Leggett (1992) model was developed to predict tissue doses and whole-body dose to people who may be exposed to americium. The model is considered an updated version of the ICRP (1989) model for americium, which has been used to establish risk-based limits of intake of241 Am (ICRP 1989). The Leggett (1992) and ICRP (1989) models predict similar long-term average doses of americium to the liver and skeleton for an injection exposure and would be expected to predict similar radiation risks and risk-based intake limits (Leggett 1992). Descriptions of applications of the Leggett (1992) model in risk assessment have not been reported. 

Jacobi, W. and Paretzke H.G. 1985, Risk Assessment for Indoor Exposure to Radon Daughters, In Proceedings, Seminar on Exposure to Enhanced Natural RAdiation and Its Regulatory Implications, Maastricht, the Netherlands, March 25-27, Elsvier Science Publisher, Amsterdam. 

Chameaud, J., Masse, R. and Lafuma, J., Influence of Radon Daughter Exposure at low Doses on Occurrence of Lung Cancer in Rats, in Radiation Protection Dosimetry Indoor Exposure to Natural Radiation and Associated Risk Assessment, (Clemente, G., F. et al, eds) pp.385-388, Nuclear Technology Publishing, Anacapri (1983). 

We have previously documented the methodology (Marks et al., 1985a) and presented a summary of the technique (Marks et al., 1985b) at the Maastricht, The Netherlands, Seminar on Exposure to Enhanced Natural Radiation and Its Regulatory Implications. This paper represents a synthesis of the work we have conducted to date on risk assessment at uranium mill tailings vicinity properties. 

Peto, Richard. 1985. Epidemiological Reservations about Risk Assessment. In Assessment of Risk from Low-level Exposures to Radiation and Chemicals. Edited by Avril D. Woodhead, Claire J. SheUabarger, and Alexander HoUaender. New York Plenum Press. 

Because of the gaps in our present understanding of carcinogenesis and the paucity of human data for most chemicals, risk assessments for chemicals are generally more uncertain than risk assessments for radiation. Tb improve such assessments, there is pai ticular need for further development and validation of methods for extrapolation from animal data to man and further refinement of methods for evaluating variations in hmnan susceptibility and human exposure, e.g., biological markers. 

Estimation of the probability of a response from exposure to radionuclides (or any other source of ionizing radiation) is greatly facilitated by the knowledge that radiation dose is the common measure of insult to any organ or tissue for any exposure situation (e.g., see NCRP, 1993a 1993b). All radiation dose or risk assessments are... 

In spite of uncertainties in the dose-response relationship for radiation discussed above, it is generally believed that radiation risks in humans can be assessed with considerably greater confidence than risks from exposure to most hazardous chemicals that cause stochastic effects. The state of knowledge of radiation risks in humans compared with risks from exposure to chemicals that cause stochastic effects is discussed further in Section 4.4.2. 

Measures of Radiation-Induced Responses. This Section discusses the measures of response from radiation exposure generally used in radiation protection and assessments of radiation risk in general terms. 

Sir Edward Pochin (1978) Why be Quantitative about Radiation Risk Estimates Hymer L. Friedell (1979) Radiation Protection-Concepts and Trade Offs Harold O. Wyckoff (1980) From Quantity of Radiation and Dose to Exposure and Absorbed Dose -An Historical Review James F. Crow (1981) How Well Can We Assess Genetic Risk Not Very Eugene L. Saenger (1982) Ethics, Trade-offs and Medical Radiation Merril Eisenbud (1983) The Human Environment-Past, Present and Future Harald H. Rossi (1984) Limitation and Assessment in Radiation Protection John H. Harley (1985) Truth (and Beauty) in Radiation Measurement Herman P. Schwan (1986) Biological Effects of Non-ionizing Radiations ... 

Additionally, before the first study with radiolabeled test substance in man can be started, a risk assessment of a human radiokinetic study is mandatory. The estimation of the radiation exposure in humans given a radiolabeled dose is based on exposure data obtained typically from QWBA studies in animals. 

Fischbein, A., Zabludovsky, N., Eltes, F., Grischenko, V., Bartov, B. (1997). Ultramorphological sperm characteristics in the risk assessment of health effects after radiation exposure among salvage workers in Chernobyl. Environ. Health Perspect. 105 (Suppl. 6) 1445-9. 

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