Health Risks from Exposure to Low Levels of Ionizing Radiation BEIR VII Phase 2 (2006) / Chapter Skim
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11 Risk Assessment Models and Methods
11 Risk Assessment Models and Methods
Pages 259-266
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From page 259... ...
Understanding the role of exposure in the occur rates and risks and their relationship to one another as a prerence of cancer in the presence of modifying effects is a lude to the sections on modeling and model fitting. difficult problem.
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From page 260... ...
eral theory of risk and risk estimation requires definitions of rates and risks that are not tied to particular types of studies Incidence Rates and Excess Risks or methods of estimation. Probability models provide a mathematical framework for studying incidence rates and risks It is clear that the incidence rate plays an important role in and also are used in defining statistical methods of estima- the stochastic modeling of disease occurrence.
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From page 261... ...
,E the case of no association. The excess relative risk ERR(t)
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From page 262... ...
. The TCSE model reveals that the dose-response for In response to the multiplicity of parameters produced by the NDR cohort is consistent with the lung cancer incidence their earlier models, Armitage and Doll proposed a simpler in the A-bomb survivors' cohort, provided that proper adtwo-stage model designed to avoid parameters not readily justments are made for the duration of exposure and differestimable from available data.
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From page 263... ...
Thus, and may require richer databases to develop properly. De- it is desirable to find suitable models in which either the spite these limitations, biologically based models have found excess risk or the excess relative risk does not depend on many applications for important epidemiologic data sets, and population-specific parameters.
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From page 264... ...
of observation in the cell, the numclass of models that includes the modifying effects on radia ber of new cases of cancer, the mean dose, the mean age at tion dose-response of attained age, age at exposure, and gen exposure, and the mean age or mean time since exposure. der has the form For an RR model, the contribution to the likelihood from (a, e, d, s, p)
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From page 265... ...
ERR models are expressed in terms of a of tools for calculating risk estimates. Risk models provide relative increase in the sex- and age-specific background the general form of the dependence of risk on dose and riskrates for the cancer of interest; these rates are usually ob modifying factors.
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From page 266... ...
Just as there are differences in the risk of ers) are likely to result in more or less random errors in cancer among males and females and among different age dose estimates (i.e., some individuals will have dose esti groups, there are differences in cancer risks among different mates that are too high and others will have estimates that populations.
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