Dose-effect coefficients

Examples of sublesions are single chromosome breaks that combine to produce a dicentric aberration or single-strand DNA breaks, which, when in close proximity, result in double-stranded DNA breaks. The expression, Eq. (35), provides the link between the micro-dosimetric quantity z, and the dose-effect coefficients a and p. 

Table 12.9. Some Dose-Effect Coefficients for Delayed Effects (per Million man-mSv) used in APS Report...

Fisher s least significant difference (LSD) test Linear regression to test for dose-effect trends Pairwise comparison Pearson s correlation coefficient Student s t-test Williams s t-test... 

DRC.J, is the effective dose rate coefficient for the radionuclide, and C is a conversion factor that determines the units for Q. ... 

From the average effluents data UNSCEAR determined the collective doses for a model site based on nuclide specific dose-conversion coefficients, which were calculated applying a simple dispersion model, nuclide specific transport parameters, and population density data of 400 km for 1-50 km, 20 km for 50-2,000 km. The normalized collective effective doses... 

Effective dose conversion coefficient for the examined body region (e.g., Stamm et al.)... 

Silk TJ, Phipps AW, Bailey MR. 1997. Effects on dose coefficients for workers of recent changes in internal dosimetry. Radiat Prot Dosim 71(1) 7-21. 

Thus, the fraction of dose absorbed is exponentially related to the absorption number. Equation (10) shows that the absorption number (and therefore the membrane permeability) is a fundamental parameter while other parameters such as the partition coefficient and pKa are useful guides but not fundamental parameters. For highly soluble drugs with linear absorption kinetics, dose and dissolution have no effect on the fraction of dose absorbed. In the case of drugs that are absorbed by a carrier-mediated process, a mean permeability should be used [30],... 

In order to compare exposures to radon decay-products with those to other forms of ionising radiation, it is useful to assess the effective dose equivalent expressed in sieverts (Sv). A conversion coefficient of 15 Sv per J h m"3, equivalent to 5.5 mSv per WLM, has been recommended (UNSCEAR, 1982). With this conversion factor, the... 

On the basis of a conversion coefficient of 5.5 mSv WLM"1, occupants of the vast majority of dwellings in the UK receive annual effective dose equivalents less than 2 mSv. Even in the areas surveyed because of their potential for high radon exposures, the annual effective dose equivalents are unlikely to exceed a few tens of mSv. However, in certain areas of Cornwall and Devon, annual effective dose equivalents higher than 25 mSv may be received in a small percentage of dwellings. In some dwellings more than 50 mSv per year may be received. 

It is noted that the ICRP has assumed a higher conversion coefficient between annual effective dose equivalent and radon concentration (ICRP, 1984) in recommending an action level for remedial measures in homes, i.e. 1 mSv y"1 per 10 Bq m"3 of equilibrium equivalent radon gas concentration (9 mSv per WLM). If this conversion coefficient were applied to our regional survey data, we would estimate, from the distribution parameters given in table 3, that about 15% of the residents of certain areas of Devon and... 

Assuming the above coefficients from rat data apply to humans, a person will have received an IC50 or LC50 dose, if the corresponding FED=1. When our knowledge of toxic hazard is complete, there will be a single algorithm for both incapacitation and death since these effects follow each other. However, for now, the FED approach which requires two separate calculations, is the latest advance. 

Lipophilicity in particular, as reflected in partition coefficients between aqueous and non-aqueous media most commonly water (or aqueous buffer) and Z-octanol,has received much attention [105,141,152,153,176,199,232,233]. Logic )W for the octanol-water system has been shown to be approximately additive and constitutive, and hence, schemes for its a priori calculation from molecular structure have been devised using either substituent tt values or substructural fragment constants [289, 299]. The approximate nature of any partition coefficient has been frequently emphasized and, indeed, some of the structural features that cause unreliability have been identified and accommodated. Other complications such as steric effects, conformational effects, and substitution at the active positions of hetero-aromatic rings have been observed but cannot as yet be accounted for completely and systematically. Theoretical statistical and topological methods to approach some of these problems have been reported [116-119,175,289,300]. The observations of linear relationships among partition coefficients between water and various organic solvents have been extended and qualified to include other dose-response relationships [120-122,160,161,299-302]. 

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