Effective dose equivalent function

Figure 7. Effective dose equivalent per hour and per unit radon concentration (AJ-B, 7 J-E) as a function of the equilibrium factor. The full lines are calculated with the mean values of the 72 measurements (Xa -. 37/h, XVent . 41/h, P -. 53, A.M.D. —. 15 lJm) and changing attachment rates.

Maximum non-effective doses for rats were established too. On general toxic action, this dose is equivalent to 0,00001 mg/kg a day during 13 weeks. As regards carcinogenic effect and impact on reproductive function, it is 0,000001 mg/kg. For monkeys, maximum non-effective dose as to teratogenic effect makes up 0,00005 mg/kg. 

The AEGL-1 concentration was based on a 1-hour (h) no-effect concentration of 8,000 parts per million (ppm) in healthy human subjects (Emmen et al. 2000). This concentration was without effects on pulmonary function, respiratory parameters, the eyes (irritation), or the cardiovascular system. Because this concentration is considerably below that causing any adverse effect in animal studies, an intraspecies uncertainty factor (UF) of 1 was applied. The intraspecies UF of 1 is supported by the absence of adverse effects in therapy tests with patients with severe chronic obstructive pulmonary disease and adult and pediatric asthmatics who were tested with metered-dose inhalers containing HFC-134a as the propellant. Because blood concentrations in this study approached equilibrium following 55 minutes (min) of exposure and effects are determined by blood concentrations, the value of 8,000 ppm was made equivalent across all time periods. The AEGL-1 of 8,000 ppm is supported by the absence of adverse effects in experimental animals that inhaled considerably higher concentrations. No adverse effects were observed in rats exposed at 81,000 ppm for 4 h (Silber and Kennedy 1979) or in rats exposed... 

In the RPF method (eqn (1)), the user must identify the constraints of the application of a set of RPFs. For example, the health effect, dose range of component doses, route(s) of exposure, and dura-tion(s) of exposure for which the RPFs can be applied must be specified (e.g., a set of RPFs may be constrained to oral exposures and not be used for exposures to the same mixture through the inhalation route). To apply the method, an RPF is estimated for each mixture component the RPF estimates the toxicity of the component relative to that of the IC. RPFs commonly are estimated from a ratio of equally toxic doses of the individual dose-response functions for the component and the IC. For example, the quotient of the effective dose at which ten percent of a test population exhibits an effect (EDio) of the IC and the component could serve as a value for the component s RPF obviously, the RPF for the IC equals 1. The index chemical equivalent dose of an individual component is the product of the component dose and the RPF of the component. These equivalent doses are summed across all components. The risk posed by the mixture is estimated by comparing the summed index chemical equivalent doses of the mixture to the dose-response function of the IC ... 

Kidneys, bladder wall, and adrenals are most exposed organs. Calculations of the effective dose are based on dose equivalents for technetium-MAGs (International Commission on Radiological Protection 1991). Depending on the functional state of the kidneys the effective dose (mSv/MBq) is given as ... 

Radiotoxicity depends on energy deposition in tissue or organs by the radionuclide, the specific tissue exposed to the radionuclide, and the tissue radiation sensitivity. Energy deposition by a radionuclide is a function of its emitted radiations and half-life. Biokinetic studies have identified for most radionuclides of interest the pattern of movement through the body and the effective turnover rate (the sum of the biological and radioactive turnover rates). Biokinetic information also identifies the appropriate type of sample to be collected among blood, urine, feces, saliva, breath, hair, teeth, nasal swipes, and tissue obtained incidental to unrelated operations, and collection frequency. The measured radionuclide concentrations are combined with biokinetic information to calculate the committed dose equivalent, the indicator of radiation impact on the subject (NCRP 1987b). 

When the duration of exposure to GT-4 was limited to 10 minutes and the percent inhibition for an agonist concentration equivalent to the 50% control response was measured at 90 minutes as a function of toxin concentration, a linear response was obtained (Figure 5). Figure 5 shows that the exposure of the preparation to 2.8 ng/ml, 7.0 ng/ml and 70 ng/ml for 10 minutes resulted in inhibitions of 30, 36, and 66% of the contractile response from control levels, respectively. In addition, exposure of the preparation to 2.8, 7.0 and 70 ng/ml for 15 minutes resulted in 45, 55, and 98% inhibition of the contractile response, respectively. We can express the effects of GT-3 by stating both the dose and time to achieve a 50% inhibition from the control or a DCI50 value. 

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