Basis risk definition

Aven and Renn argue for an uncertainty-based view on risk and risk assessment, where risk is conceptualized in line with definition class C8 (R = C U). In their view, risk assessment is an expression of an assessor s uncertainty about the occurrence of events and the consequences. Risk assessment can always be performed, as it is seen as a tool to describe uncertainties rather than a tool to uncover the truth. Their view has a strong constmctivist basis [...] risk does not exist independent of the assessor, as the uncertainties need to be assessed by somebody [...] Uncertainty is not real, it is a construct of human imagination to cope... 

In risk research literature, there is increasing focus on the theoretical basis of risk assessment, particularly in terms of the adopted conceptual risk definition and the adopted perspective on how risk is described (Aven Zio 2013). The work presented in this paper adopts the view that risk can conceptually be defined as the possibility of an unfortunate occurrence , see e.g. (Aven 2012). This concept can be summarized as follows ... 

Example 57 The three files can be used to assess the risk structure for a given set of parameters and either four, five, or six repeat measurements that go into the mean. At the bottom, there is an indicator that shows whether the 95% confidence limits on the mean are both within the set limits ( YES ) or not ( NO ). Now, for an uncertainty in the drug/weight ratio of 1%, a weight variability of 2%, a measurement uncertainty of 0.4%, and fi 3.5% from the nearest specification limit, the ratio of OOS measurements associated with YES as opposed to those associated with NO was found to be 0 50 (n == 4), 11 39 (n = 5), respectively 24 26 (u = 6). This nicely illustrates that it is possible for a mean to be definitely inside some limit and to have individual measurements outside the same limit purely by chance. In a simulation on the basis of 1000 sets of n - 4 numbers e ND(0, 1), the Xmean. Sx, and CL(Xmean) were calculated, and the results were categorized according to the following criteria ... 

A biomarker is here defined as a biological response to an environmental chemical at the individual level or below, which demonstrates a departure from normality. Responses at higher levels of biological organization are not, according to this definition, termed biomarkers. Where such biological responses can be readily measnred, they may provide the basis for biomarker assays, which can be nsed to stndy the effects of chemicals in the laboratory or, most importantly, in the field. There is also interest in their employment as tools for the environmental risk assessment of chemicals. 

Regulatory officials nevertheless act on the basis of such hypothetical risks ( hypothetical definitely does not mean imaginary it means that the risk estimates are based on certain scientific hypotheses and that they have not been empirically tested). Such actions are in part based on legal requirements (Chapter 11) and in part on the prudence that is a traditional feature of public health policies. The scientific information, assumptions, and extrapolation models upon which risk assessments are based are considered sufficiently revealing on the question of human risk to prompt risk-control measures. To put off such actions until it is seen whether the hypothesized risks are real - to wait for a human body count - is considered to be an unacceptable course. 

On the basis of two large randomized trials aimed at suppressing premature ventricular complexes after MI, so-called warning arrhythmias, it was discovered that many common antiarrhythmic medications actually increase the risk of mortality [20, 21]. Amiodarone also has been shown to have no definitive effect on mortality in patients after an MI, including in the recent SCD-HeFT trial [22-24]. In fact, of all antiarrhythmic medications, only beta blockers have been clearly shown to prevent SCD after MI [25], particularly among those with depressed LV function [11]. 

The risk of relapse in discontinuation trials depends on many non-pharmacological, often poorly controllable factors, notably the expectations of the patients, doctors and nurses, other environmental factors, the duration of hospitalization and prior treatment, and the time interval since the last acute psychotic episode. On the basis of an analysis of 14 discontinuation trials, Kane and Lieberman (1987) found that the relapse rate varied greatly from study to study depending on the trial, relapse rates of 30 86% with clustering around 60 70% have been reported in the first 12 months after placebo substitution. According to Kane and Lieberman, this scatter is a result of the different inclusion criteria applied and the different definitions of relapse . 

The fundamental question of risk assessment for potential human carcinogens requires definition of substances that exceed an evidentiary threshold. Once the scientific evidence establishes a substantial basis for conclusion of known or potential human cancer, it is then in order to determine a procedure for risk quantification. Quantitative risk assessments must always be read with the qualitative evidence of the likelihood of carcinogenicity. 

The success of the project to describe the human genome along with progress in the definition of polymorphisms in human xenobiotic-metabolizing enzymes and other proteins will certainly lead to the ability to define populations and individuals at increased risk from a particular chemical insult. This ability will be extended and put on a more mechanistic basis by advances in the new disciplines of proteomics and metabonomics. 

It follows that TVOC is difficult to use for normal regulatory risk assessment the scientific basis for this is just too small and no D-R relations have been established. TVOC at this point should only be used for screening and not for definitive conclusions. In addition, TVOC should only be associated with sensory irritation and only if there are substantial indications that VOC is a problem. In each specific case, if unusual compounds and concentrations are identified, the use of TVOC should be stopped. If TVOC is in the mg/m3 range, additional alternative methods should be used to draw any conclusions. 

Some wastes are defined by exclusion (i.e., by what they are not), not on the basis of their properties or associated risks. Low-level radioactive waste is defined as waste that is not high-level waste, spent fuel, transuranic waste, or uranium or thorium mill tailings. Because the excluded wastes are defined by their source, rather than their properties, the definition of low-level waste is not based on properties of the waste and wastes in this class can vary from essentially innocuous to highly hazardous over long time frames. 

Ultimately, the risk characterization results in a statement of the potential susceptibility of children for specific effects from specific exposures to environmental agents. This statement forms the basis, together with other considerations, on which regulatory or management decisions will be made. Often, the risk manager is not a specialist in children s health thus, it is imperative that the risk characterization be clear, definitive, and unencumbered by scientific terminology that may be misunderstood or misinterpreted. The risk assessor must effectively communicate what is known, what is not known, and what is questionable, in order for the risk assessment to be appropriately factored into the overall risk management process. 

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