Probability Of Harm Research Articles

Ethical dilemmas in epilepsy and driving

In states that do not have mandatory physician reporting of seizures, clinicians face the ethical dilemma of whether or not to breach confidentiality of poorly controlled patients who continue to drive. In making this deliberation, one should consider both the probability and magnitude of harm posed by continued driving of an individual patient. When probability and harm are low or when probability is high but harm is low, there is generally no moral obligation to breach confidentiality, and it would be wrong to do so. The most difficult situation is when probability of harm is low but magnitude of harm is high. Judgments to breach confidentiality in these situations should also include assessment of risks and benefits to the patient and to society by taking such action. Ultimately, each patient must be judged individually.

Quantitative Study on the Electromagnetic Vibration in a Squirrel-Cage Induction Motor.

1.Introduction Squirrel-cage induction motors have been widely used as constant-speed motors in many industrial applications for a long time. However, high performance speed control technology has advanced in recent times, with the result that vector-controlled squirrel-cage induction motors have been widely applied to variable speed driving systems (1),(2). Together with this increase in the use of induction motors have come increased requirements for much lower vibration and acoustic noise levels. As a result, a great deal of research on methods of reduction for both acoustic noise and vibration has been published (3)-(5). In squirrel-cage induction motors, the airgap magnetic flux density includes many harmonic components (other than fundamental component) due to harmonic magnetomotive force caused by winding and harmonic airgap permeance caused by slot opening. Harmonic torque, loss(6) and radially-directed electromagnetic forces (mentioned in this paper) are generated due to interaction of the airgap with the harmonic magnetic flux density. It is not the probability of harm, but rather the scale of the harm potentially due to these harmonics that makes them worthy of study. Therefore, it is necessary to quantitatively determine the factors which affect these harmonics (and their associated vibration and acoustic noise levels) with which to base design improvements for lower-noise squirrel-cage induction motors. In this paper, concept for quantitative study of the radially-directed electromagnetic forces which cause both vibration and acoustic noise will be offered and quantitative analytical expression will be shown. We will show the main factors causing the generation of these radially-directed electromagnetic forces, at the same time we shall describe how to perform quantitative calculations with respect to electromagnetic forces, vibration levels, and flexural vibration of the stator core. Then, the utility of the theoretical models will be evaluated by comparing calculated theoretical values against actual measured values. These include: variations in amplitude of vibrations in the stator core vibrations due to variations in, for example, supply frequency and supply voltage.

Widening the discussion on tolerability of risk

Assessments of the risks to an individual from ionising radiation currently compare the probability of the resulting harm, e.g. fatal cancer, with the probability of harm from other causes, e.g. fatal accident. However, many of the effects of exposure to radiation are expressed only after a latent period of many years, whereas the effect of an accident is usually more immediate. The difficulties inherent in such comparisons have been addressed by the International Commission on Radiological Protection who developed an 'Index of Harm' which uses loss of life expectancy as a common basis on which to compare different forms of risk. The author describes a graphical presentation of loss of life expectancy which illustrates these differences in approach to risk assessment. This type of presentation is particularly useful for broadening the perspective on the Health and Safety Executive discussions on the tolerability of risk.

Developing a statistical support system for environmental hazard evaluation

Estimating the hazard or risk to both human health and the environment has been based almost exclusively on single species toxicity tests low in environmental realism and without validation of their accuracy in more complex systems. While this may be quite appropriate for humans in a large variety of circumstances, there is no substantive body of direct experimental evidence indicating that precise predictions of harm from hazardous materials can be extrapolated from single species laboratory tests (or even multispecies laboratory tests) to the more complex highly variable natural systems. Now added to the hazardous chemical assessment problem is the accidental or deliberate release of genetically engineered microorganisms into the environment that have the additional capability of multiplying and expanding their numbers and also transferring genetic information to other organisms. This paper focuses entirely on hazard evaluation for organisms other than humans, namely predicting the potential risk or probability of harm to natural systems based on laboratory toxicity testing using single species. Not only will the basic risk assessment strategy itself be examined but also the question of determining the statistical reliability of various extrapolations from one level of biological organization to another.

Evaluation and regulation of pesticides in drinking water: A Canadian approach

Pesticides are registered in Canada under the authority of the Pest Control Products Act, administered by the Department of Agriculture. Pre-market registration requirements include submission of extensive toxicology data in order to allow evaluation of potential human hazards which may be associated with exposure to pesticides. Drinking water guidelines in Canada, although under provincial jurisdiction, are generally recommended by the federal government with collaboration of provincial authorities. In 1987, 42 pesticides were selected for development of guidelines for drinking water. When complete, the 42 pesticides will represent approximately 80% of all agricultural pesticides utilized in Canada, based on active ingredient weight sold. As do many other regulatory agencies, the Department of National Health and Welfare uses two different approaches to derive health-based guidelines or maximum acceptable concentrations of pesticides in drinking water. The threshold approach assumes that there is a dose below which no adverse effect will occur. This threshold level is closely related to the experimentally determined no observed adverse effect level and, when divided by an appropriate uncertainty or safety factor, forms the basis for the establishment of the maximum acceptable concentration. The second approach is the non-threshold or risk assessment approach and this assumes that these is some probability of harm at any level of exposure. This latter approach is generally utilized for chemicals believed to be capable of causing cancer and has not been used for any of the existing 29 pesticide drinking water guidelines developed in Canada.

On the Meaning of the Preponderance Test in Judicial Regulation of Chemical Hazard

As usually defined, the preponderance test is a standard of proof which directs the jury to accept the plaintiff's version of the disputed if they are more probably true than not. But what happens when the most important disputed facts are judgments about probability? This paper offers an interpretation of the preponderance test which can be applied to this situation. In the example of the paper, B is the benefit of a drug, C is the health cost if it is a teratogen, and p is the probability of teratogenicity. The contested fact is the magnitude of p, the probability of harm. In the interpretation considered by the paper, the jury finds in favor of the plaintiff if the jury decides that it is more likely than not that p is greater than B/C. This definition of the preponderance test does not quite minimize expected costs, and compared with expected cost minimization it is likely to be biased toward under-protection when the health costs are high compared with the benefits. But when the mean and median of the second order probability of p are the same, the definition coincides with expected cost minimization. It is also shown that under a criterion of expected cost minimization, contrary to Posner, judicial error costs are not in general the same and the number of erroneous judgments favoring undeserving plaintiffs is not likely to be the same as the number of erroneous judgments favoring undeserving defendants.

Effect-related effluent criteria for pollutants

Estimation of hazard to aquatic life and the environment due to use and disposal of metals and chemical substances is hampered presently by the lack of a systematic process for generating and evaluating effect— related criteria for pollutants. The primary thrust of this manuscript is to provide a strategy for determining environmental risk (i.e., the probability of harm) from actual or predicted concentrations of a chemical in the aquatic environment.