Hazard identification concepts

In order to understand the use and intent of the various immunotoxicology regulatory guidelines and guidance documents, the difference between two concepts familiar to toxicologists should be emphasized. Hazard, identification refers to a method which is essentially qualitative that is, it is designed to detect the ability of a test article to produce a certain (in the context of toxicology) adverse effect, without reference to exposure issues. Risk assessment, on the other hand, takes into consideration method, dose, and duration of exposure, condition(s) of the exposed population, and concurrent... 

According to Kharbanda and Stallworthy (1988) safety is a concept covering hazard identification, risk assessment and accident prevention. Safety should always come first and remain so despite of costs. Good design and forethought can often bring increased safety at less cost. 

After an introduction that considers the place of chemical industry in society, the basic concepts related to risk analysis are presented. The second section reviews the steps of the risk analysis of chemical processes discussed. Safety data are presented in the third section and the methods of hazard identification in the section after that. The chapter closes with a section devoted to the practice of risk analysis. 

Dose-response concepts. Dose-response assessment for hazardous chemicals that can cause deterministic effects begins with the toxicology data developed during the hazard identification step described in Section 3.1.4.1.2. In many cases, hazard identification and dose-response assessment occur simultaneously. For each chemical, the critical response (a specific response in a specific organ) is identified in the hazard identification process. Using the available data for the critical response, one of the following is established ... 

Although dose-response assessments for deterministic and stochastic effects are discussed separately in this Report, it should be appreciated that many of the concepts discussed in Section 3.2.1.2 for substances that cause deterministic effects apply to substances that cause stochastic effects as well. The processes of hazard identification, including identification of the critical response, and development of data on dose-response based on studies in humans or animals are common to both types of substances. Based on the dose-response data, a NOAEL or a LOAEL can be established based on the limited ability of any study to detect statistically significant increases in responses in exposed populations compared with controls, even though the dose-response relationship is assumed not to have a threshold. Because of the assumed form of the dose-response relationship, however, NOAEL or LOAEL is not normally used as a point of departure to establish safe levels of exposure to substances causing stochastic effects. This is in contrast to the common practice for substances causing deterministic effects of establishing safe levels of exposure, such as RfDs, based on NOAEL or LOAEL (or the benchmark dose) and the use of safety and uncertainty factors. 

In the concept proposed in 1983 in the US, risk assessment comprised of four steps, namely, hazard identification, dose-response analysis, exposure analysis, and risk characterisation. In a simplified procedure of risk assessment, only three types of information is needed, namely, physico-chemical characteristics, toxicology, the behavior of the chemical at the use situation. The physicochemical data is supposed to show some sense of toxicity and behaviour of the chemical. The toxicology data shows the kind of symptoms to be elucidated, the target organism, and the amount of chemicals needed for showing the symptoms. Behaviour data would show the extent the receptor - here, humans or other natural organisms - is contacted by the chemical at the use situation. The risk assessment is simply to compare the extent the receptor is contacted and the amount of the chemicals needed to show the symptom. 

Hazard identification and evaluation procedures should be applied to all relevant stages from project conception through to decommissioning, including ... 

The hazard analysis can be performed by one of many known methodologies (Mdstein 2001). In the paper a method called HAZOP is outlined, which was adopted in a knowledge-based system. It is helpful for thorough hazard identification in wide range of industries. As a result of this method it is possible to determine a list of representative risk scenarios for analyzed system. General concept of hazard analysis is shown in Fig. 3. 

Hazard identification includes determining what parts of the project constitute a hazard and determining the location of these hazards. Hazard identification continues throughout the life cycle but is concentrated in the concept and design phases and when changes are made or accidents occur (Fig. 7-2). 

During the concept phase, hazard identification is initiated and documented by preparing a preliminary hazard list (PHL). 

The most universal approach today involves a procedure outlined in Figure 3-3. The first step is hazard identification. When identifying hazards, one can apply the concepts, theories, and models listed earlier in this chapter. This will include a review of activities, conditions, and circumstances involved in hazards. The analysis may include identification and evaluation of potential consequences of undesired events. 

The quotation from the foreword of B 155.1 previously given also includes this wording The introduction of hazard identification and risk assessment as the principal method for analyzing hazards to personnel and achieving a level of acceptable risk. That language presents an interesting and significant concept. 

If all safety professionals accept the premise that hazard identification and risk assessment are to be the first steps in preventing injuries to personnel, a major concept change in the practice of safety will have been achieved. Adopting that premise takes the focus away from what have been called the unsafe acts of workers and redirects it to work system causal factors. This represents sound thinking. 

To repeat, VPP requirements are based on concepts that were appropriate in their time. The emphasis in VPP is on hazard identification and analysis. The term hazard is not defined. But, the wording with respect to hazards in the VPP requirements puts a heavy emphasis on conditions, and it is limiting. The only place in the VPP requirements where risk is mentioned is in the opening paragraph of the section on Worksite Analysis ... 

For this paper we treat hazard assessment as a combination of two interrelated concepts hazard identification, in which the possible hazardous events at the system boundary are discovered, and hazard analysis, in which the likelihood, consequences and severity of the events are determined. The hazard identification process is based on a model of the way in which parts of a system may deviate fi om their intended behaviour. Examples of such analysis include Hazard and Operability Studies (HAZOP, Kletz 1992), Fault Propagation and Transformation Calculus (Wallace 2005), Function Failure Analysis (SAE 1996) and Failure Modes and Effects Analysis (Villemeur 1992). Some analysis approaches start with possible deviations and determine likely undesired outcomes (so-called inductive approaches) while others start with a particular unwanted event and try to determine possible causes (so-called deductive approaches). The overall goal may be safety analysis, to assess the safety of a proposed system (a design, a model or an actual product) or accident analysis, to determine the likely causes of an incident that has occurred. 

The paper has already introduced the concept of differential analysis and its role in the SoS hazard assessment approach being used for LAT. Considering human users as some of the systems in a SoS architecture, effort has been directed to the development of a human factors oriented approach to differential analysis. This way forward strikes a pragmatic balance with regard to the contextual human performance problem for the purposes of hazard identification, limiting the re-analysis of existing SoS elements but maintaining an appreciation that the interaction of these elements in the novel context of a SoS may lead to hazard. 

System safety commences with hazard identification and analysis and risk assessment. So are all the subsets of the practice of safety, whatever they are called. This author is confident that application of system safety concepts in the business and industrial setting will result in significant reductions in injuries and illnesses, damage to property, and environmental incidents. 

Extensive and systematic hazard identification has been carried out based on the description of the system and the operational environment (Ludc, 2003b). All of the hazards identified during the hazard identification study have been analysed, stmctured and mapped to the Core Hazards (higher level hazard groupings) originating from the Axle Counter Concept Safety Case, which aims to support the development of Cause-Consequence models for the project. 

The term engineering RA is mainly introduced to highlight differences to the IT RA concept. The framework is well defined in the (outdated) (ISO/ IECGuide73 2002). The basic approaches and concepts as, e.g., FMEA, Fault Tree Analysis and Probabilistic Safety Analysis, are supposed to be known to the reader. Major goals are hazard identification and its impact on environment. Typical fields of application are chemical industry and nuclear power generation. 

Mishaps involve a set of causal factors that lead up to the final mishap event, and these factors are the actuated hazard conditions. Mishap causal factors can be identified prior to an actual mishap through the application of HA. Mishaps are an inevitable consequence of antecedent causes and, given the same causal factors, the same mishap is repeatable, with the frequency based on the component probabilities. Mishaps can be predicted via hazard identification, and they can be prevented or controlled via hazard elimination or hazard control methods. This safety concept demonstrates that we do have control over the potential mishaps in the systems we develop and operate. We are not destined to face an unknown suite of undesired mishaps, unless we allow it to be so (by not performing adequate system safety). In the safety sense, mishaps are preplanned events in that they are actually created through poor design and/or inadequate design foresight. 

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