Safety indicators

Purpose Confirm therapeutic efficacy and safety (indications for use, recommended dosage, contraindications, long-term administration and emergence of additional side effects)... 

Food products are systematically checked for safety indicators, including pesticides contents and chemical compounds. For this procedure highly sensitive GC and HPLC methods are used. 

The What-if, the checklists and Hazop are well publicized hazard identification tools. But as Bollinger et al. (1996) have pointed out the use of any of these techniques demands knowledge, experience and flexibility. No prescriptive set of questions or key words or list is sufficient to cover all processes, hazards and all impacted populations. Bollinger et al. find that refinement of the quantitative measurement techniques such as safety indices and convergence to a single set of accepted indices would be beneficial. 

The formation of inherent safety indices is based on the following principles (Fig.5) The basic principles of inherent safety (Chapter 6.1) are first described as parameters (Table 5). Most important of these parameters have been selected to be implemented as inherent safety subindices. 

All safety related matters, such as the selection of raw materials, are not considered in the synthesis phase but are given by the user. Also the generation of universal synthesis rules considering safety is not easy. Therefore it is important to analyze the alternative designs by inherent safety indices which describe e.g. flammability, toxicity, process conditions. 

To obtain an answer to the research questions posed, pro-active safety indicators used in today s chemical process industry were analysed and the deviations upon which they are based were compared with deviations present in the accident trajectories of 70 recent accidents. By comparing these two sets of deviations, it was observed that although re-occurring deviations with no direct perceived safety related consequences were present in the majority of accident trajectories they were nevertheless not addressed by the commonly used pro-active safety indicators. These so-called indirect perceived safety related deviations may therefore be more important indications of a possible accident than was thought previously. 

The case studies revealed a lack of overview regarding precursors, their underlying organizational root causes (the latent conditions) and their possible effects on safety barriers. This lack of overview created the opportunity for safety risks in the operational process, despite the presence of many safety indicators and measures. 

The research described in this thesis deals with safety management in complex and high-risk organizations. Companies in the chemical process industry handling hazardous substances are chosen as the subject of study. In particular this thesis will focus on the current safety indication process, and how this safety indication process works and its shortfalls. An unreliable indication process, leads automatically to wrong reactions and measures to prevent possible accidents. Increased understanding of this process helps in providing a better basis from which effective measures to prevent accidents can be derived. 

Before elaborating on the insights on safety indicators derived during the past years by research in the field of safety science, some basic concepts generally used in this field are clarified to prevent possible misinterpretation. 

Having set the fundamental definitions in the field of safety research, this Section discusses how the determination of safety indicators developed over time, and why it is still possible for accidents to happen in the chemical process industry. 

To analyse the problem posed in Chapter 1 an overview of current literature on tools, methods, and standards concerning safety indicators will be presented in Chapter 3. With this overview a better understanding of the signs currently used to indicate safety will be obtained. These signs will be compared with the signs present prior to recent accidents (1995-2002). From both literature and case histories a hypothesis will be derived that will be especially tested in Chapter 6. Moreover, in Chapter 4, the conclusions will be used to develop some generic concepts and a conceptual practical approach. The approach will consist of several steps and models derived from organizational science and safety literature. 

From Chapter 1 it appeared that all the existing safety management systems and tools cannot prevent accidents with hazardous substances in the chemical process industry. In this Chapter, the most commonly used safety indicators will be analysed to derive the set of deviations used for indicating. These deviations are then compared with deviations present in an accident trajectory prior to recent accidents. The differences between the two sets of deviations are then discussed to indicate why accidents still occur. These differences show shortcomings in current safety indicators and are used to set the criteria for a new safety indicator. 

Despite numerous safety measures, accidents with hazardous substances still occur even though Safety Indicators (Sis) have been developed as pre-warning signs to focus companies resources on risk areas. Moreover, Sis required by authorities enabled them to assess the safety performance of companies and focus their resources on companies which have problems controlling their risks, Modarres (Modarres et al., 1994). 

The definition of risk from Chapter 1 is used to set up an analysis tool to find a possible link between Sis and recent accidents. The following sub-Section will therefore introduce this analysis tool before analysing current safety indicators and accidents. 

In this sub-Section a concise overview will be presented of safety indicators commonly used in current chemical process industry. Safety Indicators in this Chapter are restricted to the safety related risk indicators present in an organization. The Sis defined here are present in the chemical process industry in the form of operational data, and in the form of results from (safety) tools. In both cases the Sis aim to indicate the safety status, or risks, Marono (Marono et al., 1998). To retrieve the risk coverage area of commonly used Sis, both the tools, as well as the data they are based on have to be known. The relations between data, tools, and indicators are depicted graphically in Figure 10. 

Risk coverage area of pro-active safety indicators... 

From this analysis it appears that a huge discrepancy exists between deviations prior to accidents, that can be found in normal operation and the pro-active safety indicators and methods in current use. The re-occurring indirect safety related deviations that are the dominant class of events causing accidents are therefore defined as the precursors for accidents, as stated in Chapter 1. Furthermore, from Table 5 it can be concluded that a clear link between risk reduction and the normal way of working is not explicitly present in one of the three methods. Finally, the feasibility of methods (except PRISMA) needs some attention additional expert knowledge is often necessary to apply the method. The focus of the method indicating safety risks developed in this thesis will lie especially on these three criteria. 

In the previous Chapter it was shown that most accidents are preceded by deviations in the operational process, e.g. Heinrich (Heinrich, 1959), Turner (Turner, 1978), Leplat (Leplat, 1987), Reason (Reason, 1997), etc. Additionally, it was shown that a specific class of deviations is present which is not covered by current pro-active safety indicators. These deviations are characterised by a high likelihood and low perceived safety related consequences and were defined as precursors and re-occur in the operational process of the organization prior to an accident. In order to find these deviations in a real life operation and to eventually find their underlying causes, the concepts of re-occurring deviation and operational process have to be explained in more detail. The various definitions and concepts derived in this Chapter are necessary to understand the next Chapters, which shows how they are applied in practice. 

In the previous Chapter it was shown that the developed protocol for analysis identified the ineffective control elements causing the precursors prior to accidents. However, due to the lack of detailed accident information the conclusions were limited. To perform the analysis, using the developed 7-stage protocol pro-actively (before any accident occurs), cases have to be selected on which the analysis can be performed and from which reliable and generic conclusions about safety indicators and the performance of current safety management systems can be obtained. The next sub-Section will discuss the selection criteria to select suitable cases. 

Marono M., Correa M.A., Sola R., 1998. Strategy for the development of operational safety indicators in the chemical industry, Proceedings of the 9th International symposium on Loss Prevention and Safety Promotion in the process industries, Barcelona, pp. 205-215. 

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