Hazard Identification Strategy

FIGURE 2.1. Initial Theoretical Hazard Identification Strategy. 

The heat of decomposition and/or reaction (in absence of ambient oxygen) is calculated (see Section 2.2.3.2). If the value of the oxygen balance is less than -240 or higher than +160 (Table 2.12) and the calculated heat of reaction/decomposition is less than 100 cal/g (420 J/g), the substance in its pure form is regarded as having a very low potential to produce a deflagration or detonation [10,11]. 

In the third step, the chemical structure is used to determine if the substance is compatible with materials which are common to the process unit, such as air, water, oxidizers and combustibles, acids, alkalies, catalysts, trace metals, and process utilities (see Section 2.2.4). Even if the substance is considered to be a non-explosion hazard (both nonenergetic and compatible with the 

A reaction is exothermic if heat (energy) is generated. Reactions in which large quantities of heat or gas are released are potentially hazardous, particularly during fast decomposition and/or complete oxidations. 

Even relatively small amounts of exothermic reaction or decomposition may lead to the loss of quality and product, to the emission of gas, vessel pressurization, and/or environmental contamination. In the worst case, an uncontrolled decomposition may accelerate into an explosion. 

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The word safety used to mean the older strategy of accident prevention through the use of hard hats, safety shoes, and a variety of rules and regulations. The main emphasis was on worker safety. Much more recently, safety has been replaced by loss prevention. This term includes hazard identification, technical evaluation, and the design of new engineering features to prevent loss. The subj ect of this text is loss prevention, but for convenience, the words safety and loss prevention will be used synonymously throughout. 

During the process hazards identification and definition phase of a project design, a basic process control system (BPCS) strategy is normally developed in conjunction with heat and material balances for the process. 

The capacity of a chemical to cause harm is what the hazard identification stage of risk assessment is intended to identify - the hazards of a chemical are the adverse effects [harm] which [it] has an inherent capacity to cause (Article 2 of Directive 93/67/EEC). The identification of adverse effects on the health of humans and wildlife relies heavily on tests on laboratory animals. I have already discussed some of the many uncertainties that result from the use of animal tests. A key question is whether there are viable alternatives. Before proposing an alternative testing strategy I first consider animal tests as scientific experiments and ask whether they are good experiments, given what we want to find out. 

Before any mitigation measures can be designed, an effective hazard identification study must be conducted. The results of such a study (a set of release scenarios) can be used to develop a coherent set of mitigation strategies. In the process industries, these studies are most commonly conducted using hazard and operability (HAZOP) studies, what-if checklists, failure modes and effects analyses (FMEA), and several other comparable techniques (CCPS, 1992). 

Thybaud V, Aardema M, Clements J, et al. Strategy for genotoxicity testing Hazard identification and risk assessment in relation to in vitro testing. Mutat Res. 2007 627(l) 41-58. 

While the standard combined chronic/cancer bioassay is helpful in hazard identification, it contributes in a more limited extent to hazard charactraization (i.e., the likelihood of causing adverse effects in humans). However, with some modification in the context of evolving integrated and hierarchical test strategies for groups of chemicals or individual substances, carcinogenicity bioassays have potential to contribute considerably additionally in this context. For example, as discussed... 

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