HAZARD-BASED RISK

The amount and type of hazards will determine the performance standard specified in site-specific control plans. This includes the content, detail, and formality of review. The approval of the plans is based on risk and hazard potential. Using the hazard-based approach, levels of risk or methods to rank risk (degree) are standardized. 

The official report sums up the lessons of the fire by saying that it might have been prevented or its severity greatly reduced if a more detailed assessment of the inherent hazards and risks of the plant had been carried out by the company beforehand and if adequate records had been kept to build up a history on which an inspection and replacement program could have been based. 

A large number of research and review papers have been published in recent years on the integration of data on physicochemical properties, in vitro derived toxicity data, and physiologically based kinetics and dynamics as a modeling tool in hazard and risk assessment [72-85]. 

The need to develop and use chiral chromatographic techniques to resolve racemates in pesticide residues will be driven by new hazard and risk assessments undertaken using data from differential metabolism studies. The molecular structures of many pesticides incorporate chiral centers and, in some cases, the activity differs between enantiomers. Consequently, in recent years manufacturers have introduced resolved enantiomers to provide pesticides of higher activity per unit mass applied. For example, the fungicide metalaxyl is a racemic mix of R- and 5-enantiomers, both having the same mode of action but differing considerably in effectiveness. The -enantiomer is the most effective and is marketed as a separate product metalaxyl-M. In future, it will not be satisfactory to rely on hazard/risk assessments based on data from metabolism studies of racemic mixes. The metabolism studies will need to be undertaken on one, or more, of the resolved enantiomers. 

The Dow and Mond Indexes provide a relative ranking of the hazards and risks in a chemical process plant. This is accomplished by assigning penalties and credits based on plant features such as the presence of hazardous materials and the safety devices which can mitigate any hazardous effects. Penalties and credits are then combined into a single hazard index for the process unit in question. 

There has been a gradual move in environmental policy and regulation from hazard-based to risk-based approaches. This is partly due to the recognition that for many environmental issues a level of zero risk is unobtainable or simply not necessary for human and environmental protection and that a certain level of risk in a given scenario is deemed acceptable after considering the benefits. 

The approach should be risk-based, not hazard-based... 

Separation distance provides the basic passive fire protection feature for process structures. The separation distance between different process structures and from storage areas, utility operations, and important buildings or facilities should be based on the hazards and risks involved. Refer to Guidelines for Facility Siting and Layout (CCPS, 2003b) for further spacing guidance. 

These, like hazardous substance substitution, are part of risk management and thus the project focus on managerial solutions, in particular on precautionary based risk management. Two approaches turned out to be particularly promising ... 

When a full SIDS Dossier on a chemical is available, an initial assessment of the information is undertaken and conclusions are drawn on the potential hazard(s) posed by the chemical and recommendations are made on the need for further work. The conclusions present a summary of the hazards of the chemical, written with sufficient detail and clarity as to be informative and to assist countries with classihcation work and other hazard-based national decision making and exposure information to put the hazard information into context (e.g., on use in the Sponsor country). The recommendation, based on these conclusions, can be either that the chemical is currently of low priority for further work or that it is a candidate for further work to clarify its potential risk (e.g., that further information is required to clarify concerns identified in the SIDS process, and that post-SIDS testing is recommended). 

As mentioned previously, the assessment of hazard and risk to humans from exposure to chemical substances is generally based on the extrapolation from data obtained in smdies with experimental animals. In the absence of comparative data in humans, a basic assumption for toxicological risk assessment is that effects observed in laboratory animals are relevant for humans, i.e., would also be expressed in humans. In assessing the risk to humans, an assessment factor is applied to take account of uncertainties in the differences in sensitivity to the test substance between the species, i.e., to account for interspecies variability (Section 5.3). If data are available from more than one species or strain, the hazard and risk assessment is generally based on the most susceptible of these except where data strongly indicate that a particular species is more similar to man than the others with respect to toxicokinetics and/or toxicodynamics. Two main aspects of toxicity, toxicokinetics and toxicodynamics, account for the namre and extent of differences between species in their sensitivity to xenobiotics this is addressed in detail in Chapter 5. 

In the following, several terms used to describe interactions between chemicals are mentioned as well as basic concepts used in the hazard and risk assessment of chemical mixmres. The description of these basic concepts, first outlined by Bliss (1939) and Placket and Hewlett (1952), are based on the publications by Konemann and Pieters (1996), Cassee et al. (1998), and Groten et al. (2001). The definitions of additivity, synergism, antagonism, and potentiation are those of Klaassen (1995) and Seed et al. (1995). 

To validate the predicted risk, the actual impact of dumped harbour sediments on local ecosystems can be determined using a dedicated set of in vitro and in vivo bioassays as well as bioindicators selected based on the information obtained from the hazard and risk assessment and on the characteristics of the local ecosystem. 

Tran, L., Kelly, F., Mudway, I., Morin, J.P., Guest, R., Jenkinson, P., Samaras, Z., Giannouli, M., Kouridis, H. and Martin, P. (2008) Hazard and risk assessment of a nanoparticulate cerium oxide-based diesel fuel additive - a case study. Inhal. Toxicol., 20 (6), 547-566. 

Vapor-phase monitoring to meet the 3X specification will most likely not be sufficient to verify agent destruction in the solid materials from the bulk sites because these materials could contain either strongly adsorbed agent or occluded agent that could be released in the future. Because of the unique analytical interferences resulting from the composition of particular waste streams, the measurement methods will have to be specific to each waste stream, and each method will have to be validated for the specific waste matrix. Criteria for determining the detection limit for each method should be based on the hazard and risk evaluations for that waste stream. 

It should be noted that hazard or risk is a function of exposure as well as of toxicity. Thus, an important aspect of this continued debate on 2,1+,5-T is the need for representative data on real exposure in humans, not only for applicators of the herbicide but for the populace at large. EPA s RPAR Position Document 1 (l) included estimates of exposure to 2,1i,5-T based on direct measurements of external contamination by other pesticides applied with equipment similar to that used for 2,li,5-T. However, in most cases, application conditions were quite different from those used for 2,1+,5-T. 

Given the assumed types of disposal systems (near-surface facilities or geologic repositories), waste would be classified as exempt, low-hazard, or high-hazard based on the magnitude of its risk index,... 

Use of the risk index in classifying waste is illustrated in Figure 6.2. Classification of waste essentially is a two-step process. The first step involves a determination of whether a waste can be classified as exempt, based on an assumed negligible risk and an exposure scenario for inadvertent intruders appropriate to disposal of waste in a municipal/industrial landfill for nonhazardous waste. If the waste is not exempt, the second step involves a determination of whether a waste can be classified as low-hazard, based on an assumed acceptable (barely tolerable) risk and an exposure scenario for inadvertent intruders appropriate to disposal in a dedicated nearsurface facility for hazardous wastes. 

Combines separate hazard-based LOE to provide a risk-based WOE determination. 

The standard gives guidance on E/E/PE Systems. The goal may be achieved by more than one safety-related system and by a bundle of measures, but always based on hazard and risk analysis, on getting the overall safety requirements right, and by developing a concept for proper safety requirements allocation. 

The important step to safety as well as security is hazard and risk analysis beforehand—and based on these, safety requirements may be defined and allocated as well as security requirements. 

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