Hazard characterization, definition

Human health hazard characterization for lead viewed over an extended time, as seen in other sections, has relied on temporal shifts in the definitions of what can be characterized as an adverse effect, i.e., evidence of organ or tissue damage. Health hazard characterization in Chapter 21 is discussed as the evidence for such assessment currently exists. The current database is obviously more extensive than that of past decades, but one cannot exclude the possibility or even the probability that the database will grow with continued research, particularly given the availability of increasingly more sophisticated tools. Table 20.1 notes that health hazard characterization in Chapter 21 mainly draws from the preceding Pb toxicity chapters. 

Hazard identification is defined as tlie process of determining whetlier human exposure to an agent could cause an increase in the incidence of a health condition (cancer, birtli defect, etc.) or whetlier exposure to nonliumans, such as fish, birds, and otlier fonns of wildlife, could cause adverse effects. Hazard identification cliaracterizes tlie liazard in terms of tlie agent and dose of the agent. Since tliere are few hazardous chemicals or hazardous agents for wliich definitive exposure data in humans exists, tlie identification of health hazards is often characterized by the effects of health hazards on laboratory test animals or other test systems. ... 

Proper identification of a hazardous waste can be a difficult and confusing task, as the Resource Conservation and Recovery Act (RCRA) regulations establish a complex definition of the term hazardous waste. To help make sense of what is and is not a hazardous waste, this chapter presents the steps involved in the process of identifying, or characterizing, a hazardous waste. 

These two definitions reflect two sides of the same situation. In this book, the term critical effect(s) will be used for the hazard/effect considered as being the essential one(s) for the purpose of the risk characterization, e.g., for the establishment of a health-based guidance value, permissible exposure level, or Reference Dose. It should be noted that the critical effect could be a local as well as a systemic effect. It should also be recognized that the critical effect for the establishment of a tolerable exposure level is not necessarily the most severe effect of the chemical substance. For example, although a substance may cause a serious effect such as liver necrosis, the critical effect for the establishment of, e.g., an occupational exposure limit could be a less serious effect such as respiratory tract irritation, because the irritation occurs at a lower exposure level. 

An important similarity between human and ecological assessment of mixtures is the structure of the assessment procedure. Both procedures are often organized along a series of consecutive steps, that is, problem definition, hazard identification, exposure assessment, effect- or dose-response assessment, and risk characterization... 

The use of animals for routine toxicity testing is now questioned by a growing segment of society. If currently used animal tests are to be successfully replaced, it is important to demonstrate that the alternative methods provide chemical hazard data equivalent to that now available from animal-based tests. Additionally, in order for toxicologists to take the best advantage of new technologies that are constantly evolving, it is important that the validation process be conducted in a manner that efficiently and definitely characterizes the performance of new test methods. 

Piwoni MD, Wilson JT, Walters DM, et al. 1986. Behavior of organic pollutants during rapid-infiltration of wastewater into soil. I. Processes, definition, and characterization using a microcosm. Hazardous Waste and Hazardous Materials 3 43-55. 

For these reasons, the characterization of hazardous solid materials has changed and, with it, the requirements for pollution control. In addition to its nature, described by certain properties (e.g., radioactive) and compositions (e.g., containing toxic components), legislation often defines the term hazardous material by below a certain particle size . With this definition, totally inert materials, consisting of or containing ultrafine particles, become hazardous by law and require processing. 

The methodology of PSA is in principle a combination of event tree and fault tree analyses. The target of the analysis decisively determines the selection and the definition of modes in which the technical system is at the end of an event sequence. These modes comprise both the safe ones resulting from successful safety measures and also those unwanted ones characterized by a certain release of hazardous materials. A PSA is extended to a PRA, if the consequences of the different system modes are determined and linked with the event frequencies of those modes. 

In common with using prevention as a basis of safety, it is essential that a full evaluation of the hazards of the process is carried out, before the type of protective measure is chosen and designed. The identification and definition of the worst case scenario is particularly important as, in contrast to prevention, any protective measure has to be able to cope with this worst case runaway reaction. In addition, the course of the runaway reaction has to be fully characterized and evaluated using the techniques described in Chapters 3 and 4. 

From the foregoing two definitions one can conclude that PHA is a set of well Organized and systematic (meaning following a certain mle) mles to identify and characterize each of the possible hazards in the process, then to assess them and prioritize them. These must be communicated suitably with basic recommendations for mitigation and control. This means that in PHA, corrective measures are also identified to improve safety and this is communicated as recommendations. So, PHA is the foundation for process safety studies, and a risk management program to save the assets and control adverse effects to people and the environment. 

Since almost all of the long-chain PFCs tested are PPAR-a agonists and/or induce xenobiotic-metabolizing enzymes in the liver, PFCs may be expected to induce some or all of the neoplastic effects seen with PFOA in rodents. There is currently insufficient information to definitively classify long-chain PFCs as human carcinogens. More complete characterization of their mechanisms of action in humans versus rodents will be necessary in order to determine whether this class of compounds poses a carcinogenic hazard to humans at current cumulative levels of exposure. 

Because hazardous environments are by definition unpredictable and uncertain, decision makers have no scripts. They can preplan actions and prepare a plan, but their plans must provide them with the ability to adapt to unpredictable and rapidly changing conditions. Plans provide minimum standards, but individuals must use their own judgment when they encounter unplanned conditions. In these environments, individuals must be able to conceive multiple, and potentially conflicting, outcomes without the sense of contradiction or ambivalence that characterizes classical unity and coher-... 

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