Hazard identification defined

Risk characterization is defined as the integration of the data and analysis of the above three components to determine the likelihood that humans wiU. experience any of the various forms of toxicity associated with a substance. When the exposure data are not available, hypothetical risk is characterized by the integration of hazard identification and dose—response evaluation data. 

The frequency analysis step involves estimating the likelihood of occurrence of each of the undesired situations defined in the hazard identification step. Sometimes you can do this through direct comparison with experience or extrapolation from historical accident data. While this method may be of great assistance in determining accident frequencies, most accidents analyzed by QRA are so rare that the frequencies must be synthesized using frequency estimation methods and models. 

Most human or environmental healtli hazards can be evaluated by dissecting tlie analysis into four parts liazard identification, dose-response assessment or hazard assessment, exposure assessment, and risk characterization. For some perceived healtli liazards, tlie risk assessment might stop with tlie first step, liazard identification, if no adverse effect is identified or if an agency elects to take regulatory action witliout furtlier analysis. Regarding liazard identification, a hazard is defined as a toxic agent or a set of conditions that luis the potential to cause adverse effects to hmnan health or tlie environment. Healtli hazard identification involves an evaluation of various forms of information in order to identify the different liaz.ards. Dose-response or toxicity assessment is required in an overall assessment responses/cffects can vary widely since all chemicals and contaminants vary in their capacity to cause adverse effects. This step frequently requires that assumptions be made to relate... 

An appropriate sampling program is critical in the conduct of a hcaltli risk assessment. This topic could arguably be part of the exposure assessment, but it has been placed within hazard identification because, if the degree of contamination is small, no further work may be necessary. Not only is it important that samples be collected in a random or representative manner, but the number of samples must be sufficient to conduct a statistically valid analysis. The number needed to insure statistical validity will be dictated by the variability between the results. The larger the variance, tlic greater the number of samples needed to define tire problem, ... 

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. ... 

Hazard identification is defined as Uie process of determining whether human e.xposure to an agent could cause an increase in tlie incidence of a health condition, or whctlier e.xposure to nonliunians could cause ad crse effects. 

NOAEL (no-observed-adverse-effect level) is defined as the highest dose at which no adverse effects are observed in the most susceptible animal species. The NOAEL is used as a basis for setting human safety standards for acceptable daily intakes (ADIs), taking into account uncertainty factors for extrapolation from animals to humans and inter-individual variabilities of humans. The adequacy of any margin of safety or margin of exposure must consider the nature and quality of the available hazard identification and dose-response data and the reliability and relevance of the exposure estimations. In some cases, no adverse endpoint can be identified such as for many naturally occurring compounds that are widespread in foods. In that case, an ADI Not Specified is assigned. ... 

For the two aforementioned steps, hazard identification and hazard characterization, data adequacy is of high importance. The data adequacy is defined by the reliability and the relevance of the data for human risk assessment [3],... 

Clearly the relationships between protein structure and function and inherent sensitizing activity are complicated and far from fully defined, and it is against this background of uncertainty that it is necessary to develop approaches suitable for hazard identification. 

The hazard identification criterion defined here is a second derivative involving the rate of heat evolution as ... 

In general, hazard identification criterion represents the deviation of one or more measured variables from specified values. This is the basis upon which a significant percentage of risk analyses are done. For a chemical process, a number of measurable variables, physical properties, and states or positions of various parts of the overall equipment, e.g., pumps, valves, and motors, can be specified for every time or phase of the process. Certain deviations from the "standard" recipe or settings can then be defined in advance as hazardous, and thus can be used for initiation of an alarm at the early stage of a runaway or upset condition. 

Various hazard identification criteria can be defined if sufficient knowledge of the process and of the equipment is available such that a mathematical model of the overall process can be constructed. The model can then be used to detect a hazardous situation, such as a runaway, developing at an early stage. This technique has potentially the highest predictive power, but does require an extensive knowledge of the chemical process and of the equipment characteristics. However, fully sufficient models are rarely available and their development is time consuming. 

As regards complex mixtures, the Dutch group initially recommended a two-step approach (see Figure 10.5) first to identify the n (e.g., 10) most risky chemicals in the mixture, and then to perform hazard identification and risk assessment of the defined mixture of the (10) priority chemicals using procedures appropriate for simple, defined mixtures (Feron et al. 1995a,b, 1998 Cassee et al. 1998. 

In hazard identification, EPA considers the adverse toxic responses from all studies. A chemical may cause a variety of adverse effects depending on the magnitude of the dose and the duration of exposure. These may range from clearly defined effects, such as death, to more... 

This chapter will address the implications of the data presented in previous chapters for assessing the risks from environmental chemical exposures. WHO/IPCS has defined risk assessment as an empirically based paradigm that estimates the risk of adverse effects from exposure of an individual or population to a chemical, physical, or biological agent. As shown in Figure 21, it includes the components of hazard identification (Is there an adverse effect ), dose-response assessment (How severe is it ), exposure assessment (What is the level of exposure ), and risk characterization (What is the risk ) (NRC, 1983 IPCS, 2000). 

Hazard identification, as defined by IPCS, is the identification of the inherent capability of a substance to cause adverse effects when an organism, system, or (sub)population is exposed to that substance (see Figure 21). The challenge in life stage risk assessment is not only to identify the hazard but to determine, in the later... 

Health risk assessment is defined as tlie process or procedure used to estimate tlie likelihood that humans or ecological systems will be adversely affected by a chemical or physical agent under a specific set of conditions. Tlie health risk evaluation process consists of four steps hazard identification, dose-response assessment or liazard assessment, exposure assessment, and risk characterization. 

A risk assessment is defined as a qualitative and quantitative process conducted by EPA to characterize the nature and magnitude of risks to public health from exposure to hazardous substances, pollutants, or contaminants released from specific sites. Risk assessments include the following components hazard identification, dose-response assessment, exposure assessment, and risk characterization. Statistical and biological models are used in quantitative risk... 

Contains information on hazard identification and dose - response assessment of over 600 hazardous substances. Covers toxicity, carcinogenicity, chemical and physical properties, and applicable regulations. Includes the reference dose as defined by US EPA, unit risk of exposure by oral and inhalation routes. Produced by the US EPA. (CIS, TOXNET available on CD as part of TOMES Plus by Micromedex and on the EPA Internet website). 

---