Hazard Characterization and Exposure

Wlien utility work is located in an exclusion zone, are workers who enter the area exposed to hazardous materials Hazard characterization and exposure assessment performed by a competent person may show that the area surrounding the equipment and an access corridor leading to the equipment can be cleaned so that the utility workers can work in the... 

The HASP should contain the information obtained during the preparation phase concerning hazard characterization and exposure potential. If the information has gaps, ranges, or is incomplete, this should be taken into consideration so that proper protective measures are taken. If and when new information is discovered, this should be included as part of the hazard characterization as an amendment. 

Work zones are designed to control access to actual and anticipated hazards. Work zone positioning is based on hazard characterization and exposure assessment. Anticipated work activity, potential releases, and the amount of contaminant dispersion are important for delineating these zones [3]. 

Risk assessment, a process used to evaluate potential adverse effects on health from human exposure to veterinary drug residues, involves four stages starting from hazard identification and terminating through the hazard characterization and exposure assessment stages to risk characterization. 

Risk characterization, the final stage of risk assessment, sets out to provide a qualitative and/or quantitative estimate, given the uncertainties of assessment, the probability of occurrence, and the severity of known or potential adverse health effects in a given population based on hazard identification, hazard characterization, and exposure assessment. The aim is to characterize the risks to the consumer from residues possibly present in animal products on the basis of use of the substance and particularly the withdrawal period, given that the period of administration and the dosage are predetermined by the objective of effectiveness. 

The conditions under which the drug is used need to be estimated as do acceptable residues linked to the level of acceptable risk to the consumer. The acceptable level of risk, which is determined in theory at the risk management stage, has already been expressed in terms of residues by the ADI under hazard characterization. Moreover, the elements considered for hazard identification, hazard characterization, and exposure assessment make it possible, for a given form of utilization of a particular substance, to establish a profile of residues in animal tissues and to associate this with a profile of consumer exposure. Comparison of this consumer profile and ADI indicates whether the mode of utilization of the substance is acceptable or not. Analysis of the different results of residue content in animal products then provides an indication of level of residues in one or several animal tissues, making it possible to differentiate between veterinary drug applications that do or do not permit compliance with the ADI. 

Newhook, R., Meek, M.E., and Walker, M., Carbon disulfide hazard characterization and exposure-response analysis, Environ. Carcinog. Ecotoxicol. Rev., C19, 125-160, 2001. 

Hughes K, Meek ME, Walker M, and Beauchamp R (2003) 1,3-Butadiene Exposure estimation, hazard characterization, and exposure-response analysis. Journal of Toxicology and Environmental Health. Part B, Critical Reviews 6(1) 55-83. 

Liteplo, R. G., and Meek, M. E. (2003). Inhaled formaldehyde Exposure estimation, hazard characterization, and exposure-response analysis. J Toxicol Environ Health B Crit Rev 6(1), 85-114. 

Hazard characterization and delineation of dose-effect or dose-response relationships. 3. Assessment of exposure 4. Risk characterization... 

The risk assessment comprises an effect assessment (hazard identification and hazard characterization) and an exposure assessment. The principles for the effect assessment of the active substances are in principle similar to those for existing and new chemicals and are addressed in detail in Chapter 4. Based on the outcome of the effect assessment, an Acceptable Daily Intake (ADI) and an Acceptable Operator Exposure Level (AOEL) are derived, usually from the NOAEL by applying an overall assessment factor addressing differences between experimental effect assessment data (usually from animal studies) and the real human exposure situation, taking into account variability and uncertainty for further details the reader is referred to Chapter 5. As a part of the effect assessment, classification and labeling of the active substance according to the criteria laid down in Directive 67/548/EEC (EEC 1967) is also addressed (Section 2.4.1.8). 

The aim of the risk characterization of a chemical substance under evaluation is to integrate the hazard assessment and exposure assessment in order to evaluate the qualitative and quantitative probability for a health risk likely to occur in a given human population due to actual or predicted exposure to that specific chemical as well as the seriousness of any health risk. 

Hazard assessment and exposure assessment of chemicals are generally common stages performed similarly independent of the chemical use category (industrial chemical, pesticide, biocide, food additive, food contact material, etc.). However, variation occurs in the way in which the exposure assessment and hazard assessment information are integrated in the risk characterization step, depending on the regulation involved and the goal of the risk assessment. This wdl be addressed in more detail in the next section. 

All leading food industries have to perform thorough risk assessments in the preservation of food products (Van Gerwen et al., 2000 Hoornstra and Notermans, 2001). The crucial point then is analysis of the production process as a whole, the so-called from farm to fork and consists of four subprocesses that are executed systematically (1) hazard identification, (2) hazard characterization, (3) exposure assessment, and (4) risk characterization (Brul et al., 2002). 

Risk characterization combines the results of the hazard assessment and exposure assessment to project the potential risk to human health or the environment. The way in which it is done in the European Union under REACH illustrates the process [76]. 

The size and quality of the available database for an environmental pollutant will vary greatly across substances and will also vary within the four components of the typical risk assessment. The variety of adverse health risks of a substance may be qualitatively well known, for example, but dose—response relationships may be poorly quantifiable because of either limits of inadequate exposure measurement data or absence of good biomarkers of adverse effect or absence of information on the full span of the dose—response curve. Hazard characterization and dose—response relationships may both be understood as general descriptors, but case-specific or scenario-specific exposure data may be lacking, requiring judgment about alternative approaches (e.g., default values). 

The final step in the risk assessment methodology employed here for environmental contaminants is quantification of the extent of risks to health in various human populations. This step combines the general elements of hazard characterization and dose—toxic response relationships for lead with case-specific data quantifying the extent of toxic exposure to arrive at some quantitative value for risk. Various regulatory entities differ in the specifics of how this methodological template is applied but retain these broad features. 

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. 

Critical to hazard characterization is the identification of hazards and the assessment of possible worker exposure. This can be accomplished in a variety of ways. As described before, one commonly used technique is a JHA with project teams that include the worker. The information collected is used by the SSHO and the radiation control officer to develop an appropriate hazard control and protection strategy. 

Hazard characterization is a quantitative or semi-quantitative evaluation of the nature, severity, and duration of adverse health effects associated with biological, physical, or chemical agents that may be present in food. The characterization depends on the nature of the toxic effect or hazard. Eor some hazards such as genotoxic chemicals, there may be no threshold for the effect and therefore estimates are made of the possible magnitude of the risk at human exposure level (dose-response extrapolation). 

Stages in hazard characterization according to the European Commission s Scientific Steering Committee are (1) establishment of the dose-response relationship for each critical effect (2) identification of the most sensitive species and strain (3) characterization of the mode of action and mechanisms of critical effects (including the possible roles of active metabolites) (4) high to low dose (exposure) extrapolation and interspecies extrapolation and (5) evaluation of factors that can influence severity and duration of adverse health effects. 

Dose-response assessment is the process of obtaining quantitative information about the probability of human illness following exposure to a hazard it is the translation of exposure into harm. Dose-response curves have been determined for some hazards. The curves show the relationship of dose exposure and the probabihty of a response. Since vahdated dose-response relationships are scarce, various other inputs are used to underpin the hazard characterization phase of risk assessment. 

Risk characterization is the last step in the risk assessment procedure. It is the quantitative or semi-quantitative estimation, including uncertainties, of frequency and severity of known or potential adverse health effects in a given population based on the previous steps. Risk characterization is the step that integrates information on hazard and exposure to estimate the magnitude of a risk. Comparison of the numerical output of hazard characterization with the estimated intake will give an indication of whether the estimated intake is a health concern. ... 

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