Quantitative risk assessment determination

Quantitative risk assessment is now used extensively for determination of chemical and microbial risks in food. This concept helps to systematically and scientifically judge whether certain hazardous compounds may reach unacceptable risk levels when ingested. Quantitative risk assessment can support both quality design and quality assurance but, we discuss it from the assurance perspective. In the past decade, much attention has been paid to assessment of microbial risks due to then-typical differences as compared to chemical risks ... 

Risk assessment is quantitative and differs from risk management, which involves weighing options to reduce the risk. The risk assessment process begins with identifying the potential hazards and their occurrence in a specihc environment (i.e., exposure assessment), their toxicity (i.e., dose-response), and a characterization of the risk (NRC, 1994). Risk assessment determines the probability of realizing harm as a result of exposure to a given hazard. 

The fundamental question of risk assessment for potential human carcinogens requires definition of substances that exceed an evidentiary threshold. Once the scientific evidence establishes a substantial basis for conclusion of known or potential human cancer, it is then in order to determine a procedure for risk quantification. Quantitative risk assessments must always be read with the qualitative evidence of the likelihood of carcinogenicity. 

In order to achieve uniform, transparent, and reliable allergy information on the label, quantitative risk assessment can be applied to set concentration levels for each major allergen and for different product categories that determine whether a product should be labeled precautionary or not. 

Because the literature describes several limitations in the use of NOAELs (Gaylor 1983 Crump 1984 Kimmel and Gaylor 1988), the evaluative process considers other methods for expressing quantitative dose-response evaluations. In particular, the BMD approach originally proposed by Crump (1984) is used to model data in the observed range. That approach was recently endorsed for use in quantitative risk assessment for developmental toxicity and other noncancer health effects (Barnes et al. 1995). The BMD can be useful for interpreting dose-response relationships because it accounts for all the data and, unlike the determination of the NOAEL or LOAEL, is not limited to the doses used in the experiment. The BMD approach is especially helpful when a NOAEL is not available because it makes the use of a default uncertainty factor for LOAEL to NOAEL extrapolation unnecessary. 

When an agent is classified as a human or probable human carcinogen, it is then subjected to a quantitative risk assessment. For those designated as possible human carcinogen, the risk assessor can determine on a case-by-case basis whether a quantitative risk assessment is warranted. 

A primary directive of CERCLA is the protection of public health. Because the hazards that exist at Superfund sites tend to be quite variable, it has not been possible to establish specific cleanup criteria for the hazardous substances regulated under CERCLA potential human health effects must be evaluated by quantitative risk assessment on a site-by-site basis. Each Superfund site is assessed individually to determine how clean is clean. The rationale is that the hazard of a contaminant is a function of its potential to reach a receptor (e.g., groundwater, population) and the potential harm to the exposed receptor. The ability of a contaminant to migrate, its potential to degrade, and its distance to a receptor of concern (i.e., the risk), all are site-specific. Only on the basis of such individualized risk assessment is it possible to achieve efficient and cost-effective cleanup of the thousands of hazardous waste sites throughout the US. 

The LLNA also conferred an additional benefit in that the protocol contained an element of dose response and this information could be used to provide an indication of the relative potency of an identified sensitization [27-29], Simply put, the LLNA dose response information is employed to determine the concentration that will generate a threshold positive response and is termed the EC3 value [30], This strength of the LLNA has proven to be of great benefit in terms of improved risk assessment for skin sensitization [31, 32], In particular, it has allowed the establishment of a quantitative risk assessment process (QRA) which establishes safe... 

TNO, Guidelines for Quantitative Risk Assessment, First Edition, CPR 18E, The Netherlands Organization of Applied Scientific Research, The Hague, 1999 TNO, Methods for the Determination of Possible Damage, First Edition, CPR 16E, The Netherlands Organization of Applied Scientific Research, The Hague, 1992... 

The necessary effort becomes largest when a quantitative risk assessment is to be performed. Besides identification techniques, quantitative consequence modelling methods and procedures to determine the event probability of the incident being considered must be applied. 

A quantitative risk assessment attempts to quantify the risk level in terms of the likelihood of an incident and its subsequent severity. Clearly the higher the likelihood and severity, the higher the risk will be. The likelihood depends on such factors as the control measures in place, the frequency of exposure to the hazard and the category of person exposed to the hazard. The severity will depend on the magnitude of the hazard (e.g. voltage, toxicity etc.). HSE suggest in HSG(65) a simple 3x3 matrix to determine risk levels. 

There are several levels of risk analysis within most methodologies for assessing risk quantitative, semi-quantitative, and qualitative. For PSSR concerns we deal almost exclusively with qualitative assessments, that is, just a determination of high or low risk. Generally any truly quantitative risk analysis (QRA) indicated for a trigger event would be performed to enhance the process hazard analysis. The associated PSSR for such a trigger event would simply follow action item progress related to the quantitative risk assessment s action items. In this case the PSSR helps assure that any action items from a QRA are appropriately followed. 

Risk assessment in human populations is broadly defined within the vocabulary of the National Academy of Science/National Research Council (NAS/ NRC) (1983) monograph on the topic as [quantitative] characterization of the potential adverse health effects from quantified exposures of humans to environmental hazards. In keeping with the NRC report s use of the term, both qualitative and quantitative risk assessments are considered when dealing with lead contamination and adverse effects in this text, although the most useful information emerged when empirical determination or modeling estimations produced a numerical outcome. Part 4 (Chapters 20—24) of this monograph presents the topic of human health risk assessment in detail. 

YU Li-jian, DUO Ying-quan, SHI Li-chen, WEI Li-jun and WU Zong-zhi. 2007. Method for Determining Probabilities of Leaks in Quantitative Risk Assessment. Journal of Safety Science and Technology. 3(6) 27-30. 

Risk assessment considers the consequences of potential hazards, faults, failures, and accident scenarios. In particular, it provides a quantitative assessment of risk in contrast to other approaches (e.g., a HAZOP study) that provide qualitative assessments. Because industrial processes are complex and interconnected, risk assessment determines overall failure probabilities from those of individual components. For example, the failure... 

The reason for such diversity in methods of determining SILs is probably due to the difficulties of arriving at reliable and credible estimates of risk in the wide variety of situations faced in industries. Whilst a quantitative risk assessment is desirable it may be worthless if the available data on fault rates is minimal or subject to huge tolerances. Qualitative methods allow persons to use an element of judgment and experience in the assessment of risk without having to come up with numerical values that are difficult to justify. 

Exposure to PAHs mainly occurs from atmospheric pollution through inhalation, ingestion and dermal contact. PAHs half-lives in humans are in fact in the range of days/hours, and metabolism is responsible of the formation of carcinogenic metabolites. Risk assessments and potency assessments of various individual and complex mixtures of PAHs have been attempted. BaP is the only PAH for which a database is available, allowing a quantitative risk assessment. PAH potencies are used to determine quantitative health risks posed by PAH exposure. The risks posed by a mixture of PAHs are based on an assumption of additively of the individual risks posed by the PAHs. 

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. 

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