Target Risk Level Research Articles

Assessment of the risk to the health of the population living in the zone influenced by atmospheric emissions from the engineering industry

Introduction. During operation, machine-building enterprises emit pollutants that can negatively affect the health of the population. The study aims to determine the impact of emissions from a machine–building plant, as well as background atmospheric pollution, on the health risk of the population of Novokuznetsk. Materials and methods. The work used data from the volume of maximum permissible emissions of a machine-building plant. The researchers calculated the maximum and average concentrations of pollutants using the "ECOcenter – Standard" program at 36 exposure points selected on the city map. Experts determined the maximum permissible concentrations of pollutants in the atmosphere in accordance with SanPiN 1.2.3685-21. The authors calculated the risks to public health in accordance with the Guidelines R 2.1.10.1920-04. The classification of risk levels was carried out on the basis of MP 2.1.10.0156-19. 2.1.10. Scientists also made a risk assessment considering background atmospheric pollution. Results. Specialists carried out a risk assessment from exposure to nitrogen dioxide, carbon monoxide, sulfur dioxide, carbon (soot), inorganic dust, hexavalent chromium. The maximum and average concentrations of pollutants, as well as the maximum concentrations calculated taking into account background pollution, did not exceed the maximum permissible level. The average concentrations of nitrogen dioxide and hexavalent chromium, taking into account the background, exceeded the hygienic standard. The values of the hazard indices for acute and chronic exposures without taking into account the background, as well as for acute exposures taking into account the background, corresponded to the minimum (target) risk level. The values of the hazard indices for chronic inhalation effects, considering the background, corresponded to the alarming risk level at five points, amounting to 3.084–3.800. With chronic exposure, taking into account the background, an alarming level of risk was revealed for the effect on the respiratory organs (at four points the hazard index was 3.117 to 3.616) and blood (at three points the hazard index was in the range from 3.090 to 3.433). The total individual carcinogenic risk, excluding background, did not exceed the permissible level, ranging from 1.08×10–8 to 2.43×10–7 at different points, taking into account the background, amounted to 1.79×10–4–2.26×10–4, which corresponds to an alarming level. Hexavalent chromium makes the main contribution to the formation of carcinogenic risk. Limitations. Calculated concentrations of pollutants were used to assess the risks. Conclusion. The risks from exposure to atmospheric emissions from the machine-building plant correspond to the minimum (target) level. Background concentrations of toxic substances in chronic inhalation exposures determine an alarming level of non-carcinogenic risk at five points, as well as an alarming level of carcinogenic risk at all points of exposure. Ethics. This study did not require the conclusion of the Ethics Committee.

Exposure risk assessment of representative phthalate acid esters and associated plastic debris under the agricultural land use in typical Chinese regions

Phthalate acid esters (PAEs) are frequently detected in the global environment and can cause potential health hazards. In this study, quantitative exposure risk assessment was undertaken to derive soil generic assessment criteria (GAC) for six representative PAEs under the agricultural land use in the evaluated Chinese regions, which coupled multi-media transport and human exposure models based on multiple exposure pathways including vegetables consumption, dermal absorption, ingestion of soil and dust, and the exposure from non-soil sources. It is identified that the PAEs in agricultural soil are dominated by DEHP and DnBP representing 72–96% of the total PAEs. The GAC for BBP and DEHP, calculated on the basis of region-specific exposure parameters and soil properties in various locations, are stringent, signifying greater potential health risks from exposure to them, warranting more rigorous contamination management. The proposed soil GAC for plastic debris are 100, 107, 73 and 88 mg kg−1 for Heilongjiang Province, Beijing City, Jiangsu and Guangdong Provinces respectively. Additionally, the potential risks of 1.68 × 10−6 and 7 × 10−6 are identified for BBP and DEHP in Guangdong Province as indicated by the exceedance of target risk level of 1 × 10−6, with the consumption of vegetables being the dominant contributor to the total estimated PAEs exposure. Overall, this methodology based on the coupled contaminant transport and exposure models incorporating region-specific data provides a technical framework to derive science-based soil GAC for representative PAEs for maintaining and assessing soil quality and food safety under the agricultural land use.

Towards risk-targeted seismic hazard models for Europe

Standards and Codes of Practice for designing new constructions and for assessing and strengthening existing ones are usually based on uniform hazard maps, where different Limit States (LSs) are associated with different hazard-exceedance probabilities. This approach yields non-homogeneous LS-exceedance probabilities across a territory, thus failing to achieve the goal of uniform risk throughout a territory. Such lack of uniformity stems from estimating the probability of failure using capacity and demand models. If the capacity of new constructions—or the capacity increase of strengthened existing constructions—are designed based on a prescribed hazard-exceedance probability, then the seismic risk depends on both the structure (depending on the design philosophy and corresponding design objectives), through the capacity model, and the location, through the hazard model. The aim of this study is threefold. First, it provides a seismic probability assessment formulation and a risk-targeted intensity measure based on a linear model in log–log coordinates of the hazard, under the assumption of log-normal capacity and demand. The proposed framework introduces a factor that multiplies the code hazard-based demand to account either for intentional (from design) over-capacity or for undesired (e.g., in existing constructions) under-capacity. Second, this paper shows an application to peak ground accelerations in Europe considering parameters taken from Standards and Codes of Practice. The developed framework is used to determine the risk-target levels of peak ground acceleration used for design in Europe, for both new and existing constructions. Third, the obtained target risk levels are used to determine a risk-based intensity modification factor and a risk-based mean return period modification factor, which can be readily implemented in current Standards to achieve risk-targeted design actions, with equal LS-exceedance probability across the territory. The framework is independent of the chosen hazard-based intensity measure, be it the commonly used peak ground acceleration or any other measure. The results highlight that in large areas of Europe the design peak ground acceleration should be increased to achieve the proposed seismic risk target and that this is particularly significant for existing constructions, given their larger uncertainties and typical low capacity with respect to the code hazard-based demand.

Considering uncertainty in the collapse fragility of New Zealand buildings for risk‐targeted seismic design

AbstractThe risk‐targeted seismic design framework is used to set design intensities, based on achieving a target risk level (e.g., collapse or fatality risk) with respect to an assumed building collapse response. This paper assesses the distribution of fatality risk associated with the risk‐targeted design intensity, considering uncertainty in both the hazard and the variety of buildings that can satisfy the minimum design requirement. The randomness among buildings and their response is due to other design decisions (aleatory variability with respect to the design intensity) and can be represented by a distribution of fragility curves that quantify the collapse probabilities of as‐built, code‐conforming buildings. First, a single design intensity is calculated based on a “design fragility,” the mean hazard curve, and a risk target. The design fragility is taken as a conservative estimate from the distribution of collapse fragilities and the selected risk target approximates the risk associated with New Zealand's previous (non‐risk‐targeted) criteria for design intensities. Then the risk distribution is assessed, considering the aleatory variability in as‐built fragilities and the epistemic uncertainty in the new National Seismic Hazard Model. Accounting for variability in design decisions and uncertainty in the hazard model produces a risk distribution that more fully represents the potential risk associated with a given design intensity. This distribution can be compared to guidance on tolerable risk ranges, which suggest that risk can be variable among buildings but should fall within acceptable bounds. Sensitivity studies consider epistemic uncertainty in the assumed model for the distribution of as‐built fragilities. This inclusion of uncertainty to assess the risk distribution offers a powerful extension to the risk‐targeted framework. While this extension would not affect engineering practice (as the output is still a single design intensity), it allows building code developers to better understand and consider the risk implications associated with the selected design intensity.

Methodology for Mobile Toxics Deterministic Human Health Risk Assessment and Case Study

Air toxic emissions from on-road mobile sources are significant contributors to the degradation of air quality in urban and dense population centers. Research led by the United States Environmental Protection Agency (EPA) identified more than 1162 hazardous air pollutants (HAPs) in the exhaust and evaporative emissions from on-road mobile sources. However, less than 70 hazardous air pollutants are monitored by regulatory agencies. HAPs emitted from Mobile Sources are known as Mobile Source Air Toxics (MSATs). The EPA estimates that approximately half of the cancer risk and 74% of noncancer health impacts from air toxics is attributed to mobile sources. The quantification of the risk associated with MSATs exposure remains limited to date, and only a few MSATs have ambient air quality standards to protect human health and welfare. This work presents a novel and validated methodology to quantify the myriad health risks associated with exposure to on-road mobile emissions. This methodology is introduced in the form of a pipelined analysis process, which may be employed in existing and new transportation projects. The proposed new methodology integrates results from three different types of models: on-road vehicle emissions inventory models such as MOVES and IVE, air dispersion models such as AERMOD and SCIPUFF, and risk estimate models for human and ecological receptors such as the 2005 Final U.S. EPA Human Health Risk Assessment Protocol for Hazardous Waste Combustion Facilities. The result of this research work is a new methodology that provides regulators and risk analysts with a more detailed awareness of the health impacts of MSATs. A case study of Saint Paul, Minnesota, validated the air dispersion modeled results against monitored data, and the agreement was acceptable (i.e., the estimates were within a factor of two of the observations). Three high-population locations in the Saint Paul area were evaluated for human health risk, with the observation that at two of these locations, the Saint Paul—Ramsey Health Center and Anderson Office Building, the calculated cancer risk is in excess of the target risk level of 1.0E-05 for benzo(a)pyrene. The methodology presented in this paper allows regulators, risk analysts, and air quality engineers to better estimate multi-pathway cancer and noncancer risk associated with acute and chronic exposure to MSATs. Moreover, this work provides a science-based aid to policy decision makers when considering factors that most significantly affect population health and ecology.

К проблеме контроля пищевой продукции в обороте в рамках риск-ориентированной модели надзора

This research is vital given great significance of food safety for population and bearing in mind that food products are an independent object of sanitary-epidemiologic control as it is stipulated by the legislation. We suggest approaches to creating a risk-based model for control over food products distributed on the market. These ap-proaches involve categorizing food products as per potential health risks for consumers; building up risk profiles of food products; optimizing laboratory support provided for control and surveillance activities taking into account food products safety management. When categorizing food products, risk is assessed as a combination of probable violation of obligatory requirements to safety and severity of consequences these violations might have. Food products that are assigned into extremely high, high and considerable risk categories are subject to systemic control once a year, every two years or every three years accordingly. In case a surveillance object seems “law-abiding’, its category and intensity of control procedures may be changed. Programs for laboratory control over food products are suggested to be based on risk profiles, spotting out priority indicators that make major contributions into risks. Also the approach involves using mathematical models that describe a relation between a number of observations and an expected answer (as a reduction in quantities of deviating samples at the next stage in the control cycle). This model determines how many samples of priority indicators should be tested in order to achieve a target risk level. It also allows predict an expected number of violations and health risk rates at the next stage in the control cycle given the present number of observations. 85 regional registers of food products were created and categories were determined as per health risks for all groups of food products under surveillance. It was shown that in some cases it was necessary to increase a number of observations over priority (“risky”) indicators in order to detect hazardous products and withdraw them from the market. Certain examinations seem redundant as they don’t play any role in making control procedures more efficient. The suggested approaches are universal and dynamic. Basic trends in the model development may include more targeted selection of products for control; risk profiles creations and systemic actualization; further development of laboratory support for control (surveillance) given that the food products market is changing dynamically in the country.

On issues related to national risk-based system for control over food products distributed on the market

This research is vital given great significance of food safety for population and bearing in mind that food products are an independent object of sanitary-epidemiologic control as it is stipulated by the legislation. We suggest approaches to creating a risk-based model for control over food products distributed on the market. These ap-proaches involve categorizing food products as per potential health risks for consumers; building up risk profiles of food products; optimizing laboratory support provided for control and surveillance activities taking into account food products safety management. When categorizing food products, risk is assessed as a combination of probable violation of obligatory requirements to safety and severity of consequences these violations might have. Food products that are assigned into extremely high, high and considerable risk categories are subject to systemic control once a year, every two years or every three years accordingly. In case a surveillance object seems “law-abiding’, its category and intensity of control procedures may be changed. Programs for laboratory control over food products are suggested to be based on risk profiles, spotting out priority indicators that make major contributions into risks. Also the approach involves using mathematical models that describe a relation between a number of observations and an expected answer (as a reduction in quantities of deviating samples at the next stage in the control cycle). This model determines how many samples of priority indicators should be tested in order to achieve a target risk level. It also allows predict an expected number of violations and health risk rates at the next stage in the control cycle given the present number of observations. 85 regional registers of food products were created and categories were determined as per health risks for all groups of food products under surveillance. It was shown that in some cases it was necessary to increase a number of observations over priority (“risky”) indicators in order to detect hazardous products and withdraw them from the market. Certain examinations seem redundant as they don’t play any role in making control procedures more efficient. The suggested approaches are universal and dynamic. Basic trends in the model development may include more targeted selection of products for control; risk profiles creations and systemic actualization; further development of laboratory support for control (surveillance) given that the food products market is changing dynamically in the country.

City Soil Ranking According to the Level of Pollution: Approach Based on the Health Risk Assessment of the Child Population

Assessment of soil pollution with chemicals in certain districts (zones) of the city of Kazan was performed according to the data of the social-hygienic monitoring of the FBHI “Center of Hygiene and Epidemiology in Republics of Tatarstan” for the period of 2010 -2016. The indices of complex assessment of soil pollution with heavy metals (HM) and oil products in the zones under study did not exceed the established regulations. The results showed uneven distribution of pollutants on the territory of the city zones. The 3-rd zone (the Vakhitovsky district) is different, there the major contribution to the total risk level is made by lead (Pb) – 51.4%, cadmium (Cd) - 36.9%, mercury (Hg) – 3.53%, oil products, and copper (Cu) – 2.6%. The level of non-carcinogenic risk for the health of the child population aged 3-6 years old with application of regional exposure factors (THI 1.0 and less) corresponds to the target risk level. The maximum contribution to THI is caused by the dermal route of the oil products’ entry (from 94.0 to 98.9 %). Ranking of the city territory according to the total hazard quotient with the account of all routes of the chemicals’ entry identified two zones ranking first in the risk level: the 2-nd zone (the Sovetsky district) and the 3-rd zone (the Vakhitovsky district). The results indicate the necessity of revising the approaches to assessment of possible health risks associated with oil hydrocarbons on the basis of new scientific data.

Cost reductions through converting platforms from permanently manned to manned-evacuated

Most platforms in Australia and the North Sea were originally designed to be permanently manned facilities. As long-term predictions of extreme weather events have intensified, it has become challenging to demonstrate acceptable life safety levels. Extreme weather events have been an ongoing area of development. With an increasing database of information and potential climate change effects, the intensity of the environmental conditions for even recently installed facilities have increased significantly. The Gulf of Mexico estimate of environmental loading has increased 63% in the past 15 years alone, with similar increases in all other regions. To continue to operate these facilities as permanently manned while maintaining the original design safety level requires extensive strengthening. In cases assessed, associated costs have been shown to easily exceed US$100 million. With the advancements in forecasting, facilities now have adequate information available to ensure a facility is evacuated, shut in or both before any major risk to the safety of the personnel and environment is intolerable. The platform response to a forecast can be referred to as a severe weather action plan (SWAP). These can be shown to be a more cost-effective means than strengthening the asset, and most assets may only require evacuation or shut-in once in their lifetime. The benefits of a manned-evacuated platform also extend to new platforms where the cost of the jacket or hull can be reduced to achieve a target risk level provided a SWAP is in place.

Assessment of the spatial distribution of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in urban soil of China.

Long-term (2004-2018) persistent organic pollutants (POPs) data were collected for urban soils of China. The dataset included concentrations of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in soils, comprising a range of different compounds. Understanding the source of OCP and PCB pollution is an important step in controlling and reducing pollution levels in the environment. This study aimed to analyze the spatio-temporal distribution, pollution sources, and potential health risks of OCPs and PCBs in urban soils in different regions of China. It was found that the total OCP concentrations ranged from 7.6 to 37331μg/kg with a mean value of 2861μg/kg, and PCBs concentrations ranged from 0.3 to 123467μg/kg with a mean value of 4984μg/kg. The highest OCP concentrations were observed in Beijing and Hebei, whereas the highest PCB concentrations were found in the Zhejiang province. The geographical distribution showed that the total mean concentration of POPs of urban soil was much higher in East China than in West China. According to the isomer ratios, about 64% of provinces and cities showed new sources of dichlorodiphenyltrichloroethane (DDT) input and dicofol input was found in 30% of China. Hexachlorocyclohexane (HCH) in urban soils was mainly derived from fresh usage of lindane (γ-HCH) in most regions of China. Lifetime carcinogenic and non-carcinogenic risks of OCPs and PCBs through ingestion, inhalation, and dermal contact indicated that PCBs in urban soils of China often exceeded safe levels. The total lifetime carcinogenic risk values of PCBs were higher than the individual lifetime acceptable risk level (10-4) in 64% of the studied regions and the non-carcinogenic risk values exceeded the target risk level (10-1) in 53% of the regions. The improved knowledge of the distribution and main pollution sources of POPs in urban soil of China as a result of this study can contribute to better decision-making support for soil pollution control and monitoring.

Potential Airborne Asbestos Exposure and Risk Associated with the Historical Use of Cosmetic Talcum Powder Products

Over time, concerns have been raised regarding the potential for human exposure and risk from asbestos in cosmetic-talc-containing consumer products. In 1985, the U.S. Food and Drug Administration (FDA) conducted a risk assessment evaluating the potential inhalation asbestos exposure associated with the cosmetic talc consumer use scenario of powdering an infant during diapering, and found that risks were below levels associated with background asbestos exposures and risk. However, given the scope and age of the FDA's assessment, it was unknown whether the agency's conclusions remained relevant to current risk assessment practices, talc application scenarios, and exposure data. This analysis updates the previous FDA assessment by incorporating the current published exposure literature associated with consumer use of talcum powder and using the current U.S. Environmental Protection Agency's (EPA) nonoccupational asbestos risk assessment approach to estimate potential cumulative asbestos exposure and risk for four use scenarios: (1) infant exposure during diapering; (2) adult exposure from infant diapering; (3) adult exposure from face powdering; and (4) adult exposure from body powdering. The estimated range of cumulative asbestos exposure potential for all scenarios (assuming an asbestos content of 0.1%) ranged from 0.0000021 to 0.0096 f/cc-yr and resulted in risk estimates that were within or below EPA's acceptable target risk levels. Consistent with the original FDA findings, exposure and corresponding health risk in this range were orders of magnitude below upper-bound estimates of cumulative asbestos exposure and risk at ambient levels, which have not been associated with increased incidence of asbestos-related disease.

Simulation optimization of risk measures with adaptive risk levels

Optimizing risk measures such as Value-at-Risk (VaR) and Conditional Value-at-Risk (CVaR) of a general loss distribution is usually difficult, because 1) the loss function might lack structural properties such as convexity or differentiability since it is often generated via black-box simulation of a stochastic system; 2) evaluation of risk measures often requires rare-event simulation, which is computationally expensive. In this paper, we study the extension of the recently proposed gradient-based adaptive stochastic search (GASS) to the optimization of risk measures VaR and CVaR. Instead of optimizing VaR or CVaR at the target risk level directly, we incorporate an adaptive updating scheme on the risk level, by initializing the algorithm at a small risk level and adaptively increasing it until the target risk level is achieved while the algorithm converges at the same time. This enables us to adaptively reduce the number of samples required to estimate the risk measure at each iteration, and thus improving the overall efficiency of the algorithm.

地域減災設計の実現に向けた震度曝露人口適合想定地震の選定手法

In Japan, each prefecture selects some scenario earthquakes, and uses them for making a regional disaster prevention plan. They select scenarios which cause the largest loss, but the scenarios' event probabilities are not considered. It is too conservative and uneconomical to plan a regional disaster prevention for a scenario which has a very low event probability. “Hazard-consistent scenario earthquake” was proposed as a method of selecting scenario earthquakes based on probability. But this method is not appropriate to be used for planning a regional disaster plan because this method is based on a hazard analysis at only one point. So, for example, this method can't distinguish a case where a seismic intensity of 5 upper is observed in only small area from a case where it is observed in almost all area in a region. “Risk-consistent scenario earthquake” (Ishiskawa & Okumura, 2001) can avoid this problem. But in a previous study, each risk curve of prefectures is calculated based on an assumption that all houses have been built at a prefectural capital. In this study, “PEX-consistent scenario earthquakes” is proposed. This is a new method of probabilistic scenario earthquakes based on the relationship between population exposure to seismic intensity (PEX) and its exceedance probability (P-PEX relation). Population distribution is thought to be positively correlated with various social wealth, so PEX represents simply an effect of earthquakes. The Proposal method consists of three steps. First, calculating P-PEX relation and each seismic zones’ contribution for it. Second, determining the seismic zone corresponding to the target risk level. Third, determining a seismic intensity distribution of the background earthquakes corresponding to the level. Following results are obtained in this study. 1) In almost all prefectures, background earthquakes are included in scenario earthquakes corresponding to the specific risk level. But only about 20 prefectures consider background earthquakes in their loss estimations. 2) In Tokyo, the seismic intensity distribution of intraplate earthquake of Philippine sea plate corresponding to 100 yr. return period is lower than the scenario of Tokyo prefectural government, and the distribution corresponding to the 2500 yr. return period is very much higher than it.

Assessing dermal exposure risk to workers from flowback water during shale gas hydraulic fracturing activity

Hydraulic fracturing is a well stimulation technique used in the production of natural gas from shale. While hydraulic fracturing has been in use for decades as a method for oil and gas recovery, recent advances in horizontal drilling techniques and fracturing fluid production have made previously unattainable natural gas reservoirs accessible and economically recoverable. Flowback water produced from the hydraulic fracturing process can pose environmental and human health risks. The objective of this study is to assess cancer risk following dermal exposure to flowback water among workers at hydraulic fracturing sites. Median, 2.5th percentile, and 97.5th percentile concentrations for high priority constituents in flowback water were collected from a previous study and used to estimate cancer risk from dermal exposure to carcinogenic agents in water compared to a target lifetime cancer risk value of 10−6. Hazard quotients, which compare exposure dose to dose at which no adverse effects are expected, were also calculated for non-carcinogenic components of flowback water and compared to an acceptable value of 1. The cancer risk estimate for median concentrations did not exceed the target lifetime cancer risk of 10−6 except for benzo(a)pyrene where the cancer risk of full hand exposure to flowback water for 3 h (one event per week for 4 years) falls within this range (2.9 × 10−6 – 1.4 × 10−5), which exceeds the target risk level even at the 2.5 percentile value. The upper limit of cancer risk form exposure to heptachlor also exceeds 10−6 in this model. Hazard quotient for barium in the same model exceeds 1 (1.7) and results in a total hazard index of 2.

Risk-Based Approaches for the Remediation of a UST Site: A Case Study

Risk-based corrective action (RBCA) is a scientifically-accepted approach to remediate polluted sites. Under the RBCA approach, the risks to human health associated with polluted sites are assessed and appropriate remedial measures are taken to reduce risks. RBCA evaluations involve the use of risk models to assess health risks to different receptors. In Taiwan, the Soil and Groundwater Remediation Act was enforced in 2000. The government of Taiwan also use risk assessment protocols to obtain acceptable remediation goals for polluted sites with low risks. In this study, the application of risk assessment to derive remediation goals and develop remedial strategies at a fuel-oil spill site were performed. After the risk evaluation, the soil and groundwater remediation goals for total petroleum hydrocarbon (TPH), benzene, toluene, ethylbenzene, and xylenes (BTEX) were determined. The remediation levels meet with the requirements for minimum target risk levels (cancer risk = 1×10-6 and hazard quotient = 1). The developed risk-based cleanup goals are calculated based on actual land use and exposure pathways rather than on assumed maximum exposure. After the completion of RBCA process, the remediation cost can be significantly reduced. Based on the risk assessment results, source zone remediation, natural attenuation, and long term monitoring were recommended as the remediation strategies of the studied site to reduce risks to human health. Results from this study provide a streamlined process for future risk assessment work at petroleum-hydrocarbon polluted sites in Taiwan. RBCA is a sound and defensible basis for site closure, and it offers a more logical framework for making site closure decisions.

Safety Analysis of the Patch Load Resistance of Plate Girders: Influence of Model Error and Variability

This study aims to undertake a statistical study to evaluate the accuracy of nine models that have been previously proposed for estimating the ultimate resistance of plate girders subjected to patch loading. For each model, mean errors and standard errors, as well as the probability of underestimating or overestimating patch load resistance, are estimated and the resultant values are compared one to another. Prior to that, the models are initially calibrated in order to improve interaction formulae using an experimental data set collected from the literature. The models are then analyzed by computing design factors associated with a target risk level (probability of exceedance). These models are compared one to another considering uncertainties existed in material and geometrical properties. The Monte Carlo simulation method is used to generate random variables. The statistical parameters of the calibrated models are calculated for various coefficients of variations regardless of their correlation with the random resistance variables. These probabilistic results are very useful for evaluating the stochastic sensitivity of the calibrated models.

Australian evidence on CEO option grants

We test the option incentive models of Hall and Murphy (2000, 2002) and Choe (2003). Hall and Murphy (2000, 2002) posit optimal grant size and exercise price contingent on the executive’s levels of risk aversion and private diversification. Choe (2003) relates these choices to firm characteristics, principally the target risk level and financial leverage. A unique hand-collected data set of Australian grants is employed, wherein exercises prices and grant sizes are unconstrained by taxation and accounting practices. The Hall and Murphy (2000, 2002) model is found to explain observed exercise prices while neither model satisfactorily explains grant sizes. However, there is some evidence that CEO influence is associated with larger grants than posited by these optimal incentive models, but does not impact on exercise prices.

Risk‐taking behaviour of Islamic banks: application of prospect theory

PurposeThe paper aims to gain an insight into behavioural characteristics of Islamic banks and how they influence the risk‐taking decisions of Islamic banks in financial markets within the prospect theory context.Design/methodology/approachThe study employs review and application of prospect theory in Islamic banking industry across the globe, making use of 99 Islamic banks across 14 countries.FindingsEmpirical evidence shows that Islamic banks located above target risk level tend to show risk‐adverse behaviour, while banks below target risk level inclined towards risk‐seeking attitude. Results also highlighted that banks which have higher loans to total asset ratio tend to take on lower risk.Practical implicationsIslamic bank regulators will be better prepared to monitor the Islamic banking system if they understand risk‐taking behaviour of Islamic bank managers. The findings will provide more effective bank regulatory oversight, thus preventing Islamic bank failures in future.Originality/valueSince there are relatively few studies conducted in risk‐taking behaviour of Islamic banks, specifically global Islamic banking, this study will broaden the scope of the literature by providing novel empirical evidence on risk‐taking practice of Islamic banks worldwide.

Quantitative indicator of homeostatic risk perception in car following

Driving behavior is largely affected by the risk perception of drivers. On the basis of risk homeostasis theory, we regard that drivers may adjust car movement according to the perceived risks fluctuating around a target level. However, the manner by which risk perception is quantified remains unclear. We propose assumptions on the quantitative indicators of risk perception and identify a suitable quantitative indicator of risk perception in car-following process. Three risk indicators are discussed, i.e. time-to-collision (TTC), time headway (TH), and safety margin (SM). Using homeostatic features as bases, we found that SM more suitably quantifies homeostatic risk perception than TTC or TH does. Data collected from video drive recorders installed in taxis operating in Beijing are used to analyze the target risk level of SM (desired SM, or DSM) of professional drivers during the car-following process. The data collected by Ahn et al. (2004) to verify Newell’s model are converted into DSM data to further analyze the target risk level of general drivers. The DSM histogram of professional drivers shows that the standard deviation of the DSM value is 0.115, with a mean value of 0.862 and a total distribution close to the normal distribution. For a general driver, the mean value of DSM is 0.896, which is higher than that of professional drivers. This research may shed lights on the understanding of driving behavior.

Representation of Bidirectional Ground Motions for Design Spectra in Building Codes

The 2009 NEHRP Provisions modified the definition of horizontal ground motion from the geometric mean of spectral accelerations for two components to the peak response of a single lumped mass oscillator regardless of direction. These maximum-direction (MD) ground motions operate under the assumption that the dynamic properties of the structure (e.g., stiffness, strength) are identical in all directions. This assumption may be true for some in-plan symmetric structures, however, the response of most structures is dominated by modes of vibration along specific axes (e.g., longitudinal and transverse axes in a building), and often the dynamic properties (especially stiffness) along those axes are distinct. In order to achieve structural designs consistent with the collapse risk level given in the NEHRP documents, we argue that design spectra should be compatible with expected levels of ground motion along those principal response axes. The use of MD ground motions effectively assumes that the azimuth of maximum ground motion coincides with the directions of principal structural response. Because this is unlikely, design ground motions have lower probability of occurrence than intended, with significant societal costs. We recommend adjustments to make design ground motions compatible with target risk levels.