An Integrated Framework for Risk Management and Population Health

The traditional medical model of health and health policy development has focused on individuals and the role of medical care in preventing and treating disease and injury. Recent attention to health inequities and social determinants of health has raised the profile of population heath and evidence-based strategies for improving the health of whole populations. At the same time, risk science has emerged as an important new discipline for the assessment and management of risks to health. This article reviews historical developments in the fields of risk management and population health and proposes a joint population health risk management framework that integrates the key elements of both fields. Applying this integrated approach to managing population health risks will facilitate the development of evidence-based health policy. It will encourage a more systematic and comprehensive evaluation of population health issues and promote the use of a broader suite of interventions to reduce health risks and enhance population health status.     

Noncancer Risk Assessment: A Probabilistic Alternative to Current Practice

Based on imperfect data and theory, agencies such as the United States Environmental Protection Agency (USEPA) currently derive “reference doses” (RfDs) to guide risk managers charged with ensuring that human exposures to chemicals are below population thresholds. The RfD for a chemical is typically reported as a single number, even though it is widely acknowledged that there are significant uncertainties inherent in the derivation of this number.

In this article, the authors propose a probabilistic alternative to the EPA's method that expresses the human population threshold as a probability distribution of values (rather than a single RfD value), taking into account the major sources of scientific uncertainty in such estimates. The approach is illustrated using much of the same data that USEPA uses to justify their current RfD procedure.

Like the EPA's approach, our approach recognizes the four key extrapolations that are necessary to define the human population threshold based on animal data: animal to human, human heterogeneity, LOAEL to NOAEL, and subchronic to chronic. Rather than using available data to define point estimates of “uncertainty factors” for these extrapolations, the proposed approach uses available data to define a probability distribution of adjustment factors. These initial characterizations of uncertainty can then be refined when more robust or specific data become available for a particular chemical or class of chemicals.

Quantitative characterization of uncertainty in noncancer risk assessment will be useful to risk managers who face complex trade-offs between control costs and protection of public health. The new approach can help decision-makers understand how much extra control cost must be expended to achieve a specified increase in confidence that the human population threshold is not being exceeded.     

Applying USEPA Risk Assessment Guidance in the 90s

Over the past decade, risk assessment has become increasingly relied upon for helping to make environmental management decisions. This trend has been accompanied by research and refinements in basic risk assessment methodologies to improve our ability to understand and evaluate the human health risks associated with chemical exposures.Despite this progress, significant uncertainties continue to be associated with the risk assessment process. These uncertainties typically derive from gaps in available data regarding chemical toxicity, and from difficulties in reliably estimating the magnitude of chemical exposures. Given these limitations, risk assessment is generally most valuable in evaluating relative risk; for example, when comparing alternatives to achieving a specified goal, setting priorities for protecting human health, or establishing procedures for properly allocating resources. Risk assessment can also be useful for developing regulatory benchmarks such as permit limits for air or water. In many cases, however, the limitations of the risk assessment process make it difficult (if not impossible) to reliably estimate an absolute level of risk, especially for a specific individual in an exposed population. In such cases, risk assessment can be seriously misapplied, and its results misinterpreted.This paper discusses some of the challenges that have been faced by the field of risk assessment during the 1990s. Current trends in risk assessment, and its use by regulatory agencies in making risk management decisions, are also described.     

Uncertainty-based dynamic multimedia human health risk assessment for polycyclic aromatic hydrocarbons (PAHs) in a land oil exploitation area

With the increasing development of the petrochemical industry and the growing demand for oil, polycyclic aromatic hydrocarbons (PAHs) pollutions in the environment, especially in petroleum exploitation areas, are caused by the discharge of waste from the petroleum extraction process into an environmental system. This study aims to develop a new health risk assessment approach based on interval dynamic multimedia fugacity (IDMF) model and uncertainty analysis that could analyze the human exposure risk level for PAH contamination. The developed IDM health risk assessment (IDMHRA) approach is applied to assess previous, current, and future risks at a case study site in Daqing, Heilongjiang, China, from 1985 to 2020 for model validation. The human health risk assessment results show that 11 PAHs (NAP, ANT, FLA, PYR, BaA, CHR, BbF, BkF, BaP, IPY, and DBA) in the study site require further remediation efforts in terms of their unacceptable non-carcinogenic and carcinogenic risk. The results of risk source analysis reveal that soil media is the main risk pathway as compared with other exposure pathways. It can be seen that remediation process for soil contamination in the study site is urgently demanded. The assessment results demonstrate that the developed IDMHRA approach provides an effective tool for decision-makers and environmental managers to make remediation decisions in contaminated sites.     

Adequacy Conditions for Reporting Uncertainty in Chemical Risk Assessments

Uncertainty may influence decision-making. A prerequisite for a decision to be well founded is thus that scientific experts inform decision-makers about all decision relevant uncertainty. A set of conditions is provided for adequate characterization of scientific uncertainty for the purposes of regulatory decision-making. These conditions require specification of (1) the character and degree of uncertainty about the assessment variables, (2) the possibility of reducing the uncertainty, and (3) the degree of agreement among experts. Furthermore, it is required that (4) the information covered by the previous conditions is presented in a clear and comprehensible way. The point of departure is that characterizing scientific uncertainty conceptually means specifying all potentially important possibilities that are consistent with the state of scientific knowledge. The conditions are intended to be applied to human health risk assessment of chemicals. However, the basic approach, to consider potentially important possibilities, should be useful also to environmental, and site-specific risk assessment.     

Does heavy metal hurt in the secondary battery production sites? The case study of occupational risk from Yangtze River Delta,China

The purpose of this study was to determine the occupational health risk to employees of lithium-ion battery factories in Yangtze River Delta, China. Soil samples were collected from materials synthesis workshop and battery assembly line workshop, which are named site A, site N1, site N2, and site Z according to different battery products. We analyzed the heavy metals for Co, Cd, Mn, Cu, and Ni. The soil heavy metal exposure model and the health risk characterization model were built to assess occupational health risk. Besides, uncertainty analysis with the aid of Monte Carlo simulation was used to perform error propagation for model parameters. The health risk assessment with uncertainty results indicated that all the four sites have relative low risk of carcinogens for employees, and N1, A, and Z sites also have relative low risk of non-carcinogen for employees, but N2 site has value of 6.94, which is heavily higher than the threshold value (defined as 1.0). It means that the employees in N2 site are facing threat of the heavy metals. These results provide basic information of heavy metal pollution control and environment management in lithium-ion battery factory. It also answered the question of the occupational risk in the sites.     

Risk Analysis,Uncertainty Factors,and the Susceptibilities of Children

This article examines the use of uncertainty factors (UFs) by the Agency for Toxic Substances and Disease Registry (ATSDR) when developing health guidance values known as minimal risk levels (MRLs) in environmental risk analysis as it applies to children. Improvements in the chemical-specific databases often reveal new information and thereby reduce uncertainty or alternatively raise new concerns. As a result, MRLs can and will change. Children, in particular, are not “small adults” and in some instances demonstrate greater risks of exposure to environmental toxicants and greater susceptibility for adverse health effects once exposed. Recent experience with risk analysis for three toxicants (organic mercury, dioxin, and manganese) is recounted to demonstrate how ATSDR has revised MRLs as the emerging science generates greater knowledge and awareness of children's special vulnerabilities to toxic substances in the environment.     

An Evaluation of Risk Drivers from a Sample of Risk Assessments Conducted for the U.S. Army

We evaluate risk drivers at selected U.S. Army installations by developing a database containing contaminant-pathway-receptor combinations that exceed regulatory thresholds for ecological (toxicity quotient greater than one), human health cancer risk (predicted incremental lifetime cancer risk greater than one in ten thousand), and noncancer human health (hazard index greater than one). We compare the risk drivers from the database to reported corrective action objectives from available decision documents. For noncancer hazards, explosives (particularly in ground water) dominate the reported exceedances of regulatory thresholds in the database. PAHs in home-grown produce show the highest number of exceedances of regulatory thresholds for cancer risk. For ecological risks, PAHs in both terrestrial and aquatic environments dominate the exceedances of regulatory thresholds. All available cleanup levels were derived based on human health exposures rather than ecological exposures, except for one site. In general, ecological risks were considered to be “more uncertain,” and that was used as a basis for not relying on backcalculated target levels on the basis of ecological risk. The reverse was true for human health risks: the “conservative” assumptions incorporated into the modeling provided the justification for backcalculating health-protective target levels.     

Public Reactions to Risk Messages Communicating Different Sources of Uncertainty: An Experimental Test

There is an abundant literature on the challenge of integrating uncertainties in experts’ risk assessments, but the evidence on the way they are understood by the public is scarce and mixed. This study aims to better understand the effect of communicating different sources of uncertainty in risk communication. A causal design was employed to test the effect of communicating risk messages varying in type of advisory warning (no risk and suggests no protective measure, or risk and recommends a protective measure) and sources of uncertainty (no uncertainty, divergence between experts, contradictory data, or lack of data) on public reactions. Participants from the general public (N = 434) were randomly assigned to read and react to variants of a fictitious government message discussing the presence of a new micro-organism found in tap water. Multiple analysis of variance showed that to report uncertainty from divergence between experts or from contradictory data reduced the adherence to the message, but not to mention the lack of data. Moreover, the communication of diverse sources of uncertainty did not affect trust in the government when the advisory warning stated there was a risk and recommended a protective measure. These findings have important implications for risk communication.     

生态安全评价研究中的若干问题

生态安全评价是对生态系统完整性以及对各种风险下维持其健康的可持续能力的识别与研判,以生态风险和生态健康评价为核心内容,并体现人类安全的主导性．生态风险识别和生态脆弱性是生态风险评价的构成要素,生态健康则表现在生态完整性、生态系统活力与恢复力三方面．生态安全评价的准则与指标体系应将生态风险与生态健康有机结合。同时兼容不同空间尺度并能体现动态变化,其中在EDI、REI和IRI分类基础上叠加暴露分析指标是较大空间尺度生态安全指标体系建立的发展方向．文中综述了现阶段主要的生态安全评价方法,表明暴露-响应综合评价模式在现阶段应用最为广泛,生态模型法评价不同尺度的生态安全则是未来主要发展领域,并注重生态过程安全评价．生态安全评价研究需要与生态安全预测及预警研究相结合,并将生态安全的保障、维护与管理研究纳入其范畴．     

The role of extreme iteroparity and risk avoidance in the evolution of mating systems

How much should a female be willing to risk in any one reproductive event? Highly iteroparous females will be risk averse and very conservative in their behaviour. Such females will be expected to avoid mortality risks and seek assurance that any current reproductive activity is safe. By way of minimizing risk, these same females will not engage in mate assessment or mate searching to the same degree as less iteroparous species, if these activities involve increased risk of mortality. Using a field experiment in a highly iteroparous species (the bluehead wrasse, Thalassoma bifasciatum ), it is shown that females in this species are indeed relatively risk averse. More importantly, the experiment also shows that individuals vary in their risk aversion depending on local population size, in a manner predicted from life-history theory. Then it is reviewed how several important aspects of the mating system in this species are best interpreted as results of conservative, risk-averse female behaviour. Finally, these ideas are generalized to suggest how basic aspects of the mating system might differ between species with many reproductive events over the lifetime (e.g. many tropical reef fishes) v. species with few reproductive opportunities (e.g. many temperate freshwater and marine fishes).     

Data Fusion Methods for Human Health Risk Assessment: Review and Application

The improved accessibility to data that can be used in human health risk assessment (HHRA) necessitates advanced methods to optimally incorporate them in HHRA analyses. This article investigates the application of data fusion methods to handling multiple sources of data in HHRA and its components. This application can be performed at two levels, first, as an integrative framework that incorporates various pieces of information with knowledge bases to build an improved knowledge about an entity and its behavior, and second, in a more specific manner, to combine multiple values for a state of a certain feature or variable (e.g., toxicity) into a single estimation. This work first reviews data fusion formalisms in terms of architectures and techniques that correspond to each of the two mentioned levels. Then, by handling several data fusion problems related to HHRA components, it illustrates the benefits and challenges in their application.     

A Probabilistic Analysis of Regional Mercury Impacts on Wildlife

We investigate the uncertainties associated with modeling the potential health effects on piscivorous animals of mercury released to the atmosphere. The multimedia modeling system combines an atmospheric fate and transport model, an aquatic cycling model, and a terrestrial food web model. First, the modeling system is used to calculate point values of the animals' hazard quotients (i.e., measures of toxic dose). Next, we use a simplified version of the modeling system to conduct a probabilistic analysis for the Great Lakes region that takes into account input uncertainty, variability, and uncertainty and variability combined. The use of two different software packages for the combined uncertainty/variability analysis led to similar results except for high values (>90th percentile) where some differences were evident. A sensitivity study was performed on the combined uncertainty and variability analysis. Regional variability caused more than 70% of the variance in the results, with the fish bioaccumulation factor accounting for the majority of the variability. The major sources of uncertainty were the speciation of the mercury emissions, the lake pH, and the sediment burial rate.