The Importance of Type II Error and Falsifiability

Aim. Before intergovernmental consensus under the Rio Declaration in 1992, ignorance of type I errors had been disfavoured in science. However, the Precautionary Principle (PP) counsels the avoidance of type II errors, rather than of type I errors. We need a new academic code for the PP. Material and methods. The risk of extinction has usually been evaluated based on conservative estimates of the present population size. I define the weight of evidence as the extinction risk of Japanese vascular plants based on unbiased estimates. Catch quotas in the fisheries are usually decided by precautionary approach. I calculate the long-term yield and risk of stock collapse under a simple stock dynamics model. Results. The weight of evidence depends on the frequency of grids with size unknown. In a few plant species, rankings based on conservative estimates have differed from rankings based on unbiased estimates. In fishery management, a catch quota based on a precautionary approach proved neither sufficient nor necessary to avoid stock collapse. The precautionary approach is one of the reasons that prevent us from maximizing a sustainable yield. Conclusions. We need to clarify the endpoint of risks, and check whether it is necessary to adopt a PP. We can obtain the weight of evidence that is measured under unbiased estimates, while the risk based on a PP is measured under conservative estimates.     

Are all distributions of risk with the same 95thpercentile equally acceptable?

When evaluating a probabilistic health risk assessment, say at a hazardous waste site, risk managers need a risk management policy that distinguishes an acceptable distribution of risks to individuals in a population from an unacceptable one. If a risk manager decides that the distribution of risk for the status quo is unacceptable, then a risk assessor needs a way to compute cleanup targets, i.e., the risk assessor needs a policy statement against which to estimate distributions of exposure point concentrations which, if engineered at a site, will achieve an acceptable distribution of risk. Some regulatory agencies base acceptability on whether the 95^th percentile of the risk distribution falls at or below a given value, without considering the behavior of the rest of the distribution. As regulatory agencies adopt risk management policies for use with probabilistic risk assessments, we recommend that they base their new policies on two simultaneously binding constraints‐one on an upper percentile and one on the arithmetic mean of the distribution of risk‐in addition to other non‐risk criteria.     

Which Effect Measure Should Be Used for Impact Assessment in a New Population Context?

One characteristic feature in impact assessment based on epidemiologic studies is the transfer of an exposure-response association into a new population context. The consequences of basing this estimation procedure either on relative effect measures (e.g., relative risks) or on measures on the difference scale (e.g., excess rate) were exemplary illustrated with two air pollution studies which quantified the association between lung cancer and PM₁₀ in cohorts with varying lung cancer incidence due to different smoking habits. This example showed that the type of measure chosen may markedly influence the result of an impact assessment, if the frequency of the disease of interest varies across different populations due to other risk factors than the one considered. Thus, it was concluded that whenever studies from different population contexts are pooled, careful considerations about the appropriate type of measure are required. In environmental health risk assessment with usually small risks and unspecific (i.e., multicausal) health endpoints, an excess rate-based approach may provide a more reliable and stable estimate than a relative risk based approach in many circumstances. Methodological details of an excess rate-based approach are presented in the paper.     

Is There a Role for Risk Assessment within Precautionary Legislation?

Posing the question of whether the precautionary principle has a role in risk assessment effectively constrains any debate of the issue within a framework predicated on the assumption that application of risk assessment is inevitable in the formulation of regulatory decisions. The question can equally validly be expressed in terms of whether there is a role for risk assessment in the formulation of precautionary legislation. This allows the debate then to turn on consideration of two questions: Firstly, does the precautionary principle have a role in policy development? and secondly, is this role consistent and compatible with a risk based approach to regulation? When recast in these terms, a more holistic comparison of the aims and objectives of both approaches and of their relative power in the formulation of regulation becomes possible. This leads to the conclusion that the precautionary principle is, when defined and applied correctly, scientifically more robust than risk assessment. Precautionary approaches utilize scientific information and conform robustly to a scientific process but also explicitly incorporate indeterminacies into the decision making framework. Moreover, the precautionary principle when applied to environmental regulation, is more likely to lead to regulation consistent with global sustainability. On this premise, this paper argues that risk based approaches are essentially incompatible with approaches based on the precautionary paradigm, and that of the two, risk assessment is more likely to lead to unsustainable underprotection of the environment.     

The Precautionary Principle in Practice: Applying the Ashford Framework to Technological Risk

The precautionary principle reflects an old adage — an ounce of prevention is worth a pound of cure. Its four central components include: taking preventative action in the face of uncertainty; shifting the burden of proof to proponents of an activity; exploring a wide range of alternatives to possibly harmful actions; and increasing public participation in decision processes. Scholars in a range of fields have identified U.S. environmental laws, regulations, and decisions exhibiting precaution de facto. This study moves beyond the traditional treatments of the subject, the morass of definitions systematizing precaution into its basic elements. It poses a further question, within the current legal system and existing laws, how might the precautionary principle be implemented by modifying aspects of a statute? By applying a conceptual legal precautionary framework to a specific example of technological risk management, Washington State's energy facility siting statute, we reveal deficiencies in four areas: compensation issues; burden of proof; Type I or II error preferences; and systematic comparisons. Supplying these would, in all likelihood, ensure a more effective statute and process as well as an outcome consistent with legislative goals. However, were an explicit statement of the precautionary principle introduced, parties dissatisfied with an outcome would seek judicial review, and extensive litigation could counter the legislative mandate of abundant energy at a reasonable cost.     

A Food Scare a Day: Why Aren't We Better at Managing Dietary Risk?

Does the existence of food scares mean that we are bad at risk management? Not necessarily. New information brings new risks to the forefront or puts known risks into a new perspective. But in some cases food scares do indicate poor risk management. There are two key problems that explain why we are not better at managing dietary risks. The first is an imbalance of effort among the three components of risk analysis: we have Hummer risk assessment, Yugo risk management, and tricycle risk communication. The second problem is inadequate risk management. The cases of risks from mad cow disease and dioxins illustrate how the quality of risk management is affected by what we do not know well enough, what we know too well, and what we have not tried to find out. Better risk management requires a two-tier approach: (1) generate broad and shallow information on risks, health outcomes, incentives, options, benefits, and costs (Toyota Prius Hybrid risk management to be used everyday) and (2) generate narrow and in-depth information on high priority risks (Hummer risk assessment to be used sparingly).     

Risk Assessment Modeling: Beyond Exposure and Effects

Problem formulation, risk analysis, and risk characterization are, respectively, the design, estimation, and interpretation stages of risk assessment. Models traditionally have been used to estimate exposure and effects; now opportunities are growing to use them to design and interpret risk assessments as well. This could raise the level of rigor, reproducibility, and transparency in the risk assessment process, and improve the way information and expertise gets integrated to advise risk managers. The importance of good design and interpretation to the success of risk assessment and risk management, and the role of modeling in that success, is becoming increasingly apparent, but to date models are used only to a fraction of their potential. We provide two examples of the use of models to design and interpret risk assessments. The first looks at the use of models to better characterize risks by modeling uncertainties and exposure from offsite sources, and the second to forecast future risks of a new technology. Following the examples, we discuss some important obstacles to translating new modeling opportunities into practice. These include practical limits on the abilities of organizations to assimilate new tools and methods, and conceptual limits in the way people think about models.     

Human Health Risks of Selenium-Contaminated Fish: A Case Study for Risk Assessment of Essential Elements

A screening level human health risk assessment (HHRA) was applied to evaluate the human health implications of consuming selenium found in fish tissues collected downstream of coal mines in southeastern British Columbia, Canada. The study evaluated the potential for adverse human health effects associated with selenium, and considered known and potential benefits of selenium and fish ingestion. The results indicated that risks of selenosis due to consumption of selenium-contaminated fish in the region are negligible. Conclusions were strengthened by consideration of the potential benefits of selenium to human health, including: selenium essentiality for maintenance of good health; potential cancer prevention properties due to its role as an antioxidant; potential benefits for cardiovascular health; and other positive health benefits. The findings indicated that some aspects of the traditional framework for HHRA (e.g., application of safety factors to “err on the side of safety”) are inappropriate for the assessment of selenium-contaminated fish. Due to both deficiency and toxicity in the selenium dose-response relationship, application of compounding conservatism in risk assessment may lead to recommended intakes of fish that are contrary to the public health interest. The need for balancing risk types, for incorporating positive responses in risk assessments, and the linkage to the precautionary principle, are discussed.     

Precaution,threshold risk and public deliberation

It has been argued that the precautionary principle is incoherent and thus useless as a guide for regulatory policy. In a recent paper in Bioethics, Wareham and Nardini propose a response to the ‘precautionary paradox’ according to which the precautionary principle's usefulness for decision making in policy and regulation contexts can be justified by appeal to a probability threshold discriminating between negligible and non‐negligible risks. It would be of great significance to debates about risk and precaution if there were a sound method for determining a minimum probability threshold of negligible risk. This is what Wareham and Nardini aim to do. The novelty of their approach is that they suggest that such a threshold should be determined by a method of public deliberation. In this article I discuss the merits of Wareham and Nardini’s public deliberation method for determining thresholds. I raise an epistemic worry about the public deliberation method they suggest, and argue that their proposal is inadequate due to a hidden assumption that the acceptability of a risk can be completely analysed in terms of its probability.     

基于生态系统服务的城市化区域生态风险表征方法研究

快速城市化导致城市周边区域生态系统服务损失并引发生态风险。以多种类型的生态系统服务作为生态风险的评价终点,构建了基于服务价值量的城市化区域生态风险表征方法,以北京市为例对方法进行了应用,并进行了风险评价结果的不确定性分析和参数敏感性分析。案例研究显示2015年北京市生态风险总体处于低风险接近中等风险水平,低风险和极低风险区域面积占全市的50%以上,主要分布于北京市西部和北部,高风险和极高风险区域面积占20%左右,主要分布于中心城区。生态风险空间格局特征表明北京市城市区域的扩张造成周边区域生态系统服务的下降,导致生态风险水平的上升。研究提出的生态风险指数同生态系统服务当量因子间具有显著的线性关系,可用于估算生态系统服务价值。不确定性和参数敏感性分析表明生态风险指数计算结果变异较小,指数具有较高的可靠性。研究方法能够综合表征城市化区域的生态风险,定量表征结果便于决策者理解,具有应用于风险评价和管理实践的价值。     

Approaches to Ecological Risk Characterization and Management: Selecting the Right Tools for the Job

Chemical-specific hazard quotient (HQ) risk characterization in ecological risk assessment (ERA) can be a value-added tool for risk management decision-making at chemical release sites, when applied appropriately. However, there is little consensus regarding how HQ results can be used for risk management decision-making at the population, community, and ecosystem levels. Furthermore, stakeholders are reluctant to consider alternatives to HQ results for risk management decisions. Chemical-specific HQs risk characterization should be viewed as only one of several approaches (i.e., tools) for addressing ecological issues; and in many situations, other quantitative and qualitative approaches will likely result in superior risk management decisions. The purpose of this paper is to address fundamental issues and limitations associated with chemical-specific HQ risk characterization in ERA, to identify when it may be appropriate, to explore alternatives that are currently available, and to identify areas that could be developed for the future. Several alternatives (i.e., compensatory restoration, performance-based ecological monitoring, ecological significance criteria, net environmental benefit analysis), including their limitations, that can supplement, augment, or substitute for HQs in ERA are presented. In addition, areas of research (i.e., wildlife habitat assessment/landscape ecology/population biology, and field validated risk-based screening levels) that could yield new tools are discussed.     

Trends in Risk Assessment of Chemicals in the European Union

Current legislation in the European Union (EU) requires a risk assessment for industrial chemicals. The underlying procedures and paradigms of such EU risk assessment for new and existing chemicals are explained. The risk assessment is performed according to a harmonised methodology, laid down in the Technical Guidance Documents (TGD). Important new, technical risk assessment aspects covered in a recent revision round of the TGD are highlighted. The most prominent change in the environmental TGD part is the addition of the marine risk assessment, including a Persistent Bioaccumulation and Toxicity (PBT) assessment. In the human health part a significant change is the new data requirement for reproductive toxicity. The performance of both the risk assessment and the risk reduction phase of EU existing chemicals have been evaluated. An important conclusion was that our a priori knowledge on possible risks of chemicals is poor. The European Commission has recently launched a proposal (REACH) for drastically changing the risk management process of industrial chemicals in the EU. Major changes are a shift in responsibility from authorities to industry (including downstream users) for the safe use of chemicals, an acceleration of data collection for ‘non-assessed’ chemicals, and an authorization step for substances of very high concern.     

Precautionary Defaults—A New Strategy for Chemical Risk Management

In order to give adequate support to risk managers, new risk assessment methods should be developed that are (1) scientifically sound, (2) simplified, and (3) suited for precautionary risk management. In this Perspective we propose that the notion of a precautionary default can be a useful tool in the development of such methods. A precautionary default is a cautious or pessimistic assumption that is used in the absence of adequate information and that should be replaced when such information is obtained. Furthermore, we point out some promising research areas for the development of such indicators, viz. connections between chemical characteristics such as persistence and effect parameters, monitoring of contaminants in polar regions, monitoring of contaminants in breast milk, application of results from (human) toxicology in ecotoxicology and vice versa, (eco)toxicological test systems that are sensitive to effects on reproduction, and the application of bioinformatic methods to complex data, both in genomic research and in ecotoxicology. We conclude that precautionary decision-making does not require less science, but to the contrary it requires more science and improved communication between scientists and risk managers.     

美国、加拿大环境和健康风险管理方法

对目前美国和加拿大多个部门使用的风险评价与风险管理方法进行了全面回顾和综合分析,论述各种不同方法的特征,深入探讨各种管理方法的基础、利弊、使用经验,辨识环境、人类健康和职业健康风险综合方法中应该包含的要素,阐述风险管理目标的确定方法,以期为中国的环境风险管理提供经验。     

Safety,Risk and the Precautionary Principle: Rethinking Precautionary Approaches to the Regulation of Transgenic Plants

Operationalizing the Cartagena Protocol on Biosafety will require resolving disputes about the meaning of the term 'precautionary approach' in the treaty text. Although the terms precautionary approach and precautionary principle have been referred to in the regulation of transgenic plants for nearly a decade, no customary expectation of what actions either requires has developed. If specific obligations for regulators, regulated entities, or both are not established, compliance will be impossible. This essay examines various interpretations of the precautionary principle, discusses their shortcomings, and suggests a way to rethink the regulation of transgenic plants that focuses on genuine uncertainty. Transgenic plants with familiar phenotypes should be subject to considerably less regulatory scrutiny than those whose risks are genuinely unknown, or known to pose heightened risk.     

The Precautionary Preference: An American Perspective on the Precautionary Principle

The precautionary principle, a familiar constituent of international and European environmental law, has only very recently entered the vocabulary of domestic environmental policy debates in the United States. The question naturally arises what role such a principle should play in American law. By breaking down statements of the precautionary principle into distinct ele ments, one can more readily find ways in which U.S. law reflects the precau tionary principle. This analysis reveals that American environmental law con tains precautionary elements and goals in many and varied settings, from the management of natural ecosystems, to pollution control standards, to risk assessment methodology. However, the precautionary approach appears in a highly diluted or compromised form. With rare exceptions, U.S. law balances precaution against other considerations, most importantly cost. Therefore, while precautionary elements are firmly entrenched in U.S. environmental law, it is more accurate to say that it reflects a precautionary preference rather than the precautionary principle.     

Quantitative ecological risk assessment of accidental oil spills on ship routes nearby a marine national park in Brazil

Fernando de Noronha (FN) is a marine protected area off the coast of Brazil. The study of risks caused by nearby ship routes is new to authorities concerned with preserving FN. We identify nearby ship routes that cause FN to be potentially exposed to oil spills from tankers. A coral species is chosen as a bioindicator of the ecosystem's health, which aids quantitative approaches. We simulate oil leakage scenarios with pessimistic occurrence frequencies and corals' mortality in case of accident. A metapopulation coral model is integrated to quantify measures of ecological risk under the potential occurrence of accidental scenarios. The categorization of risk results according to the International Union for the Conservation of Nature quantitative criteria shows that risks are negligible. Due to the considerable uncertainty in the results, we propose a more conservative categorization of risks based not on total metapopulation extinction, but on half loss. As a result, risks were considered not acceptable. The presented methodology and results are useful in supporting authorities in their preservation efforts such as the prioritization of sources of hazard as well as selection of the best cost-effective conservation measures for maintaining good environmental health on a realistic budget, using this methodology as an exploratory tool.     

The Precautionary Principle in the Information Society

The Precautionary Principle aims to anticipate and minimize potentially serious or irreversible risks under conditions of uncertainty. Thus it preserves the potential for future developments. It has been incorporated into many international treaties and pieces of national legislation for environmental protection and sustainable development. However the Precautionary Principle has not yet been applied systematically to novel Information and Communication Technologies (ICTs) and their potential environmental, social, and health effects. In this article we argue that precaution is necessary in this field and show how the general principle of precaution can be put in concrete terms in the context of the information society. We advocate precautionary measures directed towards pervasive applications of ICT (Pervasive Computing) because of their inestimable potential impacts on society.