Dimensions of the Precautionary Principle

This essay attempts to provide an analytical apparatus which may be used for finding an authoritative formulation¹ of the Precautionary Principle. Several formulations of the Precautionary Principle are examined. Four dimensions of the principle are identified: (1) the threat dimension, (2) the uncertainty dimension, (3) the action dimension, and (4) the command dimension. It is argued that the Precautionary Principle can be recast into the following if-clause, containing these four dimensions: “If there is (1) a threat, which is (2) uncertain, then (3) some kind of action (4) is mandatory.” The phrases expressing these dimensions may vary in (a) precision and (b) strength. It is shown that it is the dimension containing the weakest phrase that determines the strength of the entire principle. It is suggested that the four-dimensional if-clause be used as an analytical apparatus in negotiations of the Precautionary Principle.     

Methodologic Implications of the Precautionary Principle: Causal Criteria

Applying the Precautionary Principle to public health requires a re-evaluation of the methods of inference currently used to make claims about disease causation from epidemiologic and other forms of scientific evidence. In current thinking, a well-established, near-certain causal relationship implies highly consistent statistically significant results across many different studies, large relative risk estimates, extensive understanding of biological mechanisms and dose-response relationships, positive prevention trial results, a clear temporal relationship between cause and effect, and other conditions spelled out in terms of the widely-used causal criteria. The Precautionary Principle, however, states that preventive measures are to be taken when cause and effect relationships are not fully established scientifically. What evidentiary conditions, as reflected in the causal criteria, will be certain enough to warrant precautionary preventive action? This paper argues that minimum evidentiary requirements for causation need to be articulated if the Precautionary Principle is to be successfully incorporated into public health practice. Two precautionary changes to criteria-based methods of causal inference are examined: reducing the number of criteria and weakening the rules of inference accompanying the criteria. Such changes point in the direction of identifying minimum evidentiary conditions, but would be premature without better understanding how well current methods of causal inference work.     

Major Concerns in Developing Countries: Applications of the Precautionary Principle in Ecuador

Ecuador is a Latin American country with one of the biggest biodiversities. At the same time, social and environmental problems are also big. Poverty, political and social problems as well as questions like old transport systems, imported hazards from industrialized countries and lack of information and weak health care systems are the framework of this situation. The most common problems are the use of heavy metals in many activities without safety and health protection, a low technological oil production during two decades, intensive use of pesticides in agriculture, and some other chemical risks. A limited capacity to develop prevention strategies, reduced technical and scientific skills, and the absence of a reliable information and control system, lead to a weak response mechanism. The Precautionary Principle could help to stimulate prevention, protection and to have a new tool to improve the interest in environment and health problems. Reinforcing the presence of international organizations like WHO and ILO, establishing bridges among scientific organizations from developed and developing countries and introducing the Precautionary Principle in the legislation and daily practices of industry and agriculture could lead to an improvement in our environment and health.     

Risk Communication and the Precautionary Principle

The perception of risks for environment and health deriving from globalization processes and an uncontrolled use of modern technologies is growing everywhere. The greater the capacity of controlling living conditions, the larger is the possibility of misusing this power. In environmental and occupational health research we tend to reduce the complexity of the observed phenomena in order to facilitate conclusions. In social and political sciences complexity is an essential element of the context, which needs to be continuously considered. The Precautionary Principle is a tool for facing complexity and uncertainty in health risk management. This paper is aimed at demonstrating that this is not only a problem of technical risk assessment. Great attention should also be paid to improve risk communication. Communication between the stakeholders (experts, decision makers, political and social leaders, media, groups of interest and people involved) is possibly the best condition to be successful in health risk management. Nevertheless, this process usually runs up against severe obstacles. These are not only caused by existing conflicts of interest. Differences in values, languages, perceptions, resources to have access to information, and to express one's own point of view are other key aspects.     

The Precautionary Principle,Epidemiology and the Ethics of Delay

Ethics tells us: do good and do no harm and invokes the norms of justice, equity and respect for autonomy in protecting and promoting health and well-being. The Precautionary Principle, a contemporary re-definition of Bradford Hill's case for action, gives us a common sense rule for doing good by preventing harm to public health from delay: when in doubt about the presence of a hazard, there should be no doubt about its prevention or removal. It shifts the burden of proof from showing presence of risk to showing absence of risk, aims to do good by preventing harm, and subsumes the upstream strategies of the DPSEEA (Driving Forces Pressure Stress Exposure Effect Action) model and downstream strategies from molecular epidemiology for detection and prevention of risk. The Precautionary Principle has emerged because of the ethical import of delays in detection of risks to human health and the environment. Ethical principles, the Precautionary Principle, the DPSEEA model and molecular epidemiology all imply re-emphasizing epidemiology's classic rôle for early detection and prevention. Delays in recognizing risks from past exposures and acting on the findings (e.g., cigarette smoking and lung cancer, asbestos, organochlorines and endocrine disruption, radiofrequency, raised travel speeds) were examples of failures that were not only scientific, but ethical, since they resulted in preventable harm to exposed populations. These may delay results from, among other things, external and internal determinants of epidemiologic investigations of hazard and risk, including misuse of tests of statistical significance. Furthermore, applying the Precautionary Principle to ensure justice, equity, and respect for autonomy raises questions concerning the short-term costs of implementation to achieve long-term goals and the principles that guide compensation.     

Implementing the Precautionary Principle: Rigorous Science and Solid Ethics

The Precautionary Principle came out of European efforts to clean-up and protect marine ecosystems in the 1980s. Since then, several North American activities have elaborated on this approach in U.S. environmental programs. Unfortunately, US organizations and agencies have not developed strategies and guidelines for implementing the Precautionary Principle in either statutory or voluntary environmental programs. Recent interest in this approach from some members of the scientific, non-profit, and regulatory communities highlights the need to understand the history and conceptual basis of the Precautionary Principle. In this paper we address several of these issues. First, we summarize the pertinent US history of the Precautionary Principle. Next, we describe the scientific framework for the principle. Finally, we make the case that this provides unique opportunities for scientists to obtain meaning in their work by fulfilling what has been called the new Social Contract.     

The Precautionary Principle and Statistical Approaches to Uncertainty

The central challenge from the Precautionary Principle to statistical methodology is to help delineate (preferably quantitatively) the possibility that some exposure is hazardous, even in cases where this is not established beyond reasonable doubt. The classical approach to hypothesis testing is unhelpful, because lack of significance can be due either to uninformative data or to genuine lack of effect (the Type II error problem). Its inversion, bioequivalence testing, might sometimes be a model for the Precautionary Principle in its ability to ‘prove the null hypothesis.’ Current procedures for setting safe exposure levels are essentially derived from these classical statistical ideas, and we outline how uncertainties in the exposure and response measurements affect the No Observed Adverse Effect Level (NOAEL), the Benchmark approach and the “Hockey Stick” model. A particular problem concerns model uncertainty: usually these procedures assume that the class of models describing dose/response is known with certainty; this assumption is however often violated, perhaps particularly often when epidemiological data form the source of the risk assessment, and regulatory authorities have occasionally resorted to some average based on competing models. The recent methodology of Bayesian model averaging might be a systematic version of this, but is this an arena for the Precautionary Principle to come into play?     

Adjusting Scientific Practices to the Precautionary Principle

In most discussions of the Precautionary Principle, it is implicitly assumed that we are at a point near risk neutrality, so that the principle aims at moving away from risk neutrality in the direction of more risk-averse behavior. In this paper it is argued that actual decision-making in environmental issues is often on the opposite, risk taking, side of risk neutrality. A minimal version of the Precautionary Principle consists in moving from such a position in the direction of risk neutrality. Some methods for achieving this are discussed, such as less consensus-seeking scientific procedures, requirements that scientific committees identify less probable but serious scenarios, interpretative presumptions, and supplementary statistical measures for type II errors.     

The Precautionary Principle,Science and Human Health Protection

As technology advances rapidly, so do applications with potential adverse implications on human health. The possible threats include risks that can be substantial, far-reaching and irreversible, and currently available methods of investigation, designed to deal with direct exposure-disease associations, are not always suitable. Growing interest is being paid to health effects that may be the consequence of distal, “upstream” determinants. Considering the complex chain of events that links such determinants with health can be extremely difficult, and exposes severe limitations in science. Thus, there is often a mismatch between what is known and what would be required to inform rational, evidence-based decision making, which is increasingly called for. It has become apparent how production and use of scientific evidence in decision making must be accompanied by precaution, especially in those circumstances, more and more common in recent times, where there is an uncertain possibility that serious health consequences might take place. Several cautionary approaches have been proposed, but the Precautionary Principle (PP) has been the object of especially intense debate in recent years. Developed in the field of environmental health, the PP has been clarified, and has been applied or called for in several instances in public health. Although a unique definition is not available, the principle has been characterised, and criteria for its application have been proposed. However, many questions remain open on general as well as specific issues. In this paper, we address some of the questions that are relevant for the PP to support rational decision making in environment and health and more in general to strengthen its contribution towards human health protection.     

The Precautionary Principle and Chemical Regulation in the U.S.

Although the statutory goals for chemical regulation are consistent with the precau tionary principle, the current U.S. regulatory program governing synthetic chemicals generally adopts little precautionary controls for the manufacture of most chemicals. For the vast majority of chemicals in use, current law places the burden of producing scientific evidence on the regulatory agency, which actually may serve to discourage companies from testing the safety of their chemicals, since the results could then be used against them in regulatory proceedings. By contrast, for a small subset of chemicals — new chemicals that belong to suspect categories — regulatory controls are quite precautionary. The result of this schizophrenic approach to chemical regulation is a regulatory system that is characterized by the absence of preventative regulation for most existing chemicals, an inequitable barrier to entry for newer safer chemicals, and a lack of information upon which to understand the safety of most chemicals in the U.S. Informal reforms of the current regulatory program are already underway to provide a more consistent and precautionary approach to chemical regulation, although to fully advance the dual goals of regulatory consistency and precaution in the regulation of chemicals, legislative action is necessary.     

Some Legal Implications of the Precautionary Principle: Improving Information-Generation and Legal Protections

In creating a legal agenda in service of the Precautionary Principle, the idea of precaution requires more inventories and better monitoring of the condition of public and workforce health than at present. Rectifying problems of the past to better serve the aims of precaution will require more affirmative pre-market and much more post-market knowledge-generation by those who create and use potentially toxic substances, improved pre-market review of substances, better responses to early warnings, and quicker protective post-market responses to evidence of toxicity. This paper conceptualizes a model pre-market screening law to highlight the need for primary prevention measures and to provide philosophic ideas for improving post-market laws and addressing a large universe of existing substances that have been poorly characterized. Although retrospective personal injury law does not have good mechanisms for precaution, even this can be more protective than it is at present by enhancing causes of action for reasonable fear of disease and medical monitoring, and moving to create new causes of action for failure to develop and disseminate information needed to assess the toxicity of substances.     

Roles of positive and negative feedback in biological systems

We discuss the influence of positive and negative feedback on the stability of a system, which is not clear-cut, and involves complex, mathematical problems. We show in particular that positive feedback can have a stabilising effect on some systems. We also point out the role that positive feedback plays in the digital treatment of signals required by cellular signalling, drawing on analogies from electronics, and the role that negative feedback plays in making a system robust against alteration of its parameters. Both positive and negative feedback can be seen as important enhancers of the properties of biological systems.     

Implications of the Precautionary Principle: Is it a Threat to Science?

Scientific research is of proven value to protecting public health and the environment from current and future problems. We explore the extent to which the Precautionary Principle is a threat to this rôle for science and technology. Not surprisingly for a relatively simple yet still incompletely defined concept, supporters of the Precautionary Principle come from different viewpoints, including a viewpoint that is at least uneasy with the rôle of science, and particularly its use in risk assessment. There are also aspects of the Precautionary Principle that inherently restrict obtaining and using science. The Hazardous Air Pollutant (HAP) provisions in the US Clean Air Act Amendments are an example of the Precautionary Principle, which both shifted the burden of proof so that the onus is now on showing a listed compound is harmless, and required maximum available control technology (MACT) instead of a primarily risk-based approach to pollution control. Since its passage in 1990 there has been a decrease in research funding for studies of HAPs. Other potential problems include that once MACT regulations are established, it may be difficult to develop new technological approaches that will further improve air pollution control; that by treating all regulated HAPs similarly, no distinction is made between those that provide a higher or lower risk; and that there is a perverse incentive to use less well studied agents that are not on the existing list. As acting on the Precautionary Principle inherently imposes significant costs for what is a potentially erroneous action, additional scientific study should be required to determine if the precautionary action was successful. If we are to maximize the value of the Precautionary Principle to public health and the environment, it is crucial that its impact not adversely affect the potent preventive rôle of science and technology.     

On Being Careful What We Wish for: Some Difficulties with Operationalizing the Precautionary Principle

An important part of the Precautionary Principle is that taking action is justified for protecting public health even when there is some scientific uncertainty. We examine here the two components of this central feature of the precautionary principle, scientific uncertainty and decision making. In order to operationalize the principle we should examine the consequences of its decision rules and how they perform under various conditions. The performance of decision rules in disease screening is measured by the sensitivity and specificity of the rule, but the consequences for the patient are given by the positive and negative predictive values, determined not only by the performance of the rule by the prevalence of the disease in the population. We look at positive and negative predictive value of the Precautionary Principle from the standopoint of the costs to one or other parts of society, show that the usual rule which tends to maximize sensitivity in favor of specificity may have unexpected consequences, and demonstrate that it is sometimes possible to trade sensitivity and specificity off against each other in a way the improves both positive and negative predictive value, or worse, degrades both.We conclude by asking if certain strategies are better for one or the other kinds of uncertainty.     

Multidisciplinary Research: Strategies for Assessing Chemical Mixtures to Reduce Risk of Exposure and Disease

The Precautionary Principle is founded on the use of comprehensive, coordinated research to protect human health in the face of uncertain risks. Research directed at key data gaps may significantly reduce the uncertainty underlying the complexities of assessing risk to mixtures. The National Institute of Environmental Health Sciences (NIEHS) has taken a leadership rôle in building the scientific infrastructure to address these uncertainties. The challenge is to incorporate the objectives as defined by the Precautionary Principle with the knowledge gained in understanding the multifactorial nature of gene-environment interactions. Through efforts such as the National Center for Toxicogenomics, the National Toxicology Program, and the Superfund Basic Research Program, NIEHS is translating research findings into public health prevention strategies using a 3-pronged approach: (1) identify/evaluate key deviations from additivity for mixtures; (2) develop/apply/link advanced technologies and bioinformatics to quantitative tools for an integrated science-based approach to chemical mixtures; (3) translate/disseminate these technologies into useable, practical means to reduce exposure and the risk of disease. Preventing adverse health effects from environmental exposures requires translation of research findings to affected communities and must include a high level of public involvement. Integrating these approaches are necessary to advance understanding of the health relevance of exposure to mixtures.     

A Comparison of Three Weight-of-Evidence Approaches for Integrating Sediment Contamination Data within and Across Lines of Evidence

Multiple lines of evidence (LOE) are often considered when examining the potential impact of contaminated sediment. Three strategies are explored for combining information within and/or among different LOE. One technique uses a multivariate strategy for clustering sites into groups of similar impact. A second method employs meta-analysis to pool empirically derived P-values. The third method uses a quantitative estimation of probability derived from odds ratios. These three strategies are compared with respect to a set of data describing reference conditions and a contaminated area in the Great Lakes. Common themes in these three strategies include the critical issue of defining an appropriate set of reference/control conditions, the definition of impact as a significant departure from the normal variation observed in the reference conditions, and the use of distance from the reference distribution to define any of the effect measures. Reasons for differences in results between the three approaches are explored and strategies for improving the approaches are suggested.     

三种手术入路显露男性后尿道的比较（英文）

目的：评价经耻骨上、耻骨下及会阴三种手术入路暴露尿道膜部的优劣。方法：对35具成年男性尸体标本解剖,测量并比较耻骨上缘中点（A）、耻骨下缘中点（B）及会阴部两坐骨结节连线中点（c）分男11到尿道球膜部连接处（D）、前列腺尖（E）及膀胱颈（F）的距离及相关角度;对另20具成年男性尸体标本分别经3种手术入路显露后尿道,标记可能损伤的组织器官并评分。结果：AD=（6．5±0．5）cm,BD=（2．2±0．5）cm,CD=（3．4±0．6）cm,其中BD〈CD〈AD（P〈0．05,SNK法）;AE=（6．6±0．5）cm,BE=（3．0±0．5）cm,CE=（4．4±0．7）cm,其中BE〈CE〈AE（P〈0．05,SNK法）;AF=（5．7±0．6）cm,BF=（4．5±0．5）cm,CF=（6．5±0．6）cm,其中BF〈AF〈CF（P〈0．05,SNK法）。各点连线所成角度中,ZEAD（仅。）=（9．3±2．0）。∠EBD（α2）=（17．4±3．8）°,ZECD（α3）=（9．2±1．6）°,其中α1与α2有显著性差异（P〈0．05,t=11．1）,α3与α2有显著性差异（P〈0．05,t=-12．1）,α1与α3无显著性差异（P〉O．05,t=-0．13）;∠FAE（β1）=（22．7±2．6）°,∠FBE（β2）=（32．9±6．4）°,∠FCE（β3）=（15．0±3．2）°,其中β2〉β1〉β3（P〈0．05,SNK法）。经耻骨上入路损伤评分为13分,经耻骨下为18分,经会阴为15分。结论：暴露从优到劣依次为经耻骨下、经耻骨上、经会阴;损伤从大到小依次为经耻骨下、经会阴、经耻骨上部分。     

Incorporating Science,Technology, Fairness,and Accountability in Environmental,Health, and Safety Decisions

The Precautionary Principle is in sharp political focus today because (1) the nature of scientific uncertainty is changing and (2) there is increasing pressure to base governmental action on more “rational” schemes, such as cost-benefit analysis and quantitative risk assessment, the former being an embodiment of ‘rational choice theory’ promoted by the Chicago school of law and economics. The Precautionary Principle has been criticized as being both too vague and too arbitrary to form a basis for rational decision making. The assumption underlying this criticism is that any scheme not based on cost-benefit analysis and risk assessment is both irrational and without secure foundation in either science or economics. This paper contests that view and makes explicit the rational tenets of the Precautionary Principle within an analytical framework as rigorous as uncertainties permit, and one that mirrors democratic values embodied in regulatory, compensatory, and common law. Unlike other formulations that reject risk assessment, this paper argues that risk assessment can be used within the formalism of tradeoff analysis—a more appropriate alternative to traditional cost-benefit analysis and one that satisfies the need for well-grounded public policy decision making. This paper will argue that the precautionary approach is the most appropriate basis for policy, even when large uncertainties do not exist, especially where the fairness of the distributions of costs and benefits of hazardous activities and products are a concern. Furthermore, it will offer an approach to making decisions within an analytic framework, based on equity and justice, to replace the economic paradigm of utilitarian cost-benefit analysis.     

Probabilistic Risk Assessment and Risk Mapping of Sediment Metals in Sydney Harbour Embayments

Sediment metal concentrations in embayments of Sydney Harbour, acquired from the literature and from samples collected for this study, were used to generate contaminant probability density distributions using AQUARISK. The sediment metal concentrations often exceeded Australia's interim sediment quality guidelines. Similarly, estuarine spiked sediment toxicity test literature provided adverse biotic effects concentration data to generate species sensitivity distributions using AQUARISK. Although the harbor is subject to other inorganic and organic contamination, we have used sediment metals to demonstrate an approach for ecological risk mapping and environmental management prioritization. Sufficient spiked sediment toxicity test data were found for only three metals—Cd, Cu, and Zn—and some tests were likely to overestimate toxicity. The estimates of the hazardous concentration to 5% of species (the 50th percentile of the 95% species protection level) were 5, 12, and 40 mg/kg DW of total sediment metal for Cd, Cu, and Zn, respectively. These values were generally low when compared with the interim sediment quality guidelines due to the overestimation of toxic effects in the literature data. The parameters for the species sensitivity distributions have been combined with the measured sediment metal concentrations in Homebush Bay to generate risk maps of the estimated species impact for each metal as well as for all three metals collectively assuming proportional additivity. This has demonstrated the utility of comparing contaminants on a consistent scale—ecological risk.     

Mechanism of interaction between electromagnetic fields and living organisms

Based on nonlinear phenomena of biophoton emission observed in the past, an interference model concerning with the mechanism of interaction between living organisms and electromagnetic fields was raised. Caused by biological nonlinearly polarizable double layer, destructive interference of incoming and reflected waves establishes in the outside. As a consequence, in the inside constructive interference takes place at the same time. The interference patterns may play an important role in biological self organization and in biological functions. We investigate the boundary conditions necessary for explaining these non-linear optical effects in terms of the phase conjugation. It turns out that there are solutions of the Maxwell equations which satisfy destructive interference of biophotons in agreement with the experimental results. Necessary provisions are nonlinearly polarizable optically active double layers of distances which are small compared to the wavelength of light. In addition, they have to be a