Ecological Risk Assessment and the Precautionary Principle

The Precautionary Principle, generated during the late 1980s as a unifying principle for regulating discharge of hazardous material into the North Sea, has been broadened to include a shifting of the burden of proof to the proponent of a proposed activity, adoption of a more holistic assessment process, and encompassing all environmental management decisions, not just pollution prevention activities. We argue that the Precautionary Principle remains a management philosophy, not a substitute for risk assessment. Risk assessment is a tool for organizing information used in environmental management decisions. However, increasing attention to reducing the Type II error of risk assessment studies would significantly reduce the skepticism with which many view the risk assessment process. A critical review of default assumptions used in risk assessments, inclusion of indirect effects within an ecologically relevant spatial/temporal framework, and better communication between risk assessors and risk managers also would enhance the acceptability of the process. Risk assessment can provide a sound basis for management decisions regardless of the underlying philosophies of environmental conservation or utilitarianism, but only if the inherent biases in the risk assessment assumptions are acknowledged explicitly throughout the assessment and management processes.     

The Precautionary Principle: Implications for Risk Management Strategies

The European Commission has published a Communication on the Precautionary Principle and a White Book on Governance. These provide us (as research civil servants of the Commission) an institutional framework for handling scientific information that is often incomplete, uncertain, and contested. But, although the Precautionary Principle is intuitively straightforward to understand, there is no agreed way of applying it to real decision-making. To meet this perceived need, researchers have proposed a vast number of taxonomies. These include ignorance auditing, type one-two-three errors, a combination of uncertainty and decision stakes through post-normal science and the plotting of ignorance of probabilities against ignorance of consequences. Any of these could be used to define a precautionary principle region inside a multidimensional space and to position an issue within that region. The rôle of anticipatory research is clearly critical but scientific input is only part of the picture. It is difficult to imagine an issue where the application of the Precautionary Principle would be non-contentious. From genetically-modified food to electro-smog, from climate change to hormone growth in meat, it is clear that: 1) risk and cost-benefit are only part of the picture; 2) there are ethical issues involved; 3) there is a plurality of interests and perspectives that are often in conflict; 4) there will be losers and winners whatever decision is made. Operationalisation of the Precautionary Principle must preserve transparency. Only in this way will the incommensurable costs and benefits associated with different stakeholders be registered. A typical decision will include the following sorts of considerations: 1) the commercial interests of companies and the communities that depend on them; 2) the worldviews of those who might want a greener, less consumerist society and/or who believe in the sanctity of human or animal life; 3) potential benefits such as enabling the world's poor to improve farming; 4) risks such as pollution, gene-flow, or the effects of climate change. In this paper we will discuss the use of a combination of methods on which we have worked and that we consider useful to frame the debate and facilitate the dialogue among stakeholders on where and how to apply the Precautionary Principle.     

Cost-Benefit Analysis in a Regulatory Setting

The purpose of requiring cost-benefit analysis is to produce better out-comes from regulatory processes. If implemented well, cost-benefit analysis and risk assessment can produce improvements at several levels, by encouraging regulators to consider unintended effects of regulations and thereby avoid making things worse, to find the least burdensome approach to a goal, and to balance the pluses and minuses involved in choosing a goal. Whether these improvements will occur depends in large part on how cost-benefit analysis is implemented. Guidelines for conducting cost-benefit analysis and procedures for considering evidence on costs and benefits play an important role. This article describes how guidelines and rules of process can affect outcomes, and the issues that cost-benefit guidelines need to cover. Guidelines can affect the bias of a regulatory process toward one set of stakeholders or another, make outcomes more predictable, define the information needed for decisions, and provide a basis for legal challenges. The questions that guidelines should address include: what are costs and benefits, what constitutes good economics, what are standards of proof, how should unquantified costs and benefits be treated, how should uncertainties of cost-benefit estimates be dealt with, and how should alternatives be generated? The article concludes with recommen dations about how the adoption of cost-benefit analysis can be made most effective and beneficial in regulatory processes.     

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?     

Topics in Hazard Identification: Oxygenated Fuels,Safety Assessment,Hematological Neoplasms,and the Precautionary Principle

Hazard identification is based upon the second “law” of toxicology, the specificity of toxic effects caused by a chemical agent. Specificity reflects the differential reactivity inherent in chemical structure and in the biological niches in which chemicals interact. Just as Paracelsus is identified with the first “law” of toxicology, the dose makes the poison, Paré, a century French surgeon, should be credited with an early formulation of the second “law” of toxicology, the specificity of chemical effects. I discuss a number of aspects of hazard identification, including issues related to oxygenated fuels, to routine safety assessment, to the interpretation of hematological neoplasms and to the Precautionary Principle.     

Commentary: Barriers and Opportunities to Changing the Research Agenda to Support Precaution and Primary Prevention

Conceptual research to define the Precautionary Principle and its rôle in science, science policy, and public health is making substantial progress. In September 2001, participants at the International Summit on Science and the Precautionary Principle developed a vision for science to address the complexity of contemporary health risks in a way that could lead to more precautionary, preventive decisions under uncertainty. Its components include: (1) a more effective linkage between research on hazards and research on primary prevention; (2) increased use of interdisciplinary approaches including better integration of qualitative and quantitative data; (3) innovative methods for analyzing cumulative and interactive effects, populations and systems and vulnerable sub-populations; (4) systems for continuous monitoring to avoid unintended consequences of actions and to identify early warnings of risks; (5) more comprehensive techniques for analyzing and communicating hazards and uncertainties; and (6) a more dynamic interface between science and policy. This article addresses barriers and opportunities to the practical application of this vision for science. Scientists in many fields have recognized the need for innovative approaches and tools to address increasingly complex, uncertain risks of a global scale. While opportunities to apply precautionary concepts in the research agenda exist, public health scientists must be cognizant of current and emerging barriers in the research agenda that balance the research focus on characterizing proximate causal mechanisms of disease, to the detriment of research and policy to support primary prevention.     

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.     

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.     

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.     

Probabilistic Environmental Risk Assessment for Dibutylphthalate (DBP)

In the risk assessment methods for new and existing chemicals in the European Union (EU), environmental “risk” is characterized by the deterministic quotient of exposure and effects (PEC/PNEC). From a scientific viewpoint, the uncertainty in the risk quotient should be accounted for explicitly in the decision making, which can be done in a probabilistic risk framework. To demonstrate the feasibility and benefits of such a framework, a sample risk assessment for an existing chemical (dibutylphthalate, DBP) is presented in this paper. The example shows a probabilistic framework to be feasible with relatively little extra effort; such a framework also provides more relevant information. The deterministic risk quotients turned out to be worst cases at generally higher than the 95th percentile of the probability distributions. Sensitivity analysis proves to be a powerful tool in identifying the main sources of uncertainty and thus will be effective for efficient further testing. The distributions assigned to the assess ment factors (derivation of the PNEC) dominate the total uncertainty in the risk assessment; uncertainties in the release estimates come second. Large uncertainties are an inherent part of risk assessment that we have to deal with quantitatively. However, the most appropriate way to characterise effects and risks requires further attention. Recommendations for further study are identified.     

Comparison of Bayesian-Utilitarian and Maximin Principle Approaches

The Precautionary Principle implies the adoption of a set of rules aimed at avoiding possible future harm associated with suspected, but not ascertained, risk factors. Several philosophical, economical and societal questions are implied by precaution-based public health decision making. The purpose of the present paper is to specify the scope of the principle examining the notion of uncertainty involved, and the implication of different approaches to the decision making process. The Bayesian-utilitarian approach and the approach based on the maximin principle will be considered, and the different meaning of prudence in the two settings will be discussed. In a Bayesian-utilitarian approach the small number of attributable cases will end up in a low average expected value, easily regarded as acceptable in a cost-benefit analysis. In a maximin approach, on the other hand, the issue will be to consider the high etiologic fraction of a rare disease in the highest category of exposure. In the light of the aforementioned cautions in interpretation, the core difference between the two approaches has to do with the choice between averaging knowledge or equitably distributing technological risks.     

The precautionary principle: a double edged sword?

There is no doubt that the introduction of quality system principles and regulation to blood and tissue services in the 1990’s has brought about significant improvements in the control of processes and the quality of products being released for patient care. But, as regulation extends into new areas of cellular and tissue therapy, it is perhaps time to review the regulatory paradigm within which we work, and the principles that underpin it. At what point do the costs of regulation exceed the benefits to be gained? At what point to regulations cease to yield measurable benefits to patient care and safety at all, but instead become simply a burden on service providers and businesses, and ultimately the community as a whole? And is there a point at which regulation actually compromises patient care and safety, or the development of new technologies? In the early stages of regulation, there is demonstrable cost-benefit as assessed by product quality and patient outcomes. However, there is inevitably a “law of diminishing returns”, whereby the degree of improvement that can be achieved decreases and the cost of achieving that benefit increases. What has not yet been determined is whether, as regulations and regulators become more precise and more demanding, there remains a measurable net cost benefit over time, or whether there is a point at which the cost of further improvement matches, or even exceeds, the benefits to be gained. A key underpinning of the regulatory philosophy is the “Precautionary Principle”. This paper will focus on the application of the Precautionary Principle in the area of blood and tissues, which encompasses the burgeoning field of cellular therapies.     

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.     

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,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.     

Commentary: The Rôle of Toxicology in Prevention and Precaution

Advocates of the Precautionary Principle have recently called for a “new science” to support the goals of precaution-based environmental and occupational health policy. While much attention has been given to epidemiology, the evidentiary science most relevant to precaution, or prevention, is toxicology. Opportunities for enhancing the rôle of toxicology in public policy must consider current biases in the field. Thus, rather than a “new science,” advocates for change should focus upon ensuring that current scientific methods are appropriate and that interpretations of scientific data are accurate.     

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.     

Research Implications of Science-Informed,Value-Based Decision Making

In ‘Hard’ science, scientists correctly operate as the ‘guardians of certainty,’ using hypothesis testing formulations and value judgements about error rates and time discounting that make classical inferential methods appropriate. But these methods can neither generate most of the inputs needed by decision makers in their time frame, nor generate them in a form that allows them to be integrated into the decision in an analytically coherent and transparent way. The need for transparent accountability in public decision making under uncertainty and value conflict means the analytical coherence provided by the stochastic Bayesian decision analytic approach, drawing on the outputs of Bayesian science, is needed. If scientific researchers are to play the rôle they should be playing in informing value-based decision making, they need to see themselves also as ‘guardians of uncertainty,’ ensuring that the best possible current posterior distributions on relevant parameters are made available for decision making, irrespective of the state of the certainty-seeking research. The paper distinguishes the actors employing different technologies in terms of the focus of the technology (knowledge, values, choice); the ‘home base’ mode of their activity on the cognitive continuum of varying analysis-to-intuition ratios; and the underlying value judgements of the activity (especially error loss functions and time discount rates). Those who propose any principle of decision making other than the banal ‘Best Principle,’ including the ‘Precautionary Principle,’ are properly interpreted as advocates seeking to have their own value judgements and preferences regarding mode location apply. The task for accountable decision makers, and their supporting technologists, is to determine the best course of action under the universal conditions of uncertainty and value difference/conflict.     

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.