In this Article we take a cautionary approach to the Precautionary Principle. We argue that the hazardous air pollutant provisions of the 1990 Clean Air Act Amendments provide an example of the Precautionary Principle incorporated into U.S. environmental legislation. Evaluating the outcome thus far leads us to the conclusion that utilizing the Precautionary Principle as a basis for legislation can be problematic to public-health goals. Our reasons for this conclusion include the potential inhibition of the development of more effective air pollution control technology once the regulations have been written, the inhibitory effect on further research and the demonstration of health benefit, and the loss of focus on those hazardous air pollutant compounds and sources that provide the greatest likelihood for toxicity and misplaced focus on individual rather than population exposure--a loss of focus that undermines the public-health basis of the Clean Air Act. A clear understanding of its potential negative aspects is needed to maximize the many potential benefits of the Precautionary Principle to public-health and environmental laws and regulations.
Many advocates of more expansive environmental and public-health control measures urge prolific use of the Precautionary Principle as a rationale for regulatory intervention. One of the earliest and substantial formulations of the Precautionary Principle was adopted in the 1992 Rio Declaration: "Nations shall use the precautionary approach to protect the environment. Where there are threats of serious or irreversible damage, scientific uncertainty shall not be used to postpone cost-effective measures to prevent environmental degradation." (1)
Yet, the Precautionary Principle is a broad statement of principle, subject to varying interpretations. More recent formulations, such as the Wingspread Statement, (2) have moved away from Rio's emphasis both on cost effectiveness and how serious a threat must be to invoke the Precautionary Principle, and have extended the Precautionary Principle to address protection of public health as well as the environment.
Such broad statements can be very valuable, even if vaguely defined. Precaution is a universal value similar to "sustainable development," which serves as a rather amorphous rallying cry for many divergent interests that support economic development in a manner that does not harm the environment. (3) It is hard to imagine that anyone is against sustainable development. The Precautionary Principle also is supportable as a primary preventive approach that is as old as the Hippocratic Oath's adjuration: "Above all do no harm."
Thus, the Precautionary Principle is increasingly advocated and grounded in legally enforceable contexts such as international treaties. For instance, as urged by the European Community in the hormone-treated beef case, the World Trade Organization was forced to consider whether the Precautionary Principle is an established principle of law applicable to adjudication of international trade disputes, (4) and the WTO will undoubtedly face the issue again in future disputes over genetically modified organisms and biodiversity. In such contexts, the exact definition of the Precautionary Principle and the legal implications of its use are of critical importance.
A major motivation for advocacy and action under the Precautionary Principle is a sense of frustration with the slow pace of science and risk-based regulation. This is understandable. An all-too-familiar ploy of industry is to obstruct or delay risk-based regulation by requesting more scientific study (5) or challenging its scientific validity in the courts. (6) Even when ultimately unsuccessful, such challenges often delay regulation by years. Inevitably, in any situation in which a chemical has been regulated after the slow accretion of proof of harm, there is a time period during which advocates of control have been forced to wait until new information developed or was accepted. …