Letters M Precautionary conflict Dear Editor: In his feature article, “Life-Cycle Assessment and the Precautionary Principle” (Environ. Sci. Technol. 2002, 36, 70A–75A), Arnold Tukker raises some important points regarding the relationship between life-cycle assessment (LCA) and the precautionary principle. I agree with his analysis of the limitations of LCA in supporting precautionary policies, but not with his contention that LCA and precaution are in conflict. Albeit limited, the former is a tool for environmental decision making, while the latter is an overarching guide to decision making in the face of uncertainty. By condensing often-limited information into a single number or probabilistic distribution, both LCA and quantitative risk assessment methodologies can present an overly precise picture of uncertain risks. Doing this hides uncertainties and subjective assumptions and minimizes the scope of qualitative and quantitative information used in decision making, in essence pushing for a number at the expense of a more comprehensive understanding of risks. Although a rigorous distinction between sciencebased analysis and precaution is often drawn, our analyses have found that environmental science can often implicitly work against precautionary decisions (1). In fact, precaution demands more and more rigorous science, including broadening hypotheses to examine systems and cumulative and interactive effects of multiple stressors; greater reliance on interdisciplinary research and collaborations; integration of critical qualitative information into scientific results; and more explicit discussion about uncertainties (what is known, unknown, knowable, and suspected). The recent Lowell Statement on Science and the Precautionary Principle (www.uml. edu/centers/lcsp/precaution), the outcome of more than two years of discussions on this subject, outlines a vision for environmental science that could more effectively support decision making when there are uncertainties and complexity. Although Tukker rightly notes limitations in LCA data needed for making realistic quantitative estimates of uncertain impacts, what might be termed “life-cycle thinking” can be an important tool for implementing precautionary actions. The German Vorsorgeprinzip—literally foresight principle—was established as a forward-look-
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ing principle, to stimulate careful social planning for sustainability (2). A central element of the precautionary principle is that it shifts the types of questions asked in environmental decision making from “What level of exposure is safe or acceptable?” to “What feasible alternatives are available that could prevent damage to ecosystems and health?” (3). This shift results in a greater focus on solutions, such as cleaner production and pollution prevention options. Life-cycle thinking aids deliberations of more sustainable technologies and products by identifying and prioritizing important risks and opportunities for preventive interventions and identifying trade-offs between options. Any change in production systems or products, even a small one, potentially results in trade-off risks that scientists and decision makers should thoroughly examine, and where advisable, prevent. For example, the simple substitution of a chlorinated solvent with an aqueous cleaner may result in increased ergonomic risks to workers who clean metal parts. It is imperative under a precautionary approach that, in reducing overall risks, actions are also taken to minimize the potential consequences of realistic trade-offs —this is an area where lifecycle methodologies can be extremely helpful. In cases where trade-off risks may not be immediately obvious, we should be developing surveillance and monitoring methods to establish early warning systems for unanticipated risks, so that appropriate preventive actions can be taken before widespread damage occurs (4).
References (1) Kriebel, D., et al. Environ. Health Perspect. 2001, 109, 871–876. (2) Boehmer-Christiansen, S. The precautionary principle in Germany—Enabling government. In Interpreting the Precautionary Principle; O’Riordan, T., Cameron, J., Eds.; Earthscan: London, 1994. (3) Tickner, J., Hoppin, P. Int. J. Occup. Environ. Health 2000, 6, 327–334. (4) Late Lessons from Early Warnings: The Precautionary Principle 1898− 1998; European Environment Agency: Copenhagen, 2002.
JOEL TICKNER Lowell Center for Sustainable Production University of Massachusetts, Lowell Lowell, MA 01854 USA
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