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Ecological Risk Assessment 773

Conclusion
Environmental management has been an evolving process and the demands on ecological risk assess-
ments have evolved in parallel. In 1966, the Federal Water Pollution Control Administration reported
more than 9 million fish mortalities in 372 reported fish kill events in the United States (USDOI, 1967),
and this included only reported kills where the extent of the kill was quantified. Given this situation,
environmental science of the time focused to a large extent on understanding the causes of these events
and establishing thresholds or management practices to avoid such catastrophes. In the face of highly
visible fish kills, evaluating the long-term population impact of small reductions in growth probably
seemed irrelevant; however, as water quality in the United States has generally improved, increased
emphasis has been placed on understanding other less visible (though perhaps no less serious) effects
from environmental contaminants. In addition, there is now a heavy emphasis on predicting and avoiding
future ecological risks, rather than just reacting to those problems that already exist. On the other hand,
overreaction and overprotection in response to potential or perceived risks can create substantial economic
and social costs in an increasingly competitive global economy. The application and improvement of
ecological risk assessment as a means to objectively evaluate these issues will undoubtedly be important
components of environmental decision making well into the future.

Acknowledgments

The principles of ecological risk assessment have emerged from the work of many people. Although
guidance published by the U.S. Environmental Protection Agency was used as a primary source material,
we wish to acknowledge the contributions of the many, many people whose efforts are embodied in that
and other influential documents. We also thank Drs. Richard S. Bennett and Stephen A. Diamond for
their comments on the manuscript and Mary Ann Starus for editorial support. This document has been
reviewed in accordance with U.S. EPA policy and approved for publication. Approval does not signify
that the contents reflect the views of the Agency, nor does mention of trade names or commercial products
constitute endorsement or recommendation for use.

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