SETAC Globe - Environmental Quality Through Science
  6 October 2011
Volume 12 Issue 10

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Evaluating Human Health and Ecological Risk Assessments and Remediation Decisions: Is the Cure Worse than the Disease?

Rosalind Schoof, Human Health Risk Assessment Advisory Group and John Toll, Ecological Risk Assessment Advisory Group

Remediation decisions typically focus on taking actions to protect people and ecosystems from hazardous substances in the environment. Other criteria such as cost, permanence, and public acceptability of the remedy might come into play in selecting an option, but the side effects of remedies on the ecosystem and the people who use it are not routinely considered. A combination of factors, though, makes it risky to neglect side effects. Active remediation can damage or destroy habitats and increase exposures to hazardous substances, and risk assessors might over-prescribe active remediation because risk assessments are designed to avoid false negative results, a practice commonly referred to as the precautionary principle.

The Human Health Risk Assessment Advisory Group (HHRA-AG) and the Ecological Risk Assessment Advisory Group (ERAAG) are both concerned about the possible side effects from over-prescribing active remediation of hazardous substances. This is a natural topic for these two AGs to collaborate on because a prescription based on an assessment of ecological risk might produce side effects that harm people, or vice versa. That’s why the HHRA-AG and ERAAG have come together to organize a session for the Boston meeting addressing the question of whether risk assessment and risk management practice should give precedence to the precautionary principle, or the Hippocratic principle “first do no harm.”

Answering this question requires examination of potential conflicts in protection of health vs. environment, long-term impacts vs. short-term impacts, and highly certain impacts vs. uncertain impacts. Is it worth destroying productive habitat to remove a theoretical incremental cancer risk for humans that is so small that it can never be measured or the health benefits proven? Will the impacts of short-term habitat loss during remediation be overcome by greater long-term productivity after recovery? These are not easy questions to answer and we of course don’t expect to resolve the matter in Boston, but we do expect a very interesting session. To the extent that “first do no harm” finds favor, perhaps a third AG – Ecosystem Services – will join in to offer ideas about better accounting for what we now dismiss as side effects of active remediation.

We hope that you’ll join us on Wednesday morning in Boston for what we hope and expect to be a lively session! Our speakers will provide examples of where (and how) risk managers balance conservative risk estimates against the “cons” of more stringent remedial actions in order to achieve better outcomes. Net environmental benefits analysis and ecosystems services analyses provide useful tools in some settings, but dissimilarities in the nature of risks and varying degrees of uncertainty present difficult challenges. We have asked the session’s presenters to consider the implications of conducting risk assessments under the premise that it’s better to err on the side of conservatism in the face of uncertainty. Does this principle always lead to the most protective decisions for human health and the environment? Does it deliver maximum benefit to local human and ecological communities? If not, then what are the opportunity costs?

What if an assessment leads to an invasive remedy that damages or destroys habitat or other ecosystem assets (open space, recreation opportunities, etc.)? One of our speakers, Brett Thomas, will describe the destruction of historically created habitat in a wastewater lagoon due to potential metals exposure, and questions if the reduction in a small theoretical risk is worth this loss. In contrast, Andrea Fogg will talk about the use of net environmental benefits analysis to support vegetative stabilization of PCB-contaminated floodplain soils as a means of preserving valued parkland forest. In another study, which will be presented by Ann Michelle Morrison, net environmental benefits analysis was used to support selection of a higher chemical remediation goal that reduced the area of sediment to be dredged, thereby preserving substantial aquatic vegetation.

Certainly we wish to avoid situations where substantial harm may be associated with extensive remedies that do not yield promised reductions in health risk. Brian Magee will describe such a possibility associated with an overzealous lead paint remediation program that did not consider an array of potential harms associated with implementation of the remedy. Does overestimation of risk lead to faulty decision-making in selection of remedial alternatives? Shawn Sager will ask how much remediation is needed for a stream that is already rated as “impaired” independent of a chemical source impact.

Are we as risk assessors and risk managers doing enough to account for the risk of remedy in our actions and decisions? How certain are we of the effectiveness of our remedies? Jay Field will address a case of possible over-prediction of the rate of natural attenuation for PCB-contaminated sediments, and the associated under-prediction of risks for the selected alternative. Quantification of uncertainties is key to rational decision-making. Sara Rodney will present a data analysis approach for addressing uncertainties in interpreting exceedances of water quality criteria for aquatic life.

Risk management involves complicated tradeoffs; that’s never going to change. On the other hand, the paradigm we use to make those risk management decisions will continually evolve and improve. At least for now we lack a framework that allows us to readily calculate and weigh the relative risks to human health and the environment, and short-term vs. long term risks. Weighing the relative risks is also dependent on reliable quantification of the uncertainties associated with each risk analysis. Such analyses are frequently further hampered by regulations that force managers to focus only on reduction of current risks, without consideration of risks and benefits of the remedy. Documentation of both risks of remedy and alternative decision frameworks such as net environmental benefits analysis may help move us in the direction of making decisions that provide the greatest benefit to all receptors. We hope that this session will trigger ideas and actions help move us further down the path toward better risk management decision making, and we hope to see you there!

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