Clearance goals are goals or criteria for human or release site cleanup, decontamination, and/or remediation. They describe the amount of residual chemical remaining in an area, on an item, or on a person, following cleanup activities that is deemed to provide “acceptable” protection to human and environmental health. The goals are used to set clearance criteria, which are measures that serve as the basis for determining whether re-entry/re-occupancy into an area, re-use of an item, or entry into medical facilities is allowed. Clearance criteria are set based on public health, environmental health, political, social, economic, engineering, and other considerations, including available sampling strategies and decontamination technologies. “Clearance” of an area, item, or person indicates that these criteria have been met; residual chemical risks have been reduced to levels deemed acceptable.
The selection of clearance goals is a complex process that requires input from technical experts and a review and understanding of data on a range of subjects, such as the chemical’s physicochemical characteristics, health-based exposure guidelines, environmental conditions, composition and characteristics of the impacted areas, and other parameters. Major challenges include the absence of good dose-response data and disagreement among stakeholders regarding the adequacy of existing exposure standards. For these reasons, setting clearance goals requires expertise in a variety of areas, and is best tackled by SME stakeholder and planning groups, especially LPECs/TEPCs, EPA, etc. These groups can best apply scientifically appropriate, well-characterized exposure guidelines to ensure that human and environmental health are safeguarded without defaulting to overly conservative actions (such as cleaning/decontaminating to undetectable levels) that would divert limited resources without major benefits.
As they represent a difficult trade-off between health risk concerns and regional economic recovery concerns, clearance goals are arguably the most significant drivers for the overall post-incident remediation process, strongly influencing the remediation timeline and the associated costs and resource requirements. Therefore, having a ready set of well-understood, defensible, health-protective exposure levels that can be assessed to develop appropriate and reasonable site-specific and chemical-specific clearance goals before an incident occurs would be an asset. However, because of the potential variety in and complexities of chemical risks, setting clearance goals in advance of an incident is often not possible. Moreover, during an actual incident, any clearance goals established for pre-planning purposes must be considered flexible and re-assessed alongside incident- and site-specific information and adjusted as necessary to establish formal clearance goals through a risk-based decision process involving key stakeholders.
Guidance documents that provide the rationale for a reasonable and scientifically supported set of procedures and health-based criteria will give decision-makers maximum flexibility for weighing the numerous considerations that must be evaluated. Such considerations include the safety of decontamination personnel, public health and environmental health, time, funds, resources, and public perception, among others. Final decisions should be made by responsible site-specific authorities and should reflect considerations of acceptable risk and socioeconomic concerns. Timely and clear communication of exposure-based guidelines will help reduce public anxiety and improve the effectiveness and efficiency of post-incident response and recovery activities.