Assessment of Health Protectiveness of the Risk-Based Soil Remediation Standards of the Midwestern States

ABSTRACT

In the last decade, risk-based remediation following a framework similar to risk-based correction action (RBCA) has gained acceptance across the country and generic/Tier 1 Risk-Based Action Limits (RBALs) for hundreds of chemicals have been tabulated. However, there have been only a few studies that focused on understanding the causes of discrepancy among cleanup standards and policies of the hazardous waste programs among the states. This study aims to fill this critical need by examining the basis of generic (i.e., Tier 1) residential RBALs developed by the states, which are within the regulatory domain of U.S. Environmental Protection Agency's Region 5. Specifically, we seek to investigate the approaches/methodologies and the policy/technical rationale used in establishing RBALs, along with degree of inconsistency, and the causes and implications of inconsistencies. In addition, we developed RBALs for a case study site using both deterministic and probabilistic risk assessment approaches and compared these against RBALs developed by the states to infer about public health-protectiveness of the state-specific RBALs. We found three- and four-order-of magnitude difference among state RBALs for PAHs and VOCs, respectively. The degree of clean up deemed appropriate under Tier 1 evaluation by the midwestern states significantly differ from one another, which has both public health and economic implications.

Key Words:

• remediation
• risk assessment
• soil
• cleanup level
• midwestern U.S.
• state

ACKNOWLEDGMENTS

The authors thank state agency personnel for their help in providing various documents pertaining to the case study site. In addition, this study was partly supported by the University of Illinois-Chicago (UIC) start-up funds (2-2-25223) and UIC National Institute of Occupational Safety and Health Training Grant (T42/CCT510424-10-Industrial Hygiene).

Notes

¹Editor's note: A list of abbreviations used in this article appears at the end.

*The values with a * represent C_sat, signifying that risk-based concentrations were higher.