Decontamination Options for Surface Layers Containing Permeated Chemical Warfare Agents HD and VX and Pesticides Malathion and Fipronil
Citation:
Oudejans, L., M. Magnuson, K. Ratliff, A. Mikelonis, T. Malloy, D. See, AND C. Dodds. Decontamination Options for Surface Layers Containing Permeated Chemical Warfare Agents HD and VX and Pesticides Malathion and Fipronil. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-22/037, 2022.
Impact/Purpose:
A release of persistent chemical warfare agents such as VX or sulfur mustard (HD) but also the mis-or overuse of pesticides like malathion or fipronil will create an acute and significant exposure risk to the public as well as remediation contractors who would be tasked to cleanup a contaminated site. Remediation operations will benefit from improved knowledge on the degree of transport of these agents into porous and/or permeable building materials and its impact on the expected decontamination efficacy which typically is reported for nonporous contaminated materials . This report describes research that was conducted to measure the efficacy of various decontaminants on partially permeated chemicals into paint and sealant layers. It includes research that considered added chemicals that would function as intermediates to improve the accessibility of the water-based decontaminant to the permeated chemical agent. The results of this research will inform the EPA response community and other Federal, State, Tribal and Local agencies on the expected partitioning of VX, HD, malathion, and fipronil into permeable materials (e.g., paints and sealants) and its impact on the decontamination processes as a critical part of the remediation strategy to cleanup these contaminated sites.
Description:
Under the U.S. Environmental Protection Agency’s (EPA’s) Homeland Security Research Program (HSRP), research is being conducted necessary for identification of methods and technologies that can be used during hazardous materials remediation and cleanup efforts. The threat of a chemical warfare agent (CWA) or pesticide release into the environment is driving EPA’s HSRP to systematically evaluate potential decontamination technologies for CWAs and mis- or overused pesticides. The efficacies of many liquid decontaminants have been observed to be material dependent, attributable in part to the permeability or porosity of the materials to which the decontaminants are applied. Transport of CWA/pesticide into a permeable material often leaves the material more difficult to decontaminate, as water-based decontaminants may not be capable of similar penetration to reach the CWA/pesticide. Adequate decontamination then often becomes even more difficult to achieve if CWA/pesticide permeates into a porous material under a surface film or coating (e.g., paint or sealant). The purpose here was to evaluate the efficacies of various liquid based decontamination technologies to degrade CWA and pesticide on the surface of coating layers (films), within the layer, and into an underlying porous material. Prior to decontamination testing, fate and transport testing was performed for CWAs and pesticides to quantify the amount of each target chemical that remained on the paint or sealant film surface, permeated into (and remained in) the film, and permeated through the film to the porous material during a selected contact time. Decontaminants were then first tested (baseline decontamination condition) to determine which would be efficacious in decontamination of CWA and pesticides from two freestanding coating layers, paint, and sealant.