U.S. Environmental Protection Agency, 26 W. Martin Luther King Dr., Cincinnati, OH 45268

A -- RESEARCH ON RISK ASSESSMENT ISSUES WITH COMMERCIAL MIXTURES USING TOXAPHENE AS A CASE STUDY SOL PR-OH-97-00274 POC Billy Oden -( 513)366-2126 E-MAIL: U.S. EPA -- CINCINNATI CONTRACTS MANAGEMENT DIVISION, oden.billy@epamail.epa.gov. Research on Risk Assessment Issues with Commercial Mixtures Using Toxaphene as a Case Study The U.S. Environmental Protection Agency has a requirement for research support on risk assessment issues with commercial mixtures using toxaphene as a case study. The goal of this project is to determine whether the toxicologic data used in setting the screening levels in soil (SSL) for mixtures are compatible with the exposure data that are gathered for comparison with the screening levels. Three issues are to be investigated: -- The exposure levels given in the toxicity studies that support the SSLs should directly represent, or least indicate by analogy through a biomarker, the critical effects caused by the complete mixture. -- Toxicity data should be available for each of the main chemicals (that drive the toxicity) in the original manufactured mixture as well as for each of the main chemicals after years of environmental degradation. -- The environmental monitoring data should adequately characterize the concentrations of the toxicologically important chemicals. Which chemicals are the most important will likely change over time as the mixture degrades and changes in composition. The proposed acquisition will be processed as a Request for Proposal (RFP), using FAR Part 13 -- Simplified Acquisition procedures, which will result in a firm fixed price contract. All required deliverables shall be submitted by 9/30/97. The proposed contract is 100% set aside for small businesses. All requests for the RFP must in writing. No telephone requests will be accepted. Facsimile is acceptable. The facsimile number is (513) 366-2004. "See Note 1." (0105)

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