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l� <br /> A T UNITED STATES ENVIRONMENTAL PROTECTION AGENCY <br /> V' <br /> 'c >` REGION IX <br /> r' <br /> 75 Hawthorne Street <br /> San Francisco, CA 94105-3901 <br /> August 1, 1996 <br /> �; 4� , �� ) <br /> Subject: Rezion 9 Preliminary Remediation Goals TRG5I 1996 <br /> JUL 31 1997 <br /> From: Stanford J. Smucker, Ph.D. <br /> Regional Toxicologist (H-9-3) ENVIRONMENTAL HEALTH <br /> Technical Support Team PERMIT / SERVICES <br /> To: PRG Table Mailing List <br /> Please find the annual update to the Region 9 PRG table. The table has been revised to reflect the <br /> most current EPA toxicological and risk assessment information. Updates to EPA toxicity values <br /> were obtained from IRIS through July 1996, HEAST through May 1995, and EPA's National Center <br /> for Environmental Assessment (NCEA, formerly ECAO). <br /> Region 9 PRGs are "evergreen" and have evolved as new methodologies and parameters have been <br /> developed. In several cases the models, equations, and assumptions presented in RAGS HHEM, Pan <br /> B, Development of Risk-Based Preliminary Remediation Goals (1991) have been replaced with new <br /> information that is consistent with the document, Soil Screening Gufdance, recently issued by the <br /> Office of Solid Waste and Emergency Response (OSWER), dated April 1996. <br /> The updated-PRG table also contains soil screening levels (SSLs) for protection of groundwater. The <br /> SSLs were obtained directly from EPAIOSWER's Soil Screening Guidance document which is <br /> available from NTIS as EPA/540/R-96/018 and EPA/540/R-95/128. Please note that because R 9 <br /> PRGs currently evaluate intermedia transfer of volatile organic chemicals (VOCs) and heavy metals <br /> from soil to air, the P9134* 4loes=norinelude a separate list of SSLs for the air pathways <br /> To help users rapidly identify substances with new PRGs, these contaminants are printed in boldface <br /> type. Changes in PRG values are either due to new toxicity constants or new physicochemical <br /> information. This version of the table contains revised toxicity values for acetaldehyde, chlorine <br /> cyanide, 1,3-dichlorobenzene, 2dichloroethane, endosulfan, manganese, phosphoric acid, and 1,1,1- <br /> trichloroethane. Also, 23 additional VOCs have been identified and evaluated for inhalation <br /> exposures resulting from intermedia transfer from soil and water to air. <br /> EPA Region 9 has established a homepage on the World Wide Web which you can find at <br /> http://www.epa.gov/region 9/. Our homepage will soon include the PRG table in downloadable <br /> form. The electronic table contains additional information not presented in the printed table (e.g. <br /> physicochcmical constants, non-can= PRGs for carcinogens, pathway-specific PRGs, and <br /> volatilization factors for VOCs). Meanwhile, we still provide the electronic PRG table (PRG96.zip) <br /> on California Regional Water Board's BBS (510.286.0404) for those of you who have a modem <br /> Before relying on any number in the table, it is recommended that the user verify the numbers with <br /> an agency toxicologist or risk assessor because the toxicity / exposure information in the table may <br /> contain errors or default assumptions that need to be refined based on further evaluation. If you find <br /> an error please send me a note via email at Smucker.Stan®epamail.epa.gov or fax at 415.744.1916. <br /> Primtd on R,"cl,d Pap <br />