Document NGbnXJGV6ezk1wDLgLnwkDezy

A Division of McLaren/Hart Environmental Engineering The CourUand Hast Building 29225 Chagrin Boulevard Cleveland, OH 44122 (216)464-6564 FAX (216) 464-6101 October 7, 1996 VIA FACSIMILE/FEDERAL EXPRESS Mr. W. Caffey Norman, III Patton, Boggs & Blow, L.L.P. 2550 M Street, N.W. Washington, DC 20037 PH: (202)457-5270 RE: Amendment to: Proposal CL96-0145 to Evaluate 1, 1,2-Trichloroethane with Regard to a Proposed HAP Test Rule Dear Mr. Norman, As per the meetings with USEPA held last week and the conference call between you, Peter Voytek and I, the following scope of work is proposed for ChemRisk: ChemRisk prepared for and presented at the USEPA meetings in Washington, DC (work already completed) We will prepare the first draft of a document to be submitted to the USEPA on or before October 24, 1996 describing our rationale for filling data gaps with PBPK modeling for 1,1,2-TCA. Specifically: Describe model development for the mouse and validation of models for both rats and mice. To be performed in conjunction with other possible studies (i.e., acute). DO 1 4?., OONF IDFNTTAl Mr. Norman Page 2 October 7. 1996 Use validated mouse and rat models to fill subchronic data gap using White et al., 1985 and Sanders et al. mouse studies and NCI (1978) study for rats and mice. Will need to carefully evaluate use of NCI data. Propose filling neurotoxiciiy data gaps using NCI (1978) data with rat and mouse models. Use Niklasson et al. 1993 and Frantik et al. 1994 to further support this work. Propose using rat and mouse PBPK modeling to fill carcinogenicity data gaps for inhalation. Extrapolate from NCI (1978) oral results. Propose modeling Sanders et al., 1985 study to fill immunotoxicity data gap. Propose to model DNA binding as a surrogate for cytogenic effects. A draft report will be sent to all Task Force members (list to be provided by Mr. Norman) for delivery on Monday, October 21, 1996. Comments from members must be returned to ChemRisk (via FAX) by 3:00 p.m. on Tuesday, October 22, 1996 so we may make all appropriate changes and deliver to USEPA by October 24, 1996. The cost estimated for this work is outlined below and includes the preparation for and presentation at the USEPA meetings, including travel (work already performed). A more complete description of the basis for these costs can be found in the attached worksheets. Attend USEPA Meeting (with Travel) -- Prepare Draft and Final Submittal to USEPA = $ 4,130 SIS OM Total for This Amendment $19,144 If the work outlined in this amendment for 1,1,2-TCA is acceptable, please sign and return one copy of the enclosed Project Authorization Form. Sincerely, M Principal Health Scientist MLG/rmh OO 1?9?46 OONFTDFNT TAl