UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
                              WASHINGTON, D.C. 20460
                                   NOV  -8 J999
                                                                             OFFICE OF
                                                                         AIR AND RADIATION
Dear Recipient:

       As part of EPA's role to provide up-to-date technical information on radiation protection
issues, we are providing you with the final version of Federal Guidance Report No. 13 (FOR 13).
This document replaces the interim version that you previously requested.  The new FOR 13
contains cancer risk coefficients for over 800 radionuclides. There is also new information on
sources of uncertainty in these risk coefficients and an expanded discussion of the dose-response
relationship.

       Additional copies may be obtained from the EPA National Service Center for
Environmental Publications (NSCEP) by phone (800-490-9198) or by the Internet
(www.epa.gov/ncepihom). You will soon be able to download an electronic copy from the
Radiation Protection Division's web site at www.epa.gov/radiation/federal.

       We hope that you will find this document to be a useful and timely reference for
conducting risk assessments or for understanding the methodology behind EPA's risk
coefficients.
                                         Sincerely,
                                         StepheryD. Page,
                                         Office of Radiation anc
Enclosure
           Recycled/Recyclable .Printed with Vegetable Oil Based Inks on 100% Recycled Paper (40% Postconsumer)

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