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###### Environmental Protection Agency

          - [FRL-6710-7]

# AGENCY:

Environmental Protection Agency.

# ACTION:

Notice of availability. 

# SUMMARY:

                        This notice announces the availability of the U.S. Environmental Protection Agency (EPA) Benchmark Dose Software (BMDS Version 1.2). BMDS was developed by EPA's National Center for Environmental Assessment (NCEA) as a tool to facilitate the application of benchmark dose methods to the assessment of hazardous pollutants. The software and supporting documentation are available  to Agency                               ( print page 35926)                            personnel and to the general public, and can be downloaded from the NCEA internet web site or requested directly from NCEA (see addresses below).                    

# ADDRESSES:

To obtain a copy of the Benchmark Dose Software Version 1.2, direct your internet browser to http://epa.gov/​ncea/​bmds.htm. You will be instructed on how to download a self-extracting compressed file containing the BMDS program. Windows 95/98/NT and at least sixteen megabytes of RAM are required to run this version of the BMDS.

                        Accessing a copy of the BMDS program via the internet is highly recommended as the BMDS web site will be the official and most current source of updates and notifications. However, those for whom internet access is impractical may obtain a copy of the program via E-mail or CD-ROM by contacting Ms. Diane H. Ray, National Center for Environmental Assessment-RTP Office (MD-52), U.S. Environmental Protection Agency, Research Triangle Park, NC 27711; telephone: 919-541-3637; facsimile: 919-541-1818; E-mail:                         *ray.diane@epa.gov.*

                        All comments on the BMDS software, help system and the model source code files are welcome. Please email comments, recommendations, suggested revisions, or corrections to                         *bmds.ncea@epa.gov.*

# FOR FURTHER INFORMATION CONTACT:

                        Dr. Jeffrey S. Gift, National Center for Environmental Assessment-RTP Office (MD-52), U.S. Environmental Protection Agency, Research Triangle Park, NC 27711; telephone: 919-541-4828; facsimile: 919-541-1818; E-mail:                         *bmds.ncea@epa.gov.*

# SUPPLEMENTARY INFORMATION:

Use of benchmark dose methods involves fitting mathematical models to dose-response data, obtained primarily from toxicology studies, and using the results to determine the dose of a toxicant that is associated with a predetermined benchmark response, such as a 10% increase in the incidence of a particular lesion or a 10% decrease in body weight gain. BMDS estimates the lower-bound confidence limit on the benchmark dose (BMDL), which can serve as a point of departure for a non-cancer or cancer chemical risk assessment. BMDS facilitates these operations by providing simple data-management tools, a comprehensive help manual and online help system, and an easy-to-use interface to run multiple models on the same dose-response data set. At this time, BMDS (Version 1.2) offers sixteen (16) different models that are appropriate for the analysis of dichotomous (quantal) data (Gamma, Logistic, Log-Logistic, Multistage, Probit, Log-Probit, Quantal-Linear, Quantal-Quadratic, Weibull), continuous data (Linear, Polynomial, Power, Hill) and nested developmental toxicology data (NLogistic, NCTR, Rai & Van Ryzin). Results from all models include a reiteration of the model formula and model run options chosen by the user, goodness-of-fit information, the benchmark dose, and the estimate of the lower-bound confidence limit on the benchmark dose (BMDL). Model results are presented in textual and graphical output files which can be printed or saved and incorporated into other documents.

The software announced here is the result of several years of research and development, expert review and quality assurance testing conducted by NCEA, with support from EPA's National Health and Environmental Effects Research Laboratory and NCEA contractors. Extensive peer review input was also received from expert scientists, particularly toxicologists and statisticians, from both inside and outside the Agency. Following a public review of BMDS Beta Version 1.1b, which ended on March 31, 1999 (63 FR 71465, Dec. 28, 1998), NCEA revised the software based on its experience with the program and in response to public comments received. Finally, an extensive and independent quality assurance assessment of all facets of the BMDS system was conducted, and appropriate modifications were made to create BMDS Version 1.2.

EPA/NCEA will continue to improve the BMDS system in response to the needs of Agency and other risk assessors. One example of such a project is the ongoing development of the EPA Hybrid model, a statistical approach to treating continuous data as dichotomous endpoints. A beta version of the Agency's Hybrid model is included in BMDS Version 1.2. Another example is the ongoing development of a model specifically designed for assessing cancer incidence data, which is being developed to support the proposed EPA cancer guidelines currently in development. As these and other modifications or additions are completed, they will be made available to users of the software via the NCEA BMDS web site.

Currently, the BMDS web site contains the complete BMDS program along with its extensive online help system, a separately downloadable help manual, and background information concerning the development of the software. The executable and source code files for the individual models used by BMDS can also be downloaded from the web site.

Dated: May 25, 2000.

George W. Alapas,

Acting Director, National Center for Environmental Assessment.

[FR Doc. 00-14177  Filed 6-5-00; 8:45 am]

BILLING CODE 6560-50-M