Comment submitted by Klaus L. E. Kaiser, TerraBase Inc.

On behalf of TerraBase Inc., a Canadian company founded in 1996, it is my pleasure to comment on this docket as follows: 1. TerraBase Inc. has developed a computer program (TerraQSAR[tm] - E2-RBA) which provides quantitative estimates of the "estrogen receptor binding affinity" (RBA) of substances. This program is based on the measured RBA of over 2000 individual chemicals, using 3D molecular structures and a proprietary computational algorithm. 2. The RBA is the most relevant effect of an "endocrine disrupting substance". A substance's ability to bind to a steroid receptor, especially the estrogen receptor, is directly linked to its endocrine disrupting effect. 3. This TerraQSAR program is available for purchase, or on a individual compound by compound computation cost basis. 4. More information on the TerraQSAR - E2-RBA program is available from our web site at http://www.terrabase-inc.com, or on request. The TerraQSAR -E2-RBA Manual is attached to this message (file: TerraQSAR-E2-RBA.pdf). 5. TerraBase Inc. would be pleased to work with EPA in its attempts to screen and assess the endocrine disrupting effects of chemicals.