Comment submitted by The Sapphire Group, On Behalf of The Dow Chemical Company and Shell Oil Company

Attached are the comments prepared by The Sapphire Group on behalf of The Dow Chemical Company. These comments reflect our evaluation of the quality of the toxicologic data relied upon by EPA in its draft Toxicological Review of 1,2,3-Trichloropane In Support of Summary Information on the Integrated Risk Information Suystem (IRIS) (dated October 2007) and most importantly on state-of-the-art methods relied upon by public health professionals in estimating safe levels of exposure for chemicals, including TCP, in drinking water. Overall, we find that EPA?s non-cancer RfD reflects a reasonable interpretation of the available data. However, we also note that the Agency?s estimated cancer potency value for TCP, while certainly protective of public health, does not take into account the full measure of understanding about the toxicologic data for TCP and their significance to human health. As a result, the current draft is apt to provide those exposed and the regulated community with an incomplete perspective of the range of human doses that are likely to be equally protective of human health. We recommend that EPA share with users of IRIS the range of reasonable and authoritative interpretations of the relevant data so that the most informed risk management decisions can be made on TCP. By including these considerations, EPA is encouraged to recognize in its documentation that equally plausible cancer potency values may be as much as a few orders of magnitude below that estimated by the Agency. As a final note, we ask EPA to report that the drinking water MCL of 600 ppt for TCP adopted by the State of Hawaii using the same data reviewed by EPA and using conservative approaches to risk assessment. Hawaii?s drinking water standard is considered to be fully protective of public health (HDOH, 2005). According to the regulatory authorities in Hawaii, the MCL for TCP represents a theoretical one in a million upper-bound risk level in drinking water.