trimethylbenzenes (1,3,5-, 1,2,4-, and 1,2,3-trimethylbenzene), and vinyl chloride. The report also summarizes the committee’s conclusions and recommendations for improving the Standing Operating Procedures for Developing Acute Exposure Guideline Levels for Hazardous Substances published in 2001.


At its meeting held on May 12-14, 2008, the committee reviewed the AEGL technical support document (TSD) on bromine pentafluoride (BrF5). A presentation on the TSD was made by Sylvia Talmage, of Oak Ridge National Laboratory. The following is excerpted from the executive summary of the TSD.

BrF5 is a strong oxidizing chemical that is used as a fluorinating agent and as an oxidizer in rocket propellant fuels. No data on human exposures were available. A single study provided information on lethal and nonlethal values for the rat. No information on time scaling could be ascertained from this study, although the data did indicate that the dose-response curve for lethality was steep. In the absence of empirical data, no AEGL-1 values were developed. …In the absence of data relevant to derivation of AEGL-2 values for BrF5, data for the structurally related chemical, chlorine pentafluoride (ClF5), were considered…. The AEGL-3 values are based on the highest nonlethal value from the one rat study.

General Comments

A revised document should be submitted to the committee for review.

There is a paucity of toxicologic information for making a valid assessment for this chemical. There is little neurotoxicity information, and there is no reproductive and developmental, genotoxicity, carcinogenicity, or chronic toxicity data. Toxicologic studies that are available are 30 to 40 years old. Because there is a lack of data, the TSD should provide more discussion on why a modifying factor was not used to adjust for uncertainties in the overall database or for known differences in toxicity among structurally similar chemicals. One approach is to state that differences in toxicity were accounted for in the lower toxicity of BrF5 compared with chlorine pentafluoride (ClF5). In addition, time scaling in the TSD needs to be revised to be in agreement with the revised ClF5 document.

Because the BrF5 AEGL values are based on the ClF5 TSD, and that TSD is compared to chlorine trifuoride (ClF3), we recommend republishing the ClF3 TSD (from AEGLs report, Volume 5) with bromine trifluoride (BrF3) (see below), BrF5, and ClF5—possibly as an appendix so that it is easy to reference.

Specific Comments

Page 4, line 12: The text states, “In the absence of data relevant to derivation of AEGL-2 values for BrF5, data for the structurally-related chemical, chlorine pentafluoride (ClF5), were considered.” Change “were considered” to “were used.” If they were not used, then this statement is not needed.

Page 4, lines 19-21: The text states, “For chemicals with similar actions, such as HF and ClF3, interspecies and intraspecies uncertainty factors (UFs) of 3 each for a total of 10 were shown to be protective of sensitive individuals.” Provide better rationale for selecting the interspecies and intraspecies UF values. The rationale must be consistent with the standing operating procedures (SOP) (NRC 2001). The phrase “were shown to be protective of sensitive individuals” is a very strong statement. The

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