Tenth Interim Report of the Subcommittee on Acute Exposure Guideline Levels (2004)

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TENTH INTERIM REPORT OF THE SUBCOMMITTEE ON ACUTE EXPOSURE GUIDELINE LEVELS 24 COMMENTS ON ANILINE At its July 21–23, 2003 meeting, the subcommittee reviewed the AEGL document on aniline. The document was presented by Sylvia of Oak Ridge National Laboratory. The subcommittee recommends that the following revisions be made to the document. A revised draft should be reviewed by the subcommittee at its next meeting. Comments Development of 10-min AEGLs for Aniline When the AEGL program was initiated, the plan was to develop AEGL values for exposure durations of 30 min, 1 hr, 4 hr, and 8 hr, which the subcommittee reviewed for the initial group of hazardous chemicals (aniline, arsine, chlorine, fluorine, 1,2-dichloroethane, phosphine, methylhydrazine, and dimethylhydrazine). AEGLs for four of these chemicals were published in the first volume of the subcommittee's series Acute Exposure Guideline Levels for Selected Airborne Chemicals, Volume 1 (NRC 2000). Subsequently, in response to a request from the sponsors, the subcommittee developed 10-min AEGL values for those chemicals, and 10-min AEGLs for all chemicals beginning with the subcommittee's fifth meeting in 1999. However, this is the first revision of any previously established AEGL document, therefore, the NAC must ensure that all data published since the publication of AEGLs Volume 1 have been reviewed, and that no recent data are available that warrant changing the adopted values. Since the material presented in these documents is an exact copy of the summary of documents in Volume 1 (NRC 2000) and the data in the tables are identical to those in Volume 1 (except for the addition of the 10-min AEGL values), the subcommittee requires assurance that such a search has been carried out, and that all relevant new data have been considered. The subcommittee concludes that 10-min AEGLs derived for aniline are appropriate. However, the NAC should explain the scientific rationale to support linear extrapolation of the 8-hr values to a 10-min duration of exposure. Expanded details should be provided for the supporting studies, particularly, that of Kakkar et al. study. Page 31, paragraph 2. Is there a reason to believe that a 15,302 ppm exposure will not result in mortality in a typical acute lethal study design (i.e., a 10-min exposure followed by a 14-day observation period)? Did the study protocol include measurement of circulating methemoglobin? If not, this study should be viewed cautiously in supporting the 10-min AEGL-3 values. Page 33, line 2–3. The text should read: Following a 10-min exposure, the concentration of methemoglobin in blood is unlikely to reach equilibrium values, as typically seen 6–8 hr after the initiation of exposure. Page 33, line 4. “very…. 10 min” should be deleted.