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 13 releases of phosphine. It is prudent to be conservative in the derivation of the AEGL-2 values based on the slope of the dose-response curve for lethality. One problem with derivation of the AEGL-2 is that the concentration selected as the basis of the AEGL-2 was the highest concentration (10 ppm) from the Newton et al. (1993) study. However, the nasal discharge observed in these rats is stated to have occurred at all concentrations (page 10). The fact that the 10 ppm exposure causing “red nasal discharge” following the 6-hr exposure is extremely close to the lethal concentration for 6-hr exposures is readily apparent from the animal-data plot. Use of the lowest concentration for the effect of “red nasal discharge,” 2.5 ppm, may be more appropriate for derivation of the AEGL-2. The actual data for this effect should be added to the section discussing this study on page 10. Section 6.3 on page 16 states that the red mucoid discharge observed in this study was “less severe than the effects defined by AEGL-2” and that “the resulting values should be protective.” Was the “red discharge” due to nasal bleeding? As the text is written, it is not clear whether this is or is not a significant adverse effect. As the concentrations at which this effect occurs are so close to the lethal concentration for a similar exposure time of 6- hr, this statement is inappropriate and should be deleted. Specific Comments Page i. COPD is preferred to “asthma” (chronic obstructive pulmonary disease). Page 3. Are phosphine or the impurities responsible for garlic odor? Page 4. 1st paragraph. The detected ethanol is unlikely to have originated from malathion hydrolysis. Ethanol is commonly formed post-mortem both in blood and in tissues. That is more likely the explanation for its presence. Page 4, 3rd paragraph. Measurement by Drager tubes is only semi-quantitative and cannot be representative. Regarding post-mortem findings: Is cardiotoxicity the primary pathology or secondary to hemolysis. Page 5. It is very unlikely to reach 713 ng/ml A1 in blood by A1-phosphide. This is a lethal concentration in hemodialysis patients heavily exposed to parenteral A1. Page 7. The discussion concerning chromosomal aberrations suggests more than can be derived from Section 2.5. Page 7, Section 3.11, line 4. “including” is not correct: hyperemia of the ears is not a result of respiratory irritation. Page 13, Section 4.1. The last sentence needs to be stated more clearly.