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TENTH INTERIM REPORT OF THE SUBCOMMITTEE ON ACUTE EXPOSURE GUIDELINE LEVELS 6 The longitudinal study of approximately 600 or more individuals exposed to EtO years ago in Buffalo, N.Y., should be examined. The study is well-known, and many papers have appeared on various aspects of the study. Special attention was given to the incidence of cancer in this population and the value of SCE examinations as a marker for DNA damage and potential carcinogenesis. These data help to determine the relevance of animal data to human experience and the possibility that for EtO, the rodent may be an inappropriate model. Data are available on the off-gassing of EtO from plastic bags used to hold intravenous fluids. AEGL-1: It is acceptable that AEGL-1 is not set in this case. However, the wording for justification should be revised to that it is consistent with what is stated elsewhere in AEGL documentation for other chemicals in similar situations. AEGL-2: Why is a repeated exposure study used to set AEG1â2? Is not there an Oakridge study investigating effects following a single day exposure to EtO? If acute studies of relevance are nonexistent, this should be made clear. Further, only the key study should be presented and used to derive AEGL values. The other studies can be used to provide support or corroborate the derived AEGL values. The justification for an intraspecies uncertainty factor based on asthmatic people not responding differently (from the rest of population âto irritant effects) is unclear and should be improved. Section 6.3, 2nd paragraph. Is gluthione-S-transferase associated with developmental toxicity? If not, the explanation for using a UF of 3 for intraspecies extrapolation does not hold if the AEGL-2 is based upon developmental toxicity (Snellings study). AEGL-3: Even though the LC50/LC01 values are lower for the mice and dogs, the data from rats are used to derive AEGL-3. Why? Further, a UF of 3 is used on the basis that the rat is not the most sensitive species, which indicates the use of a UF of 3 would protect the known sensitive species such as mice and dogs. The presentation should be improved to clarify why the data from known sensitive species were not used and what the basis of the magnitude of UF was? Other Comments Measurement of adducts should be considered a parameter for exposure rather than the mechanism of toxicity: Formation of protein adducts might even be considered a way of detoxification: reactive intermediates are bound to proteins before they affect genetic material (cf. HbAiC: glucose adduct formation to hemoglobin in diabetics; ethyl adducts in alcohol consumers). It is remarkable that lethal accidents with EtO have never been described in the clinical toxicology literature, in spite of the widespread use of the substance. Apparently its acute toxicity is not very high. This should be mentioned in this document, especially because the NAC based acute exposure guidelines on long- term/chronic effects.