(the cancer-risk calculation involves a linear extrapolation from 25,600 days to 0.5 to 8 h whereas AEGL values were extrapolated from a single 7-h exposure using either n = 3 or n = 1, and different uncertainties are addressed by the two methods).
A summary of the AEGL values for BCME is shown in Table 1-16.
8.2. Comparison with Other Standards and Criteria
The existing standards and guidelines for BCME are shown in Table 1-17. OSHA, NIOSH, Germany, Austria, and Sweden have no permissible limits for BCME because it is a human carcinogen. A TLV-TWA of 0.001 ppm was adopted by the ACGIH and the Belgium based on the carcinogenic potential of BCME.
A large chemical manufacturer in Philadelphia has developed internal Emergency Response Planning Guideline (ERPG) values (1-h exposure) for BCME of 1 ppb for the ERPG-2 and 100 ppb for ERPG-3 (no ERPG-1) (Rohm and Haas, personal communication, Feb. 1998).
8.3. Data Quality and Research Needs
No studies of BCME had defined exposures and responses that fell within the scope of AEGL-1 severity. Perhaps a more sensitive, molecular-based assay could be developed to detect subclinical respiratory toxicity.
Adequate single-exposure animal studies were available for derivation of AEGL-2 and AEGL-3 values. The AEGL-2 and AEGL-3 values were each supported by several studies with rats and hamsters. However, no relevant human studies were available that adequately documented exposures to BCME (time and concentration).
TABLE 1-16 Summary of AEGLs Values for bis-Chloromethyl Ether
|Classification||10 min||30 min||1 h||4 h||8 h|
|AEGL-2||0.055 ppm (0.26 mg/m3)||0.055 ppm (0.26 mg/m3)||0.044 ppmb (0.21 mg/m3)||0.028 ppmb (0.13 mg/m3)||0.020 ppmb (0.095 mg/m3)|
|AEGL-3||0.23 ppmb (1.1 mg/m3)||0.23 ppmb (1.1 mg/m3)||0.18 ppmb (0.86 mg/m3)||0.11 ppmb (0.52 mg/m3)||0.075 ppmb (0.36 mg/m3)|