A review of available sources identified exposure limits (LOC, OEL-STEL/TWA) and acute toxicity data (LCLo, LD50) for several species and routes. Data sources were selected according to the hierarchy listed in Table 3.1. Toxicity data were selected according to type of exposure, species, and route according to the hierarchies stated in Sections 3.3.1, 3.3.2, and evaluated using factors in Tables 3.2, 3.3, and 3.4. Analysts evaluated the LC¬Lo as a TEEL basis; however, this source was determined overly conservative because it resulted in a TEEL-3 < TEEL-2. Instead, the lowest dose rat oral LD50 was selected as the TEEL-3 basis. The LOC was selected as the TEEL-2. The OEL-TWA was considered as a TEEL-1 basis, however this resulted in a TEEL-2 < TEEL-1; instead, the OEL-STEL (Romania) was selected as the TEEL-1.
• TEEL-1 = OEL-STEL (Romania, 0.6 mg/m3)
• TEEL-2 = LOC (listed as “Diphosphoramide, Octamethly-“; 0.0008 gm/m3)
• TEEL-3 = Rat oral LD50 (5 mg/kg)
This review generated TEEL-3 and TEEL-1 values inconsistent with Rev. 29A. The Rev. 29A and current TEEL-2 values, source, and methodology are consistent. The Rev. 29A and current TEEL-3 bases are both rat oral LD50; however, the current dose is more conservative. The Rev. 29A TEEL-1 was derived from the TEEL-2 (Table 3.5), while the current TEEL-1 is an exposure limit for (OEL-STEL) Octamethyldiphosphoramide. This TEEL-1 value is less than 3 x OEL-TWA (0.9 mg/m3); the lower value TEEL-1 was used according to Handbook guidelines (Section 4.2-4.3).