A review of available sources identified the following: two rat LC50 and rat oral LD50 acute toxicity data. Data sources were selected according to the hierarchy listed in Table 3.1. Toxicity data were evaluated based on the type of exposure, species, and route according to the hierarchies stated in Sections 3.3.1, 3.3.2, and using factors in Tables 3.2, 3.3, and 3.4. The concentrations were scaled to 60-minute equivalents using the ten Berge equation (Section 3.3.4). Of the two LC50, one resulted in a TEEL-3=47 mg/m3 (1056 mg/m3/4H, assumed) while another resulted in a TEEL-3=220 mg/m3 (>5000 mg/m3/4H). Dihydro-2(3H)-furanone is reported to have applications as a flavoring agent in food; the Flavor and Extract Manufacturers' Association reports expected concentrations per food category, with the maximum concentration of 20 ppm (70 mg/m3) in baked goods (1994). As this concentration appears to be safe to consume and is greater than one of the results derived from the concentration data, it is determined that the less conservative rat LC50 was more appropriate for TEEL development, and it was selected as the TEEL-3 basis. TEEL-2 and TEEL-1 were derived according to Table 3.5.
• TEEL-1 = TEEL-2/11
• TEEL-2 = TEEL-3/6
• TEEL-3 = Rat LC50 (>5100 mg/m3/4H)
The recommended TEEL-3 is less conservative than the Rev. 29A value, where the rat oral data was chosen. Inhalation data is preferred over oral data (Section 3.3.2). The recommended TEEL-2 is less conservative, as a monkey oral TDLo dose was previously found, resulting in a discrepancy with Rev.29A TEEL-1 as well. This monkey data was not able to be confirmed in this analysis.