The chemical of interest, silicon Y-6607, is specifically dimethylamino terminated polydimethylsiloxane. A review of limited available sources for this chemical identified rat LC50 toxicity data. The rat LC50 data was evaluated using factors in Tables 3.2, 3.3, and 3.4, and was used as the TEEL-3 basis. The ten Berge equation was used to scale the LC50 data to 60 minutes (Section 3.3.4). TEEL-1 and TEEL-2 were calculated based on Table 3.5.
• TEEL-1 = TEEL-2/11
• TEEL-2 = TEEL-3/6
• TEEL-3 = Rat 240-min LC50 (774 ppm)
This review generated TEEL values that are less conservative than those in Rev. 29A. It appears the same LC50 toxicity data as Rev. 29A was found, but because different molecular weights were used to calculate values, the results are inconsistent. In Rev. 29A the molecular weight used was 75 Da, where this review found it to be 220.46 Da. Although the basis was the same, the difference in the molecular weight resulted in values that are less conservative than the previous revision. Siloxanes and silicones cover a range of chemicals with various molecular weights, but Silicon Y-6607 has a molecular weight of 220.46 Da.