Table 5. Summary of BMDs (AM_BMDs), BMDLs (AM_PODs), HECs, and MOEs.
| Nasal tissue | Sex | Lesion | BMD | BMDL [PODRat (nmol/min-g tissue)] | HEC (ppm) | HEC (mg/m3) | MOE |
|---|---|---|---|---|---|---|---|
| Ventral respiratory epithelium | Male | Hyperplasia | 2.00 | 0.78 | 0.63 | 3.30 | 3706 |
| Squamous metaplasia | 5.12 | 3.82* | –* | –* | > 63,000† or not applicable | ||
| Female | Hyperplasia | 4.99 | 3.84* | –* | –* | > 63,000† or not applicable | |
| Squamous metaplasia | 4.95 | 3.74* | –* | –* | > 63,000† or not applicable | ||
| Dorsal olfactory epithelium | Male | Degeneration | 4.41 | 1.25 | 0.99 | 5.19 | 5824 |
| Hyperplasia | 6.83 | 1.60 | 1.43 | 7.49 | 8412 | ||
| Female | Degeneration | 4.41 | 1.25 | 0.99 | 5.19 | 5824 | |
| Hyperplasia | 4.41 | 1.25 | 0.99 | 5.19 | 5824 |
BMD = Benchmark Dose. As shown here, the BMD is equal to the average of the BMDs from all adequately fitting models (AM_BMD from Table 4), BMDL = 95% Lower Confidence Limit on the Benchmark Dose (10% response). As shown here, the BMDL is equal to the average of the BMDLs from all adequately fitting models (AM_POD from Table 4), POD = Point of Departure, HEC = Human Equivalent Concentration, Margin of Exposure (MoE) is the HEC divided by the typical residential exposure level of 0.00017 ppm (0.95 μg/m3).
*Rate of metabolism in the rat precludes calculation of an HEC due to the saturation of metabolism in humans (i.e., > 4.5 nmol/min-g tissue in the dorsal olfactory; > 1.5 nmol/min-g tissue in the ventral respiratory; at > 10.7 ppm continuous exposure) (Campbell et al. 2014).
†MOE is HEC divided by 10.7 ppm (highest continuous exposure concentration evaluated in the model).
1 ppm = 5.24 mg/m3.