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Table 4 Sensitivity of results in dependence on modified input data (MPPD input parameters, steady state particle volume, clearance half time in humans) and different MPPD program versions: Estimated NOAEC in rats, calculated adaptation factors AF lung burden and AF clearance , and the derived human equivalent concentration (HEC) according to the second Model B procedure described by Equation (7) on p.182 and Equations (8), (9), (10) on p. 186 in [14]

From: Translational toxicology in setting occupational exposure limits for dusts and hazard classification – a critical evaluation of a recent approach to translate dust overload findings from rats to humans

MPPD Version MPPD input parameters* Alveolar deposition fraction in rats /% Alveolar deposition fraction in humans/% Critical steady state particle volume burden/μL per kg-rat Alveolar clearance half time in humans/days NOAEC/mg/m 3 AF lung burden /1 AF clear ance /1 HEC/mg/m 3
2.0 IA switched off OMB 7.5 16.4 1 400 0.53 0.93 0.93 0.53
2.0 IA ONA 6.3 8.4 1 400 0.63 1.52 0.93 1.03
2.11 3.3 8.8 1 400 1.21 0.76 0.93 0.98
2.0 IA ONA 6.3 8.4 4.2 400 2.66 1.52 0.93 4.33
2.11 3.3 8.8 4.2 400 5.07 0.76 0.93 4.14
2.0 IA ONA 6.3 8.4 1 250 0.63 1.52 0.58 1.65
2.11 3.3 8.8 1 250 1.21 0.76 0.58 1.58
2.0 IA ONA 6.3 8.4 4.2 250 2.66 1.52 0.58 6.93
2.11 3.3 8.8 4.2 250 5.07 0.76 0.58 6.62
  1. *IA, Inhalability Adjustment; OMB, Oronasal-Mouth Breather; ONA, Oronasal-Normal Augmenter; Other input data used invariantly and in accordance with [14] and [11]: reference body weights = 1 kg-rat, 70 kg-human; ventilation rates = 0.29 m3/kg-rat and day, 10 m3/70 kg-human and day; macrophage pool volumes = 7x1010 μm3/kg-rat and 50x1010 μm3/kg-human; alveolar clearance half time in rats = 60 days; MMAD = 1.8 μm, GSD = 2, density = 1 g/cm3 (particle characteristics); other MPPD input parameters as listed in the MAK document ([11], p. 57, 58 and Appendix).