toxicological profile for malathion - Agency for Toxic Substances and ...

MALATHION 124
3. HEALTH EFFECTS
Table 3-6. Kinetic and Physiological Parameters and Constants
Used in PBPK Human Malathion Deposition Model
Values
Hydrolytic liver metabolism
Adult (70 kg) Child (10 kg)
Apparent Vmax (moles x min-1)
-4
4.89x10
-4
1.12x10
Apparent Km (M) 1.35x10 -4 1.35x10 -4
Oxidative liver metabolism
Apparent Vmax (moles x min -1 ) 2.0x10 -5 4.65x10 -6
Apparent Km (M) 2.10x10 -4 2.10x10 -4
Other kinetic parameters b
Permeability constant
(skin surface to viable epidermis)(min -1 )
1.0x10 -5 –5x10 -4
Evaporation constant
(skin surface to air)(min -1 )
1x10 -4 –5x10 -4
Fecal constant
0.1–0.25
(intestine to feces)(min -1 )
Tissue volumes (liter)
Fat 10.0 1.420
Intestine 2.4 0.343
Kidney VRG 2.7 0.386
Liver 1.5 0.404
Muscle 30.0 6.185
Skin
Tissue perfusion rates (liter x min
2.6 0.371
-1 )
Fat 0.2 0.073
Intestine 1.2 0.276
Kidney VRG 2.25 0.517
Liver 1.5 0.380
Muscle 1.2 0.276
Skin 0.065–0.15 0.015
Cardiac output
Tissue/blood partition coefficients
6.4–6.5 1.540
a
Fat 775
Intestine 15
Kidney VRG 17
Liver 34
Muscle 23
Skin 25
a These values pertain to adults and children.
Source: Rabovsky and Brown 1993