Table 3.
PBPK parameters used for the child-specific model estimated using each child’s age, height and weight. Tissue: Blood partition coefficient only shown for chlorpyrifos as an example.
| Parameter | Compartment/Chemical | Range | Mean | Median |
|---|---|---|---|---|
| Compartment Volume (m3) | Blood | 0.0006–0.0012 | 0.0009 | 0.0008 |
| Brain | 0.0006–0.0010 | 0.0008 | 0.0008 | |
| Slowly Perfused | 0.0017–0.0031 | 0.0024 | 0.0022 | |
| Richly Perfused | 0.00040–0.00078 | 0.00057 | 0.00055 | |
| Fat | 0.0023–0.0084 | 0.0048 | 0.0049 | |
| Liver | 0.00022–0.00044 | 0.00032 | 0.00032 | |
| Kidneys | 0.00004–0.00008 | 0.00006 | 0.00006 | |
| Alveolar Air | 0.00037–0.00088 | 0.00060 | 0.00055 | |
| Perfusion Rate (m3/h) | Brain | 0.020–0.031 | 0.026 | 0.025 |
| Slowly Perfused | 0.007–0.013 | 0.010 | 0.009 | |
| Richly Perfused | 0.009–0.017 | 0.013 | 0.013 | |
| Fat | 0.004–0.015 | 0.009 | 0.009 | |
| Liver | 0.013–0.026 | 0.019 | 0.019 | |
| Kidneys | 0.008–0.016 | 0.011 | 0.012 | |
| Cardiac Output (m3/h) | 0.062–0.119 | 0.087 | 0.087 | |
| Ventilation Rate (m3/h) | 0.14–0.25 | 0.20 | 0.22 | |
| Renal Clearance (m3/h) | Chlorpyrifos | 0.00038–0.00053 | 0.00046 | 0.00044 |
| Chlorpyrifos Oxon | 0.00027–0.00038 | 0.00032 | 0.00031 | |
| Diazinon | 0.0028–0.0040 | 0.0034 | 0.0033 | |
| Diazinon Oxon | 0.000001–0.00107 | 0.00005 | 0.000001 | |
| DETP | 0.0033–0.0047 | 0.004 | 0.0038 | |
| DEP | 0.017–0.024 | 0.021 | 0.020 | |
| Creatinine Excretion (mol/h) | 0.00003–0.00007 | 0.00005 | 0.00004 | |
| Tissue:Blood Partition Coefficient | Blood | 2.09–2.10 × 106 | 2.09 × 106 | 2.09 × 106 |
| Brain | 4.2–5.1 | 4.6 | 4.5 | |
| Slowly Perfused | 3.3–3.5 | 3.4 | 3.4 | |
| Richly Perfused | 3.3–3.5 | 3.4 | 3.4 | |
| Fat | 86.4–112.3 | 102.5 | 108.7 | |
| Liver | 5.1–5.6 | 5.4 | 5.3 | |
| Kidneys | 4.1–4.5 | 4.3 | 4.3 | |
| Maximum Velocity Vmax (mol/h) | Chlorpyrifos → Chlorpyrifos Oxon | 0.00009–0.00018 | 0.00013 | 0.00013 |
| Chlorpyrifos → DETP | 0.00017–0.00033 | 0.00024 | 0.00024 | |
| Chlorpyrifos Oxon → DEP | 0.006–0.0117 | 0.0086 | 0.0087 | |
| Diazinon → Diazinon Oxon | 0.0002–0.00039 | 0.00028 | 0.00029 | |
| Diazinon → DETP | 0.00031–0.0006 | 0.00044 | 0.00044 | |
| Diazinon Oxon → DEP | 0.19–0.35 | 0.27 | 0.27 | |
| First Order Metabolism (mol/h) | DETP | 0.5–0.98 | 0.72 | 0.73 |
| DEP | 0.23–0.44 | 0.32 | 0.33 | |
| Protein Binding (fraction bound) | Chlorpyrifos | 0.962–0.963 | 0.962 | 0.962 |
| Chlorpyrifos Oxon | 0.974–0.976 | 0.975 | 0.975 | |
| Diazinon | 0.937–0.939 | 0.938 | 0.937 | |
| Diazinon Oxon | 0.863–0.868 | 0.865 | 0.864 | |
| DETP | 0.912–0.915 | 0.913 | 0.913 | |
| DEP | 0.079–0.083 | 0.081 | 0.08 | |
| Hand Surface Area (m2) | 0.01–0.018 | 0.014 | 0.013 |