Table 2. Estimated Radiation Exposure from 14C-Labeled Nutrients over the Biological Mean-Life (τbiological) as a Function of Time since Dose.
| α-tocopherol (20) |
||||||
|---|---|---|---|---|---|---|
| unit | β-carotene (18) | lutein (19) | RRR | all-rac | folic acid (21) | |
| subject body weight | kg | 76.8 ± 23.2 (n = 8) | 64.1 (n = 1) | 79.5 (n = 1) | 79.5 (n = 1) | 78.3 ± 22.3 (n = 13) |
| dose | nCi | 100 | 36 | 101.5 | 99.95 | 100 |
| half-life (t1/2) | day | 25 | 14 | 2.5 | 2.5 | 100 |
| mean-life (τbiological = t1/2/Ln 2) | day | 36.1 | 20.2 | 3.6 | 3.6 | 144.3 |
| tissue weighting factor, WT, liver | 0.04 | 0.04 | 0.04 | 0.04 | 0.04 | |
| fractional nutrient, FN, liver | 0.8 (as carotene) 0.9 (as retinol) |
0.5 | 0.8 | 0.8 | 0.333 | |
| radiation exposurea | ||||||
| whole body, WB | μSv | 1.3 ± 0.4 | 0.3 | 0.12 | 0.12 | 5.2 ± 1.5 |
| liver, 1.5 kgb | μSv | 63.3 (as carotene) 354 (as retinol) |
12.7 | 6.4 | 6.3 | 253 |
| liver, 1.5 kgc | μSv | 2.0 (as carotene) 12.8 (as retinol) |
0.3 | 0.2 | 0.2 | 3.4 |
a
Nutrient absorption is assumed 100%.
b
Radiation exposure regardless of WT and FN.
c
Radiation exposure regard of WT (ICRP 103, 2008) and FN. The dimensionless multiplicative factors (WT and FN) are 1 for WB.