TABLE Il Factors for Converting Air Concentrations of Radioiodine to Thyroid Dose via the Milk Pathway* (mrem/yrper pCi/m?) Age I-129 Tyr 5830 4 yr 2400 14 yr 2040 Adult 2850** * ° 1-130 I-13) 1-132 29.1 2665. 0.619 12.8 1100. 0.267 4.81 462. 3.75 379. 1-133 1 1-134 T-135 0.0624 8.30 41.3 0.0269 3.56 0.0968 16.0 0.00968 1.27 0.0747 12.3 0.00749 0.980 Assuming: 1} Grazing 365 days/yr. Factors for other grazing Seasons can be obtained by multiplying tabulated values by fraction of year during which cows graze. 2) 3) 4) 5) 6) ** No other radioiodine intake by cow or person. No decay between milking and consumption. Consumption of 1 liter/day of milk. All radioiodine is inorganic. If only 2% of radioiodine is in an inorganic form, then multiply DF's by (Z/100). Ignoring long-term accumulation in soil, which for I-129 would add 1.3% in one year or 50% in 40 years. Dose in first year. Maximum dose rate after equilibrium is reached between thyroid burden and intake rate would be 1.09 times this value. Revised May 1976 J. K. Soldat