Milk Transfer Comparisons of Different Chemical Forms of Radioiodine

Abstract

Lactating cows were orally dosed with I,, CH31, NaI and NaIO, labeled with radioiodine. For these 4 chemical forms, the effective half-life in milk was approximately 1 day for the first 5 days. The peak thyroid concentration occurred approximately 2.8 days after ingestion in all the cows. Ion-exchange analysis indicated that, regardless of the chemical form administered, 97'3, of the iodine in the milk was inorganic. These results suggest that in dairy cows there are no significant differences in the thyroid uptake and milk transfer among the compounds tested.

The Importance of Source-Dependent Bioavailability in Determining the Transfer of Ingested Radionuclides to Ruminant-Derived Food Products

“…There appears to be no difference in the bioavailability of the sources administered, absorption being close to complete in all cases. Other authors have noted no difference in the transfer to milk and thyroid of radioiodine from a variety of sources (39,(52)(53)(54)(55). For instance, Bretthauer et al (54) orally administered four different chemical forms of radioiodine (I2, CH3I, NaI, and NaIO3) to lactating cows and found no differences in the transfer to either thyroid or milk.…”

Parameters used in the environmental pathways and radiological dose modules (DESCARTES, CIDER, and CRD codes) of the Hanford Environmental Dose Reconstruction Integrated Codes (HEDRIC)

“…The chemicalform of the radionuclide may affectits transportand accumulation in variousenvironmental pathways. Much researchhas beendone on the quantitative differences causedby the different chemicalformsof iodinefor atmospheric deposition (seeVd parameter, Sehmel1980)and dairycow ingestion of iodine(e.g.,see TFmilk_ind parameter) (Bretthauer et al 1972). Muchless is knownabout the effects of chemical form for all other pathways.…”

“…Ingestion intakesare expectedto be significantly greaterthan . The biological availability of ingested iodine is independent of its chemical form at consumption (Garner et al 1960;Bretthauer et al 1972).…”

Iodine-131 Releases from Radioactive Lanthanum Processing at the X-10 Site in Oak Ridge, Tennessee (1944-1956)- An Assessment of Quantities released, Off-Site Radiation Doses, and Potential Excess Risks of Thyroid Cancer, Volume 1

“…For controlled conditions in which cows were fed various soluble forms of iodine, Bretthauer et al (1972) found no significant difference in the transfer to milk. Furthermore, Miller (1996) has suggested from his experience that if 131 I is ingested in a soluble form, the feed-to-milk transfer coefficient should not depend on the mode of administration (e.g., encapsulated feeding versus feeding of contaminated forage).…”