Gastrointestinal Absorption of Americium-241 by Orally Exposed Swine: Comparison of Experimental Results with Predictions of Metabolic Models

Abstract

Two groups of 11-week-old swine (40 miniature and 40 domestic swine) received a single oral administration of 1.9 X 10(8) Bq (5.2 mCi) of 241Am citrate, and groups of eight animals, four of each type, were killed and sampled at 1, 2, 4, 8, 16, 24, 48, 72, and 96 h and 30 days later. Uptake and excretion patterns of the radioactivity appeared to occur in three phases: rapid uptake, rapid excretion, and then a slower excretion. All animals were systematically dissected, and the eviscerated carcasses were autoclaved for separation of bone and muscle. The predominant site of deposition was bone, and autoclaving had little effect on releasing 241Am from either bone or muscle. The maximum fractional gastrointestinal absorption of 1.1 X 10(-3) occurred 8 h after radionuclide administration. The tissue distribution data suggest partitions of 50, 20, and 30%, for bone, liver, and other soft tissues, respectively. Two metabolic models were evaluated: a modified Mewhinney-Griffith model and the ICRP 30 model to compare the biological data with model predictions. All models underestimated the actual early time data, but the fits to the experimental results were better at later times.

ICRP Publication 141: Occupational Intakes of Radionuclides: Part 4

“…(933) Results for other species are in the same range. They ranged from 10 −5 to 10 −3 for americium citrate in swine (Eisele and Erickson, 1985; Eisele et al., 1987), from 1.7 to 3 × 10 −4 for americium nitrate in guinea pigs (Sullivan, 1980), and from 0.6 × 10 −4 (oxide) to 5 × 10 −4 (nitrate) in hamsters (Stather et al., 1979c; Harrison et al., 1981). In other studies performed on dairy animals, absorption of americium chloride in cows and americium nitrate in goats was estimated to be 2 × 10 −4 and 2.6 × 10 −4 , respectively (Howard et al., 2009).…”

Literature Review and Assessment of Plant and Animal Transfer Factors Used in Performance Assessment Modeling

“…No other experimental data were found for young animals. Eisele et al (1987) dosed 11-week-old swine with a single oral dose of 241 Am citrate, and reported a fractional gastrointestinal absorption of 1.1×10 -3 at 8 hours after radionuclide administration and tissue distribution at 30 hours of 50, 20, and 30% for bone, liver, and other soft tissues, respectively. Experimental data are limited for Am transfer coefficients in pork, but Coughtrey's (1990) model gives a value of 1.7×10 -4 d/kg.…”

Transfer of radionuclides to animals — An historical perspective of work done in the United States

“…In more recent years some work was done with transuranic radionuclides, notably americium (23). The facilities are currently part of the Oak Ridge Associated Universities (ORAU).…”