Urinary Excretion of Tritium following Exposure of Man to HTO - a Two Exponential Model

Abstract

Data on urinary excretionof tritium hy a 41.year-oltl male who accidentally inhaled (or ingested) tritium, presumed to h e In the form of HTO, a r e presented along wlth an interpretation of these data and an e-timate of the radiation dose delivered to tissue<. JIeasurements of levels in urine were made as long as 255 clays after the intake of the tritium. The data could he represented as a sum of two exponential terms, one with a half-life of about 9 clays, the other of ahout 31 day.:. The total dose t o body water was estlmated to be ahout 16 rem, the long-term esponentlal contributing about 2"b of the total. A two-compartment model was applied to the data. Equations were derived for the amounts of tritium i n each compartment, and an estimate was obtained for the total tloae in a n y tisaue, ha.;ed on a comparinon with the content of hydrogen in the ti;iue. This method of estlmatlng the dose may he applicable for other raclionuclide~ anti compound-. I t assumes the stable element and Its radioactive isotope hehaw similarly, or itlenticallj-, in the hotly, but does not involve assumptions concernunp the mathematical form o f t h e retention function.

Free and esterified fatty acid and cholesterol synthesis in adult malesand its effect on the doubly-labelled water method

“…This is a significant effect and, if repeated in human subjects, would represent a potentially serious error in the determination of energy requirements and even in relative measurements when comparing DLW-derived estimates of energy expenditure between groups with different intrinsic rates of fat synthesis. Simple estimates of fat deposition cannot be used to estimate sequestration since 2 H incorporation into fat can occur during the normal process of fat turnover; indeed fat synthesis has been detected in adult weight-stable human subjects from the long-term turnover of 3 H 2 O (Snyder et al 1968) and the incorporation of 2 H into circulating fatty acid (Jones et al 1988(Jones et al , 1994Leitch & Jones, 1991. However, the latter tracer studies have only been carried out over relatively short periods in relation to the likely rates of turnover of fat and cholesterol (Rittenberg & Schoenheimer, 1937;Goodman et al 1973).…”

Retention and Excretion of Inhaled 3H and 14C Radiolabeled Methane in Rats

“…There are several recorded accounts of 3 H elimination from the adult human body following its accidental inhalation or ingestion (Snyder et al 1968;Radwan et al 1977;Jeanmaire et al 1980;Hill and Johnson 1993;Trivedi et al 1997). It is estimated that the biological half-time for tritiated water in the human body ranges from 4 to18 d, with a mean value of 10 d. The loss of organically bound 3 H from humans is longer, and its retention has been estimated to follow two exponential functions of time: one with a T b ½ of 21 to 76 d and another with a retention Table 7.…”

Underground Test Area Subproject Phase I Data Analysis Task. Volume VIII - Risk Assessment Documentation Package

“…Although chronic exposure to tritiated water results in higher tritium incorporation into the OBT compartment, the increase in dose due to OBT is only a few percent because almost all of the tritium in the cell is present as HTO (Diabate and Strack, 1993). The ICRP, in their Publication 30 (ICRP, 1978), and several authors (Snyder et al, 1968;Sanders and Reinig, 1968;Lambert and Clifton, 1967;and Moghissi et al, 1972) suggest that the contribution from OBT accounts for less than 10 percent of the dose. The biological rate of elimination constant is unknown for OBT; however, if HTO is ingested, only a small fraction becomes OBT.…”