Thorium in urine

Perkins RW, Kalkwarf DR. 1956. Determination of thorium in urine. Anal Chem 28 1989-1993. 

Twitty BL, Boback MW. 1970. Rapid determination of thorium in urine by thermal neutron activation analysis. Anal Chim Acta 49 19-24. 

PleskachSD. 1985. Determination of uranium and thorium in urine by neutron activation. Health Phys 48 303-308. 

Ting, B.G., Paschal, D.C., Jarrett, J.M., Pirkle, J.L., Jackson, R.J., Sampson, E.J., Miller, D.T., Candill, S.P (1999) Uraninm and thorium in urine of United States residents reference range concentrations. Environmental Research,... 

The concentrations of thorium in both hard and soft tissues of humans have been determined by a few authors. The concentration of thorium-232 in the blood of normal populations (not occupationally or otherwise known to be exposed to levels higher than background level of thorium) in the United Kingdom was 2.42 pg/L. The thorium-232 level in the urine of the same population was below the detection limit of 0.001 pg/L, although the concentration in the urine of exposed workers ranged from less than 0.001-2.24 pg/L. The highest value (2.24 pg/L) was found in a worker in the thorium nitrate gas mantle industry (Bulman 1976 Clifton et al. 1971). 

Benkhedda, K., Epov, V. N., and Evans, R. D., Flow-injection technique for determination of uranium and thorium isotopes in urine by inductively coupled plasma mass spectrometry, Anal. Bioanal. Chem., 381, 1596-1603, 2005. 

Becker, J. S., Burow, M., Boulyga, S. F., Pickhardt, C., Hille, R., and Ostapczuk, P. 2002. ICP-MS determination of uranium and thorium concentrations and U-235/U-238 isotope ratios at trace and ultratrace levels in urine. Atom Spectrosc 23(6), 177-182. 

Z2. Zurlo, N., GrifiBni, A. M., and Colombo, A., Determination of lead in urine by atomic absorption spectrophotometry after coprecipitation with thorium. Anal. Chim. Acta 47, 203-208 (1969). 

In the comprehensive study of the uranium and thorium levels in urine of 500 US residents, a magnetic sector ICPMS with a microconcentric nebulizer was used (Ting et al. 1999). The sample handling was carried out in a clean laboratory and all reagents were of high purity in order to avoid cross contamination. The samples were spiked with iridium that served as an internal standard and the creatinine concentration was also determined in order to normalize the results. The distribution of the uranium concentration, normalized to creatinine is shown in the top frame of Figure 4.12 while the bottom frame shows the frequency distribution of uranium in 350 urine samples in Israel (Karpas et al. 1996). 

Pappas, R.S., Ting, B.G., Jarret, J.M. et al. (2002). Determination of uranium-235, uranium-238 and thorium-232 in urine by magnetic sector inductively coupled plasma mass spectrometry, J. Anal. Atom. Spectrosc. 17,131-134. 

Ting, B. G., Paschal, D. C., and Caldwell, K. L. (1996). Determination of thorium and uranium in urine with inductively coupled argon plasma mass spectrometry./Ana/. At. Spec-trom. 11(5), 339. 

Special tests that measure the level of radioactivity from thorium or thorium isotopes in your urine, feces, and air you breathe out can determine if you have been exposed to thorium. These tests are useful only if run within several days to a week after exposure. The tests cannot, however, tell you if your health will be affected by the exposure. The tests can be run only with special equipment and are probably not available at your local clinic or hospital. For more information, see Chapters 2 and 6. 

After inhalation exposure, the primary route of excretion is in the feces following ciliary clearance from the lungs to the gastrointestinal tract (Wrenn et al. 1981). Fecal excretion may account for as much as 97% of total excretion (Fisher et al. 1983). Higher levels of thorium-230 were excreted in the feces by active crushermen (uranium mill workers exposed to uranium ore dust in the crusher building) compared to retired workers or controls (Fisher et al. 1983). Levels of thorium-230 in the urine were comparable to those of retired workers, and the levels in both were significantly greater than controls. 

It was determined in several species of animals (mice, rats, rabbits) that more than 95% of the ingested amount is excreted in the feces within several days (approximately 2-4 days) (Patrick and Cross 1948 Scott et al. 1952 Sollmann and Brown 1907). Sollmann and Brown (1907) concluded that, since very little thorium was excreted in the feces following intravenous or intramuscular injection, and since very little thorium was excreted in the urine following ingestion, appreciable amounts of thorium were neither absorbed nor excreted from the gastrointestinal tract. 

A very small percentage of injected thorium-232 dioxide (Thorotrast) in humans was excreted (more in the feces than urine) (Kaul and Muth 1978 Molla 1975). Jee et al. (1967) found that a patient excreted 0.7% of the injected amount of Thorotrast in the 17 days between injection and the death of the patient (mode of excretion not reported). Kemmer (1979) determined that the amount of thoron (radon-220) exhaled by the lungs in humans correlated to the amount of Thorotrast intravenously injected. The thoron (radon-220) correlated with a "radium-224 equivalent value."... 

In contrast to the thorium from Thorotrast (a thorium dioxide and dextran suspension) after intravenous injection, a higher percentage of thorium from more soluble thorium compounds is excreted. Following intravenous injection of thorium-234 citrate in humans, there is a relatively rapid but small (7%) amount of excretion within the first 20 days. A urine/feces ratio of 12 for male subjects and 24 for female subjects was determined. About 93% of the injected thorium-234 was retained at 100 days after injection, with a biological half-time of more than 5 years (Maletskos et al. 1969). 

Less than 5% of thorium was excreted in the urine up to 42 days after intravenous injection of thorium-234 sulfate in rats and guinea pigs (Scott et al. 1952). After intravenous injection, the amount of thorium excreted in the feces was 0.7-24.5% of the level administered for 14-42 days in rats, 0.6 and 14.6% for 2 and 5 days in guinea pigs, and 0.9% for 7 days in rabbits. In dogs injected with thorium-228 citrate, urinary excretion dominated initially, but after 2.5 years, the fecal to urinary ratio approximated 1.0 (Stover 1981 Stover et al. 1960). Thomas et al. (1963) reported the excretion of thorium citrate administered as thorium-234 tracer plus thorium-232 carrier in rats. No differences were found in the rate and route of excretion following various routes of administration (intravenous, intraperitoneal, intratracheal, and intramuscular). In the first 2 days, 25-30% of the thorium was excreted. Most of the thorium was excreted in the feces and not in the urine. At a high exposure level, the feces/urine ratio was 45 and at a low level, it was 1.6. This indicates that at the... 

Exposure to thorium can be determined by measurement of radioactive thorium and/or daughters in the feces, urine, and expired air. The primary route of excretion of thorium is in the feces following either inhalation or oral exposure. Fecal excretion is essentially complete in a matter of several days (Patrick and Cross 1948 Scott et al. 1952 Sollman and Brown 1907 Wrenn et al. 1981). The measurement of external gamma rays emitted from thorium daughters present in the subject s body and of thoron in the expired air many years following exposure can be used to estimate the body burden of thorium (Conibear 1983). 

MS. After careful homogenization, the dried urine samples were analyzed directly by LA-ICP-MS without any time consuming digestion procedure. Matrix matched synthetic laboratory standards doped with Th (IRMM 60), uranium with natural isotope composition ( U/ U = 0.00725) and uranium isotope standard reference material (NIST U-930) at the low pgml level were prepared in order to smdy the figures of merit of the analytical methods developed. The recovery rate for thorium and uranium concentration measured on a synthetic urine laboratory standard by LA-ICP-MS varied between 91 and 104%. The precision and accuracy of the analytical methods was found to be 7 % and < 1 %, respectively, for uranium concentration, by using urine laboratory standards (at uranium concentration O.lngml. ... 

Lucas, H.F. and Markun, F. (1970). Thorium and uranium in blood, urine and cigarettes. Argonne National Laboratory Radiation Physics Division annual report. Part 2 (pp. 47-52), ANL-7760. Argoime, IL Argonne National Laboratory. 

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