Use of the true absorption coefficient as a measure of bioavailability of radiocaesium in ruminants
Mayes, R.W.; Beresford, N.A.; Howard, B.J.; Vandecasteele, C.M.; Stakelum, G.. 1996 Use of the true absorption coefficient as a measure of bioavailability of radiocaesium in ruminants. Radiation and Environmental Biophysics, 35 (2). 101-109. 10.1007/BF02434032Full text not available from this repository.
Limitations of existing methods to describe the bioavailability of dietary radionuclides to ruminants (the transfer coefficient and apparent absorption coefficient) have led to the alternative suggestion of using the true absorption coefficient (A t). Various approaches to estimatingA t for radiocaesium, involving the intravenous administration of a second isotope, are presented and discussed with reference to results from studies in which a range of radiocaesium sources were examined in sheep. Although estimates ofA t differed between the sources, they were reasonably consistent between measurement techniques. Those methods which involved the estimation of endogenous faecal excretion of radiocaesium could be used with previously contaminated animals and did not require continuous administrations of radiocaesium isotopes, but gave unreliable results for sources of low bioavailability. Methods based on estimating the turnover rate of dietary radiocaesium through blood plasma were sufficiently sensitive to measureA t for the range of sources studied. However, they require previously uncontaminated animals and continuous administration of both isotopes for approximately 7 days. Bioavailability is more effectively measured asA t than as the transfer or apparent absorption coefficients sinceA t does not incorporate factors relating to the metabolism of radiocaesium in the tissues of the animal. The results of these studies show that differences in transfer coefficients between sheep and cattle and between sheep of differing ages are not due to variation in absorption across the gut. The potential for applying these approaches to other radioactive elements is discussed.
|Programmes:||CEH Programmes pre-2009 publications > Other|
|CEH Sections:||_ Pre-2000 sections|
|NORA Subject Terms:||Ecology and Environment|
|Date made live:||12 Jun 2012 08:59|
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