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Biokinetic models range

Some 20% is assumed to enter the blood compartment. The ICRP biokinetic model for radium has the same general structure as that for strontium and uranium (see Figure 26.2-2). Bone is the critical organ with a biological half-life for radium in the range of 20 years. Since the decay of radium leads to the noble gas radon with a physical half-life of 3.8 days, most of the radioactivity of the decay product escapes from the body before further decays occur. [Pg.1162]

Secondly, biomagnification of Zn in fish (TTFs of 1-2) may occur in specihc circumstances. The authors of four biokinetic studies reported TTFs of 1.1-6.0 for fish feeding on planktonic crustacean and clams, and, in one, a TTF of 0.2 (Online Resource 3). Yet all but one laboratory-derived TTF >1, for a TL3 hsh, was associated with dietary Zn concentrations <100 pg/g dry wt, the upper end of the essential range for dietary Zn (Fig. le). Thus, it is possible that the test hsh may have been deficient in Zn. In addition, some of the values used to parameterize the biokinetic model may be suspect The highest Zn TTFs for fish of 4.9 and 6.0 did not quantify K, which can affect biokinetic results because it can be comparable to efflux rate (Baines et al. 2002 Dutton and Fisher 2010). This may have produced an overestimate of the TTF (Xu and Wang 2002 Zhang and Wang 2007). Overall, it appears that Zn TTFs between 1 and 2 are possible for fish. [Pg.114]

Current biokinetic models differ in their flexibility for use in other than stable, (near) steady-state Pb exposures of human risk populations. The lEUBK is only operative in cases where Pb exposures are stable and long term. By contrast, the O Haherty PB-PK model is constructed to reflect acute or episodic Pb exposures. Current biokinetic models also differ in the age ranges of exposed populations to be modeled. The lEUBK model is for children up to 84 months old. The PB-PK models are basically hfetime in their application. [Pg.325]

The lEUBK model in its intake, uptake, and biokinetic components attempts to take some cognizance of interindividual variability of Pb in children s blood. Overall, this variability derives from both Pb exposure variation across children in a population as well as differences internally (bioki-netically) in the form of differing Pb retention and excretion rates. Comparatively speaking, it is exposure variability that ranges more widely. Pb intake rates and subsequent uptake rates, for example, can differ by orders of magnitude across Pb-contaminated environmental media... [Pg.332]

North Americans carried 300-fold higher body Pb burdens than prehistoric humans. Flegal and Smith (1992) reported that prehistoric adults would have typically had a PbB value of 0.016 pg/dl, using extrapolation estimates from bone Pb contents of preindustrial and contemporary samples and animal data. Mushak (1993), using a computerized biokinetic Pb exposure simulation model and published estimates of prehistoric Pb levels in human diet, water, ambient air, etc., calculated a PbB for prehistoric children in the narrow range of 0.06—0.12 pg/dl, in good accord with the estimate of Flegal and Smith (1992). [Pg.349]


See other pages where Biokinetic models range is mentioned: [Pg.27]    [Pg.115]    [Pg.32]    [Pg.433]    [Pg.176]    [Pg.368]    [Pg.146]    [Pg.274]    [Pg.336]   
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