Dosimetry data

The calculation of potential total dermal exposure of mixer-loaders and re-entry workers using dosimetry data and calculation of the internal dose using biological monitoring data is complex but will be discussed briefly. 

Major questions that arise whenever a pesticide exposure evaluation is completed are how good are the data and how close to the real answer have we gotten For most commercially sold insecticides, there are no appreciable pharmacokinetic data in human systems, although some data normally exist for animal models. Because such pharmacokinetic data do not exist for most active insecticides, passive dosimetry measurements must be used to estimate the exposure and eventually dose. Once such passive dosimetry data exist, certain assumptions must be made to arrive at an estimate of dose. 

Epidemiological and Human Dosimetry Studies. The target population for HDI toxicosis is the worker using products that contain both HDI and/or HDI in combination with the HDI prepolymers, usually in the form of automobile paint hardeners. One flaw in these reports is that the dosimetry data were not well described in many cases (Baur et al. 1984 Grammar et al. 1990 Malo et al. 1983 ... 

Epidemiological and Human Dosimetry Studies. A number of epidemiological studies have been performed on workers exposed to BCME in the past. While these studies are limited by the absence of reliable dosimetry data and the presence of other risk factors (smoking, other chemicals), the data nevertheless constitute strong evidence that BCME increases risk of lung cancer in humans. Although prospective... 

Graft Polymerization. Cobalt-60 Initiation. The cobalt-60 source was a Gammacel 200 unit from Atomic Energy of Canada, Ltd. Dose rate at the center of the chamber was 0.44-0.42 Mrad/hr, as calculated from the original dosimetry data provided by the manufacturer and the decay rate of cobalt-60. 

Table 1.3 Comparison of biomonitoring and passive dosimetry data from atrazine exposure studies using closed mixing/loading systems and closed cabs (USEPA, 2002, 2003)...

Table 1.4 Comparison of concurrent biomonitoring and passive dosimetry data s from chlorpyrifos exposure studies (USEPA, 2001)...

One special function would be dosimetry which establishes a relationship between the voltage provided by the beam monitor and the absorbed irradiation dose. For convenience, in several experimental set-ups dose is expressed as the initial radical concentration in the measuring cell. From optical measurements, the concentration can be calculated for a known molar absorptivity. The plot of concentration vs. the electrical value should result in a straight line. The slope and, possibly, a small intercept, are stored as the dosimetry data. If in a second channel the conductance is measured simultaneously, the cell constant can be determined for a known change in conductance. 

Based on the safety, efficacy, and dosimetry data from Phase I and II studies of PDT with verteporfin for subfoveal CNV, large, multicenter, randomized, placebo-controlled trials were conducted, providing the evidence for the widespread clinical use of this treatment modality in patients with AMD and other ocular conditions. The key findings of the Phase III trials of verteporfin PDT can be summarized as follows ... 

Portal to all NIST data systems see B.l Atomic and molecular spectra, cross sections, X-ray attenuation, and dosimetry data Portal to all National Library of Medicine databases NMR data submitted by users Cr) tal structures of nucleic acids See B.ll... 

Model refinement and validation for both the chltnpyrifos and the diazinon PBPK/PD models wa.s accomplished by conducting a scries of in vivo pharmacokinetic and pharmacodynamic studies in the rat and by evaluating the capability of the model to accurately simulate in vivo data published in the literature. The experimental details are fully described in Timchalk et ai (2002b) and Poet et at. (2004). In brief, these studies involved an acute oral exposure to chlorpyrifos or diazinon and the blood time course of the parent compounds and metabolites was determined, as well as the time course for the cholinesterase inhibition in several tissues. Representative results and model simulations are presented in Fig. 12 and 13 for the pharmacokinetic and pharmacodynamic response in rats following comparable oral doses (50 and 100 mg/kg) of chlorpyrifos and diazinon, respectively, The overall response was fairly comparable for these two insecticides, and the models reasonably simulated both dosimetry and the dose-dependent cholinesterase inhibition. These results arc very consistent with a fairly rapid oral absorption for both insecticides and subsequent metabolism and distribution of the active oxon metabolites. Figure 14 illustrates the capability of the diazinon PBPK/PD model to simulate rodent dosimetry data from the open literature and the capability of the model to accommodate alternative exposure routes (Poet et ai, 2004). In these examples, the time course of diazinon in plasma and cholinesterase inhibition in tissues (i.e.. blood,... 

Based on the pharmacokinetic and dosimetry data, administration of a single oral lOO-pCi dose of the radiolabel would not be expected to represent a significant radiation exposure risk in man (Tables 18.A3 and 18.A4). 

Atomic and molecular spectra, cross sections, x-ray attenuation, and dosimetry data... 

Dosimetry data are analyzed using the neutron transport code TRIPOLI in order to determine neutron fluences for energies over 1 MeV, parameter which indexes the aging results. The primary coolant temperatures are 286 °C for most 900 MWe units, 288 °C for 1300 MWe units and 293 °C for 1450 MWe units. The primary coolant temperature of Chooz-A increased from 257 to 265 °C due to a power uprate. 

Look for a decrease in the absolute lymphocyte count if exposure was recent. If at the same time, the initial white blood cell and platelet counts are abnormally low, consider the possibility of an exposure 3-4 weeks earlier. Additional daily blood counts will be needed. The cytogenetic biological dosimetry through chromosome aberration analyses should be done as early as possible. A careful differential diagnosis is the task of the physician based on the anamnesis, physical dosimetry data, clinical observation on the patient, and laboratory assays. 

Wellman, H.N., Kereiakes, J.G. and Branson, B.M. (1970). Total- and partial-body counting of children for radiopharmaceutical dosimetry data, page 133 in Medical Radionuclides Radiation Dose and Effects, Report No. CONF-691212, Cloutier, R.J., Edwards, C.L. and Snyder, W.S. Eds. (Oak Ridge National Laboratory, Oak Ridge, Tennessee). 

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