The development and evaluation of a thermally-desorbable miniature passive dosimeter for the monitoring of organic vapors

A thermally desorbable passive dosimeter for organic vapors has been developed in conformity with theoretical and practical aspects of passive dosimeter design. The device was optimized for low sample loadings which result from short-term and/or low concentration level exposure. Laboratory evaluation of this device for factors critical to the performance of passive dosimeters included the following: desorption efficiency, capacity, sensitivity, accuracy and precision, concentration level, environmental conditions (e.g., air face velocity, relative humidity) and sample stability during short and long periods of time. This device has been shown to operate in accordance with theoretically predicted performance and should be adequate for short-term exposure limits and/or low concentration monitoring of organic vapors in the workplace.     

Stain length passive dosimeter for monitoring of carbon monoxide

A new passive dosimeter for the personal monitoring of carbon monoxide exposure in the workplace has been developed. This new type of sampling device does not require follow-up analysis of the collected sample to determine the exposure. Rather, the time-weighted average concentration is determined directly from the length of a colored stain which is produced instantaneously during the exposure period in a specially prepared indicator tube. The colored stain length is a function of both contaminant concentration and exposure time. The effects of carbon monoxide concentration in the range of 0.5 T TLV to 2.0 X TLV on the response of the dosimeter were evaluated in a dynamic exposure chamber. In this range of concentration, plots of stain length against exposure collapsed onto a single curve. At the TLV exposure the stain length was 2.1 cm and the 95% confidence interval about this point was +/- 17%. Relative humidity in the range of 26 to 92% and face velocity in the range of 0.01 to 1.0 m/s (2 to 200 fpm) did not significantly affect the dosimeter response. These data were fitted to the appropriate model equation with a correlation coefficient of 0.968. By eliminating the need for follow-up analysis, this stain length dosimeter significantly reduces the cost of monitoring. The instantaneous readout eliminates the delay between exposure and quantification, enabling more careful control of the workplace environment.     

A portable miniature IMD-01 X-ray dosimeter for monitoring the dose power in radiodiagnosis

The paper presents a portable miniature [symbol: see text]-01 X-ray dosimeter designed by the Research Institute of Introscopy, Spektr Moscow Research-and-Production Association, for monitoring the power of a dose during X-ray diagnosis. The device ensures the monitoring of the power of a dose at the input of X-ray detectors of diagnostic apparatuses and, with the use of special methods, makes it possible to control the state of the protection devices of X-ray diagnostic apparatuses. An ionization chamber is used as a detector of X-ray radiation. The technical data of the dosimeter are given.     

The ID-03 X-ray dosimeter for monitoring the radiation parameters of X-ray equipment in roentgenography

The paper presents an [symbol: see text]-03 X-ray dosimeter designed by the Research Institute of Introscopy, Spektr Moscow Research-and-Production Association, for monitoring the radiation parameters of X-ray plants at roentgenography. A Si(Li)-based semiconductor detector with the p-i-n structure is used as a detector of X-ray radiation. The technical data of the dosimeter are given.     

Evaluation of methyl bromide exposure on the plant quarantine fumigators by environmental and biological monitoring

The study was undertaken to assess the potential risk of exposure to methyl bromide (MB) gas of plant quarantine fumigators who wore full facepiece gas masks with respirator canisters. The mean ambient concentrations of MB determined by a personal sampling device exceeded the TLV-ACGIH level of 5 ppm in the degassing processes at three fumigation sites except at the silos. The mean urinary bromine concentration of 379 non-MB workers was 6.3 +/- 2.5 mg/l with 95% confidence limits of 10 mg/l. There were 44.6% of 251 MB workers whose urinary bromine levels exceeded the 10 mg/l. There was a significantly positive correlation between the urinary bromine concentrations of the MB workers and the ambient MB concentrations in the degassing process. The MB levels in the workers' exhalation were positive in the degassing process, while those were below the detection limit in the dispersion process. Three possible routes through which the workers are exposed to MB gas are considered to exist: leakage through the interstice between the facepiece of a gas mask and the wearer's face, breakthrough of MB gas in the respirator canister, and percutaneous absorption of MB gas. Biological monitoring of urinary bromine and exhalatory MB as well as environmental monitoring of the ambient MB provided useful information for evaluating exposure of workers to MB.     

A method of determining accuracy and precision for dosimeter systems using accreditation data

A study of the uncertainty of dosimeter results is required by the national accreditation programs for each dosimeter model for which accreditation is sought. Typically, the methods used to determine uncertainty have included the partial differentiation method described in the U.S. Guide to Uncertainty in Measurements or the use of Monte Carlo techniques and probability distribution functions to generate simulated dose results. Each of these techniques has particular strengths and should be employed when the areas of uncertainty are required to be understood in detail. However, the uncertainty of dosimeter results can also be determined using a Model II One-Way Analysis of Variance technique and accreditation testing data. The strengths of the technique include (1) the method is straightforward and the data are provided under accreditation testing and (2) the method provides additional data for the analysis of long-term uncertainty using Statistical Process Control (SPC) techniques. The use of SPC to compare variances and standard deviations over time is described well in other areas and is not discussed in detail in this paper. The application of Analysis of Variance to historic testing data indicated that the accuracy in a representative dosimetry system (Panasonic? Model UD-802) was 8.2%, 5.1%, and 4.8% and the expanded uncertainties at the 95% confidence level were 10.7%, 14.9%, and 15.2% for the Accident, Protection Level-Shallow, and Protection Level-Deep test categories in the Department of Energy Laboratory Accreditation Program, respectively. The 95% level of confidence ranges were (0.98 to 1.19), (0.90 to 1.20), and (0.90 to 1.20) for the three groupings of test categories, respectively.     

OSL剂量计参与2017年全国个人剂量监测比对结果及分析

目的 对2017年参与全国个人剂量监测比对的结果进行分析。方法 结合OSL剂量计自身的性能特点，分别从OSL剂量计的能量响应、角度响应、线性响应几个方面对5组比对OSL剂量计的评定结果进行分析。结果 比对中照射了不同的射线能量、入射角度、照射剂量的5组剂量计的单组性能评定值P，能够反映出OSL剂量计的性能特征，主要表现为，OSL剂量计在低能区存在较明显的过响应，这一特性使照射了低能X射线的两组剂量计的单组性能评定值P较高；在662 keV能量照射下，OSL剂量计具有很好的角响应，这一特性使各组评定值没有明显受到照射角度的影响。结论 比对结果为合格，说明我实验室利用OSL剂量计对放射工作人员进行外照射个人剂量监测，满足质量保证的要求。     

Empirical data in support of a skin notation for methyl chloride

This article presents the first empirical experimental data on the skin absorption of methyl chloride gas using an in vitro technique and human skin. Methyl chloride is a commonly used industrial agent that is known to be an inhalational hazard but is also reported to be absorbed through human skin in amounts that contribute substantially to systemic intoxication. As a result, is has been assigned a skin notation by the ACGIH. Other than predictive models, there is a general paucity of experimental data on the skin absorption of methyl chloride and therefore a distinct lack of empirical evidence in the open literature to support the assignment of a skin notation for this chemical. This study found that methyl chloride permeates through human epidermis when exposed at high atmospheric concentrations within relatively short timeframes. Therefore, providing important initial empirical evidence in support of the assignment of a skin notation.     

An experience of using the DRK-1 dosimeter with conduit ionizing chamber for monitoring the parameters of X-ray diagnostic equipment

An experience of using, at the State Sanitary and Epidemiologic Supervision (SSES), the Control X-ray Dosimeter (DRK-1) to calculate the dose-square product in the radiation-and-hygienic evaluation of medical X-ray units of different types is described in the paper. The qualitative evaluation monitoring applicable to X-ray equipment is based on the finding and subsequent analysis of graphic dose-square relationships, i.e. anode voltage(measured manually or by X-ray exposure meter), exposition time, anode current, and current-time product. Real graphs for both normally functioning and for malfunctioning units are depicted. The unit radiation output is described.     

Production of vinylidene chloride from the thermal decomposition of methyl chloroform

This study investigated the extent to which methyl chloroform undergoes thermal decomposition to form vinylidene chloride. The experiment was conducted under laboratory conditions that approximate those found in industrial environments. Methyl chloroform vapors at approximately the TLV concentration of 1910 mg/m3 were passed through a heated quartz tube packed with glass or copper beads. In the presence of glass, the decomposition reaction began at 350 degrees C and was essentially complete at 605 degrees C. Vinylidene chloride was detected in nearly stoichiometric amounts. In the presence of copper, the reaction occurred initially at 180 degrees C. At 442 degrees C no methyl chloroform was detected. Once again, the conversion to vinylidene chloride was nearly complete. Two major conclusions have been derived from this study. First, under these experimental conditions, methyl chloroform undergoes thermal decomposition to yield substantial quantities of vinylidene chloride. Second, the dehydrohalogenation reaction proceeds at much lower temperatures in the presence of copper.     

社区医疗监护系统的研究进展

社区医疗是一种新型的医疗模式，它的出现适应了社会经济发展、满足了人类的健康需要。远程监护是社区医疗监护系统中一个必不可少的功能，目前社区远程监护主要有基于电话网、Internet网以及无线网等几种，本文主要介绍社区医疗监护系统研究的新进展。     

Surveillance systems for monitoring the development of spatial patterns

Statistical methods concerned with the identification of temporal patterns may be classified into those that examine retrospectively a set of observations, and those that constitute surveillance systems that monitor changes as new observations become available. A similar distinction applies to the identification of geographical patterns in spatial data. There has been a notable lack of attention given to the surveillance of spatial pattern. This paper concerns development of a cumulative sum statistic and procedure for the monitoring of spatial pattern, and its application to both simulated data and to data on Burkitt's lymphoma in Uganda. © 1997 by John Wiley & Sons, Ltd.     

The influence of age on the gastrointestinal absorption of mercuric chloride and methyl mercury chloride in the rat

The intestinal absorption of mercuric chloride and methyl mercury chloride was determined in neonatal (6-day-old) and mature (7-week-old) rats. No differences between the two age groups were observed in the absorption of methyl mercury chloride (0.08 μg Hg/ml) determined up to 2 hr after administration in vivo into closed segments of the duodenum or ileum. In contrast, the 1-hr duodenal absorption of mercuric chloride (8 μg Hg/ml) was significantly greater in neonatal animals (18.1%) as compared to 23-day-old weanling (7.3%) or mature (3.6%) animals. Ileal absorption of mercuric chloride was also higher in neonates than in mature animals, but the magnitude of the difference was less than that observed in the duodenum. GI absorption of mercuric chloride (46 μg Hg/kg) was also assessed in neonatal, weanling, and mature rats at 4 and 43 hr after gastric intubation. The percentage of the dose in the carcass, determined after removal of the GI tract, was significantly higher at both times in neonatal and weanling rats as compared to mature animals. Analysis of mercury content in the gastrointestinal tract of these animals also indicated age-dependent differences in mercury transit through the GI lumen. The extent of gastric emptying of mercury by 4 hr after dosing was significantly less in neonatal and weanling rats compared to mature animals. In addition, the small intestinal transit of mercury was markedly slower in neonates with 74.8% of the dose in the GI tract after 43 hr as compared to 5.2% and 3.0% in weanling and mature animals, respectively. These findings indicate that in the neonate, exposure to inorganic mercury by the oral route can be expected to result in higher systemic, as well as small intestinal, levels of mercury because of enhanced GI absorption and decreased luminal transit, respectively.     

Toxicokinetic modelling of methyl formate exposure and implications for biological monitoring

A toxicokinetic (TK) model was developed to describe the inhalation exposure in humans to methyl formate (MF), a catalyst used in foundries, and to discuss biological monitoring. The TK model consisted of four compartments: MF, the metabolites – methanol (MeOH) and formic acid (FA) – and, in addition, a urinary compartment describing the saturable reabsorption of FA. Levels of MeOH and FA in urine, from an experimental study (100 ppm MF, 8 h at rest), validated the present model. The TK model describes well the general behaviour of MeOH and FA in urine after MF exposure. A nonlinear and a linear relationship respectively, was predicted between MF exposure and FA or MeOH excretion in urine, and this has previously been seen after occupational MF exposure. The present model has been modified to simulate MeOH exposure as well. Generally low exposures (concentration or exercise) produce only marginal increases in FA urinary excretions, but when exposure is elevated, urinary FA excretion increases because of saturation in the mechanism of reabsorption. Using FA urinary excretion as the critical indicator, because of its link to health effects, an occupational exposure limit value for MF of no greater than 50 ppm should be selected (based on predictions with the TK model). MeOH in urine can be considered as a biomarker for MF at low exposure, because of lower background values and of a linear relationship with exposure. At higher exposures, however, FA could be used as a biomarker as it becomes progressively more sensitive. But the use of biological monitoring for MF is difficult because of individual variations in background values. Under the present state of knowledge both FA and MeOH should be used to estimate only group exposures, rather than individual exposures. Received: 13 December 1999 / Accepted: 25 April 2000