Permeation of aromatic solvent mixtures through nitrile protective gloves

The permeation of binary and ternary mixtures of benzene, toluene, ethyl benzene and p-xylene through nitrile gloves were investigated using the ASTM F739 test cell. The more slowly permeating component of a mixture was accelerated to have a shorter breakthrough time than its pure form. The larger differences in solubility parameter between a solvent mixture and glove resulted in a lower permeation rate. Solubility parameter theory provides a potential approach to interpret the changes of permeation properties for BTEX mixtures through nitrile gloves. Using a one-dimensional diffusion model based on Fick's law, the permeation concentrations of ASTM F739 experiments were appropriately simulated by the estimated diffusion coefficient and solubility. This study will be a fundamental work for the risk assessment of the potential dermal exposure of workers wearing protective gloves.     

Permeation of Comite through protective gloves

The goal of the study was to assess how protective disposable (Safeskin) and chemical protective (Sol-Vex) nitrile gloves were against Comite emulsifiable concentrate formulation containing propargite (PROP) as active pesticidal ingredient, because there were no explicit recommendations for the gloves that should be worn for hand protection. The glove material was exposed in ASTM-type I-PTC-600 permeation cells at 30.0+/-0.5 degrees C, and gas chromatography-mass spectrometry used for PROP analysis. Aqueous solutions of Comite at 40.4 mg/mL permeated both Safeskin and Sol-Vex nitrile by 8h. Safeskin showed a mean PROP mass permeated of 176+/-27 microg after 8h compared with a mean mass permeated for Sol-Vex of 3.17+/-4.08 microg. Thus, Sol-Vex was about 56 times more protective than Safeskin for an 8-h exposure. However, the kinetics of the permeation revealed that Safeskin can be worn for at least 200 min before disposal. When undiluted Comite challenged both types of nitrile, much faster permeation was observed. Safeskin gloves showed two steady state periods. The first had lag times (t(l)) values of about 1h, although normalized breakthrough times (t(b)) were < 10 min. The second steady state rate (P(s)) was on average four times the rate of the first period, and the second steady state period t(l) was about three times as long as that of the first steady state period, and about the same t(l) as for the aqueous solution. Sol-Vex gloves exposed continuously to undiluted Comite permeated above the normalized breakthrough threshold beyond 2.7h. A risk assessment revealed that the PROP skin permeation rate of 7.1 ng cm(-2)h(-1) was much slower than the first steady state Safeskin glove P(s) of 62,000 ng cm(-2)h(-1). Infrared analysis showed that the glove surfaces were not degraded by the Comite challenge. The chemically protective Sol-Vex gloves protected adequately against undiluted formulation for about 2.7h, whereas they provided protection for nearly 8h when the formulation was diluted with water to the highest concentration for field application. In contrast, the disposable Safeskin gloves did not protect at all for the undiluted formulation, but did for 200 min when the formulation was diluted with water to the highest concentration for spraying.     

Occupational exposure to external ionising radiation in Poland, 1999

In 1999 about 6208 radiation workers from 389 departments were monitored by CLOR in Poland. The distribution of annual personal doses shows that 85% of controlled workers received doses below the MDL (0.4 mSv) and about 97% controlled workers received doses below 5 mSv. Doses higher than 50 mSv were received by three operators of industrial radiography units. The radiation workers under control are divided into four main work sectors: nuclear industry, research and education, medicine, and general industry. The average annual dose for all workers in each particular sector was 0.22 mSv, 0.22 mSv, 0.30 mSv and 0.80 mSv, respectively. The average annual dose for the entire monitored population was 0.47 mSv. The average annual dose in each particular sector for number of workers receiving E > 0, i.e. Hp(10) > or = 0.4 mSv, amounted to 1.78 mSv, 2.03 mSv, 1.88 mSv and 4.85 mSv, respectively. The average annual dose for the full number of workers receiving E > 0 was 3.21 mSv. This paper contains the detailed analysis of occupational exposure. The distributions of annual occupational exposure in different work sectors are also given.     

Transition in occupational radiation exposure monitoring methods in diagnostic and interventional radiology

Radiation exposure monitoring is a traditional keystone of occupational radiation safety measures in medical imaging. The aim of this study was to review the data on occupational exposures in a large central university hospital radiology organisation and propose changes in the radiation worker categories and methods of exposure monitoring. An additional objective was to evaluate the development of electronic personal dosimeters and their potential in the digitised radiology environment. The personal equivalent dose of 267 radiation workers (116 radiologists and 151 radiographers) was monitored using personal dosimeters during the years 2006-2010. Accumulated exposure monitoring results exceeding the registration threshold were observed in the personal dosimeters of 73 workers (59 radiologists' doses ranged from 0.1 to 45.1 mSv; 14 radiographers' doses ranged from 0.1 to 1.3 mSv). The accumulated personal equivalent doses are generally very small, only a few angiography radiologists have doses >10 mSv per 5 y. The typical effective doses are <10 μSv y(-1) and the highest value was 0.3 mSv (single interventional radiologist). A revised categorisation of radiation workers based on the working profile of the radiologist and observed accumulated doses is justified. Occupational monitoring can be implemented mostly with group dosimeters. An active real-time dosimetry system is warranted to support radiation protection strategy where optimisation aspects, including improving working methods, are essential.     

Adsorption behavior of Cr(VI) on modified natural zeolite by a new bolaform N,N,N,N',N',N'-hexamethyl-1,9-nonanediammonium dibromide reagent

The demand for effective adsorbents is to increase in response to the widespread recognition of the deleterious health effects of Cr(VI)-oxyanions exposure through drinking water. In this study, Cr(VI)-oxyanions uptake from aqueous solutions by a new bolaform N,N,N,N',N',N'-hexamethyl-1,9-nonanediammonium dibromide reagent-modified natural zeolitic materials from Zahedan, Iran, was investigated using batch technique. Spectrophotometry method was used for Cr determination. The Cr(VI)-solution concentration varied between 2 and 104 mg L(-1). It was shown that the Cr(VI) uptake strongly depended on pH. The maximum removal of Cr(VI) occurred in acidic media at pH<1.5. The amounts of Cr(VI) adsorbed increased with increase in dose of both adsorbents and their contact time. Based on results an adsorption mechanism has been suggested. The adsorption data for modified zeolite using the amine was consistent with Langmuir isotherm equation and the equilibrium data was analyzed using the Langmuir isotherm.     

Occupational radiation exposure during removal of radioactive reactor components from GRR-1 pool

The aim of the study was to control occupational exposure during the removal of radioactive reactor components from a Greek research reactor pool. The method comprised the prediction of the radiation levels, the design of special shielding structures and the occupational dose assessment. Activation calculations were performed using the FISPACT code to predict the source term. Monte Carlo simulations using MCNP code were utilized to estimate the ambient dose equivalent rates. The results of the calculations were verified by measurements and were found to be in good agreement. Thermoluminescence dosemeter (TLD) and electronic personal dosemeter (EPD) were implemented to measure the radiation exposure of the workers. The total collective dose of 14 participating workers was 0.15 man mSv. The maximum individual effective dose was 0.02 mSv, and the maximum extremity equivalent dose was 0.09 mSv. The discussed method provides a useful tool enabling work planning during reactor decommissioning and renovation activities ensuring that exposures will be maintained ALARA.     

Esorex 2005

The European Study on Occupational Radiation Exposure called ESOREX was initiated by the European Commission in the 1997 year. The objectives of this European study are: (1) to provide the European Commission and the national competent radiation protection authorities with reliable information on how personal radiation monitoring, reporting and recording of dosimetric results is structured in European countries; (2) to collect reliable and directly comparable data on individual and collective radiation exposure in all occupational sectors where classified workers are employed. Therefore, it is important to receive information about the levels of individual personal radiation doses to workers in the different sectors and the trends and developments of these doses over a period of several years; (3) at present, all 25 European Union Member States, plus Bulgaria, Iceland, Norway, Romania and Switzerland, participate in the study; and (4) the study was executed under the leadership of German BfS in co-operation with Czech SUJB. First results and analyses based on the data collected in the previous studies are presented in the paper 'Frasch, Petrová: Dose trends in occupational radiation exposure in Europe-Results from the ESOREX project'. As a result of a call for tender of the European Commission/DGTREN in the year 2003, the new ESOREX study called 'ESOREX2005' has been initiated. This study will end at the year 2007 and its main objectives are-to finalise the updating of the country-wise reports by describing the current situation in the field of occupational exposure control, evaluation and registration of personal doses of radiation workers and as a second part of the study, to collect dosimetric data for the period 2001-2005.     

Exposure of workers in Tusnica coal mine

The aim of this paper is to identify potential exposure of the workers in the coal mine Tusnica. The results of the investigation showed increased activity of brown coal up to 1060 ± 88 Bq kg(-1) for (238)U, 976 ± 30 Bq kg(-1) for (226)Ra and 118 ± 31 Bq kg(-1) for (232)Th. Dose rate measurements ranged from 0.07 to 0.25 μSv h(-1). The annual effective dose, taking into account external exposure to ambient gamma radiation and internal exposure due to inhalation of the resuspended dust, would be 1.6 mSv a(-1). The results presented lead to the conclusion that Tusnica coal mine contains brown coal with significant radioactivity, indicating that the working hours in the area should be regulated and the use of respiratory protective equipment is obligatory.     

Dispersion modeling of PM10 released during decontamination activities

The decontamination and decommissioning of radioactively contaminated structures and facilities, volume reduction of massive metal structures, and demolition of large concrete structures, result in release of large quantities of contaminants that become airborne and thus could be inhaled by workers and population living in the neighborhood. In order to provide adequate protection to the workers, adequate monitoring of the airborne particulates and proper models that predict the dispersion of the airborne contaminants are needed. The dispersion model will enable development of decision tools on the extent of decontamination that needs to be performed prior to dismantlement and the optimization of personal protective equipment requirements during D&D operations. The Gaussian plume dispersion model is used in this study to predict the dispersion of airborne particulate PM10 (dp<10 microm) released from: (1) a 35 m height contaminant plant where the plume is affected by the presence of 36 buildings around the emission source, (2) a building during decontamination and removal of process equipment and (3) demolition of contaminant building. The potential impact of PM10 on 180 receptors located at five downwind distances between 0.1 and 20 km around the emission source was performed. A short-term (1-48 h) prediction of average concentration of PM10 from point and area sources on receptors located at ground level was obtained. The concentrations of PM10 over 24h time period were compared to the U.S. air quality standards. The results obtained in the course of this study are used to predict the inhalation exposures of workers and population living in neighborhood.     

Dose measurement for medical staff with glass dosemeters and thermoluminescence dosemeters during 125I brachytherapy for prostate cancer

Photoluminescence glass dosemeters (PLDs) and thermoluminescence dosemeters (TLDs) are commonly used as a personal monitoring dosemeter. PLDs and TLDs were used for surface dose monitoring of medical staff involved in (125)I brachytherapy for prostate cancer because these dosemeters have a wide dose-response linearity and high sensitivity for low photon energy. Surface doses measured with PLDs agreed with those with TLDs within ～20 % except for a few cases. Surface doses at a surgeon's left hand and arm were higher than those at the other measuring points. A surgeon received a maximum dose of 650 μGy at the back of left hand. Surface doses to an assistant were <100 μGy. Surface doses to a nurse, a radiologist, an anaesthesiologist and a radiological technologist were <10 μGy. The occupational exposure to a surgeon could be reduced by the adjustment of fluoroscopic parameters and the use of lead gloves.     

Occupational exposure of medical radiation workers in Lithuania, 1950-2003

This study presents the summary of historical exposures, measurementpractice and evolution of the recording of the individual dosesof medical radiation workers during 1950–2003 in Lithuania.The aim of this study is to present occupational exposure ofmedical radiation workers in Lithuania since the earliest appearanceperiod. Data from publications have been used for the earliesttwo periods prior to 1969; data from the archives of the largesthospitals, for the period 1970–1990 and data from LithuanianSubdivision of Individual Dosimetry of Radiation ProtectionCenter, for the period 1991–2003. The analysis of thedata obtained from personal records allows to conclude thatthe average annual effective dose of Lithuanian medical radiationworkers was greatly reduced in radiology, radiotherapy and nuclearmedicine in all occupational categories from 1950 to 2003. Duringthe last period 1991–2003 extremity doses clearly decreasedand after 1994 were no longer present in Lithuania.     

The calibration of personal dosemeters used for evaluating exposure to solar UV in the workplace

In the framework of an epidemiological study regarding the correlation between solar UV radiation exposure and skin pathologies in a population of outdoor workers, the possibility of using polysulphone film personal dosemeters to quantify the Subjects UVB exposure has been evaluated. An original experimental set-up is presented. in a preliminary version, which ill be used both for solar irradiance spectroradiometric measurements and for the reading of personal dosemeters. The polysulphone absorption is similar to the CIE erythemal response curve. Due to UVB radiation exposure, the polysulphone film dosemeters photodegrade with a measrable absorbance change. The absorbance variation after the dosemeter exposure to UV radiation has been correlated to the UVB effective dose. The calibration curve obtained by this method may be particularly useful for the evaluation of small closes. The method will be used to quantify the personal exposure of workers whose exposure conditions are characterised by high variability.     

Effects of some hydrophilic permeation enhancers on the absorption of bepridil through excised human skin

The permeation of Bepridil through excised human skin was measured from vehicles composed of various mixtures of aqueous buffer and the permeation enhancers ethanol, DMSO or DMF. Only DMSO was found to act as a true permeation enhancer for the drug, the magnitude of its action depending on its concentration in the vehicle. At concentrations greater than 50% DMSO the permeability coefficient of the drug was increased over and above that which could be accounted for by changes in partitioning of the drug between vehicle and skin. The effects of ethanol could be related to changes in the measured skin/vehicle partition coefficients of the drug. DMF showed a complicated, concentration dependent influence on permeation.     

Radon progeny in Egyptian underground phosphate mines

In addition to the workers in uranium mines, the staff of other underground mines, such as workers in underground phosphate mines, can be exposed to 222Rn and its progeny. In this study the individual radon progeny concentrations were measured in three Egyptian underground phosphate mines to estimate the occupational exposure of the workers at those sites. A filter method was used to measure individual radon progeny concentrations (218Po, 214Pb and 214Po). The reported mean values of radon progeny concentrations exceed the action levels which are recommended by ICRP 65 (1993). Based on the measured individual radon progeny concentrations (218Po, 214Pb and 214Po) in these mines, the annual effective dose for the workers has been calculated using the lung dose model of ICRP 66 (1994). According to the obtained results, some countermeasures were recommended in this study to minimise these exposure levels.     

Controlling the hydration of the skin though the application of occluding barrier creams

The skin is a barrier membrane that separates environments with profoundly different water contents. The barrier properties are assured by the outer layer of the skin, the stratum corneum (SC), which controls the transepidermal water loss. The SC acts as a responding membrane, since its hydration and permeability vary with the boundary condition, which is the activity of water at the outer surface of the skin. We show how this boundary condition can be changed by the application of a barrier cream that makes a film with a high resistance to the transport of water. We present a quantitative model that predicts hydration and water transport in SC that is covered by such a film. We also develop an experimental method for measuring the specific resistance to water transport of films made of occluding barrier creams. Finally, we combine the theoretical model with the measured properties of the barrier creams to predict how a film of cream changes the activity of water at the outer surface of the SC. Using the known variations of SC permeability and hydration with the water activity in its environment (i.e. the relative humidity), we can thus predict how a film of barrier cream changes SC hydration.     

Design and evaluation of shock-absorbing rubber tile for playground safety

Rubber tiles are commonly used in playgrounds as protective surfacing to reduce the incidence of head injuries in children caused by falling from equipment. This paper presents a newly designed rubber tile consisting of a surface layer of solid and a base layer of honeycomb shape plate-cell. This tile was applied to investigate head injury protective performance. A validated technique combined with experimental and numerical methods was utilized to perform head impact on the rubber tile. The peak acceleration and head injury criterion (HIC) were employed to assess the shock-absorbing capability of the tile. The better protective ability of the honeycomb-core was attributed to its lower transverse shearing stiffness. As a result, the likelihood of establishing safe protection in playground and reducing severe child head injuries could be magnified.     

Effects of some hydrophilic permeation enhancers on the absorption of bepridil through excised human skin

Abstract

The permeation of Bepridil through excised human skin was measured from vehicles composed of various mixtures of aqueous buffer and the permeation enhancers ethanol, DMSO or DMF. Only DMSO was found to act as a true permeation enhancer for the drug, the magnitude of its action depending on its concentration in the vehicle. At concentrations greater than 50% DMSO the permeability coefficient of the drug was increased over and above that which could be accounted for by changes in partitioning of the drug between vehicle and skin. The effects of ethanol could be related to changes in the measured skin/vehicle partition coefficients of the drug. DMF showed a complicated, concentration dependent influence on permeation.     

Evaluation of topical application of clobetasol 17-propionate from various cream bases

The effect of clobetasol 17-propionate (CP), a potent corticosteroid, in various cream bases on the permeation through artificial membrane was sought. Four formulations were then chosen for a further in vivo skin blanching assay. After calculation of the relationship between in vivo flux_0-8hr determined from a surface recovery technique and in vitro release rate_0-8hr of CP from various formulations, a high correlation coefficient of 0.9996 was achieved. Therefore, the in vitro release study could be used as an index to predict and evaluate the in vivo penetration capacity of CP cream to screen the effective formulation preclinically. After a series of in vivo investigations in this study, it was concluded that myristic acid-added formulations may show a bioequivalence with commercial Dermovate®. Furthermore, the flux calculated from the surface recovery technique and ΔE^* detected from the skin blanching assay may be useful as parameters evaluating the quality and effectiveness of CP cream.     

NORM workers: a challenge for internal dosimetry programmes

The mining, milling and processing of uranium and thorium bearing minerals may result in radiation doses to workers. The control of occupational exposures from these natural sources of radiation imposes a challenge to regulators and radiation protection advisers. A survey pilot programme, which included six mines in Brazil and a monazite plant, was established, consisting of the collection and analysis of concentrations of uranium, thorium and polonium in urine, faeces and air samples. Results from workers were compared to background data from their families living in the same area and from residents from the population of Rio de Janeiro. Positive exposure results were identified among the coal miners, the niobium miners and the monazite sand workers. Difficulties in the application of internal dosimetry programmes are discussed in relation to the control of NORM workers.