Search

The rate of ventilation in buildings is regulated in most European countries to provide a sufficient exchange of clean air to maintain and ensure the health and comfort of building occupants. Information on the actual level of ventilation rates is needed to estimate the consequences of reduced ventilation on the potential increasing risk of health problems. Unfortunately only limited population based data are available on the measured ventilation rates of residences in European countries. To fill this data gap a model was developed that combines information from existing measurements, national legislation and building codes to estimate the probability distributions of ventilation rates in the residences of 26 European countries. These distributions were analysed against national building statistics to produce information on the number of residences which do not meet ventilation requirements as defined by the relevant national building codes. Earlier results suggest that the mean ± SD air change r...

In this work the Cd, Cu and Zn accumulation in potatoes, their influence on starch, water-soluble (WSS) and water-insoluble saccharide (WIS) contents and content of heavy metals in various saccharide fractions of pota - toes were determined. The fraction of WSS was isolated by Somogyi method, the WIS fraction was obtained from delipided portion of potatoes. Enhanced pseudototal Cd contents in relationship to limit value 0.7 mg/kg of soil were determined in 13 soil samples (0.72-1.06 mg/kg). Contents of Zn and Cu were lower than their limit values in all observed soil samples. Observed heavy metals have not influence on their accumulation in potatoes, the Cd content in potatoes (0.0015-0.0042 mg/kg f.m.), Cu (0.0590-0.1780 mg/kg f.m.) and Zn contents (0.1887-0.3517 mg/kg f.m.) were also lower than their limit values. The proportion of observed heavy metals in selected saccharide fractions: Cd (mg/kg): 0.017-0.140 (starch), 0.0133-0.2293 (WIS), 0.8711-109.7713 (WSS); Cu (mg/kg): 0.067-1.433 (starch), 0.2844-6.9877 (WIS), 18.0134-1070.5216 (WSS); Zn (mg/kg): 6.667-66.300 (starch), 0.7869-23.3673 (WIS), 101.4842-4020.790 (WSS)

This paper is focused on the use of an innovative Process Analytical Technology for the fast design and optimization of freeze-drying cycles for pharmaceuticals. The tool is based on a soft-sensor, a device that uses the experimental measure of product temperature during freeze-drying, a mathematical model of the process, and the Extended Kalman Filter algorithm to estimate the sublimation flux, the residual amount of ice in the vial, and some model parameters (heat and mass transfer coefficients). The accuracy of the estimations provided by the soft-sensor has been shown using as test case aqueous solutions containing different excipients (sucrose, polyvinylpyrrolidone), processed at various operating conditions, pointing out that the soft-sensor allows a fast estimation of model parameters and product dynamics without involving expensive hardware or time consuming analysis. The possibility of using the soft-sensor to calculate in-line (or off-line) the design space of the primary drying phase is here presented and discussed. Results evidences that by this way, it is possible to identify the values of the heating fluid temperature that maintain product temperature below the limit value, as well as the operating conditions that maximize the sublimation flux. Various experiments have been carried out to test the effectiveness of the proposed approach for a fast design of the cycle, evidencing that drying time can be significantly reduced, without impairing product quality.

SUMMARY Current standard specifications for the laboratory evaluation of denture base materials require subjective assessment of colour stability. This study evaluates a new objective measurement technique for translucent denture base materials, by comparing quantitative data with the results obtained from a standard subjective method. Preliminary work on three representative commercial acrylic materials resulted in the selection of a white background for the quantification of colour change of these translucent materials. One half of each sample was exposed to artificial sunlight for 24 h. The colour of both exposed and unexposed resin was measured on the CIE L*a*b* scale using a photoelectric colorimeter. Significant changes in the b* and E* values (P < 0.001) were observed following light exposure. Objective data for a wide range of commercial materials were compared with the results of a subjective evaluation and it was shown that a change in b* of 1.5 units was discernable subjectively by eye for 100% of the cases. It is suggested that this method and limit value could form the basis of a new objective colour change specification for polymeric dental materials.

In this paper, we propose an economic model predictive control (MPC) framework with a self-tuning terminal weight, which builds on a recently proposed MPC algorithm with a generalized terminal state constraint. First, given a general time-varying terminal weight, we derive an upper bound on the closed-loop average performance which depends on the limit value of the predicted terminal state. After that, we derive conditions for a self-tuning terminal weight such that bounds for this limit value can be obtained. Finally, we propose several update rules for the self-tuning terminal weight and analyze their respective properties. We illustrate our findings with several examples.

Background: Minimally invasive surgeries have increased dramatically during the last decades. Carbon dioxide (CO2) is the gas used for insufflation during laparoscopies, creating space and visibility. The CO2 leaks into ambient air through ports where instruments are inserted. If the CO2 reaches a certain concentration it affects personnel health. There are national occupational exposure limits (OEL) for CO2, including a level limit value (LLV) of 5000 ppm. We are not aware of any previous studies addressing occupational exposure to CO2 during laparoscopies. The aim of this study was to assess the compliance to national OELs for CO2 during laparoscopies. Methods: A gas detector was placed in the breathing zone of personnel in the operating theatre. The detector measured CO2 concentrations every tenth minute during laparoscopies in three locations. Results: During 27 laparoscopies, the measured CO2 reached a maximum concentration of 1100 ppm, less than one fourth of the LLV. Median CO2 concentration was 700 ppm. Conclusion: Results show that the occupational exposure to CO2 during laparoscopies is well below set OELs. Our findings support personnel safety associated with routine use of CO2 during laparoscopies.

Aims The methodology agreed within the framework of the HBM4EU project is used in this work to derive HBM-GVs for the general population (HBM-GVGenPop) and for workers (HBM-GVWorker) exposed to cadmium (Cd) and its compounds. Methods For Cd, a significant number of epidemiological studies with dose–response relationships are available, in particular for kidney effects. These effects are described in terms of a relation between urinary Cd (U-Cd) or blood Cd (B-Cd) levels and low molecular weight proteinuria (LMWP) markers like beta-2-microglobulin (β2M) and retinol-binding protein (RBP). In order to derive HBM-GVs for the general population and workers, an assessment of data from evaluations conducted by national or international organisations was undertaken. In this work, it appeared relevant to select renal effects as the critical effect for the both groups, however, differences between general population (including sensitive people) and workers (considered as an homogenous population of adults who should not be exposed to Cd if they suffer from renal diseases) required the selection of different key studies (i.e. conducted in general population for HBM-GVGenPop and at workplace for HBM-GVWorker). Results and conclusions For U-Cd, a HBM-GVGenPop of 1 µg/g creatinine (creat) is recommended for adults older than 50 years, based on a robust meta-analysis performed by EFSA ( EFSA, 2009a ). To take into account the accumulation of Cd in the human body throughout life, threshold or ‘alert’ values according to age were estimated for U-Cd. At workplace, a HBM-GVWorker of 2 μg/g creat is derived from the study of Chaumont et al., (2011) for U-Cd, and in addition to this recommendation a HBM-GVworker for B-Cd of 5 µg/L is also proposed. The HBM-GVWorker for U-Cd is similar to the biological limit value (BLV) set by the new amendment of the European Carcinogens and Mutagens Directive in June 2019 (2 µg/g creat for U-Cd).

The Monte Carlo simulation (MCS) of the thermalization of subexcitation electrons in rare gases is performed for both the hard‐sphere and Maxwell model gases. The MCS result for the mass ratio m/M≲0.01 is found to be in agreement within the statistical error with the rigorous solution of the Fokker–Planck equation; therefore the upper limit value of m/M=0.01 is sufficient for the MCS to be performed within a reasonable computation time.

Training subsidies and disadvantaged workers: regression with a limited depen- dent variable. Based on data from a sample of Ontario trainees, larger govern- ment subsidies were found to go to companies that provide on-the-job training to advantaged rather than disadvantaged workers. This conclusion holds whether ordinary-least-squares estimation techniques are used or whether Tobit analysis is employed - the latter being the correct technique for limited dependent vari- ables whereby many observations are clustered at a limit value. In our particular case the limit value was zero, since companies received zero subsidy for trainees that did not complete training.

We report concentrations of brominated flame retardants (BFRs) in 23 plastic samples from 20 new and second-hand children's toys sourced from the UK that had been previously shown to be Br-positive by XRF. The results reinforce existing evidence that the recycling of BFR-treated electronic plastics has led to the unintentional BFR contamination of articles not required to be flame-retarded. The principal BFRs detected were PBDEs (and in particular BDE-209), HBCDD and TBBP-A. PBDEs were detected in all samples with a maximum concentration of BDE-209 of 2500 mg/kg, and while TBBP-A was detected in 11 samples with a maximum concentration of 3100 mg/kg. HBCDD was detected in 14 cases and was present in four toys at concentrations (139–840 mg/kg) that would currently prevent their sale on the EU market. While estimated exposures to PBDEs via accidental ingestion of toy plastic fell well below USEPA reference doses, a child weighing 8.67 kg and ingesting 8 mg/day of a toy (the default assumption of the European Commission's Toy Safety Directive for scraped-off toy material) contaminated at our arithmetic mean concentration would be exposed to 0.2 ng/kg bw/day BDE-99. This compares closely to a health-based limit value (HBLV) proposed in The Netherlands of 0.23–0.30 ng/kg bw/day BDE-99. Of greater concern, the same child playing with a toy contaminated at the maximum concentration in this study would be exposed to 1.4 ng/kg bw/day BDE-99, thereby exceeding the HBLV. This paper is the first to consider BFR exposure via incidental ingestion of plastic from both contemporary and historical toys, revealing it to be considerable and for some children their most significant pathway of exposure.

In this study, we applied the EMEP/MSC-W model at a high spatial resolution of 4 km × 4 km over Poland (EMEP4PL), and ran the model for the whole of the years 2015 and 2030. For the second simulation we used GAINS PRIMES emission projection and kept the meteorology from 2015. Although the model results are satisfactory and comparable to the results in other European countries, the number of days with exceedances of the limit value is highly underestimated in comparison to observations for 2015. It shows that the model is limited in its simulation of very high particulate matter concentrations in the winter season. Therefore, we applied a bias correction for the year 2030 based on the observations and model results for the year 2015. Bias corrected simulation shows that at 60 stations (out of 104), the PM10 daily limit value will be exceeded at least 35 times in 2030.

Background Metal ions such as iron and copper are among the key nutrients that must be provided by dietary sources. Numerous foodstuffs have been evaluated for their contributions to the recommended daily allowance both to guide for satisfactory intake and also to prevent over exposure. In the case of heavy metal ions, the focus is often on exposure to potentially toxic levels of ions such as lead and mercury. The aim of this study is to determine target hazard quotients (THQ) from literature reports giving empirical levels of metal ions in table wines using the reference upper safe limit value. Contributions to the THQ value were calculated for seven metal ions along with total values for each wine. Results The THQ values were determined as ranges from previously reported ranges of metal ion concentrations and were frequently concerningly high. Apart from the wines selected from Italy, Brazil and Argentina, all other wines exhibited THQ values significantly greater than one indicating levels of risk. The levels of vanadium, copper and manganese had the highest impact on THQ measures. Typical potential maximum THQ values ranged from 50 to 200 with Hungarian and Slovakian wines reaching 300. THQ values for a sample of red and white wines were high for both having values ranging from 30 to 80 for females based on a 250 mL glass per day. Conclusion The THQ values calculated are concerning in that they are mainly above the safe level of THQ