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Raduntz T.,Federal Institute for Occupational Safety and Health
Advances in Intelligent Systems and Computing | Year: 2017

Complex and highly automated systems impose high demands on employees with respect to cognitive capacity and the ability to cope with workload. Prevention of over-and underload at workplaces with high cognitive demands can be achieved by objectively registering mental workload. Hence, the goal of this work is the development of such an objective method. We briefly introduce the so-called Dual Frequency Head Maps (DFHM) for registering mental workload by means of the electroencephalogram (EEG). Based on them, we obtain an index of mental state every 5 s ranging between the classes low, moderate, and high workload. Finally, we present results from a sample set of 54 people who executed cognitive tasks like switching and AOSPAN in a laboratory setting. We then verify the integrity of the new method by comparing the results with further workload relevant biosignal data, performance data, and the NASA-TLX questionnaire. © Springer International Publishing Switzerland 2017.


Raduntz T.,Federal Institute for Occupational Safety and Health
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2014

Neuronal workload measurement is a key-technology for optimizing work conditions in human-machine systems. Specific aims are the identification of neurophysiological parameters indicative for workload and their validation by systematic variation of external load conditions. The battery consists of tasks with diverse complexity and difficulty. The sample consists of 34 people and shows high variability in respect to the cognitive capacity and hence to the experienced mental workload. The electroencephalogram (EEG) as well as further workload relevant bio signal data and the NASA-TLX as a subjective questionnaire method are registered. Results from the NASA-TLX questionnaire reveal the predominant role of the mental dimension at the implemented task battery. Furthermore, the NASA-TLX indicates the existence of diverse levels of difficulty with several tasks per level. Analysis of EEG spectra demonstrates an increase of frontal theta band power and a decrease of alpha band power with increasing task difficulty level. © 2014 Springer International Publishing.


Mohner M.,Federal Institute for Occupational Safety and Health | Kersten N.,Federal Institute for Occupational Safety and Health | Gellissen J.,Federal Institute for Occupational Safety and Health
Occupational and Environmental Medicine | Year: 2013

Objectives: The present study sought to examine the long-term effects of exposure to respirable quartz on pulmonary function with particular focus on chronic obstructive pulmonary disease (COPD). Methods: The study is based on the Wismut cohort of former uranium miners. Spirometric data were ascertained together with quantitative estimates of cumulative exposure to respirable quartz for each of 1421 study subjects born between 1954 and 1956. The case definition for COPD is based on the criteria of the Global Initiative for Chronic Obstructive Lung Disease. Linear mixed regression models were fitted to identify significant determinants of longitudinal changes in lung function parameters. Results: An average of five spirometries were available for each miner. It was shown that cumulative exposure to 1 mg/m3-year respirable quartz leads, on average, to a relative reduction in forced expiratory volume in 1 s/ orced vital capacity (FEV1/FVC) of 2.75% (p<0.001). A nested case-control approach demonstrated that the risk for COPD stage I increases with increasing cumulative exposure to respirable quartz (OR 1.81 per 1 mg/m 3-year). Conclusions: This paper adds further evidence on the long-term effects of exposure to respirable quartz, which include a decline in pulmonary function parameters and an increase in the incidence of COPD.


Mohner M.,Federal Institute for Occupational Safety and Health
Occupational and Environmental Medicine | Year: 2016

The Diesel Exhaust in Miners Study (DEMS) demonstrated a strong exposure-response relationship between diesel exhaust exposure, measured as respirable elemental carbon, and lung cancer mortality. However, the results seem conflicting insofar as the results of the analysis by standardized mortality ratios (SMR) seem to be not compatible at all with the other results. A synthesis of the published results leads to a new explanation. The key to this hypothesis is the assumption that workers, who switch from surface job to underground job are very likely in much better physical conditions than other surface workers. Thus, the healthy-worker-effect could explain the apparent self-contradictory results of the DEMS cohort. A modified analysis by unconditional logistic regression yields as a crude risk estimator adjusted for smoking OR = 0.92 for miners ever worked underground jobs. Hence, the results of the different approaches for the DEMS cohort are compatible with each other.


Skotte J.,Helmholtz Center Munich | Korshoj M.,Helmholtz Center Munich | Kristiansen J.,Helmholtz Center Munich | Hanisch C.,Federal Institute for Occupational Safety and Health | Holtermann A.,Helmholtz Center Munich
Journal of Physical Activity and Health | Year: 2014

Background: The aim of this study was to validate a triaxial accelerometer setup for identifying everyday physical activity types (ie, sitting, standing, walking, walking stairs, running, and cycling). Methods: Seventeen subjects equipped with triaxial accelerometers (ActiGraph GT3X+) at the thigh and hip carried out a standardized test procedure including walking, running, cycling, walking stairs, sitting, and standing still. A method was developed (Acti4) to discriminate between these physical activity types based on threshold values of standard deviation of acceleration and the derived inclination. Moreover, the ability of the accelerometer placed at the thigh to detect sitting posture was separately validated during free living by comparison with recordings of pressure sensors in the hip pockets. Results: Sensitivity for discriminating between the physical activity types sitting, standing, walking, running, and cycling in the standardized trials were 99%-100% and 95% for walking stairs. Specificity was higher than 99% for all activities. During free living (140 hours of measurements), sensitivity and specificity for detection of sitting posture were 98% and 93%, respectively. Conclusion: The developed method for detecting physical activity types showed a high sensitivity and specificity for sitting, standing, walking, running, walking stairs, and cycling in a standardized setting and for sitting posture during free living. © 2014 Human Kinetics, Inc.


Gebel T.,Federal Institute for Occupational Safety and Health
Archives of Toxicology | Year: 2012

Materials that can be described as respirable granular biodurable particles without known significant specific toxicity (GBP) show a common mode of toxicological action that is characterized by inflammation and carcinogenicity in chronic inhalation studies in the rat. This study was carried out to compare the carcinogenic potency of GBP nanomaterials (primary particle diameter 1-100 nm) to GBP micromaterials (primary particle diameter >100 nm) in a pooled approach. For this purpose, the positive GBP rat inhalation carcinogenicity studies have been evaluated. Inhalation studies on diesel engine emissions have also been included due to the fact that themode of carcinogenic action is assumed to be the same.As it is currently not clear which dose metrics may best explain carcinogenic potency, different metrics have been considered. Cumulative exposure concentrations related to mass, surface area, and primary particle volume have been included as well as cumulative lung burden metrics related to mass, surface area, and primary particle volume. In total, 36 comparisons have been conducted. Including all dose metrics, GBP nanomaterials were 1.33- to 1.69-fold (mean values) and 1.88- to 3.54-fold (median values) more potent with respect to carcinogenicity than GBP micromaterials, respectively. Nine of these 36 comparisons showed statistical significance (p<0.05, U test), all of which related to dosemetrics based on particlemass. Themaximum comparative potency factor obtained for one of these 9 dose metric comparisons based on particle mass was 4.71. The studies with diesel engine emissions did not have a major impact on the potency comparison. The average duration of the carcinogenicity studies with GBP nanomaterials was 4 months longer (median values 30 vs. 26 months) than the studies with GBP micromaterials, respectively. Tumor rates increase with age and lung tumors in the rat induced by GBP materials are known to appear late, that is, mainly after study durations longer than 24 months. Taking the different study durations into account, the real potency differences were estimated to be twofold lower than the relative potency factors identified. In conclusion, the chronic rat inhalation studies with GBP materials indicate that the difference in carcinogenic potency between GBP nanomaterials and GBP micromaterials is low can be described by a factor of 2-2.5 referring to the dose metrics mass concentration. © Springer-Verlag 2012.


Martin E.,Federal Institute for Occupational Safety and Health | Kampfer P.,Justus Liebig University | Jackel U.,Federal Institute for Occupational Safety and Health
Annals of Occupational Hygiene | Year: 2010

Employees at agricultural working places are often exposed to complex bioaerosols. Investigations of bioaerosols in duck houses revealed concentrations of cultivable bacteria between 0.4 and 3×105 colony forming units (CFU) m-3 on tryptone soy agar, 0.3 and 2×105 CFU m-3 on actinomycetes isolation agar, and 0.8 and 5×103 CFU m-3 on Middlebrook agar, respectively, when incubated at 25°C. At an incubation temperature of 37°C, 0.6-3×102 CFU m-3 were counted on MacConkey agar and 0.3-2×103 CFU m-3 on Middlebrook agar, and the concentrations of bacteria on glycerol-arginine agar and oatmeal agar incubated at 50°C varied between 0.1 and 2×103 and 1 and 7×103 CFU m-3, respectively. In addition, high concentrations of cells were observed by fluorescence microscope quantification of cell counts after 4′,6-diamidino-2-phenylindol staining with 3-8×107 cells m-3. A total of 213 colonies with different morphological appearance were selected and the isolated pure cultures were identified at the genus level using the 16S rRNA gene sequence analyses. In summary, 19 different genera of Actinobacteria, four genera of the Firmicutes, one genus of the Bacteroidetes, and five genera of the Proteobacteria were identified. Several isolates represent new phylogenetic lineages. Based on 16S rRNA gene analyses, some isolates were most closely related to Cellulosimicrobium funkei, Corynebacterium falsenii, Corynebacterium xerosis, Mycobacterium arupense, and Staphylococcus epidermidis, which have been grouped into Risk group 2 of biological agents and may cause negative pulmonary health effects. These bacterial species were present in high concentrations up to 104 CFU m-3. For this reason, we recommend an adequate personal breathing protection at these working places.


Raduntz T.,Federal Institute for Occupational Safety and Health
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2016

Complex and highly automated systems impose high demands on employees with respect to cognitive capacity and the ability to cope with workload. Objectively registering mental workload at workplaces with high cognitive demands would enable prevention of overand underload. Although urgently needed, such technical measurement is currently unfeasible. Hence, the goal of this work is the establishment of precisely such an objective method. In this article we briefly present a new method for registering mental workload by means of the electroencephalogram (EEG). Based on so called Dual Frequency Head Maps (DFHM) every 5 s we obtain an index of mental state ranging between the classes low, moderate, and high workload. Finally, we present results from a sample set of 54 people during the execution of the cognitive tasks 0-back, stroop test and AOSPAN in a laboratory setting. We compare them with our expectations based on the knowledge of task requirements on the executive functions as well as with further workload relevant biosignal data, performance data, and the NASA-TLX as a subjective questionnaire method. By this we gain proof of the integrity of the new method. © Springer International Publishing Switzerland 2016.


Martin E.,Federal Institute for Occupational Safety and Health | Jackel U.,Federal Institute for Occupational Safety and Health
Journal of Environmental Monitoring | Year: 2011

Today's large-scale poultry production is often accompanied by high concentrations of airborne microorganisms at working places. However, the microbial communities in those bioaerosols are rarely characterised. In this study, we investigated the bacterial population in bioaerosols from a duck hatchery by both cultivation based and molecular methods and compared the results. Depending on used media, concentrations of airborne culturable bacteria varied between 6 × 101 and 7 × 106 CFU per m3 air. The corresponding total cell count of DAPI stained cells was 2 × 107 cells per m3 air. 16S rRNA gene analyses of bacterial isolates and clone libraries revealed a low species richness in hatcheries air, respectively. More than 50% of bacterial isolates were phylogenetically most closely related to bacterial species of the risk group 2 (German TRBA). The sequence composition in clone libraries supported the result of cultivation based approaches, whereby sequences assigned to Staphylococcus, Acinetobacter and Enterococcus are the most common. The high concentration of airborne bacteria which are most closely related to species of potential health risk requires further detailed investigations for these bacterial species. © The Royal Society of Chemistry 2011.


Gebel T.,Federal Institute for Occupational Safety and Health
Archives of Toxicology | Year: 2013

The evaluations in Gebel (Arch Toxicol 86(7):995-1007, 2012) were carried out according to established procedures in regulatory toxicology. The variability in the available data was taken into account. The quality of the underlying data set should not be overestimated. The relevant conclusion in Gebel (Arch Toxicol 86(7):995-1007, 2012) is that the difference in carcinogenic potency comparing nanosized to microsized respirable granular biodurable particles without known significant specific toxicity (GBP) is low and lower than previously estimated. © 2013 Springer-Verlag Berlin Heidelberg.

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