Eberhard Alexander Pfister

Mobile Augmented Reality in industrial applications: Approaches for solution of user-related issues

Augmented Reality (AR) uses computer-generated virtual information to enhance the userpsilas information access. While numerous previous studies have demonstrated the large potential of AR to improve industrial processes by enhancing product quality and reducing production times it is still unclear if and how long term usage of such AR technology produces stress and strain. This paper presents an approach to use the analysis of Heart Rate Variability to objectively measure current user strain during different work tasks. Results of a user study comparing strain during an AR supported and a non-AR supported work task in a laboratory setting are presented and discussed.

Influence of occupational exposure to organic solvent mixtures on contrast sensitivity in printers

Learning ObjectivesExplain why contrast sensitivity was used as a measure of visual function in this study of organic solvent exposure in the print industry.Recall when visual function was tested in relation to solvent exposure.Summarize the findings of this study and their implications for the role of contrast sensitivity testing of printers exposed to solvent mixtures in the course of their work. Contrast sensitivity measurement accurately evaluates the sensitivity of all human visual channels, even in a more detailed manner than simple acuity measures can. This is a study of visual contrast sensitivity in a series of subjects occupationally exposed to organic solvents. Contrast sensitivity was measured for 42 printers and 28 age-stratified controls using the Vistech VCTS 6500 chart. The exposed workers distinguished between following three groups of printers: “low exposed,” “middle exposed,” and “high exposed.” Abnormal contrast sensitivity results were recorded for the right eye in 38% of the printers and 11% of the controls and for the left eye in 38% of the printers and 7% of the controls. Especially, we found a reduced contrast sensitivity in all three groups exposed to solvents for both eyes. We conclude that contrast sensitivity is abnormal in workers exposed to organic solvents. The reduced contrast sensitivity in printers seems to be an indicator of visual defects induced in response to organic solvents exposure.

Einfluss langjähriger beruflicher Lösemittelexposition auf das Farbensehen

ZusammenfassungHintergrund. Ziel der Arbeit ist es, bei Autolackierern den Einfluss einer chronischen beruflichen Lösemittelgemischexposition auf das Farbensehen zu untersuchen. Probanden und Methoden. Die 123 Arbeitnehmer (zwei Gruppen von lösemittelexponierten Lackierern und eine Kontrollgruppe) wurden mittels Ishihara-Tafeln, Lanthony-Desaturated-Panel-D-15-Test,Velhagen-Tafeln und Tritan-Album untersucht. Ergebnisse. Mittels Velhagen-Tafeln wurde bei 3% der aktuell lösemittelexponierten Lackierer und bei 11% der ehemalig Lösemittelexponierten eine Blau-Gelb-Störung für das rechte Auge festgestellt.Alle Kontrollpersonen konnten fehlerfrei die Tafeln lesen; 3% der aktuell und 26% der ehemalig Lösemittelexponierten hatten im Tritan-Test für das rechte Auge eine Blau-Gelb-Störung, aber auch in der Kontrollgruppe zeigten 7% der Probanden die Anomalität. Ähnliche Ergebnisse in beiden Tests wurden für das linke Auge festgestellt.Die CCI-Unterschiede in dem D-15-Test zwischen den drei Gruppen waren statistisch signifikant. Schlussfolgerung. Die Beeinträchtigung des Farbensehens ist ein wichtiger Indikator der neuroophthalmologischen Veränderungen, die durch chronische Lösemittelexposition hervorgerufen werden können.AbstractBackground. The study was designed to determine the influence of chronic occupational exposition of organic solvent mixtures on colour vision of car painters. Subjects and methods. The 123 subjects (2 groups differing in organic solvents exposure and 1 control group) were examined using Ishihara-Panel,Lanthony Desaturated Panel D-15,Velhagen-Panel, and Tritan-Album. Results. In the Velhagen-Panel 3% of the probands currently exposed to organic solvents, and 11% of formerly exposed probands developed a blue/yellow vision defect for the right eye. All control subjects perfectly finished this panel. In the Tritan-Album 3% of currently exposed subjects and 26% of formerly exposed painters expressed a blue/yellow vision defect for the right eye, but also 7% of controls showed anomalies. Similar results were found for both panels with the left eye.The CCI difference in the D-15 Ttest was significant between all three groups. Conclusion. The impaired colour vision may also be an important indicator of neuro-ophthalmological effects after long-term occupational exposure to organic solvents.

Assessing the suitability of cross-sectional and longitudinal cardiac rhythm tests with regard to identifying effects of occupational chronic lead exposure.

The aim of this study was to examine whether signs of neurotoxic influence on the autonomic nervous system, after lengthy occupational lead exposure, could be revealed by appropriate cardiac rhythm analysis. A total of 109 male lead-exposed workers and 27 controls were examined in a cross-sectional study. In addition, 17 lead-exposed participants were investigated a second time in a follow-up study 4 years later. Heart rate variability was assessed in rest, strain, and recovery phases. In the cross-sectional study, lead-exposed persons showed a delayed restoration of cardiac rhythm parameters to the initial vegetative state after the strain phase. This effect significantly increased over a period of 4 more years of exposure in the 17 workers participating in the follow-up study. We found vagal depression caused by long-term lead exposure within the current threshold limit value range, which can be interpreted as an adverse effect.

Vegetative function diagnosis for early detection of lead intoxication

In the search for the early effects of neurotoxic lead poisoning, vegetative function diagnosis is a potential approach, focusing on the behaviour of the cardiac rhythm. Four groups of male subjects (109 copper workers exhibiting mean lead levels in blood of 31.2 μg/dl after long-term lead exposure; 27 control subjects having a similar job in the iron and steel industry without neurotoxic exposure; 35 reference subjects from Magdeburg University Hospital without neurotoxic exposure, and 5 subjects to whom benefits have been awarded for disability resulting from lead intoxication) were studied. All subjects underwent the same psychometric test battery. Special attention was paid to the restoration of vegetative tone after exposure. The more extensive the exposure to lead, the longer was the delay in restoration. This effect seems to be reversible, as workers heavily exposed to lead, but otherwise healthy, were more affected than the patients included in this investigation. Simply comparing the cardiac rhythm of exposed and non-exposed subjects at rest is not sufficient for early detection of lead intoxication. The behaviour of cardiac rhythm in humans at rest is the result of long-term influence by a wide range of factors, of which lead exposure is only one.

Psychological effects of occupational exposure to organic solvent mixtures on printers

Purpose: Neuropsychiatric symptoms associated with long-term exposure to organic solvents have been investigated for a long time in many occupational studies. The aim of our study was to identify preclinical effects of low-level chronic solvent exposure on the cognitive performance of silk-screen printers. Methods: A cross-sectional study was conducted including 38 printers which were exposed to organic solvent mixtures and 45 controls without neurotoxic exposure. The psychometric test battery included nine tests and two questionnaires. Results: The sum of scales or the total score of the PNF was also significantly (p < 0.001) higher in the exposed group than in the non-exposed. The printers performed worse in some psychometric tests than did controls. Cross validation with the psychometric performances resulted in 69.6% of participants being correctly classified (55.9% printers and 80% controls). Highly significant differences (p < 0.001) between both groups of exposed and non-exposed workers were found for the mean values of the multidimensional psychometric score. Conclusions: These results of our study proved not only that chronic exposure to organic solvent mixtures could induce a psychological effect but also that the psychological/psychometrical tests performed in this study were capable of predicting neurotoxicity.

Influence of chronic exposure to organic solvent mixtures on contrast sensitivity in silk-screen printers: matched-pair analysis.

The aim of the study was the determination of the influence of chronic occupational exposure to organic solvent mixtures on the contrast sensitivity (CS) of silk-screen printers. Contrast sensitivity was measured for 28 matched (age, sex) pairs of silk-screen printers and controls using the Vision Contrast Test System - VCTS 6500 chart. The duration of exposure to industrial neurotoxic substances was about 9 years. Contrast sensitivity impairments were recorded in 28.6% of the printers for both eyes at several spatial frequencies. Males and females differed in CS significantly, but no interaction between gender (male vs. female) and exposure (printers vs. controls) was found.

Arbeitsmedizinische Bedeutung der Herzschlagfrequenzvariabilität

ZusammenfassungDie Herzschlagfrequenzvariabilität (HRV) wird durch die Analyse einer Herzaktionszeitreihe ermittelt und charakterisiert mehrere Aspekte, die mit dem vegetativen Nervensystem und dem Zustand des Herz-Kreislauf-Systems verbunden sind. Da die Arbeitsmedizin verstärkt psychisch bzw. neurobezogen ist und sich auch zunehmend kardiopräventiv orientieren muss, gewinnt die HRV auch hier an Stellenwert. Obwohl es sich bei der HRV- Analyse um eine etablierte Methode handelt, findet sie in der Arbeitsmedizin bisher noch eine unzureichende praxisbezogene Anwendung. Gründe dafür sind u.a. — die HRV ist ein Summenparameter vieler Einflussfaktoren— hohe inter- und intraindividuelle Streubreite— fehlende Aufnahme- und Auswertetechnik sowie— hoher zeitlicher Aufwand bei knappem Zeitbudget. Dazu kommt auch die Unterrepräsentanz kardiozentrierter Fragestellungen in der arbeitmedizinischen Praxis.Es werden Möglichkeiten und Grenzen dieses Verfahrens für die Arbeitsmedizin in der betrieblichen Praxis aufgezeigt. Damit soll eine entsprechende Leitlinie der Deutschen Gesellschaft für Arbeitsmedizin und Umweltmedizin e.V. untersetzt werden. Unter gewissenhafter Beachtung von Störfaktoren und Interpretationsgrenzen eignet sich die HRV-Analyse mindestens für folgende arbeitsmedizinische Aufgaben: — Differenzierung des Herz-Kreislauf-Risikos eines Patienten im Rahmen arbeitsmedizinischer Vorsorgeuntersuchungen— Erfolgskontrolle verhaltensorientierter Prävention in Fällen, bei denen das vegetative Nervensystem beteiligt ist (z.B. bei Bewegungsmangel)— Frühdiagnostik der Neurotoxizität entsprechender aufgenommener Schadstoffe, z.B. Schwermetalle, organische Lösemittel, und— arbeitsphysiologische bzw. psychophysiologische Beanspruchungsanalysen an Arbeitsplätzen mit vorrangig psychischen und psychomentalen Belastungen. Es soll einerseits zur HRV-Analyse im Rahmen betriebsärztlicher Untersuchungen deutlich ermutigt werden. Andererseits muss aber auch vor einer unkritischen Anwendung gewarnt werden, da die HRV durch eine Vielzahl von Einflussfaktoren bestimmt wird, die man einbeziehen oder zumindest für die Interpretation kennen sollte.SummaryThe heart rate variability (HRV) is established by means of analysis of a heart rate sequence and characterises several aspects connected with the vegetative nervous system and the condition of the circulatory system. Since occupational medicine is increasingly psychic- or neuro-related, and so far increasingly cardio-preventive, the HRV is also becoming increasingly important in this respect. Although HRV analysis is already an established method, it has previously not been applied adequately to occupational medicine. The reasons for this, amongst other things, are that HRV represents a sum of many influencing factors, high inter- and intra-individual distributions, lacking recording and evaluation techniques and a high time requirement with a restricted time budget. This is further exacerbated by the low representation of cardiocentric questions in current German occupational medicine. The possibilities and limits of this procedure for occupational medical specialists will be pointed out. This is intended to support a corresponding guideline of the “Deutsche Gesellschaft für Arbeitsmedizin und Umweltmedizin e. V. (DGAUM)” (“German Society for Occupational Medicine and Environmental Medicine”). Under conscientious observance of confounders and interpretation limits, HRV analysis is suitable at least for the following occupational medical tasks: — differentiation of the circulatory risk of a patient in the course of preventive examinations,— success control of behaviour-orientated prevention in cases involving the vegetative nervous system (e.g. lack of exercise),— early diagnosis of the neuro-toxicity of ingested hazardous materials (heavy metals, organic solvents) und— occupational-physiological and psycho-physiological stress analyses at workplaces with primarily psychic stresses. This should be significantly encouraged, on the one hand in the course of occupational medical examinations, while on the other hand a warning should be given against uncritical application, since HRV is determined by means of a range of influencing factors, which should be included or at least known for the purposes of interpretation.RésuméLa variabilité de la fréquence cardiaque ou Heart Rate Variabilty (HRV) est définie par le biais de l’analyse d’une série de réactions cardiaques et caractérise plusieurs aspects associés au système nerveux végétatif et à l’état du système cardiovasculaire. Etant donné que la médecine du travail est fortement dominée par les aspects psychiques voire neurologiques et qu’elle doit s’engager plus fortement dans la prévention de maladies cardiaques, l’HRV acquiert ici aussi une place de plus en plus importante. Bien que l’analyse de la variabilité de la fréquence cardiaque soit une méthode établie, elle a été, jusqu’ici, insuffisamment utilisée dans la médecine du travail. Et ce, entre autres, pour les raisons suivantes: l’HRV est le paramètre global de nombreux facteurs d’influence, d’une dispersion interindividuelle et intraindividuelle importante, de l’absence d’une technique de collecte et d’évaluation ainsi que d’une grande durée et d’un budget réduit. Il faut également ajouter la sous-représentation de questions centrées sur la cardiologie dans la médecine du travail actuellement en Allemagne. Des possibilités et des limites de cette méthode pour les médecins d’entreprise sont présentées. Ceci afin d’étayer une ligne directrice correspondante de la „Deutsche Gesellschaft für Arbeitsmedizin und Umweltmedizin e. V. (DGAUM)“. L’analyse de la variabilité de la fréquence cardiaque est une méthode adéquate au moins pour les tâches suivantes de la médecine du travail lorsque les confondeurs et limites d’interprétation sont scrupuleusement respectés: — différenciation du risque cardiovasculaire d’un patient dans le cadre d’examens préventifs,— contrôle de la réussite d’une prévention orientée sur le comportement dans les cas où le système nerveux végétatif est impliqué (manque de mouvement par exemple),— diagnostic précoce de la neurotoxicité d’une substance nocive absorbée (métaux lourds, solvants organiques) et— analyses du stress psychophysiologique voire de la physiologie du travail sur les postes de travail avec, primairement, des stress psychiques. Il s’agit d’une part de promouvoir sensiblement l’analyse de la variabilité de la fréquence cardiaque dans le cadre d’examens pratiqués dans la médecine d’entreprise et d’autre part également de prévenir une utilisation non-critique de cette méthode car l’HRV est définie par un grand nombre de facteurs d’influence dont on devrait tenir compte ou du moins que l’on devrait connaître pour être à même d’interpréter les résultats obtenus.

Early Effects of Long-Term Neurotoxic Lead Exposure in Copper Works Employees

The situation of exposure in a copper works facility in Germany enabled early lead-induced neurotoxic effects to be investigated in the workers. The aim of the investigation was to study the long-term effects of small doses of lead on psychometric/psychophysiological performance of workers. The study involved 70 male lead exposed workers and 27 male controls with no neurotoxic exposure. All test persons were subjected to the method of investigation involving performance data, physiological strain data, and the subjective state. It was found that of the psychometric performance parameters, only the mainly motor performance parameters had a potential for being neurotoxic early indicators. Preferably centrally influenced performance parameters were found to be less suitable early indicators. The lead-exposed subjects exhibited a slowed poststrain resetting behaviour of the vegetative nervous system, which correlated with the individual blood lead level. This was attributed to vagus depression, which had already started in the prevailing situation of exposure and was reflected by diminished cardiac phase duration variability. Our results indicate that it is necessary to more critically choose the lead level standards in the air on the working area. Heart rate variability may be affected even at small lead concentration.

Ophthalmologische Kontrolluntersuchung bei bleibelasteten Polizeischießausbildern

Zusammenfassung1.Hintergrund Bei Sportschützen, Polizisten, Schießstandtrainern und -reinigungspersonal kann eine hohe Bleibelastung vorkommen. Ziel der Untersuchungen war, den Einfluss langjähriger Bleiexposition bei Schießausbildern der Polizei auf die Kontrastempfindlichkeit (KE) und das Farbsehen zu klären, um neue Aspekte für die Früherkennung und frühzeitige Prävention bei den betroffenen Polizeibeamten zu gewinnen.2.Patienten und Methoden Elf Schießausbilder haben folgende Verfahren absolviert: Ishihara- und Velhagen-Tafeln, Tritan-Album, Lanthony Desaturated Panel D-15d-Test und Allfarbenanomaloskop zur Bestimmung von Farbfehlsichtigkeiten sowie die Prüftafel VCTS 6000 zur Bestimmung der Kontrastempfindlichkeit.3.Ergebnisse Nach einer langjährigen Bleibelastung ist mit einem Verlust an KE bei Schießausbildern zu rechnen, mehrere KE-Werte lagen direkt auf der unteren Grenze der schwellwertigen KE-Kurve bzw. unter dem Normbereich. 73% der untersuchten Polizisten zeigten Farbsinnanomalien.4.Schlussfolgerung Die Beeinträchtigung der Kontrastempfindlichkeit und des Farbensehens stellt ein Zeichen einer chronischen beruflichen Neurotoxizität dar.Abstract1.BackgroundIn sports marksmen, police officers, rifle range instructors and cleaning staff a high lead strain may be found. The aim of this study was to investigate the impact of long term lead exposure in police rifle range instructors for contrast sensitivity and colour vision, to gain new aspects for early detection and early prevention for effected police officers.2.Patients and MethodsEleven rifle range instructors have been subjected to the following methods: Ishihara and Velhagen table, Tritan-Album, Lanthony Desaturated Panel D-15d-Test and All Colour Anomaloscope to determine laps in colour vision and table VCTS 6000 to determine contrast sensitivity.3.ResultsAfter long term lead strain a loss of contrast sensitivity in rifle instructors can be expected, several colour sensitivity values were located at the bottom range of the threshold value sensitivity range curve or below the normal range. 73% of the examined police officers showed colour sense anomalies.4.ConclusionThe impediment of contrast sensitivity and colour vision is a symptom for chronic neuro-toxicity at work.