Reducing heat stress under thermal insulation in protective clothing: microclimate cooling by a 'physiological' method.

Heat stress caused by protective clothing limits work time. Performance improvement of a microclimate cooling method that enhances evaporative and to a minor extent convective heat loss was tested. Ten male volunteers in protective overalls completed a work-rest schedule (130 min; treadmill: 3 × 30 min, 3 km/h, 5% incline) with or without an additional air-diffusing garment (climatic chamber: 25°C, 50% RH, 0.2 m/s wind). Heat loss was supported by ventilating the garment with dry air (600 l/min, ≪5% RH, 25°C). Ventilation leads (M ± SD, n = 10, ventilated vs. non-ventilated) to substantial strain reduction (max. HR: 123 ± 12 b/min vs. 149 ± 24 b/min) by thermal relief (max. core temperature: 37.8 ± 0.3°C vs. 38.4 ± 0.4°C, max. mean skin temperature: 34.7 ± 0.8°C vs. 37.1 ± 0.3°C) and offers essential extensions in performance and work time under thermal insulation. PRACTITIONER SUMMARY: Heat stress caused by protective clothing limits work time. Performance can be improved by a microclimate cooling method that supports evaporative and to a minor extent convective heat loss. Sweat evaporation is the most effective thermoregulatory mechanism for heat dissipation and can be enhanced by insufflating dry air into clothing.

Meta-analyses of published epidemiological studies, 1979-2006, point to open causal questions in silica-silicosis-lung cancer research.

BACKGROUND AND OBJECTIVES: Following up on a previous meta-analysis of lung cancer risk in individuals without silicosis, we provide more detailed results of silica associated lung cancer risk in both silicotics and non-silicotics. The objective was to examine in depth whether current data allows to answer the pressing question "does silica cause lung cancer in the absence of silicosis"? METHODS: We updated earlier meta-analyses of silicosis and lung cancer and compared the results with our 2009 meta-analysis of risks in individuals without silicosis. We performed fixed (FE) and random (RE) effects meta-analyses, calculated heterogeneity statistics, stratified the study material, performed sensitivity analyses with modified study results and meta-regressions to detect effect modification. RESULTS: In silicotics, lung cancer risks were found to be doubled in 38 studies (FE: RR = 2.1; 95% CI = 2.0-2.3). In non-silicotics, eight studies without smoking adjustment suggested marginally elevated risks (FE: RR = 1.2; 95% CI = 1.1-1.3; RE: RR = 1.2; 95% CI =1.0-1.4) but three studies which were controlled for smoking showed null results (FE and RE: RR = 1.0; 95% CI = 0.8-1.3). Heterogeneity was substantial but could be linked to study characteristics, like sector of industry, and other second-level data in meta-regression. As no excess was observe dfor other smoking-related effects in studies ofllung cancer among non-silicotics, smoking was not considered to be an important confounder or modifier. CONCLUSIONn: Our meta-analyses further substantiate evidence of a strong association between silicosis and lung cancer. However, questions remain regarding lung cancer caused by silica in non-silicotics. Ideally, future investigations should consider the entire exposure-response range between silica exposure, silicosis development and lung cancer occurrence, and analyze data in terms of processes taking intermediate confounding into account.

[Sound levels in nursery schools]. / Lärm in Kindertagesstätten.

INTRODUCTION: Children and teenagers often suffer from hearing loss because of exposure to sound levels above 100 dB generated by toys, portable music players and stereo equipment in discotheques. Even in nursery schools and schools, considerable noise levels are produced by children's voices. METHODS: Sound levels were measured in a nursery school in Cologne in four different rooms, each with 22 children aged between 3 and 6 years and two teachers. Sound dosimeters detected sound levels in each room for 5 days of the week. These were positioned in the room above the playing children as well as near the teachers' ears. The same measurements were repeated after the children had been instructed about noise and possible noise damage. In addition, the children were now able watch the "noise lights", an instrument resembling traffic lights which translated the sound levels actually measured in their room into optical signals. A questionnaire containing 13 questions about noise and sensitivity to noise was distributed to 35 teachers at nursery schools in the Cologne municipal area. RESULTS: Mean sound levels of an 8-h/day measuring period (L(eq)) were 80.1 ± 2.3 dB(A) near the ear of the teacher and 70.87 ± 2.5 dB(A) measured in the room. The maximal sound level for 1 s, L(max) dB(A), was 112.55 ± 2.3 dB(A) near the ear and 103.77 ± 8.1 dB(A) in the room. After the children had learned about noise and were able to check the sound level they produced with the help of the "noise lights", a tendency towards a reduction of sound levels in the room and near the teachers' ears could be seen. An evaluation of the questionnaire revealed the high physical strain and emotional stress the teachers were subjected to due to noise. CONCLUSIONS: Children and teachers in nursery schools are subjected to high sound levels. Therefore, the education and early sensitization of children to noise in order to prevent prospective hearing damage, e.g. using the "noise light", should be set as a goal. Soundproofing measures are also possible. Further investigations to assess the effects of these measures are planned.

Performance, training and lifestyle parameters of marathon runners aged 20-80 years: results of the PACE-study.

Successful finishing of marathon requires regular endurance training and appropriate lifestyle. Thus, marathon running times and training data from large samples of physically active and fit elderly are ideal for the assessment of age-related performance. In the present study we analyzed 439 278 running times from result lists of 108 marathon competitions and data from a survey via internet questionnaire about training and behavioural factors of marathon finishers. Marathon times and 6 992 data sets from the internet questionnaire were separated into groups based on age and sex and analyzed by two-way ANOVA. Our main findings are that 1) there are virtually no relevant running time differences (p<0.01) in marathon finishers from 20 to 55 years and 2) the majority of middle-aged and elderly athletes have training histories of less than seven years of running. With the exception of marathon running times we did not encounter any significant gender related differences (p>0.01). The present findings strengthen the concept that considers aging as a biological process that can be considerably speeded up or slowed down by multiple lifestyle related factors.

Maximal manual stretcher carriage: performance and recovery of male and female ambulance workers.

The effects of a maximal duration stretcher carriage on heart rate (HR), lactate concentration, hand steadiness and hand-grip strength were studied up to 72 h post-exercise in 17 male and 15 female military ambulance personnel. Using both hands for transport, the participants walked on a treadmill ergometer at a speed of 4.5 km/h. Force measurements at the handlebars yielded mean loads of 245 N (25 kg) on each side. Each step on the treadmill induced additional force oscillations with peak forces up to 470 N corresponding to 130% (women) and 98% (men) of maximal voluntary contraction (MVC). In the males the maximal transport time was about twice the time in women (mean +/- SD: 184 +/- 51 s vs. 98 +/- 34 s). These differences had no significant effect on HR and lactate values. The same applies to hand steadiness, which showed only a transient deterioration immediately after exercise. In contrast to these parameters, substantial differences were seen in hand-grip strength recovery. Immediately after exercise, maximal hand-grip strength decreased by 150 N (25% MVC) in the males vs. 50 N (14%) in the females. Irrespective of gender, individuals with larger hand-grip strength and longer carriage durations (range 120 s-280 s) showed the slowest strength recoveries (up to 72 h) as compared to 1 h of recovery in participants with short transport durations (range 27 s-120 s). These findings suggest that the increasing number of eccentric strains during uninterrupted stretcher carriage induces cumulative muscle damages that may require some days for complete recovery.

An epidemiological study of the respiratory health of workers in the European refractory ceramic fibre industry.

OBJECTIVES: To investigate possible relations between respiratory health and past airborne exposure to refractory ceramic fibres (RCFs) and respirable dust in workers at six European factories, studied previously in 1987. METHODS: The target population comprised all current workers associated with RCF production, plus others who had participated in 1987 "leavers". Information was collected on personal characteristics, chest radiographs, lung function, respiratory symptoms, smoking, and full occupational history. Regression analysis was used to study relations between indices of health of individual workers and of cumulative exposure to airborne dust and fibres, and likely past exposure to asbestos. RESULTS AND DISCUSSION: 774 workers participated (90% of current workers, 37% of leavers). Profusion of small opacities in exposed workers (51% 0/1+; 8% 1/0+) was similar to that among an unexposed control group but higher than in new readings of the 1987 study films (11% 0/1+, 2% 1/0+). The large difference between 1987 and recent films may be, at least in part, a reading artefact associated with film appearance. Small opacities of International Labour Organisation (ILO) category 1/0+ were not associated with exposure. An association of borderline significance overall between 0/1+ opacities and exposure to respirable fibres was found for some exposure periods only, the time related pattern being biologically implausible. Pleural changes were related to age and exposure to asbestos, and findings were consistent with an effect of time since first exposure to RCFs. Among men, forced expired volume in 1 second (FEV(1)) and forced vital capacity (FVC) were inversely related to exposure to fibres, in current smokers only. FEV(1)/ FVC ratio and transfer factor (TL(CO)) were not related to exposures. The estimated restrictive effect was on average mild. Prevalence of respiratory symptoms was low. Chronic bronchitis and its associated symptoms (cough, phlegm) showed some association with recent exposure to respirable fibres. This could be due to an irritant effect of RCFs.

[Comparison of digital selenium radiography with an analog screen-film system in the diagnostic process of pneumoconiosis according to ILO classification]. / Vergleich der digitalen Selenradiographie mit einem analogen Film-Folien-System in der Diagnostik von Staublungenerkrankungen anhand der ILO-Klassifikation.

UNLABELLED: Comparison of digital selenium radiography with an analog screen-film system in the diagnostic process of pneumoconiosis according to ILO classification. PURPOSE: The aim of the study was to determine the diagnostic value of digital selenium radiography in patients with pneumoconiosis. For this purpose chest x-rays by digital selenium radiography and analog screen-film system were compared according to the ILO classification of pneumoconiosis. METHOD: After approval of the study by the local ethic commission and the Federal German Office for Radiation Protection 50 patients were subjected to x-rays by digital selenium radiography (Thoravision; Philips Medical Systems, Hamburg, Germany) and analog screen-film system of the same day within the scope of an industrial medicine preventive checkup. Four investigators rated the chest x-rays according to the ILO classification of pneumoconiosis. RESULTS: The findings demonstrated by chest x-rays according to ILO classification were rated similar by digital selenium radiography and analog screen film systems. Image quality of the digital pictures was rated significantly better. CONCLUSION: The use of digital selenium radiography in evaluating chest x-rays according to the ILO classification does not result in over- or underestimation of pulmonary pathologies. Hence, in the diagnosis of pneumoconiosis, digital selenium radiography can replace the tested analog screen-film system.

The evaluation of workplaces subjected to heat stress: can ISO 7933 (1989) adequately describe heat strain in industrial workplaces?

The International Standard ISO 7933 (1989) Hot environments--Analytical determination and interpretation of thermal stress using calculation of required sweat rate has been proposed for the evaluation of climatic stress within the European system of CEN standards. Comparison of results of studies performed in climatic chambers and those in the field with the predictions of ISO 7933 show that there are considerable problems in using this index in practice. In its present state of development, ISO 7933 seems to be rather a step towards a useable index for evaluating climatic conditions rather than an established climatic index which is applicable in practice. Within the CEN standards, the deficiencies of ISO 7933 are reflected mainly by a restriction of the limits of application within EN 12 515 (1997) which is based on ISO 7933.

Does winter darkness in the Artic protect against cancer? The melatonin hypothesis revisited.

The melatonin hypothesis states that excess exposure to environmental light may contribute to breast cancer risks via impaired pineal secretion of melatonin. A corollary, not considered previously, is that a net annual increase in oncostatic melatonin would be expected in persons who experience a light deficit during extended winter darkness periods; thus, hormone-dependent cancers should occur less frequently in people who reside north, rather than south, of the Arctic circle. Consistent with our prediction, epidemiological data indicate uniformly low risks for hormone-dependent cancers in the Arctic. The available literature on genetic, reproductive, nutritional, life-style, and environmental risk factors provides no obvious clues to the observed cancer patterns. Moreover, diurnal and 24-hour melatonin concentrations in humans living in Arctic regions were reported as high in November-January, when light intensity is low. Since these observations are consistent with our corollary and the associated prediction, we suggest that research on a melatonin-inhibited carcinogenesis in the low-risk populations of the Arctic should be pursued.

Synergy between asbestos and smoking on lung cancer risks.

We have examined data from 12 epidemiologic studies for quantitative evidence of biologic synergy between asbestos and smoking on lung cancer risks. Estimates of the effect associated with joint exposure to the two agents exceeded the sum of their separate effects in each study. We explored the variations in the strength of the synergistic effect across the studies using three indices: the ratio of the combined effects to the sum of the separate effects of smoking and asbestos (S), the relative excess risk due to interaction (RERI), and the attributable proportion of risk due to interaction (AP). The weighted average of S across all studies was 1.64 (95% confidence interval = 1.33-2.03). The attributable proportion associated with this average S was estimated as 33%, that suggests that one-third of cancer cases among smokers who were exposed to asbestos can be attributed to the synergistic behavior of the two carcinogens, as distinct from their separate effects and those attributable to other ("background") factors.

Climatic stress in coalmining in Germany: occupational health aspects.

Coalmining in Germany is performed in depths as low as 1400 m. Owing to an average thermal gradient of 30 m/K the work underground is burdened by heat stress to which occupational medicine must pay special attention. Therefore heat stress standards and mining safety regulations have been set up not only for coal production but also for mine rescue activities. This specific situation of heat burdened work in the coal mining industry in Germany is discussed under the specific aspects of German coalmining regulations (Klima-Bergverordnung und Plan für das Grubenrettungswesen).

[Ergospirometry: a suitable method for evaluating work capacity in occupational medicine?]. / Ergospirometrie: Eine geeignete Methode zur Leistungsbeurteilung in der Arbeitsmedizin?

In various industrial tasks elevated physical strain of workers can be expected. In order to identify possible health hazards as soon as possible and to effectively prevent occupational diseases and accidents, a series of occupational health medical examinations are mandatory according to German accident prevention regulations such as VBG 100 "Occupational Health Care", Regulations for Climatic Conditions Underground (KlimaBergV), Regulations for Mine Rescue Teams, etc. Besides a clinical medical inspection and a laboratory blood test as well as urine test the physical fitness and aptitude for several specific occupational hazards are tested by means of a mandatory ergometry test. In the present publication the possible predictive limits as well as the making sense or nonsense of the use of ergometry in occupational aptitude tests under the auspices of German accident prevention regulations will be discussed.