Unstable sitting in the workplace--are there physical activity benefits?

The increasingly popular practice of using a stability ball (exercise/fitness ball) as a sitting surface runs counter to conventional human factors/ergonomics guidelines for seated workspace design. Employees sitting on stability balls in an office environment present safety risks that might be justifiable if the practice has a definitive benefit to the promotion of health. However, the published studies and best evidence to date call into question even the theoretical basis for this practice and do not suggest significant health benefits. First, biomechanical studies do not confirm the intended trunk muscle activation. Second, energy expenditure studies show a small (if any) increase in metabolic demand that is unlikely to be effective in combating sedentary work risk factors. Until studies demonstrate more conclusive benefits, the practice of stability ball sitting should be viewed skeptically as a general workplace recommendation in the interest of health or wellness.

A Bayesian network model for biomarker-based dose response.

A Bayesian network model was developed to integrate diverse types of data to conduct an exposure-dose-response assessment for benzene-induced acute myeloid leukemia (AML). The network approach was used to evaluate and compare individual biomarkers and quantitatively link the biomarkers along the exposure-disease continuum. The network was used to perform the biomarker-based dose-response analysis, and various other approaches to the dose-response analysis were conducted for comparison. The network-derived benchmark concentration was approximately an order of magnitude lower than that from the usual exposure concentration versus response approach, which suggests that the presence of more information in the low-dose region (where changes in biomarkers are detectable but effects on AML mortality are not) helps inform the description of the AML response at lower exposures. This work provides a quantitative approach for linking changes in biomarkers of effect both to exposure information and to changes in disease response. Such linkage can provide a scientifically valid point of departure that incorporates precursor dose-response information without being dependent on the difficult issue of a definition of adversity for precursors.

Recent advances in research on radiofrequency fields and health: 2004-2007.

The widespread use of wireless telecommunications devices, particularly mobile phones and wireless networks, has resulted in increased human exposure to radiofrequency (RF) fields. Although national and international agencies have established safety guidelines for exposure to RF fields, concerns remain about the potential for adverse health outcomes to occur in relation to RF field exposure. The extensive literature on RF fields and health was reviewed by a number of authorities, including the Royal Society of Canada (1999). This report is the third in a series of updates to the original report of the Royal Society of Canada, covering the period 2004-2007. In particular, the present study examined new data on (1) dosimetry and exposure assessment, (2) biological effects of RF fields such as enzyme induction, and (3) toxicological effects, including genotoxicity and carcinogenicity. Epidemiological studies of the potential health effects of RF exposure, particularly from mobile phones, were determined, along with human and animal studies of neurological and behavioural effects. Within the last 4 yrs investigators concluded that there is no clear evidence of adverse health effects associated with RF fields, although continued research is recommended to address specific areas of concern, including exposure to RF fields among children using mobile phones. The results of the ongoing 13-country World Health Organization INTERPHONE study of mobile phones may provide important new information on the potential cancer risks associated with mobile phone use.

Rapid diagnosis of pulmonary TB by BAL enzyme-linked immunospot assay in an immunocompromised host.

Immunocompromised patients with acid-fast bacilli (AFB) smear-negative active pulmonary tuberculosis (pTB) often present with nonspecific clinical symptoms and findings. T-cell interferon-gamma release assays (TIGRA) performed on whole blood (using ELISA) or peripheral blood mononuclear cells (using enzyme-linked immunospot assay (ELISPOT)) are more sensitive for the diagnosis of Mycobacterium tuberculosis (MTB) infection than the tuberculin skin test (TST), but cannot distinguish active from latent MTB infection. The present authors report a 38-yr-old female presenting with a 3-week history of malaise, dyspnoea, fevers and coughing, who had received immunosuppressive therapies over 8 months for mixed connective tissue disease. Chest radiograph and thoracic computed tomography showed ground glass opacities in both lower lobes. The TST-induration was 0 mm and AFBs or MTB nucleic acid was not detected on sputum and bronchial secretions. However, TIGRAs performed on peripheral blood cells were reactive. A high frequency of MTB-specific T-cells compatible with the immunodiagnosis of active pTB was detected among bronchoalveolar lavage cells using ELISPOT. Antituberculous therapy was initiated 18 days before MTB was discovered on sputum cultures. Detection of Mycobacterium tuberculosis-specific T-cells in the bronchoalveolar lavage using enzyme-linked immunospot assay is a promising tool for the diagnosis of active pulmonary tuberculosis in immunocompromised patients with negative acid-fast bacilli smears.

Recent advances in research on radiofrequency fields and health: 2001-2003.

The widespread use of wireless telecommunications devices, particularly mobile phones, has resulted in increased human exposure to radiofrequency (RF) fields. Although national and international agencies have established safety guidelines for exposure to RF fields, concerns remain about the potential for adverse health outcomes to occur in relation to RF field exposure. The extensive literature on RF fields and health has been reviewed by a number of authorities, including the Royal Society of Canada (1999), the European Commission's Scientific Committee on Toxicity, Ecotoxicity, and the Environment (CSTEE, 2001), the British Medical Association (2001), the Swedish Radiation Protection Authority (Boice & McLaughlin, 2002), and the Health Council of The Netherlands (2002). This report provides an update on recent research results on the potential health risks of RF fields since the publication of the Royal Society of Canada report in 1999 (See Krewski et al., 2001a) and our previous 2001 update (Krewski et al., 2001b), covering the period 2001-2003. The present report examines new data on dosimetry and exposure assessment, biological effects such as enzyme induction, and toxicological effects, including genotoxicity, carcinogenicity, and testicular and reproductive outcomes. Epidemiological studies of mobile phone users and occupationally exposed populations are examined, along with human and animal studies of neurological and behavioral effects. All of the authoritative reviews completed within the last 2 yr have concluded that there is no clear evidence of adverse health effects associated with RF fields. However, following a recent review of nine epidemiological studies of mobile phones and cancer, Kundi et al. (2004) concluded that the possibility of an enhanced cancer risk cannot be excluded. These same reviews support the need for further research to clarify the possible associations between RF fields and adverse health outcomes that have appeared in some reports. The results of the ongoing World Health Organization (WHO) study of mobile phones will provide important new information in this regard.

Investigation of protein expression in magnetic field-treated human glioma cells.

We previously reported phenotypic changes in human breast cancer cells following low-level magnetic field (MF) exposure. Here proteomic methods were used to investigate the biochemical effect of MF exposure in SF767 human glioma cells. Protein alterations were studied after exposure to 1.2 microTesla (microT) MF [12 milliGauss (mG), 60 Hertz (Hz)] +/- epidermal growth factor (EGF). SF767 cells were exposed for 3 h to sham conditions (<0.2 microT ambient field strength) or 1.2 microT MF (+/-EGF; 10 ng/ml). Solubilized protein fractions (sham; 1.2 microT; sham + EGF; 1.2 microT + EGF) were loaded for electrophoresis by 2D-PAGE and stained using a colloidal Coomassie blue technique to resolve and characterize the proteins. Protein patterns were compared across groups via Student's t-test using PDQUEST software. Cell profiles revealed significant alterations in the spot density of a subset of treated cells. Automated spot excision and processing was performed prior to peptide mass fingerprinting proteins of interest. Fifty-seven proteins from the detectable pool were identified and/or found to differ significantly across treatment groups. The mean abundance of 10 identified proteins was altered following 1.2 microT exposure. In the presence of EGF six proteins were altered after low magnetic field treatment by increasing (4) or decreasing (2) in abundance. The results suggest that the analysis of differentially expressed proteins in SF767 cells may be useful as biomarkers for biological changes caused by exposure to magnetic fields.

Changes in gene and protein expression in magnetic field-treated human glioma cells.

Because few cancer studies have examined protein profiles and genetic regulation from a single carcinogen exposure, the objective of this study was to determine genetic change via microarray and to evaluate whether that change was a precursor to cellular protein changes. In separate but experimentally identical studies, human glioma SF767 cells were exposed for 3 h to 60-Hz magnetic fields (sham or 1.2 muT). Microarray results suggested that magnetic field treatment resulted in the up-regulation of 5 genes, whereas 25 genes were down-regulated. The mean abundance of 10 identified proteins was altered following 1.2 muT exposure relative to sham (3 increase, 7 decrease). These studies suggest a limited but complicated response in the glioma cells to the magnetic field treatment.

Ornithine decarboxylase activity in tissues from rats exposed to 60 Hz magnetic fields, including harmonic and transient field characteristics.

Ornithine decarboxylase (ODC) activity is used widely as a biomarker for tumor promotion in animal model systems. Several previous studies have reported increases in ODC activity in tissues of rats exposed to 60 Hz magnetic fields. The goals of this study were to confirm these findings and to determine whether ODC activity is increased in tissues of animals exposed to magnetic fields containing complex metrics. Three experiments were conducted in male F344 rats. Each study included a sham control group and a group exposed to pure continuous 60 Hz fields (0.2 mT). Additional groups included animals exposed to randomly time-varying 60 Hz fields (range of 0.02 to 0.2 mT); intermittent 60 Hz fields (2 mT) with on-off cycles ranging from 5 s to 5 min; pure continuous 180 Hz fields (2 mT); 60 Hz fields with a superimposed 3rd harmonic (total field strength, 2 mT); 60 Hz fields with superimposed third, fifth, and seventh harmonics (total field strength, 2 mT); 60 Hz fields (2 mT) with superimposed transients; and randomly time-varying 60 Hz fields (range of 0.02 to 0.2 mT) with superimposed transients. After 4 weeks of exposure (18.5 h/day), eight animals per group were euthanized within 1 h of magnetic field deactivation. Homogenates of liver, kidneys, spleen, and brain were prepared from each animal, quick-frozen, and shipped for analysis by four independent laboratories. No consistent pattern of differences in the ODC activity among experimental groups was found either within a laboratory or among laboratories. The results do not support the hypothesis that exposure to extremely low frequency magnetic fields stimulates ODC activity.

Recent advances in research on radiofrequency fields and health.

Since the Royal Society of Canada report on potential health risks of radiofrequency (RF) fields from wireless telecommunications in the spring of 1999, there have been several newly published reports on risks associated with the use of mobile phones. This article provides a summary of scientific research on the potential health effects of radiofrequency fields that has been reported since the original Royal Society report was published. This update also discusses several earlier results not included in the original report.

Evaluation of in vitro effects of 50 and 60 Hz magnetic fields in regional EMF exposure facilities.

A weak association between magnetic-field exposure and increased incidences of cancer has been reported. While alterations in cellular processes after in vitro magnetic-field exposures have also been reported to provide plausibility for this association, other laboratories have been unable to repeat the findings. As part of an accelerated electric- and magnetic-field (EMF) research program, the National Institute of Environmental Health Sciences with the Department of Energy identified the replication of the published positive effects as a priority. Regional EMF exposure facilities were established to investigate major in vitro effects from the literature. These included effects on gene expression, intracellular calcium, colony growth in soft agar, and ornithine decarboxylase activity. The laboratories that first reported these effects provided experimental protocols, cell lines, and other relevant experiment details. Regional facility studies included sham/sham exposures (no applied field in either chamber) and were done in a blinded fashion to minimize investigator bias. In nearly all experiments, no effects of magnetic-field exposure were found. The effort provided insight into dealing with the difficulty of replication of subtle effects in complex biological systems. Experimental techniques provided some clues for the differences in experimental results between the regional facility and the original investigator. Studies of subtle effects require extraordinary efforts to confirm that the effect can be attributed to the applied exposure.

50-Hertz magnetic field and calcium transients in Jurkat cells: results of a research and public information dissemination (RAPID) program study.

An effect on intracellular calcium continues to be proposed as a biochemical pathway for the mediation of biologic effects of electrical-power-frequency magnetic fields (MF). However, reproducible results among laboratories are difficult to attain and the characteristics of magnetic field effects on intracellular free calcium ([Ca(2+)](i)) are not well understood. We attempted to repeat the studies of Lindström et al. [Intracellular Calcium Oscillations in a T-Cell Line by a Weak 50 Hz Magnetic Field. J Cell Physiol 156:395-398 (1993)] by investigating the effect of a 1.5-G 50-Hz MF on [Ca(2+)](i) in the Jurkat lymphocyte T-cell line. Changes in [Ca(2+)](i) were determined using microscopic imaging of fura-2 loaded Jurkat cells on poly-l-lysine-coated glass coverslips. The MF was generated by a single coil constructed with bifilar wire and located in the same plane as the cells. Cells were randomly exposed for 8 min to MF, sham field (SF), or no field (NF) conditions. The exposure condition remained coded until data analysis was complete. Each exposure period was preceded by an 8-min data collection to establish a baseline for [Ca(2+)](i). After each exposure condition, cells were exposed to anti-CD3 antibody that induced a rapid increase in [Ca(2+)](i) in responsive cells; this provided a positive control. [Ca(2+)](i) was analyzed for individual cells as spatially-averaged background-corrected 340/380 nm ratios, and a [Ca(2+)](i) transient was considered significant for positive deviations from baseline of 3 [multiple] an estimate of noise in the baseline. Typically, 25-50 cells/field were viewed and approximately 50% had no [Ca(2+)](i) transients in the baseline period and also responded to positive control. Only cells responding to positive control and lacking changes in [Ca(2+)](i) during the baseline period were considered qualified for assessment during the exposure period. The incidences of [Ca(2+)](i) transients during the exposure period for two experiments (40 [multiple] objective) were 16.5, 14.6, and 14.2% for MF, SF, and NF, respectively, and were not statistically significantly different. Previous studies by Lindström et al. [Intracellular Calcium Oscillations in a T-Cell Line after Exposure to Extremely-Low-Frequency Magnetic Fields with Variable Frequencies and Flux Densities. Bioelectromagnetics 16:41-47 (1995)] showed a high response rate (92%) for exposure to 1. 5-G 50-Hz MF when individual cells were preselected for investigation. We found no such effect when examining many cells simultaneously in a random and blind fashion. These results do not preclude an effect of MF on [Ca(2+)](i), but suggest that responsive cells, if they exist, were not identified using the approaches that we used in this study.

Two outbreaks of trichinellosis in the state of Northrhine-Westfalia, Germany, 1998.

Illness or death from trichinellosis is statutorily notifiable in Germany. Between nought and ten cases were reported each year from 1987 to 1997. From November 1998 to January 1999, however, 52 cases of trichinellosis were identified by the public health

Electric field-induced changes in agonist-stimulated calcium fluxes of human HL-60 leukemia cells.

The mechanism of biological effects of extremely-low-frequency electric and magnetic fields may involve induced changes of Ca2+ transport through plasma membrane ion channels. In this study we investigated the effects of externally applied, low-intensity 60 Hz electric (E) fields (0.5 V/m, current density 0.8 A/m2) on the agonist-induced Ca2+ fluxes of HL-60 leukemia cells. The suspensions of HL-60 cells received E-field or sham exposure for 60 min and were simultaneously stimulated either by 1 microM ATP or by 100 microM histamine or were not stimulated at all. After E-field or sham exposure, the responses of the intracellular calcium levels of the cells to different concentrations of ATP (0.2-100 microM) were assessed. Compared with control cells, exposure of ATP-activated cells to an E-field resulted in a 20-30% decrease in the magnitude of [Ca2+]i elevation induced by a low concentration of ATP (<1 microM). In contrast, exposure of histamine-activated HL-60 cells resulted in a 20-40% increase of ATP-induced elevation of [Ca2+]i. E-field exposure had no effect on non-activated cells. Kinetic analysis of concentration-response plots also showed that compared with control cells, exposure to the E-field resulted in increases of the Michaelis constant, Km, value in ATP-treated cells and of the maximal [Ca2+]i peak rise in histamine-treated HL-60 cells. The observed effects were reversible, indicating the absence of permanent structural damages induced by acute 60 min exposure to electric fields. These results demonstrate that low-intensity electric fields can alter calcium distribution in cells, most probably due to the effect on receptor-operated Ca2+ and/or ion channels.

Effects of three hydration beverages on exercise performance during 60 hours of heat exposure.

Without adequate hydration, profound heat stress and dehydration can occur in people who work in hot environments. This study evaluated the effectiveness of three beverages on temperature regulation, cardiovascular response, and work performance during 60 h of dry heat exposure. Volunteer subjects lived in a climatic chamber in simulated desert conditions varying from 25-45 degrees C at 20% relative humidity. They performed three submaximal exercise sessions on a motorized treadmill at 4-h intervals each day. All of the subjects consumed one of three beverages: a water placebo, a 5% carbohydrate-electrolyte drink, or a 4% carbohydrate-electrolyte drink containing 1% glycerol, during each 60-h session. During exercise, the rating of perceived exertion and heart rate were similar for all beverages and all sessions, but oxygen consumption, core body and average skin temperatures, and sweat rate differed among beverages and sessions. Water alone appeared to provide adequate hydration for working in desert conditions over the 60 h when compared to carbohydrate-electrolyte beverages, with or without a small amount of glycerol.

Piscine gill epithelial cell necrosis due to Mycoplasma mobile strain 163 K: comparison of in-vivo and in-vitro infection.

This paper describes experiments with Mycoplasma mobile 163 K in tench inoculated via the gills, skin, peritoneal cavity or whole body surface and kept at two different temperatures (20 and 25 degrees C). Gill tissues from experimentally infected tench and rainbow-trout gill tissue explants infected in vitro were compared by transmission electron microscopy, revealing that M. mobile was capable of producing gill epithelial cell necrosis in both, but that it was much more severe in the explants. M. mobile was found attached to chloride cells in the tench and between necrotic epithelial cells in the trout gill explants. M. mobile was recovered from the gills for up to 28 days after inoculation, from the skin and swim bladder for up to 14 days, and from the hind gut, kidneys and spleen for up to 8 days. There was no significant difference between the results at 20 and 25 degrees C.

Developmental patterns of laryngeal and respiratory function for speech production.

Estimates of subglottal air pressure, laryngeal airflow, and laryngeal airway resistance from syllable repetitions of children and adults were used in describing developmental changes in these variables and in hypothesizing corresponding changes in respiratory function. A trend was found for pressure and resistance to decrease with increases in flow from preschool age through adulthood. These patterns could be explained by the smaller size of laryngeal airway structures and increased expiratory muscle forces during speech in the younger subjects. When the subglottal air pressures were combined with published data on air volume expired during speech and recoil pressures of the respiratory system, hypothetical functions were derived for respiratory muscle forces and the work of speech breathing. These functions predict (a) a developmental shift from the use of net expiratory muscle force in the speech of preschool children to the adult patterns of combined inspiratory and expiratory muscle forces, and (b) the expiratory work of speech breathing is greater in preschool children than in older children and adults.

Combined chemical, physical hazards make exposures harder to calculate. Studies show multiple exposures must be evaluated wholly rather than 'adding up' individual risks.

Clearly, current research adds to the mounting scientific evidence that combined exposures can produce greater toxicity than would be predicted using an additive model. Although there is not yet a quantitative method to determine the risks associated with multiple exposures, safety and health specialists must begin to consider the health effects from the entire work process, rather than individual chemical or physical agents. Moreover, organizations involved in risk assessment and standard-setting must evaluate the interactive effects of combined chemical and physical agent exposures. This will make personnel exposure standards comprehensive in addressing realistic occupational health risks.

Successful nasoendoscopic and aerodynamic examinations of children with speech/voice disorders.

An 8-year retrospective analysis of aerodynamic and nasoendoscopic examinations of children with a variety of speech and voice disorders shows that these examinations can be completed with a high rate of success. Moreover, the examinations were achieved with relative ease in children as young as 2 years old. Several clinicians were involved in the examinations, illustrating the viability of the methods. It is suspected that the failures to complete the examinations relate more to the examiners' methods and skills than to the child's tolerance of the instrumentation.