Dealing with crosstalk in electromagnetic field measurements of portable devices.

Portable devices measuring radiofrequency electromagnetic fields (RF-EMF) are affected by crosstalk: signals originating in one frequency band that are unintentionally registered in another. If this is not corrected, total exposure to RF-EMF is biased, particularly affecting closely spaced frequency bands such as GSM 1800 downlink (1,805-1,880 MHz), DECT (1,880-1,900 MHz), and UMTS uplink (1,920-1,980 MHz). This study presents an approach to detect and correct crosstalk in RF-EMF measurements, taking into account the real-life setting in which crosstalk is intermittently present, depending on the exact frequency of the signal. Personal measurements from 115 volunteers from Zurich canton, Switzerland were analyzed. Crosstalk-affected observations were identified by correlation analysis, and replaced by the median value of the unaffected observations, measured during the same activity. DECT is frequently a victim of crosstalk, and an average of 43% of observations was corrected, resulting in an average exposure reduction of 38%. GSM 1800 downlink and UMTS uplink were less often corrected (6.9% and 8.9%), resulting in minor reductions in exposure (7.1% and 0.92%). The contribution of DECT to total RF-EMF exposure is typically already low (3.2%), but is further reduced after correction (3.0%). Crosstalk corrections reduced the total exposure by 1.0% on average. Some individuals had a larger reduction of up to 16%. The code developed to make the corrections is provided for free as an R function which is easily applied to any time series of EMF measurements. Bioelectromagnetics. 39:529-538, 2018. © 2018 Wiley Periodicals, Inc.

Occupational Exposure to Cobalt and Tungsten in the Swedish Hard Metal Industry: Air Concentrations of Particle Mass, Number, and Surface Area.

Exposure to cobalt in the hard metal industry entails severe adverse health effects, including lung cancer and hard metal fibrosis. The main aim of this study was to determine exposure air concentration levels of cobalt and tungsten for risk assessment and dose-response analysis in our medical investigations in a Swedish hard metal plant. We also present mass-based, particle surface area, and particle number air concentrations from stationary sampling and investigate the possibility of using these data as proxies for exposure measures in our study. Personal exposure full-shift measurements were performed for inhalable and total dust, cobalt, and tungsten, including personal real-time continuous monitoring of dust. Stationary measurements of inhalable and total dust, PM2.5, and PM10 was also performed and cobalt and tungsten levels were determined, as were air concentration of particle number and particle surface area of fine particles. The personal exposure levels of inhalable dust were consistently low (AM 0.15mg m(-3), range <0.023-3.0mg m(-3)) and below the present Swedish occupational exposure limit (OEL) of 10mg m(-3) The cobalt levels were low as well (AM 0.0030mg m(-3), range 0.000028-0.056mg m(-3)) and only 6% of the samples exceeded the Swedish OEL of 0.02mg m(-3) For continuous personal monitoring of dust exposure, the peaks ranged from 0.001 to 83mg m(-3) by work task. Stationary measurements showed lower average levels both for inhalable and total dust and cobalt. The particle number concentration of fine particles (AM 3000 p·cm(-3)) showed the highest levels at the departments of powder production, pressing and storage, and for the particle surface area concentrations (AM 7.6 µm(2)·cm(-3)) similar results were found. Correlating cobalt mass-based exposure measurements to cobalt stationary mass-based, particle area, and particle number concentrations by rank and department showed significant correlations for all measures except for particle number. Linear regression analysis of the same data showed statistically significant regression coefficients only for the mass-based aerosol measures. Similar results were seen for rank correlation in the stationary rig, and linear regression analysis implied significant correlation for mass-based and particle surface area measures. The mass-based air concentration levels of cobalt and tungsten in the hard metal plant in our study were low compared to Swedish OELs. Particle number and particle surface area concentrations were in the same order of magnitude as for other industrial settings. Regression analysis implied the use of stationary determined mass-based and particle surface area aerosol concentration as proxies for various exposure measures in our study.

Exposure to thoracic aerosol in a prospective lung function study of cement production workers.

INTRODUCTION: An exposure study was conducted as part of a multi-national longitudinal study of lung function in cement production workers. AIM: To examine exposure to thoracic aerosol among cement production workers during a 4-year follow-up period. METHODS: Personal shift measurements of thoracic aerosol were conducted among the cement production workers within seven job types, 22 plants, and eight European countries (including Turkey) in 2007, 2009, and 2011. The thoracic sub-fraction was chosen as the most relevant aerosol fraction related to obstructive dynamic lung function changes. Production factors, job type, and respirator use were recorded by questionnaire. The exposure data were log-transformed before mixed models analysis and results were presented by geometric mean (GMadj) exposure levels adjusted for plant or job type, worker, and season as random effects. RESULTS: A total of 6111 thoracic aerosol samples were collected from 2534 workers. Repeated measurements were obtained from 1690 of these workers. The GMadj thoracic aerosol levels varied between job types from 0.20 to 1.2mg m(-3). The highest exposure levels were observed for production, cleaning, and maintenance workers (0.79-1.2mg m(-3)) and could reach levels where the risk of lung function loss may be increased. The lowest levels were found for administrative personnel (0.20mg m(-3)) serving tasks in the production areas. Office work was not monitored. GMadj exposure levels between plants ranged from 0.19 to 2.0mg m(-3). The time of year/season contributed significantly to the total variance, but not year of sampling. Production characteristics explained 63% of the variance explained by plant. Workers in plants with the highest number of employees (212-483 per plant) were exposed at a level more than twice as high as those in plants with fewer employees. Other production factors such as cement production, bag filling, and tidiness were significant, but explained less of the exposure variability. These determinants factors can be useful in qualitative exposure assessment and exposure prevention in the cement production industry. Respirator use was minor at exposure levels <0.5mg m(-3) but more common at higher levels. CONCLUSION: Production, cleaning, and maintenance work were the job types with highest exposure to thoracic aerosol in cement production plants. However, plant had an even larger effect on exposure levels than job type. The number of employees was the most important factor explaining differences between plants. Exposure reached levels where the risk of lung function loss may be increased. No significant differences in exposure between sampling campaigns were observed during the 4-year study period.

Historical Asbestos Measurements in Denmark-A National Database.

OBJECTIVES: Due to the long lag-time for health outcomes, historical asbestos exposure measurements are valuable to support assessments of associated occupational health effects, and also to assess time trends and effects of preventive measures. METHODS: Different sources of stored data were collated, assessed and refined to create a harmonized database on historical asbestos fibre concentrations measured in specific work tasks and different industries. The final database contains 9236 asbestos measurements from Danish workplaces collected from 1971 to 1997. RESULTS: The geometric mean of asbestos concentrations in different occupations and tasks ranged from 0.003 to 35 fibres cm-3. Highest concentrations were registered during handling of asbestos products in the construction services during the period 1981-1997. Although all the measured asbestos exposures without the use of respiratory equipment by the worker in the period of 1971-1997 exceeded the current 8-h time-weighted average exposure limit of 0.1 fibres cm-3, the majority of samples collected in the earlier period of 1971 to 1980 did not exceed the exposure limit of 2 fibres cm-3, which was in place at the time. All exposure data obtained from 1980 and onwards were found to be one seventh of the mean fibre concentrations in the previous measurement period. The impact of time shows a clear exponentially decreasing trend-line. CONCLUSIONS: Despite limitations in coverage of different occupations and tasks associated with the inventoried historical asbestos measurements, the data are helpful to identify specific work scenarios within an industry, where relatively high asbestos exposure levels may still occur or have occurred from 1971 to 1997.

Measurements and determinants of children's exposure to background gamma radiation in Switzerland.

Epidemiological studies of children's cancer risks associated with background gamma radiation exposure have used geographic exposure models to estimate exposure at their locations of residence. We measured personal exposure to background gamma radiation, and we investigated the extent to which it was associated with children's whereabouts. We collected data on whereabouts and exposure to background gamma radiation over a 5-day period among children aged 4-15 years in Switzerland. We used D-Shuttle dosimeters to measure children's exposure, and we asked parents to write their children's activities in diaries. We used Poisson mixed-effects and linear regression models to investigate the association of hourly and overall doses, respectively, with children's reported whereabouts. During the observed time, 149 participating children spent 66% indoors at home; 19% indoors away from home; and 15% outdoors. The mean personal exposure was 85.7 nSv/h (range 52.3 nSv/h-145 nSv/h). Exposure was 1.077 (95% CI 1.067, 1.087) times higher indoors than outdoors and varied by building material and (predicted) outdoor dose rates. Our study provides detailed information about children's patterns of exposure to background gamma radiation in Switzerland. Dwelling building materials and outdoor dose rates are important determinants of children's exposure. Future epidemiological studies may benefit from including information about building materials.

Risk assessment of farmers handling pelleted seeds containing crystalline silica and attapulgite.

OBJECTIVES: This study aimed to assess the risk to farmers from handling pelleted seeds that include crystalline silica and attapulgite. METHODS: We measured personal exposure levels to respirable crystalline silica and attapulgite in the experimenter representing a farmer in a simulated workplace. From these values, the annual occupational exposure levels were estimated and compared with the established occupational exposure limits. To assess the toxicity of respirable crystalline silica and attapulgite, digital chest images of workers in a factory producing pelleted seeds were examined. RESULTS: The personal exposure measurement results showed that the concentrations of total dust, respirable dust, and respirable crystalline silica generated during work handling of pelleted seeds were 0.27, 0.06, and 0.00043 mg/m3 , respectively. The estimated annual occupational exposure level to total dust, respirable dust, and respirable crystalline silica in farmers was 103 to 104 times lower than established occupational exposure limits. Attapulgite was not detected by analysis of the pelleted seeds themselves or dust collected during the personal exposure measurements. No pulmonary parenchymal or pleural lesions were detected in the digital chest images of the factory workers. CONCLUSION: We found that farmers handling pelleted seeds would not be exposed to levels of total dust, respirable dust, respirable crystalline silica, and attapulgite derived from pelleted seeds exceeding occupational exposure limits. These results suggest that the risk to farmers of handling pelleted seeds is negligible.

Piezoelectric Micro-dosing System for Spiking Quality Samples in Occupational Hygiene Laboratories.

Quality control is crucially important in the arena of chemical analysis. Reference materials are essential for calibration and quality control processes, and for verification of the accuracy and reliability of the analytical results obtained. Owing to the complexity of their manufacture, reference materials for chemical agents occurring at workplaces are expensive and available only on a limited scale and for a small number of substances. Therefore, their cost-effective and fast production is an important aim. The Institute for Occupational Health and Safety (IFA) of the German Social Accident Insurance (DGUV) currently pursues different strategies for the production of reference materials. One strategy entails the use of a piezoelectric micro-dispensing system for non-contact spiking of extremely small quantities of substances with high reproducibility. The dispensing system is coupled to a semi-automated assembly unit for loading high numbers of samples. It is used for spiking phosphoric and sulphuric acid onto quartz fibre filters. Comparison of the results obtained on different days shows higher variability than results observed on the same day. However, after daily adjustment of the number of droplets to the current droplet volume, highly reproducible series with an adequate number of samples (>500) could be realized. The results of the internal quality control were verified in an interlaboratory comparison. Furthermore, storage stability was investigated systematically over a period of 2 years. The samples produced are suitable for use as reference materials for both inorganic acids.

Ecological momentary assessment study of exposure to radiofrequency electromagnetic fields and non-specific physical symptoms with self-declared electrosensitives.

The main objective of the study is to determine if non-specific physical symptoms (NSPS) in people with self-declared sensitivity to radiofrequency electromagnetic fields (RF EMF) can be explained (across subjects) by exposure to RF EMF. Furthermore, we pioneered whether analysis at the individual level or at the group level may lead to different conclusions. By our knowledge, this is the first longitudinal study exploring the data at the individual level. A group of 57 participants was equipped with a measurement set for five consecutive days. The measurement set consisted of a body worn exposimeter measuring the radiofrequency electromagnetic field in twelve frequency bands used for communication, a GPS logger, and an electronic diary giving cues at random intervals within a two to three hour interval. At every cue, a questionnaire on the most important health complaint and nine NSPS had to be filled out. We analysed the (time-lagged) associations between RF-EMF exposure in the included frequency bands and the total number of NSPS and self-rated severity of the most important health complaint. The manifestation of NSPS was studied during two different time lags - 0-1 h, and 1-4 h - after exposure and for different exposure metrics of RF EMF. The exposure was characterised by exposure metrics describing the central tendency and the intermittency of the signal, i.e. the time-weighted average exposure, the time above an exposure level or the rate of change metric. At group level, there was no statistically significant and relevant (fixed effect) association between the measured personal exposure to RF EMF and NSPS. At individual level, after correction for multiple testing and confounding, we found significant within-person associations between WiFi (the self-declared most important source) exposure metrics and the total NSPS score and severity of the most important complaint in one participant. However, it cannot be ruled out that this association is explained by residual confounding due to imperfect control for location or activities. Therefore, the outcomes have to be regarded very prudently. The significant associations were found for the short and the long time lag, but not always concurrently, so both provide complementary information. We also conclude that analyses at the individual level can lead to different findings when compared to an analysis at group level.

Hazardous off-gassing of carbon monoxide and oxygen depletion during ocean transportation of wood pellets.

Five ocean vessels were investigated for the characterization and quantification of gaseous compounds emitted during ocean transportation of wood pellets in closed cargo hatches from Canada to Sweden. The study was initiated after a fatal accident with several injured during discharge in Sweden. The objective with the investigation was to better understand the off-gassing and issues related to workers' exposure. Air sampling was done during transport and immediately before discharge in the undisturbed headspace air above the wood pellets and in the staircase adjacent to each hatch. The samples were analyzed with Fourier transform infrared spectroscopy and direct reading instruments. The following compounds and ranges were detected in samples from the five ships: carbon monoxide (CO) 1460-14650 ppm, carbon dioxide (CO2) 2960-21570 ppm, methane 79.9-956 ppm, butane equivalents 63-842 ppm, ethylene 2-21.2 ppm, propylene 5.3-36 ppm, ethane 0-25 ppm and aldehydes 2.3-35 ppm. The oxygen levels were between 0.8 and 16.9%. The concentrations in the staircases were almost as high as in the cargo hatches, indicating a fairly free passage of air between the two spaces. A potentially dangerous atmosphere was reached within a week from loading. The conclusions are that ocean transportation of wood pellets in confined spaces may produce an oxygen deficient atmosphere and lethal levels of CO which may leak into adjacent access spaces. The dangerous combination of extremely high levels of CO and reduced oxygen produces a fast-acting toxic combination. Measurement of CO in combination with oxygen is essential prior to entry in spaces having air communication with cargo hatches of wood pellets. Forced ventilation of staircases prior to entry is necessary. Redesign, locking and labeling of access doors and the establishment of rigorous entry procedures and training of onboard crew as well as personnel boarding ocean vessels are also important.

Individual variation in temporal relationships between exposure to radiofrequency electromagnetic fields and non-specific physical symptoms: A new approach in studying 'electrosensitivity'.

BACKGROUND: Everyday exposure to radiofrequency electromagnetic fields (RF-EMF) emitted from wireless devices such as mobile phones and base stations, radio and television transmitters is ubiquitous. Some people attribute non-specific physical symptoms (NSPS) such as headache and fatigue to exposure to RF-EMF. Most previous laboratory studies or studies that analyzed populations at a group level did not find evidence of an association between RF-EMF exposure and NSPS. OBJECTIVES: We explored the association between exposure to RF-EMF in daily life and the occurrence of NSPS in individual self-declared electrohypersensitive persons using body worn exposimeters and electronic diaries. METHODS: We selected seven individuals who attributed their NSPS to RF-EMF exposure. The level of and variability in personal RF-EMF exposure and NSPS were determined during a three-week period. Data were analyzed using time series analysis in which exposure as measured and recorded in the diary was correlated with NSPS. RESULTS: We found statistically significant correlations between perceived and actual exposure to wireless internet (WiFi - rate of change and number of peaks above threshold) and base stations for mobile telecommunications (GSM + UMTS downlink, rate of change) and NSPS scores in four of the seven participants. In two persons a higher EMF exposure was associated with higher symptom scores, and in two other persons it was associated with lower scores. Remarkably, we found no significant correlations between NSPS and time-weighted average power density, the most commonly used exposure metric. CONCLUSIONS: RF-EMF exposure was associated either positively or negatively with NSPS in some but not all of the selected self-declared electrohypersensitive persons.

Comparing the Advanced REACH Tool's (ART) Estimates With Switzerland's Occupational Exposure Data.

The Advanced REACH Tool (ART) is the most sophisticated tool used for evaluating exposure levels under the European Union's Registration, Evaluation, Authorisation and restriction of CHemicals (REACH) regulations. ART provides estimates at different percentiles of exposure and within different confidence intervals (CIs). However, its performance has only been tested on a limited number of exposure data. The present study compares ART's estimates with exposure measurements collected over many years in Switzerland. Measurements from 584 cases of exposure to vapours, mists, powders, and abrasive dusts (wood/stone and metal) were extracted from a Swiss database. The corresponding exposures at the 50th and 90th percentiles were calculated in ART. To characterize the model's performance, the 90% CI of the estimates was considered. ART's performance at the 50th percentile was only found to be insufficiently conservative with regard to exposure to wood/stone dusts, whereas the 90th percentile showed sufficient conservatism for all the types of exposure processed. However, a trend was observed with the residuals, where ART overestimated lower exposures and underestimated higher ones. The median was more precise, however, and the majority (≥60%) of real-world measurements were within a factor of 10 from ART's estimates. We provide recommendations based on the results and suggest further, more comprehensive, investigations.

A comprehensive review on the quasi-induced exposure technique.

OBJECTIVE: The goal is to comprehensively examine the state-of-the-art applications and methodological development of quasi-induced exposure and consequently pinpoint the future research directions in terms of implementation guidelines, limitations, and validity tests. METHODS: The paper conducts a comprehensive review on approximately 45 published papers relevant to quasi-induced exposure regarding four key topics of interest: applications, responsibility assignment, validation of assumptions, and methodological development. RESULTS: Specific findings include that: (1) there is no systematic data screening procedure in place and how the eliminated crash data will impact the responsibility assignment is generally unknown; (2) there is a lack of necessary efforts to assess the validity of assumptions prior to its application and the validation efforts are mostly restricted to the aggregated levels due to the limited availability of exposure truth; and (3) there is a deficiency of quantitative analyses to evaluate the magnitude and directions of bias as a result of injury risks and crash avoidance ability. CONCLUSIONS: The paper points out the future research directions and insights in terms of the validity tests and implementation guidelines.