Adjusting for Berkson error in exposure in ordinary and conditional logistic regression and in Poisson regression.

BACKGROUND: INTEROCC is a seven-country cohort study of occupational exposures and brain cancer risk, including occupational exposure to electromagnetic fields (EMF). In the absence of data on individual exposures, a Job Exposure Matrix (JEM) may be used to construct likely exposure scenarios in occupational settings. This tool was constructed using statistical summaries of exposure to EMF for various occupational categories for a comparable group of workers. METHODS: In this study, we use the Canadian data from INTEROCC to determine the best EMF exposure surrogate/estimate from three appropriately chosen surrogates from the JEM, along with a fourth surrogate based on Berkson error adjustments obtained via numerical approximation of the likelihood function. In this article, we examine the case in which exposures are gamma-distributed for each occupation in the JEM, as an alternative to the log-normal exposure distribution considered in a previous study conducted by our research team. We also study using those surrogates and the Berkson error adjustment in Poisson regression and conditional logistic regression. RESULTS: Simulations show that the introduced methods of Berkson error adjustment for non-stratified analyses provide accurate estimates of the risk of developing tumors in case of gamma exposure model. Alternatively, and under some technical assumptions, the arithmetic mean is the best surrogate when a gamma-distribution is used as an exposure model. Simulations also show that none of the present methods could provide an accurate estimate of the risk in case of stratified analyses. CONCLUSION: While our previous study found the geometric mean to be the best exposure surrogate, the present study suggests that the best surrogate is dependent on the exposure model; the arithmetic means in case of gamma-exposure model and the geometric means in case of log-normal exposure model. However, we could present a better method of Berkson error adjustment for each of the two exposure models. Our results provide useful guidance on the application of JEMs for occupational exposure assessments, with adjustment for Berkson error.

Understanding occupational safety and health surveillance: expert consensus on components, attributes and example measures for an evaluation framework.

BACKGROUND: Occupational safety and health (OSH) surveillance systems track work-related fatalities, injuries and illnesses as well as the presence of workplace hazards and exposures to inform prevention efforts. Periodic evaluation is critical to the improvement of these systems to meet the demand for more timely, complete, accurate and efficient data processing and analysis. Despite the existence of general guidance for public health surveillance evaluation, no tailored guidance exists for evaluating OSH surveillance systems to date. This study utilized the Delphi technique to collect consensus among experts in the United States on surveillance elements (components, attributes and measures) to inform the development of a tailored evaluation framework. METHODS: A Delphi study approach with three survey rounds invited an expert panel to rate and comment on potential OSH surveillance evaluation framework elements, resulting in an optimal list of elements through the panel's consensus. Additionally, experts completed a review of OSH surveillance systems they worked with and answered questions regarding the development of an evaluation framework. Descriptive statistics of the ratings were compiled for the Delphi process. Major themes from experts' comments were further identified using content analysis to inform contextual information underlying their choices. RESULTS: Fifty-four potential experts across the United States were contacted to participate in the Delphi study. Ten experts began the first survey round with eight then seven experts continuing in the subsequent rounds, respectively. A total of 64 surveillance components, 31 attributes, and 116 example measures were selected into the final list through panel consensus, with 134 (63.5%) reaching high consensus. Major themes regarding current OSH surveillance focused on resources and feasibility, data collection, flexibility, and the inter-relatedness among elements. CONCLUSIONS: A Delphi process identified tailored OSH surveillance elements and major themes regarding OSH surveillance. The identified elements can serve as a preliminary guide for evaluating OSH surveillance systems. A more detailed evaluation framework is under development to incorporate these elements into a standard yet flexible approach to OSH surveillance evaluation.

Evaluating Oregon's occupational public health surveillance system based on the CDC updated guidelines.

BACKGROUND: The Oregon Occupational Public Health Program (OOPHP) monitors occupational health indicators (OHIs) to inform occupational safety and health (OSH) surveillance. In 2018, OOPHP evaluated the performance of the OSH surveillance system and identified areas for future improvement. METHODS: Following the Centers for Disease Control and Prevention (CDC) updated guidelines for evaluating public health surveillance systems, the OOPHP evaluation team engaged internal and external stakeholders using a mixed-methods approach. Operational measures for ten surveillance attributes were developed. Multiple data collection methods resulted in credible evidence for evaluation conclusions. Analyses included summary statistics and qualitative analysis of interviews, a focus group, and online surveys. RESULTS: Twenty stakeholders took part in this evaluation, with an average participation rate of 55%. Results showed the Oregon OSH surveillance system was simple, flexible, and highly accepted by its stakeholders. Funding security presents challenges for stability. A lack of timeliness of OHIs, low relevance of OHIs to local OSH issues, and the system's ineffectual data dissemination all limit the usefulness of the OSH surveillance system. A review of key data sources for the system showed good data quality and predictive value positive, but relatively poor sensitivity and representativeness. CONCLUSIONS: The evaluation team successfully adapted attributes and examples in the CDC guidelines to this Oregon OSH surveillance evaluation. The evaluation findings have informed the development of recommendations for improvements to OOPHP's OSH surveillance. Future research is needed to develop guidance specific to OSH surveillance evaluation.

Prevalence of work-related musculoskeletal pain in masonry apprentices.

The construction industry, specifically masonry, reports more work-related musculoskeletal disorders (WMSD) rates than the general industry. Masonry apprentices are assumed to be healthy, yet may have WMSDs. The purpose of this study was to evaluate the prevalence of musculoskeletal symptoms (MSS), time loss, and healthcare use among apprentices. 183 brick and block masonry apprentices completed surveys on demographics, work history, MSS, and functional well-being. The prevalence of MSS was calculated by body region, time loss, and healthcare use. The relationship between MSS, and perceived global physical and mental health was assessed. Approximately 78% of apprentices reported MSS, most in several body regions. Low back and wrists/hands were most prevalent, although few missed work or sought healthcare. Lower functional health and well-being was reported. Apprentices reported MSS comparable to previous studies of journey-level masons. Apprenticeship programmes could integrate ergonomics education to help apprentices develop safety culture early in their careers. Practitioner Summary: New masonry workers (apprentices) are assumed to be healthy yet work-related musculoskeletal symptoms (MSS) may be common early in their career. The prevalence of MSS was assessed among apprentices. Approximately 78% of apprentices reported MSS, most in several body regions, comparable to journey-level masons. Abbreviations: WMSD: work-related musculoskeletal disorders; MSS: musculoskeletal symptoms; SAVE: SAfety voice for ergonomics; MNQ: modified nordic questionnaire; FTE: full-time equivalent; SF-12: short from-12v2.

Development of an environmental health tool linking chemical exposures, physical location and lung function.

BACKGROUND: A challenge in environmental health research is collecting robust data sets to facilitate comparisons between personal chemical exposures, the environment and health outcomes. To address this challenge, the Exposure, Location and lung Function (ELF) tool was designed in collaboration with communities that share environmental health concerns. These concerns centered on respiratory health and ambient air quality. The ELF collects exposure to polycyclic aromatic hydrocarbons (PAHs), given their association with diminished lung function. Here, we describe the ELF as a novel environmental health assessment tool. METHODS: The ELF tool collects chemical exposure for 62 PAHs using passive sampling silicone wristbands, geospatial location data and respiratory lung function measures using a paired hand-held spirometer. The ELF was tested by 10 individuals with mild to moderate asthma for 7 days. Participants wore a wristband each day to collect PAH exposure, carried a cell phone, and performed spirometry daily to collect respiratory health measures. Location data was gathered using the geospatial positioning system technology in an Android cell-phone. RESULTS: We detected and quantified 31 PAHs across the study population. PAH exposure data showed spatial and temporal sensitivity within and between participants. Location data was used with existing datasets such as the Toxics Release Inventory and the National Oceanic and Atmospheric Administration (NOAA) Hazard Mapping System. Respiratory health outcomes were validated using criteria from the American Thoracic Society with 94% of participant data meeting standards. Finally, the ELF was used with a high degree of compliance (> 90%) by community members. CONCLUSIONS: The ELF is a novel environmental health assessment tool that allows for personal data collection spanning chemical exposures, location and lung function measures as well as self-reported information.

Dungeness crab commercial fishermen's perceptions of injuries inform survey development.

INTRODUCTION: The West Coast Dungeness crab fishery is high-risk for occupational fatalities. The Fishermen Led Injury Prevention Program (FLIPP) explored this worker population's nonfatal injuries and safety perspectives. METHODS: Focus groups were held along the West Coast to (a) review reported injuries, (b) discuss risk factors, and (c) identify content to inform future FLIPP research activities, including survey development. Focus group data were transcribed and analyzed qualitatively. The FLIPP survey was pilot tested with groups of fishermen before broad distribution. RESULTS: Nineteen fishermen participated in focus groups and 21 pilot tested the FLIPP survey. These discussions illuminated injury risk perceptions, crews' current safety provisions, and what survey items would be relevant for fishermen. CONCLUSION: To engage fishermen in the process of identifying and developing injury prevention efforts, focus groups, and pilot testing were effective methods for incorporating their ideas into a survey.

Injury and illness among onshore workers in Alaska's seafood processing industry: Analysis of workers' compensation claims, 2014-2015.

BACKGROUND: Alaska's onshore seafood processing industry is economically vital and hazardous. METHODS: Accepted Alaska workers' compensation claims data from 2014 to 2015 were manually reviewed and coded with the Occupational Injury and Illness Classification System and associated work activity. Workforce data were utilized to calculate rates. RESULTS: 2,889 claims of nonfatal injuries/illnesses were accepted for compensation. The average annual claim rate was 63 per 1000 workers. This was significantly higher than Alaska's all-industry rate of 44 claims per 1000 workers (RR = 1.42, 95%CI = 1.37-1.48). The most frequently occurring injuries/illnesses, were by nature, sprains/strains/tears (n = 993, 36%); by body part, upper limbs (1212, 43%); and by event, contact with objects/equipment (1020, 37%) and overexertion/bodily reaction (933, 34%). Incidents associated with seafood processing/canning/freezing (n = 818) frequently involved: repetitive motion; overexertion while handling pans, fish, and buckets; and contact with fish, pans, and machinery. CONCLUSIONS: Ergonomic and safety solutions should be implemented to prevent musculoskeletal injuries/illnesses in seafood processing.

Emergency Medical Training for the Commercial Fishing Industry: An Expanded Role for Wilderness Medicine.

This article describes the conception, implementation, and evaluation of a wilderness medicine-based first aid class for the commercial fishing industry. Commercial fishing is a dangerous occupation in the United States. Currently, commercial fishermen often only have access to basic first aid classes. Because of its focus on austere environments, hazardous conditions, and distance from definitive medical care-hallmarks of commercial fisheries-wilderness medicine offers a more appropriate approach to decreasing morbidity and mortality in the industry. A 2-d, 16-h pilot wilderness medicine course for commercial fishermen, Fishermen First Aid and Safety Training (FFAST), conducted for Dungeness crab fishermen, was effective and well received, based on pre- and postcourse knowledge, skill, and attitude surveys. FFAST has been approved by the Coast Guard and is being made more widely available to commercial fishermen in the Pacific Northwest. The FFAST program offers an example of how wilderness medicine can improve safety and emergency medical response for a wide variety of austere environments not traditionally linked to the backcountry.

Silicone wristbands compared with traditional polycyclic aromatic hydrocarbon exposure assessment methods.

Currently there is a lack of inexpensive, easy-to-use technology to evaluate human exposure to environmental chemicals, including polycyclic aromatic hydrocarbons (PAHs). This is the first study in which silicone wristbands were deployed alongside two traditional personal PAH exposure assessment methods: active air monitoring with samplers (i.e., polyurethane foam (PUF) and filter) housed in backpacks, and biological sampling with urine. We demonstrate that wristbands worn for 48 h in a non-occupational setting recover semivolatile PAHs, and we compare levels of PAHs in wristbands to PAHs in PUFs-filters and to hydroxy-PAH (OH-PAH) biomarkers in urine. We deployed all samplers simultaneously for 48 h on 22 pregnant women in an established urban birth cohort. Each woman provided one spot urine sample at the end of the 48-h period. Wristbands recovered PAHs with similar detection frequencies to PUFs-filters. Of the 62 PAHs tested for in the 22 wristbands, 51 PAHs were detected in at least one wristband. In this cohort of pregnant women, we found more significant correlations between OH-PAHs and PAHs in wristbands than between OH-PAHs and PAHs in PUFs-filters. Only two comparisons between PAHs in PUFs-filters and OH-PAHs correlated significantly (rs = 0.53 and p = 0.01; rs = 0.44 and p = 0.04), whereas six comparisons between PAHs in wristbands and OH-PAHs correlated significantly (rs = 0.44 to 0.76 and p = 0.04 to <0.0001). These results support the utility of wristbands as a biologically relevant exposure assessment tool which can be easily integrated into environmental health studies. Graphical abstract PAHs detected in samples collected from urban pregnant women.

The INTEROCC case-control study: risk of meningioma and occupational exposure to selected combustion products, dusts and other chemical agents.

BACKGROUND: Little is known about occupational risk factors for meningioma. OBJECTIVES: To study whether risk of meningioma is associated with several occupational exposures, including selected combustion products, dusts and other chemical agents. METHODS: The INTEROCC study was an international case-control study of brain cancer conducted in seven countries. Data collection by interview included lifetime occupational histories. A job exposure matrix was used to derive estimates of exposure for the 12 agents. ORs for ever versus never exposed and for exposure-response using duration of exposure and cumulative exposure were derived using conditional logistic regression stratified by sex, age group, country/region, adjusted for education. RESULTS: These analyses included 1906 cases and 5565 controls. For 11 of the 12 agents, no excess risk was found for ever exposed. For ever exposure to oil mists, an elevated OR of 1.57 (95% CI 1.10 to 2.22, 51 exposed cases) was found. Statistically significant exposure-response relationships were observed with cumulative exposure (p=0.01) and duration of exposure (p=0.04). Among women, there were also significant trends for cumulative and duration of exposure to asbestos and excesses in the highest exposure categories for formaldehyde. CONCLUSIONS: Most agents examined did not provoke excess risks of meningioma. The main finding from this study is that it is the first study to identify a statistical association between exposure to oil mists and meningioma. This may be a chance finding or could be due to confounding with iron exposure and further research is required to understand whether the relationship is causal.

Occupational solvent exposure and risk of glioma in the INTEROCC study.

BACKGROUND: The aetiology of glioma remains largely unknown. Occupational solvent exposure has been suggested as a putative cause of glioma, but past studies have been inconsistent. We examined the association between a range of solvents and glioma risk within the INTEROCC project, a study of brain tumours and occupational exposures based on data from seven national case-control studies conducted in the framework of the INTERPHONE study. We also investigated associations according to tumour grade. METHODS: Data from the seven countries were standardised and then combined into one aggregate data set. Pooled odds ratios (ORs) were estimated for adjusted models that included sex, age, country-region of residence and level of educational attainment. Exposures to any solvent or 11 specific solvents or subgroups were assessed using a modified version of the FINJEM job exposure matrix (JEM) specifically developed for the study, called INTEROCC-JEM. RESULTS: Analysis included 2000 glioma cases and 5565 controls. For glioma and ever/never exposure to any solvent, the OR was 0.91 (95% confidence interval: 0.74-1.11). All ORs were <1.0 for specific solvents/subgroups. There were no increases in risk according to high or low grade of tumour. CONCLUSIONS: The results of this study show no consistent associations for any solvent exposures overall or by grade of tumour.

Interactions between occupational exposure to extremely low frequency magnetic fields and chemicals for brain tumour risk in the INTEROCC study.

OBJECTIVES: In absence of clear evidence regarding possible effects of occupational chemical exposures on brain tumour aetiology, it is worthwhile to explore the hypothesis that such exposures might act on brain tumour risk in interaction with occupational exposure to extremely low frequency magnetic fields (ELF). METHODS: INTEROCC is a seven-country (Australia, Canada, France, Germany, Israel, New Zealand and UK), population-based, case-control study, based on the larger INTERPHONE study. Incident cases of primary glioma and meningioma were ascertained from 2000 to 2004. Job titles were coded into standard international occupational classifications and estimates of ELF and chemical exposures were assigned based on job-exposure matrices. Dichotomous indicators of cumulative ELF (≥50th vs <50th percentile, 1-4 year exposure time window) and chemical exposures (ever vs never, 5-year lag) were created. Interaction was assessed on both the additive and multiplicative scales. RESULTS: A total of 1939 glioma cases, 1822 meningioma cases and 5404 controls were included in the analysis, using conditional logistic regression. There was no clear evidence for interactions between ELF and any of the chemical exposures assessed for either glioma or meningioma risk. For glioma, subjects in the low ELF/metal exposed group had a lower risk than would be predicted from marginal effects. Results were similar according to different exposure time windows, to cut-points of exposure or in exposed-only analyses. CONCLUSIONS: There was no clear evidence for interactions between occupational ELF and chemical exposures in relation to glioma or meningioma risk observed. Further research with more refined estimates of occupational exposures is recommended.

Lifetime occupational exposure to metals and welding fumes, and risk of glioma: a 7-country population-based case-control study.

BACKGROUND: Brain tumor etiology is poorly understood. Based on their ability to pass through the blood-brain barrier, it has been hypothesized that exposure to metals may increase the risk of brain cancer. Results from the few epidemiological studies on this issue are limited and inconsistent. METHODS: We investigated the relationship between glioma risk and occupational exposure to five metals - lead, cadmium, nickel, chromium and iron- as well as to welding fumes, using data from the seven-country INTEROCC study. A total of 1800 incident glioma cases and 5160 controls aged 30-69 years were included in the analysis. Lifetime occupational exposure to the agents was assessed using the INTEROCC JEM, a modified version of the Finnish job exposure matrix FINJEM. RESULTS: In general, cases had a slightly higher prevalence of exposure to the various metals and welding fumes than did controls, with the prevalence among ever exposed ranging between 1.7 and 2.2% for cadmium to 10.2 and 13.6% for iron among controls and cases, respectively. However, in multivariable logistic regression analyses, there was no association between ever exposure to any of the agents and risk of glioma with odds ratios (95% confidence intervals) ranging from 0.8 (0.7-1.0) for lead to 1.1 (0.7-1.6) for cadmium. Results were consistent across models considering cumulative exposure or duration, as well as in all sensitivity analyses conducted. CONCLUSIONS: Findings from this large-scale international study provide no evidence for an association between occupational exposure to any of the metals under scrutiny or welding fumes, and risk of glioma.

Analysis of workers' compensation disabling claims in Oregon's seafood preparation and packaging industry, 2007-2013.

BACKGROUND: Few occupational health and safety studies have focused on the US seafood preparation and packaging industry, and none on Oregon's seafood industry. METHODS: Oregon workers' compensation (WC) disabling claims data were analyzed. Oregon Employment Department and US Census Bureau data were used as denominators for rates. RESULTS: During 2007-2013, there were 188 accepted disabling claims, with an average annual rate of 24 claims per 1000 workers. Men experienced a significantly higher rate (27.6 per 1000) than women. The most frequent incident characteristics and circumstances were: by nature-traumatic injuries to muscles, tendons, ligaments, joints (42%); by body part-upper extremities (44%); and by event-overexertion and bodily reaction (48%), and contact with objects and equipment (31%). CONCLUSION: Analyzing WC disabling claims data provides important preliminary information for understanding workplace hazards to develop control strategies. Reducing traumatic and cumulative injury risk among seafood workers is paramount.

Occupational exposure to metals and risk of meningioma: a multinational case-control study.

The aim of the study was to examine associations between occupational exposure to metals and meningioma risk in the international INTEROCC study. INTEROCC is a seven-country population-based case-control study including 1906 adult meningioma cases and 5565 population controls. Incident cases were recruited between 2000 and 2004. A detailed occupational history was completed and job titles were coded into standard international occupational classifications. Estimates of mean workday exposure to individual metals and to welding fumes were assigned based on a job-exposure-matrix. Adjusted odds ratios (ORs) and 95 % confidence intervals (CIs) were estimated using conditional logistic regression. Although more controls than cases were ever exposed to metals (14 vs. 11 %, respectively), cases had higher median cumulative exposure levels. The ORs for ever vs. never exposure to any metal and to individual metals were mostly greater than 1.0, with the strongest association for exposure to iron (OR 1.26, 95 % CI 1.0-1.58). In women, an increased OR of 1.70 (95 % CI 1.0-2.89) was seen for ever vs never exposure to iron (OR in men 1.19, 95 % CI 0.91-1.54), with positive trends in relation with both cumulative and duration of exposure. These results remained after consideration of other occupational metal or chemical co-exposures. In conclusion, an apparent positive association between occupational exposure to iron and meningioma risk was observed, particularly among women. Considering the fact that meningioma is a hormone dependent tumor, the hypothesis that an interaction between iron and estrogen metabolism may be a potential mechanism for a carcinogenic effect of iron should be further investigated.

Emissions of Polycyclic Aromatic Hydrocarbons from Natural Gas Extraction into Air.

Natural gas extraction, often referred to as "fracking", has increased rapidly in the United States in recent years. To address potential health impacts, passive air samplers were deployed in a rural community heavily affected by the natural gas boom. Samplers were analyzed for 62 polycyclic aromatic hydrocarbons (PAHs). Results were grouped based on distance from each sampler to the nearest active well. Levels of benzo[a]pyrene, phenanthrene, and carcinogenic potency of PAH mixtures were highest when samplers were closest to active wells. PAH levels closest to natural gas activity were comparable to levels previously reported in rural areas in winter. Sourcing ratios indicated that PAHs were predominantly petrogenic, suggesting that PAH levels were influenced by direct releases from the earth. Quantitative human health risk assessment estimated the excess lifetime cancer risks associated with exposure to the measured PAHs. At sites closest to active wells, the risk estimated for maximum residential exposure was 0.04 in a million, which is below the U.S. Environmental Protection Agency's acceptable risk level. Overall, risk estimates decreased 30% when comparing results from samplers closest to active wells to those farthest from them. This work suggests that natural gas extraction is contributing PAHs to the air, at levels that would not be expected to increase cancer risk.

Trends in OSHA Compliance Monitoring Data 1979-2011: Statistical Modeling of Ancillary Information across 77 Chemicals.

OBJECTIVES: The Integrated Management Information System (IMIS) is the largest multi-industry source of exposure measurements available in North America. However, many have suspected that the criteria through which worksites are selected for inspection are related to exposure levels. We investigated associations between exposure levels and ancillary variables in IMIS in order to understand the predictors of high exposure within an enforcement context. METHODS: We analyzed the association between nine variables (reason for inspection, establishment size, total amount of penalty, Occupational Safety and Health Administration (OSHA) plan, OSHA region, union status, inspection scope, year, and industry) and exposure levels in IMIS using multimodel inference for 77 agents. For each agent, we used two different types of models: (i) logistic models were used for the odds ratio (OR) of exposure being above the threshold limit value (TLV) and (ii) linear models were used for exposure concentrations restricted to detected results to estimate percent increase in exposure level, i.e. relative index of exposure (RIE). Meta-analytic methods were used to combine results for each variable across agents. RESULTS: A total of 511,047 exposure measurements were modeled for logistic models and 299,791 for linear models. Higher exposures were measured during follow-up inspections than planned inspections [meta-OR = 1.61, 95% confidence interval (CI): 1.44-1.81; meta-RIE = 1.06, 95% CI: 1.03-1.09]. Lower exposures were observed for measurements collected under state OSHA plans compared to measurements collected under federal OSHA (meta-OR = 0.82, 95% CI: 0.73-0.92; meta-RIE = 0.86, 95% CI: 0.81-0.91). A 'high' total historical amount of penalty relative to none was associated with higher exposures (meta-OR = 1.54, 95% CI: 1.40-1.71; meta-RIE = 1.18, 95% CI: 1.13-1.23). CONCLUSIONS: The relationships observed between exposure levels and ancillary variables across a vast majority of agents suggest that certain elements of OSHA's process of selecting worksites for inspection influence the exposure levels that OSHA inspectors encounter. Nonetheless, given the paucity of other sources of exposure data and the lack of a more demonstrably representative data source, our study considers the use of IMIS data for the estimation of exposures in the broader universe of worksites in the USA.

A Source-based Measurement Database for Occupational Exposure Assessment of Electromagnetic Fields in the INTEROCC Study: A Literature Review Approach.

INTRODUCTION: To date, occupational exposure assessment of electromagnetic fields (EMF) has relied on occupation-based measurements and exposure estimates. However, misclassification due to between-worker variability remains an unsolved challenge. A source-based approach, supported by detailed subject data on determinants of exposure, may allow for a more individualized exposure assessment. Detailed information on the use of occupational sources of exposure to EMF was collected as part of the INTERPHONE-INTEROCC study. To support a source-based exposure assessment effort within this study, this work aimed to construct a measurement database for the occupational sources of EMF exposure identified, assembling available measurements from the scientific literature. METHODS: First, a comprehensive literature search was performed for published and unpublished documents containing exposure measurements for the EMF sources identified, a priori as well as from answers of study subjects. Then, the measurements identified were assessed for quality and relevance to the study objectives. Finally, the measurements selected and complementary information were compiled into an Occupational Exposure Measurement Database (OEMD). RESULTS: Currently, the OEMD contains 1624 sets of measurements (>3000 entries) for 285 sources of EMF exposure, organized by frequency band (0 Hz to 300 GHz) and dosimetry type. Ninety-five documents were selected from the literature (almost 35% of them are unpublished technical reports), containing measurements which were considered informative and valid for our purpose. Measurement data and complementary information collected from these documents came from 16 different countries and cover the time period between 1974 and 2013. CONCLUSION: We have constructed a database with measurements and complementary information for the most common sources of exposure to EMF in the workplace, based on the responses to the INTERPHONE-INTEROCC study questionnaire. This database covers the entire EMF frequency range and represents the most comprehensive resource of information on occupational EMF exposure. It is available at www.crealradiation.com/index.php/en/databases.

Safety voice for ergonomics (SAVE) project: protocol for a workplace cluster-randomized controlled trial to reduce musculoskeletal disorders in masonry apprentices.

BACKGROUND: Masons have the highest rate of overexertion injuries among all construction trades and rank second for occupational back injuries in the United States. Identified ergonomic solutions are the primary method of reducing exposure to risk factors associated with musculoskeletal disorders. However, many construction workers lack knowledge about these solutions, as well as basic ergonomic principles. Construction apprentices, as they embark on their careers, are greatly in need of ergonomics training to minimize the cumulative exposure that leads to musculoskeletal disorders. Apprentices receive safety training; however, ergonomics training is often limited or non-existent. In addition, apprenticeship programs often lack "soft skills" training on how to appropriately respond to work environments and practices that are unsafe. The SAVE program - SAfety Voice for Ergonomics - strives to integrate evidence-based health and safety training strategies into masonry apprenticeship skills training to teach ergonomics, problem solving, and speaking up to communicate solutions that reduce musculoskeletal injury risk. The central hypothesis is that the combination of ergonomics training and safety voice promotion will be more effective than no training or either ergonomics training alone or safety voice training alone. METHODS/DESIGN: Following the development and pilot testing of the SAVE intervention, SAVE will be evaluated in a cluster-randomized controlled trial at 12 masonry training centers across the U.S. Clusters of apprentices within centers will be assigned at random to one of four intervention groups (n = 24 per group): (1) ergonomics training only, (2) safety voice training only, (3) combined ergonomics and safety voice training, or (4) control group with no additional training intervention. Outcomes assessed at baseline, at the conclusion of training, and then at six and 12 months post training will include: musculoskeletal symptoms, general health perceptions, knowledge of ergonomic and safety voice principles, and perception and attitudes about ergonomic and safety voice issues. DISCUSSION: Masons continue to have a high rate of musculoskeletal disorders. The trade has an expected increase of 40 % in the number of workers by 2020. Therefore, a vetted intervention for apprentices entering the trade, such as SAVE, could reduce the burden of musculoskeletal disorders currently plaguing the trade. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02676635 , 2 February 2016.

Impact of natural gas extraction on PAH levels in ambient air.

Natural gas extraction, often referred to as "fracking," has increased rapidly in the U.S. in recent years. To address potential health impacts, passive air samplers were deployed in a rural community heavily affected by the natural gas boom. Samplers were analyzed for 62 polycyclic aromatic hydrocarbons (PAHs). Results were grouped based on distance from each sampler to the nearest active well. PAH levels were highest when samplers were closest to active wells. Additionally, PAH levels closest to natural gas activity were an order of magnitude higher than levels previously reported in rural areas. Sourcing ratios indicate that PAHs were predominantly petrogenic, suggesting that elevated PAH levels were influenced by direct releases from the earth. Quantitative human health risk assessment estimated the excess lifetime cancer risks associated with exposure to the measured PAHs. Closest to active wells, the risk estimated for maximum residential exposure was 2.9 in 10 000, which is above the U.S. EPA's acceptable risk level. Overall, risk estimates decreased 30% when comparing results from samplers closest to active wells to those farthest. This work suggests that natural gas extraction may be contributing significantly to PAHs in air, at levels that are relevant to human health.