Yat Chow

Characterization of Environmental Sources of the Human and Animal Pathogen Cryptococcus gattii in British Columbia, Canada, and the Pacific Northwest of the United States

ABSTRACT Cryptococcus gattii has recently emerged as a primary pathogen of humans and wild and domesticated animals in British Columbia, particularly on Vancouver Island. C. gattii infections are typically infections of the pulmonary and/or the central nervous system, and the incidence of infection in British Columbia is currently the highest reported globally. Prior to this emergence, the environmental distribution of and the extent of colonization by C. gattii in British Columbia were unknown. We characterized the environmental sources and potential determinants of colonization in British Columbia. C. gattii was isolated from tree surfaces, soil, air, freshwater, and seawater, and no seasonal prevalence was observed. The C. gattii concentrations in air samples were significantly higher during the warm, dry summer months, although potentially infectious propagules (<3.3 μm in diameter) were present throughout the year. Positive samples were obtained from many different areas of British Columbia, and some locations were colonization “hot spots.” C. gattii was generally isolated from acidic soil, and geographic differences in soil pH may influence the extent of colonization. C. gattii soil colonization also was associated with low moisture and low organic carbon contents. Most of the C. gattii isolates recovered belonged to the VGIIa genetic subtype; however, sympatric colonization by the VGIIb strain was observed at most locations. At one sampling site, VGIIa, VGIIb, VGI, and the Cryptococcus neoformans serotype AD hybrid all were coisolated. Our findings indicate extensive colonization by C. gattii within British Columbia and highlight an expansion of the ecological niche of this pathogen.

Cryptococcus gattii Dispersal Mechanisms, British Columbia, Canada

C. gattii may be spread through soil disturbances, wind, water, distribution of tree and soil byproducts, and human movement.

Measuring posture for epidemiology: Comparing inclinometry, observations and self-reports

The objective of this study was to use and evaluate three postural assessment methods for epidemiological studies of back disorders. The methods were: (1) a data-logging inclinometer; (2) observations by trained observers; (3) self-reports by employees. All methods were feasible in 50 heavy industry worksites. Inclinometry provided quantitative measures of flexion–extension (mean 17°, SD 11.2°), lateral flexion (mean 8.5°, SD 2.6°) and trunk movement speed (mean 14.3° per second, SD 4.9° per second). Observations and self-reports provided estimates of time spent in various trunk angles, general postures, materials handling and vehicles. Compared to observations, self-reports under-reported less common tasks, but over-reported task durations. In statistical modelling to determine if observations or self-reports could be used to estimate measured postures, observations accounted for 30 to 61% of the inclinometer measurement variance and self-reports for 33 to 40%. A combination of inclinometry and observations would be an ideal option to provide both depth and breadth of data on postures and other physical exposures for epidemiological research.

Contact with livestock – a protective effect against allergies and asthma?

Background A ‘protective farm factor’ possibly related to livestock exposure is hypothesized to reduce the risk for allergic sensitization.

Development and evaluation of an observational Back-Exposure Sampling Tool (Back-EST) for work-related back injury risk factors

We developed and evaluated an observational Back-Exposure Sampling Tool. A literature review suggested 53 exposure variables; these were reduced to 20 following field trials. Kappas for agreement beyond chance between six observers assessing exposures in 72 photos ranged from 0.21 to 1.0, with the highest values for posture type, trunk angle, manual materials handling, hands on item, and load weight. Intraclass correlations for agreement between pairs observing 17 workers once per minute for a full-shift were >0.74 for most postural, trunk angle, and manual materials handling variables. In validity testing, the proportions of shifts in flexion/extension and lateral bending observed for 169 full-shifts were compared to inclinometer measurements. Pearson correlations were 0.42 for 45-60 degrees flexion and 0.9 for >60 degrees flexion, but only 0.11-0.19 for lateral bending and trunk flexion less than 45 degrees . When lower flexion angles were collapsed to include trunk extension, correlations increased to >0.5.

Assessing whole body vibration exposure for use in epidemiological studies of back injuries: measurements, observations and self-reports

Improved assessment of whole body vibration exposure is needed for epidemiological studies investigating the causes of low back disorders. Vibration was measured on 54 worker-days in five heavy industries, with data collected on observed and self-reported driving conditions, demographics, and vehicle characteristics. Variables significant at p < 0.1 in simple linear regressions (20 of 34) were retained for mixed effects multiple regressions to determine the best prediction of rms vibration level and 8-h equivalent vibration exposure. Vibration was measured, on average, for 205 min per work shift (SD 105). Means and standard deviations in m · s−2 were: x-axis 0.35 (0.19); y-axis 0.34 (0.28); z-axis 0.54 (0.23); vector sum 0.90 (0.49); and 8-h equivalent vector sum 0.70 (0.37). The final three regression models retained only 2 or 3 of the 34 variables (driving speed (<20 km/h and/or 20–40 km/h) and industry and/or vehicle type and explained up to 60% of the variance (R 2 = 0.26–0.6). Practitioner summary The purpose of the project was to create a model that can predict whole body vibration exposure from a number of observed or self-reported variables. This could eliminate the need for costly and time-consuming field measurements of WBV in epidemiological studies. Despite a large number of variables included in the model (34) and 54 worker-days of WBV measurement, the final models contained only two or three variables, and explained 60% of the variance. While this is an improvement over use of job title in epidemiological studies, it still leaves a considerable amount of WBV variance unexplained.

Quality of life and employment status of workers with Western red cedar asthma.

Objective: The impact of current employment status and other factors on quality of life was evaluated for workers diagnosed with western red cedar asthma in British Columbia, Canada. Methods: Telephone interviews by questionnaire included the Short Form 36 (SF-36) and Marks Asthma quality-of-life instruments. Results: Of the 302 subjects contacted, 70.5% (n = 213) participated. Employment status was the most consistent predictor of quality-of-life domains, with highest scores for employed subjects, particularly those who were no longer exposed to red cedar. Subjects who had quit work because of their asthma had worse scores, particularly for vitality and general health perceptions. Other factors independently associated with specific aspects of poor quality of life were having asthma-like symptoms, taking medication, and not being married. Conclusions: Continued employment was associated with better quality of life for workers with western red cedar asthma.

Respiratory Health of Two Cohorts of Terminal Grain Elevator Workers Studied 30 Years Apart

INTRODUCTION We evaluated the respiratory health of two cohorts of grain terminal elevator workers who participated in one of either respiratory health surveys undertaken in 1978 and 2008. METHODS Questionnaire and spirometry data from 584 workers from the 1978 survey and 215 workers from the 2008 survey were compared using logistic regression and general linear modeling. RESULTS The geometric means of area samples of grain dust averaged 8.28 mg/m(3) in 1978 and 2.06 mg/m(3) in 2008. Workers in the 1978 survey had a significantly higher prevalence of respiratory symptoms (with the largest adjusted odds ratio of 3.78, 95% CI 2.07-7.25, for shortness of breath), a lower prevalence of atopic conditions and lower mean lung function. CONCLUSION Current grain workers had a lower risk of respiratory health consequences and a greater prevalence of atopic conditions than workers surveyed 30 years prior, most likely associated with reduced exposure to grain dust in the terminal elevator environment.

Exposures to Atmospheric Effects in the Entertainment Industry

Theatrical fogs are commonly used in the entertainment industry to create special atmospheric effects during filming and live productions. We examined exposures to mineral oil– and glycol–based theatrical fogs to determine what fluids and effects were commonly used, to measure the size distributions of the aerosols, and to identify factors associated with personal exposure levels. In nonperformance jobs in a range of production types (television, film, live theater, and concerts), we measured airborne concentrations of inhalable aerosol, aldehydes, and polycyclic aromatic hydrocarbons, and collected observations about the sites and tasks performed. Both mineral oil and glycols were observed in use on about one–half the production days in the study. The most common effect produced was a generalized haze over the entire set. Mean personal inhalable aerosol concentrations were 0.70 mg/m3 (range 0.02 to 4.1). The mean proportion of total aerosol mass less than 3.5 microns in aerodynamic diameter was 61%. Exposures were higher when mineral oils, rather than glycols, were used to generate fogs. Higher exposures were also associated with movie and television productions, with using more than one fog machine, with increased time spent in visible fog, and for those employed as “grips.” Decreased exposures were associated with increasing room temperature, with increasing distance from fog machines, and for those employed as “sound technicians.” Exposures to theatrical fogs are just beginning to be measured. It is important to consider these exposures in light of any health effects observed, since existing occupational exposure limits were developed in other industries where the aerosol composition differs from that of theatrical fogs.

Atmospheric effects in the entertainment industry: constituents, exposures and health effects

In 1999, SHAPE (a tripartite organization to promote Safety and Health in Arts, Production, and Entertainment) asked the University of British Columbia to help investigate several questions related to the safety of theatrical smokes and fogs. These questions were: What products and equipment are being used in the BC entertainment industry, what chemicals do these products actually contain, and do these chemicals change when the products are heated during use? What measuring equipment can be used for on-site monitoring by production staff, to measure the levels of smokes and fogs chemicals in the air at entertainment industry worksites? What levels of smokes and fogs chemicals are actually present in the air? What are the sizes of the airborne fog droplets? How much are BC entertainment industry employees exposed to during their work? What factors at the worksite contribute to more or less exposure? Are BC entertainment industry employees suffering ill health effects as a result of exposure to theatrical smokes and fogs? If so, is it possible to link the ill effects to any particular chemical or type of work? The study plan was endorsed by the Board of SHAPE, IATSE Local 891, the Canadian Film and Television Production Association, the Directors Guild of Canada, the Alliance of Motion Picture and Television Producers, and the Vancouver Musicians’ Association. Funding for the study came from the BC Workers’ Compensation Board, the BC Lung Association, SHAPE, and UBC.