A continuing challenge in occupational hygiene is that of estimating exposure to the multitude of airborne chemicals found in the workplace and surrounding community. Occupational exposure limits (OELs) have been established to prescribe the acceptable time weighted average for many different chemicals. Comparing the OELs to the measured workplace concentration allows occupational hygienists to assess the health risks and the need for control measures. Hence, methods to more effectively sample contaminants in the workplace are necessary to ensure that accurate exposure characterizations are completed. Evacuated canisters have been used for many years to collect ambient air samples for gases and vapors. Recently, increased interest has arisen in using evacuated canisters for personal breathing zone sampling as an alternative to sorbent samplers. A capillary flow control device was designed at McGill University mid 1990s. The flow control device was designed to provide a very low flow rate to allow a passive sample to be collected over an extended period of time. This research focused on the development and evaluation of a methodology to use a small canister coupled with the capillary flow controllers to collect long term time weighted air samples for gases and vapors. / A series of flow rate experiments were done to test the capillary flow capabilities with a 300 mL canister for sampling times ranging from a few minutes to over 40 hours. Flow rates ranging from 0.05 to 1.0 mL/min were experimentally tested and empirical formulae were developed to predict flow rates for given capillary geometries. The low flow rates allow for the collection of a long term air sample in a small personal canister. / Studies to examine the collection of air contaminants were conducted in laboratory and in field tests. Air samples for six volatile organic compounds were collected from a small exposure chamber using the capillary-canisters, charcoal tubes and diffusive badges at varied concentrations. The results from the three sampling devices were compared to each other and to concentration values obtained by an on-line gas chromatography. The results indicate that the capillary-canister compares quite favorably to the sorbent methods and to the on line GC values for the six compounds evaluated. / Personal air monitoring was conducted in a large exposure chamber to assess the effectiveness of the capillary-canister method to evaluate breathing zone samples. In addition, field testing was performed at a manufacturing facility to assess the long term monitoring capabilities of the capillary-canister. Precision and accuracy were found to parallel that of sorbent sampling methods. / The capillary-canister device displayed many positive attributes for occupational and community air sampling. Extended sampling times, greater capabilities to sample a broad range of chemicals simultaneously, ease of use, ease of analysis and the low relative cost of the flow controller should allow for improvements in exposure assessment.

The work describes the results obtained following the development and testing of a new device used to measure ventilation efficiency for indoor air quality (IAQ) in office buildings. The method uses concentration data obtained by the repeated injection of CO$ sb2$, used as a tracer gas simulating human respiration. The device measures the efficiency of the ventilation in reducing and evacuating pollutants. Ventilation efficiency was measured in a test chamber and was demonstrated in an office building. The method was tested to determine if it responded well to the effect of air flows, air velocities, air temperatures, number of diffusers and room temperatures. Results compared well with the theoretical predictions obtained from a two-chamber compartment model and could be predicted using simple regression models (r = 0.85). The work concludes that the new method can be used to measure ventilation efficiency and a chart is proposed for using the method with respect to recommended outdoor air flow rates in an office.

The purpose of this research is to examine the effectiveness of the Bill C-45 amendments to the Criminal Code in addressing workplace fatality incidents. This research involved both qualitative and quantitative research and utilized two research methods. The first method involved a secondary analysis of thirty-eight Incident Investigation Reports completed by WorkSafeBC. These were supplemented with additional case information about these incidents provided via the Freedom of Information offices in British Columbia. The second method utilized nine semi-structured interviews with respondents in the field of occupational health and safety and corporate criminality who were familiar with the Bill C-45 amendments. The study found that employers could be found liable in half of the cases examined; that there appeared to be unique characteristics of British Columbia that effect the use of criminal charges; that the criminal law is not very effective in cases of criminal negligence for workplace fatality; and that improvements could be made to the criminal law.

Sampling methods used for the assessment of exposure to volatile organic chemicals (VOCs) in the workplace or for environmental studies are now limited to an upper integrative sampling time of 24 hours or less. Generally, these methods lack versatility and are difficult to use. A passive sampler that can extend sampling periods was developed as part of this research. This novel sampler relies on capillary tubes to restrict and control ambient air entry into an evacuated sample container. / A mathematical model was derived by modifications to the Hagen-Poiseuille and ideal gas laws. This model defines the relationship between container volume and capillary geometry (length/internal diameter) required to provide selected sampling times. Based on theoretical considerations, simulations were performed to study the effects of dimensional parameters. From these results, capillaries having 0.05 and 0.10 mm internal diameters were selected according to their ability to reduce sampling flow rates and to increase sampling times. Different capillary lengths were tested on various sampler prototypes. It was found that a constant sampling flow rate was delivered when a maximum discharge rate was established under the influence of a pressure gradient between a vacuum and ambient pressure. Experimental flow rates from 0.018 to 2.6 ml/min were obtained and compared with model predictions. From this comparison, empirical relationships between capillary geometry and maximum discharge rate given by the pressure gradient were defined. Essentially, based on these empirical relationships, capillary sampling flow controller specifications can be calculated to offer extended integrated sampling periods. On this basis, sampler prototypes were configured for stationary sampling and personal sampling. / Studies, based on theory, have indicated that factors such as temperature, humidity and longitudinal molecular diffusion are not likely to influence the passive sampling process. Subsequent experiments confirmed that temperature changes should not significantly affect flow rates delivered by controllers, and that molecular diffusion does not have any impact on the representativeness of long-term samples. Recovery tests provided acceptable results demonstrating that selected capillaries do not contribute to adsorption that could seriously affect the validity of this sampling approach. / Field demonstration studies were performed with both stationary and personal sampler prototypes in the indoor and outdoor environments. The performance of the sampler compared favorably, and in some instances, exceeded that of accepted methodology. These novel samplers were more reliable, had greater versatility and principally, allowed sampling periods extending from hours to a month. These inherent qualities will assist industrial hygienists and environmentalists in the study of emission sources, pollutant concentrations, dispersion, migration and control measures. This novel sampler is presently the only device available for the effective study of episodic events of VOC emission. / Selected capillary geometries acting as a restriction to the entry of ambient air into evacuated sample container can provide a simple, versatile and reliable alternative for the collection of VOCs. This approach can contribute to a better understanding of VOC effects on human health and the environment.

The purpose of this research is to examine the effectiveness of the Bill C-45 amendments to the Criminal Code in addressing workplace fatality incidents. This research involved both qualitative and quantitative research and utilized two research methods. The first method involved a secondary analysis of thirty-eight Incident Investigation Reports completed by WorkSafeBC. These were supplemented with additional case information about these incidents provided via the Freedom of Information offices in British Columbia. The second method utilized nine semi-structured interviews with respondents in the field of occupational health and safety and corporate criminality who were familiar with the Bill C-45 amendments. The study found that employers could be found liable in half of the cases examined; that there appeared to be unique characteristics of British Columbia that effect the use of criminal charges; that the criminal law is not very effective in cases of criminal negligence for workplace fatality; and that improvements could be made to the criminal law.

This thesis describes a retrospective cohort study of cancer mortality among employees of the Celanese Canada Inc. synthetic textiles plant in Drummondville, Quebec. The study was commissioned by the company to confirm or refute a previous observation (Vobecky et al., Cancer 54:2537-2542, 1984) that there were higher mortality rates from colorectal cancer among male employees of the textiles unit, the cellulose acetate fiber manufacturing unit, and the cellulose triacetate and polypropylene extrusion units and to investigate whether mortality rates for other sites of cancer were associated with employment in each area of the plant and with occupational exposures. / Workers with more than one year experience at the plant were eligible for study if they were employed on January 1, 1947 or if they were newly hired between that date and December 31, 1977. Vital status as of December 31, 1986 was ascertained for 7,422 men and 2,720 women through a probabilistic record linkage to the Canadian Mortality Data Base. Among men, there were about 220,000 person-years of observation and 1,738 deaths and, among women, there were about 89,000 person-years of observation and 241 deaths. / Three reference regions were used to derive standardized mortality ratios (SMR): the entire Province of Quebec, semi-rural regions of the Province, and the area in which the plant is located. Results based on rates for these regions were generally similar. For men, the SMR for all causes of death was significantly less than unity (SMR = 0.71, 95%CI:0.68-0.74), as were the SMRs for most sites of cancer (SMR all neoplasms = 0.73, 95%CI:0.66-0.80). The SMR for colorectal cancer was 0.68 (95%CI:0.51-0.91). Of the 20 cancer sites examined in men, reticulum cell sarcoma was the only one having a significantly elevated SMR, and this occurred only among the subcohort of men hired prior to 1947 (SMR = 2.84, 95%CI:1.04-6.18, 6 deaths). For women, the SMR for all causes of death was 0.75 (95%CI:0.66-0.85) and there were moderately elevated SMRs for a number of sites of cancer, but none were significantly greater than expectation (SMR all neoplasms = 0.97, 95%CI:0.80-1.17). / SMRs were also calculated according to employment in each processing unit and exposure to occupational agents, and case-control analyses were carried out within the cohort for selected sites of cancer. Of the scores of associations tested, very few were significantly elevated. There were excesses of biliary cancers and non-Hodgkin's lymphomas among workers in the cellulose acetate fiber manufacturing unit. There were also significant associations between stomach cancer and exposure to cutting oils, and between prostate cancer and exposure to glycol monobutyl ether. However, none of these associations were persuasive. / With regards to colorectal cancer, there was a nonsignificant elevation in risk among workers who had ever worked in the polypropylene and cellulose triacetate extrusion unit (OR$ sb{ rm e}$ = 2.3, 95%CI:0.5-9.9) but there was no apparent increase in risk with increasing duration of employment. Thus, the evidence for an association was not convincing. For the cellulose acetate fiber manufacturing unit, the evidence of an increase, although based on few cases, was slightly more persuasive (OR$ sb{ rm e}$ = 1.9, 95%CI:1.0-3.6), but no trend was observed with duration. No association was observed with employment in the textiles unit (OR$ sb{ rm e}$ = 1.1, 95%CI:0.6-2.2) nor were there any noteworthy associations between colorectal cancer and any of the agents evaluated in the case-control analyses.

The prevalence of asthma and the role of occupational exposures was investigated in a cross-sectional study of 498 Montreal adults aged 20 to 44 years. Prevalences of asthma standardised for age and gender, using four definitions were: current wheeze: 23 8%, asthma symptoms and/or medicine: 12.9%, airway hyper-responsiveness: 15.1%, airway hyper-responsiveness and current wheeze: 7.0%. Imputation to adjust for non-response to airway challenge gave similar results. 56.9% of subjects reported occupational exposure ever to sensitisers and 10.8% to irritants. Current wheeze was associated with exposure to irritants (OR: 2.12 (1.03, 4.34)), and airway hyper-responsiveness with exposure to sensitisers (OR: 2.20 (1.10, 4.38)). Childhood asthma and atopy did not affect the associations. Population attributable risk was about 30% for airway hyper-responsiveness with exposure to sensitisers, and 5% for current wheeze with exposure to irritants. Studies with more precise exposure information may provide better evidence for the causality of the association.

The influence of psychological status on recovery from a first lifetime episode of acute low-back pain was assessed in compensated workers seen in a physiatry clinic. One hundred thirty-four participants of a back school intervention trial were selected and followed for 1 year. The objectives were to determine the evolution of psychological distress, well-being, pain, self-reported disability and spinal flexibility, and to determine the psychological factors associated with return to work and recurrence. Improvement occurred post-treatment in all measures except well-being which did not fluctuate over the year. Additional improvement in functional disability occurred at 6 and 12 months. Using multiple logistic regression, low baseline psychological distress predicted late return to work and high baseline well-being predicted recurrence. A second model for recurrence that was constructed with post-treatment scores on the longitudinal measures had greater predictive power than the model using baseline scores. These results have implications for the management of return to work.

The goal of this study was to verify if differences in respirable dust and respirable quartz concentrations exist with respect to the mines, the ore deposit types and the nature of workstations. / One hundred and seventy-nine respirable dust samples were collected in the six mines studied, in compliance with the method recommended by the Institut de recherche en sante et securite du travail du Quebec (IRSST). Then, samples were analysed using X ray powder diffraction technique to determine respirable quartz concentrations. / Results indicated statistically significant differences in the normalised exposure levels to respirable dust (p = 0.017), to respirable quartz (p < 0.001) as well as the quartz percentage in the respirable dust (p < 0.001) of the six mines studied. When grouped by ore deposit type, normalized exposure levels to respirable dust were not statistically different. However, statistically significant differences were noticed for normalized exposure levels to respirable quartz (p = 0.004) and respirable quartz percentage (p < 0.001) according to ore deposit types. / For all mines studied, respirable dust concentrations were all below the admissible exposure value whereas about 9% of the respirable quartz concentrations were equal or above the admissible exposure limit. Gold ore deposits hosted in quartz veins had the highest normalized respirable quartz exposure levels, as well as the highest percentage of quartz in the respirable dust when compared to gold ore deposits with sulfide lodes, the copper-zinc ore deposit and the disseminated gold ore deposit. / The study also revealed that workers who worked in the ore crushing and hoisting departments as well as loading and transport had higher normalised exposure levels to respirable quartz than workers who worked in the drilling and blasting or those who worked in the maintenance department. / In conclusion, this study stressed that quartz content in the mined rocks seems to be the most important factor influencing on respirable quartz concentrations in the mine worker's respiratory zone, but the relation between the two variables were not strongly correlated (Rs = 0.254, p = 0.005). Furthermore, the study showed that the gold ore deposits with quartz lodes had the highest normalized exposure levels to respirable quartz. Also, the workers assigned to ore crushing and hoisting departments as well as transport and loading had the highest exposure levels to respirable quartz. (Abstract shortened by UMI.)

This thesis presents a new conceptual model of occupational outcome based on the results of input from 5 key stakeholder groups in the field of occupational health including patients, healthcare providers, employers, unions, and insurers. Data from 77 participants who took part in one of either 18 individual interviews or 11 focus groups were qualitatively content analyzed. The goals were to: 1) compare the range of meanings given to the concepts of health, occupational health, and occupational outcome, 2) understand the range of opinions among stakeholders and identify areas of agreement or disagreement and, 3) to develop a framework of occupational outcome incorporating the views of all key stakeholders. Health, occupational health, and occupational outcome were found to have different and complex meanings that extended beyond those in existing research, and that related to the role a variable is hypothesized to have in a larger framework. Stakeholders differed in the depth, breadth, and qualitative nature of the themes discussed. Natural alignments among some stakeholder groups emerged which varied depending on the context, however a specific focus could be identified for each group. No single stakeholder group alone expressed all the themes and the complexity of the relationships among them; the whole could only be understood in terms of the sum of the stakeholder parts. A new model emerges in which occupational outcome is encompassed by the interactions of 3 key factors: Function and Ability, Individual Behaviours, and Environmental Factors. These are embedded within larger models of both occupational health that includes both individual health and workplace health, and of quality which is comprised of the interactions between structure variables, system participant factors, and outcome. The new model and the process undertaken to develop it meet two important needs for occupational health; enhancing understanding and conceptualization of occupational outcome, and enhancing understanding of the perspectives of stakeholders in the occupational healthcare system. The findings have implications for research, and delivery of quality care to patients with occupational disease or injuries. Some next steps include model validation and testing, measurement scale development, clarifying new variables through ongoing stakeholder discussion, and model application.