Despite the known health hazards associated with exposure to lead, occupational lead poisoning remains a health problem. Although a variety of public health programs have been implemented to control this exposure, knowledge of which occupational groups are at greatest risk is incomplete. This research developed and applied a lead risk model that generated estimates of lead-using industries and numbers of employees potentially exposed to lead, and then, validated the model through a lead exposure prevalence survey among construction workers. The lead risk model was developed using data from the National Occupational Exposure Survey, state lead registries, lead inspection results from the Occupational Safety and Health Administration, and other sources. The model was applied to Massachusetts County Business Patterns and Department of Employment and Training databases to produce state and county estimates of numbers of employees potentially exposed to lead, and lead-using companies, ranked by exposure risk. The sensitivity of the state lead registry was evaluated using estimates from this model. To validate the model, a prevalence survey of lead exposure was conducted among a sample of 127 western Massachusetts plumbers. Based on the model, an estimated 1% (20,825) of Massachusetts employees are potentially exposed to lead, 53% are at moderate or high risk of lead exposure, and 74% work within a 5 contiguous-county area in eastern Massachusetts. There are 3,448 lead-using facilities, representing 2% of total companies. The model also showed a high sensitivity (70%) for state regulated construction groups within the lead registry, but low sensitivities for all other construction industries. The geometric mean for blood lead and zinc protoporphyrin among plumbers in the prevalence survey were 7.0 $\mu$g/dl and 30.9 $\mu$g/dl, respectively, indicating relatively low levels of lead exposure. Current smokers, smoking at the workplace, and hand scraping metal were associated with higher lead levels, while wearing protective equipment at work was associated with lower levels. The model identified non-traditional lead-using industries, thus, potentially allowing the state to better target educational and medical intervention activities to reduce the risk of occupational lead exposure. Similar lead-reduction activities can be applied to other states that adopt the model.

Injury epidemiology, a relatively new sub-discipline of epidemiology, has continued to evolve since the ground-breaking work by Dr. William Haddon during the 1960s. The case-crossover design is a relatively new epidemiological methodology developed specifically for investigating the transient effects of a brief exposure on the onset of an acute outcome. This dissertation work provides some initial empirical data illustrating the strengths and limitations of the case-crossover design as applied within the field of occupational injury epidemiology. The review of the literature details the utility of the case-crossover study design, the currently known strengths and limitations, and confirms the under-utilization of this design to date. Examples from an on-going multi-center, interview-based, case-crossover study of acute traumatic occupational hand injuries are utilized to highlight some of the strengths and weaknesses of this new method, as applied to injury research. The application demonstrates the importance of temporal factors in determining the etiology of occupational acute traumatic hand injury. The findings point out the need to know more about the timing of high risk work tasks and transient exposures throughout the work day. These factors should be taken into consideration when developing intervention strategies for the prevention of hand injuries in the workplace. To evaluate the potential impact of information bias on the results of this study, a reliability study was also conducted. The findings from this test-retest study suggest that the frequency and duration of unusual transient workplace exposures, occurring proximal to the time of an injury, can be reliably recalled using a telephone interview.

Enhancing our understanding of the relation that exists between productivity and musculoskeletal disorders is essential to the successful design of person-machine systems for safe and comfortable human use. This research comprises two experiments to study the trade-offs between productivity and shoulder musculoskeletal discomfort in a repetitive task performed at different repetition rates. The objective of the first experiment was to determine from velocity profiles which theoretical movement time model adequately predicted the times for a mail sorting task. Based on the percentage of the total variance explained by the regression models, it was concluded that the optimized initial impulse model (Meyer et al., 1988) using one sub-movement provided the best prediction for the movement times associated with the repetitive task. In addition, the effects of different duty cycles upon movement time were studied. It was found that a decrease in repetition rate produced an increase in mean movement time. In the second experiment a regression model that related biodemographic, anthropometric, workplace and kinematic factors to shoulder musculoskeletal discomfort was developed. Also, the effects of these ergonomic factors upon shoulder musculoskeletal discomfort were studied. It was found that the kinematic variables played the most important role in increasing the percentage of the total variance explained by the regression model. Results showed a significant linear relationship between weight and shoulder musculoskeletal discomfort. High weight values were associated with higher discomfort scores. To diminish the discomfort values it was recommended the improvement of the worker-machine system by designing adjustable equipment within the capabilities of the people to optimize their performance at work. The associations between (1) the number of repetitions, (2) movement time and (3) shoulder musculoskeletal discomfort were studied. It was determined that, if the anthropometry of the working population is considered, an adjustment point for the movement time could be identified (which determines the productivity level of the workers) and a better design of a repetitive task could be achieved. Finally regarding the discomfort-productivity trade-off evaluation, it was found that higher SMD scores were associated with longer movement time values regardless of the experimental population percentile.

<p> The lack of adequate equipment and measurement tools in whole-body vibration has imposed significant constraints on what can be measured and what can be investigated in the field. Most current studies are limited to single direction measurements while focusing on simple postures. Besides the limitation in measurement, most of the current biomechanical measures, such as the seat-to-head transmissibility, have discrepancies in the way they are calculated across different labs. Additionally, this field lacks an important measure to quantify the subjective discomfort of individuals, especially when sitting with different postures or in multiple-axis vibration. </p><p> This work begins by explaining discrepancies in measurement techniques and uses accelerometers and motion capture to provide the basis for more accurate measurement during single- and three-dimensional human vibration responses. Building on this concept, a new data collection method is introduced using inertial sensors to measure the human response in whole-body vibration. The results indicate that measurement errors are considerably reduced by utilizing the proposed methods and that accurate measurements can be gathered in multiple-axis vibration. </p><p> Next, a biomechanically driven predictive model was developed to evaluate human discomfort during single-axis sinusoidal vibration. The results indicate that the peak discomfort can be captured with the predictive model during multiple seated postures. The predictive model was then modified to examine human discomfort to whole-body vibration on a larger scale with random vibrations, multiple postures, and multiple vibration directions. The results demonstrate that the predictive measure can capture human discomfort in random vibration and during varying seated postures. </p><p> Lastly, a new concept called effective seat-to-head transmissibility is introduced, which describes how to combine the human body's biodynamic response to vibration from multiple directions. This concept is further utilized to quantify the human response using many different vibration conditions and seated postures during 6D vibration. The results from this study demonstrate how complicated vibrations from multiple-input and multiple-output motions can be resolved into a single measure. The proposed effective seat-to-head transmissibility concept presents an objective tool to gain insights into the effect of posture and surrounding equipment on the biodynamic response of the operators. </p><p> This thesis is timely as advances in seat design for operators are increasingly important with evolving armrests, backrests, and seat suspension systems. The utilization of comprehensive measurement techniques, a predictive discomfort model, and the concept of effective seat-to-head transmissibility, therefore, would be beneficial to the fields of seat/equipment design as well as human biomechanics studies in whole-body vibration.</p>

There are three primary routes by which occupational exposure to hazardous substances occurs: inhalation, dermal absorption, and ingestion. Of these, ingestion has been the least studied. Ingestion exposure is typically controlled in workplaces by the provision of clean eating areas that are separated from the work areas, and by encouraging hand-washing prior to eating. However, this control strategy does not affect ingestion exposure that can occur when contaminated hands or objects contact the mouth; these sorts of exposures can occur during work tasks in the general work area. For example, these sorts of contacts can occur when workers wipe their mouths or noses, chew pens or glasses, or bite their nails. Exposure by this pathway is called inadvertent ingestion exposure. In addition to the insertion of contaminated hands and objects directly into the oral cavity, contact can occur with the perioral area (the area surrounding the mouth) and transferred substances can subsequently transfer to the mouth. The aim of this thesis was to study inadvertent ingestion exposure in order to develop a generic predictive screening model to allow occupational hygienists and risk assessors to estimate exposure by inadvertent ingestion for a range of exposure scenarios. The thesis project was carried out in a series of steps, all of which are described below. The steps were carried out in the order presented and the findings from the work on earlier steps influenced the work carried out in later steps.

<p> Inadequate leadership is the reason workplace accidents in the mining industry remain high, making the industry one of the most hazardous operational activities in the world. Unsafe leadership practices may result in death or injury to workers. A group of 30 mining company leaders from 3 gold mines in Zimbabwe revealed an exception to these hazardous practices, however, notable through their outstanding safety improvement records. To better understand what these practitioners were doing, this multicase study research design explored their strategies to improve the workplace safety environment in the mines. Data were collected using audio-recorded semistructured interviews and document analyses. Shewhart&rsquo;s plan-do-check-act conceptual framework anchored the study. Data analysis followed the thematic data analytic approach involving classification, coding, and interpretation to identify common themes. The following themes emerged: planning and organizing, leading, and risk management. The findings indicate that the business leaders created a safe work environment by planning the work to be performed; how the task would be executed; and when, where, and who performed the task. The results of study also indicate that leaders designed the work environment, trained, empowered, and equipped employees with the relevant skills, and provided appropriate technology and personal protective equipment to improve workplace safety. Finally, the research findings indicate that leaders embedded risk management principles and practices in every process or activity, and continuously learned from each event to create a safe work environment. The findings promote social change by encouraging safe behavior and risk-based thinking and practices in the workforce and the community.</p>

<p> The impact of occupational stress on employees' health and work performance costs U.S. companies $300 billion annually; work-related stress is an issue for private security organizations all over the world. The purpose of this single case study was to explore strategies private security organizational leaders used to mitigate private security officers' occupational stress. The study participants were 4 leaders of a private security organization in Bahrain who had a minimum of 5 years of experience in the private security field and had addressed occupational stress successfully. The human capital theory was the conceptual framework used for this study. Data were collected using semistructured interviews and review of archival documents. Yin's 5-step data analysis plan was applied to the data to generate 4 themes: private security occupational stressors, occupational stress reduction practices, leaders-officers open communication, and health protection policies. The identification and development of job stressor mitigation strategies has multiple implications for positive social change including protecting employees' well-being and increasing their working performance, productivity, and business success. Improving work performance and productivity produces opportunities for employment and supports economic growth and community goodwill. The practices of a successful organization positively influence the society by providing jobs and capital investments, which can improve the quality of life in the community.</p><p>

<p> The purpose of this study was to explore and understand the successful prevention and mitigation of workplace violence (WPV) against nurses in the Emergency Department (ED), and to learn what multidisciplinary hospital leaders are doing to accelerate progress. Specifically, the research considers the strategies, policies and actions hospital leaders are using to prevent and mitigate WPV; the positive progress or outcomes that have been realized thus far; what these leaders have learned in the process, and what they aspire to achieve in the future. In the process of exploring why and how positive progress accelerated, it was found that hospital leaders experienced positive progress in WPV prevention and mitigation when their hospitals provided a WPV program utilizing these exemplary strategies: (a) collaborative multidisciplinary partnerships, (b) fully engaged executive support, and (c) operationalized data. It was interesting to note that as multidisciplinary partners and fully engaged executives collaborated, and supported their teams in the process of establishing these WPV initiatives, a culture of respect was catalyzed and WPV initiatives gained momentum. The details of this research highlight that operationalized data&mdash;WPV data put to use in a centralized, customized, evidence-based approach&mdash;appears to have functioned as a key accelerant of positive progress in WPV prevention and mitigation for these hospital leaders. </p><p>

Three multiplicative models commonly used in the analysis of occupational cohort studies are logistic, Poisson, and Cox proportional hazards regression. Although the underlying theories behind these are well known, this has not always led to clear decisions for selecting which to use in practice. This research was conducted to examine the effect model choice has on the epidemiologic interpretation of occupational cohort data. The three models were applied to a National Cancer Institute historical cohort of formaldehyde-exposed workers. Samples were taken from this dataset to create scenarios for model comparisons, varying the study size (n = 600, 3000, 6000), proportion of subjects experiencing the outcome (2.5%, 10%, 50%), strength of association between exposure and outcome (weak, moderate, strong), follow-up length (5, 15, 30 years), and proportion of subjects lost to follow-up (0%, 10%, 17.5%). Other factors investigated included how to handle subjects lost to follow-up in logistic regression. Models were compared on risk estimates, confidence intervals, and practical issues such as ease of use. The Poisson and Cox models yielded nearly identical relative risks and confidence intervals in all situations except when confounding by age could not be closely controlled in the Poisson analysis, which occurred when the sample size was small or outcome was rare. Logistic regression findings were more variable, with risk estimates differing most from the Cox results when there was a common outcome or strong relative risk. Logistic was also less precise than the others. Thus, although logistic was the easiest model to implement, it should only be used in occupational cohort studies when the outcome is rare (5% or less), and the relative risk is less than about 2. Even then, since it does not account for follow-up time differences between subjects or changes in risk factors values over time, the Cox or Poisson models are better choices. Selecting between these can usually be based on convenience, except when confounding cannot be closely controlled in the Poisson model but can in the Cox model, or when the Poisson assumption of exponential baseline survival is not met. In these cases Cox should be used.

MPH / Department of Public Health / Occupational Health and Safety has become one of the leading concerns throughout the cleaning industry. Compliance with safety regulations among cleaners of the University of Venda is still a challenge. The study aims to investigate factors contributing to non-compliance with safety regulations among cleaners: A selected rural university in South Africa. The study was conducted at the University of Venda, South Africa. A quantitative approach using cross-sectional descriptive survey design was employed. A pre-test was carried out to determine the reliability of the researcher-developed questionnaire. A total population will be applied and all the 164 was included in the study. The data collected was analyzed using SPSS 23.0. Data was presented in the form of graphs, tables and charts. A self-administrated questionnaire was used to collect data. Results: A total population of 164 cleaners took part in the research project, 119 (74%) were females and 45 (26%) were males. Among the participant 5%, n = 9 had no form of education background, 28%, n = 46 with a primary education background, 48%, n = 79 with a secondary education back and only 19%, n = 30 with a post-secondary background. Participants with a post- Matric back ground showed significant understanding (90%, n = 27) on the importance of complying with safety guidelines, as compared to those with no form of formal education (44%, n = 4). There was a significant relationship between gender and level of education with regards to the factors contributing to non-compliance with safety regulations among cleaners. The study revealed that the female participants are more likely to adhere to safety regulations (65%, n = 74) as compared to male participants (63%, n = 26). Majority of cleaners have a fair knowledge on the safety compliance within the working environment, however there is a need to put more effort on the safety regulations practice. Conclusion: The study concludes that female participants are more cautious within the workplace as compared to the male participants and that the level of education also has significant relationship on the level of compliance with regards to safety regulations. Recommendations: There is a need to have a functional safety committee that will ensure that all safety protocols are being followed, the committee may also amend the existing policy on given period of time. / NRF