The first aim of this thesis was to describe the characteristics of Posttraumatic Stress Disorder (PTSD) and to elucidate its place as a symptom disorder that sometimes develops when people are exposed to a traumatic event. The current major theoretical approaches to account for why some people who are exposed to trauma develop PTSD and the mechanisms by which this occurs were described. Three classes of theories were reviewed: conditioning/learning approach; information processing theories with a particular focus on the meaning of the trauma event; and biological models with an emphasis on recent neurocircuitry and neurochemistry models. Successful treatment approaches were then reviewed which indicated two major contenders for the most efficacious treatment for PTSD: traditional cognitive behaviour therapies (CBT) using either stress inoculation or prolonged exposure; and eye movement desensitisation and processing (EMDR). Prior to the first study (Lee, Gavriel, Drummond, Richards, & Greenwald, 2002), a review of the literature indicated equivalent effects for EMDR and CBT. There had been very few direct comparison studies and each had serious methodological flaws, particularly with respect to random assignment and treatment fidelity. Therefore, the first study ensured adequate attention to these areas and involved a direct comparison between the two procedures using a sample of 24 participants diagnosed with PTSD. EMDR and stress inoculation training with prolonged exposure were found to lead to similar symptom improvement at the end of treatment, apart from a slight advantage for EMDR on intrusion symptoms. Both treatments led to significantly greater symptom reduction than a wait list control condition. At follow-up, EMDR led to greater gains on both self-report and observer rated measures of PTSD and self-report measures of depression. Overall, the findings were similar to those described in previously published studies, with a suggestion that EMDR was slightly more efficient than the standard CBT approach. Given that the evidence suggested that EMDR was a more efficient treatment, it became critical to understand the underlying processes. A process study was undertaken that examined the responses of people with PTSD receiving EMDR treatment (Lee, Taylor, and Drummond, 2006). Guided by process studies of other treatments and theories that might account for why EMDR is effective, participants’ responses were examined to see which models better accounted for symptom improvement. The main analysis tested whether or not the responses were consistent with processes that occurred during traditional CBT treatment, which prior research had identified as reliving, or whether they were more consistent with Shapiro’s proposal that enhanced information processing occurs because there is a dual focus of attention (that is, the person simultaneously focuses on an external stimulus and on the traumatic memory) (Shapiro, 1995). The responses made by 44 participants were coded by an independent rater according to whether they were primarily reliving, distancing, affect or material other than the primary trauma. The coding system was found to have satisfactory inter-rater reliability. Greatest improvement occurred when the participant processed in a more detached or distant manner, whereas reliving responses were not associated with improvement. Cross-lagged panel correlations suggested that processing in a more detached manner was a consequence of the EMDR procedure rather than a measure that co-varied with improvement. The findings underscored a difference in the processes that underlie EMDR and traditional CBT. The major question left unanswered from this second study was what causes this distancing process? Competing views were that it was facilitated by eye movement; alternatively, the therapist’s instructions to participants might have precipitated this distancing phenomenon. The third study tested these ideas by randomly assigning 48 participants to either an eye movement or a no eye movement condition under two types of therapist instructions (reliving or distancing). Participants recalled personal distressing memories, and measures of distress and vividness were taken after treatment and at follow up. Only the eye movements made a significant difference to people’s level of distress. This conclusion appeared at odds with some of the previous literature that had tested the effects of eye movement on levels of distress. A meta-analysis of some of this research had suggested that there was no significant advantage of including eye movement in EMDR treatment unless the person had been diagnosed with PTSD. However, a close examination of this meta-analysis indicated some major methodological flaws in the computation; therefore, this was recalculated. The conclusion from this fourth study was consistent with study three in that EMDR with eye movement was found to lead to significantly greater improvement that EMDR without eye movement. The results of these four studies were then discussed in terms of their implications for the theoretical models presented in Chapter 1. Aspects of learning theory that might account for EMDR efficiency were discussed as well as the failure of this model to account for treatment gains following EMDR. Information processing models were seen to better account for some of the phenomena observed in EMDR and for the findings from the four studies. Some suggestions of how eye movements might facilitate improved information processing were presented. Finally, the relative merits of EMDR and CBT treatments were discussed and suggestions made for when to combine approaches. The conclusions highlight the point that EMDR appears to be the most promising treatment for PTSD.

Human biomonitoring aims to measure the amount of certain substances in all aspects of the environment, how much of this that reach humans and in what way, and finally how this affects our health. In all aspects of this process lays challenges that must be overcome. When measuring substances in the environment, one must make sure that one is measuring the biomarker which gives the most precise results according to what one seeks to find. Dependent on the biomarker in question, multiple factors can potentially affect the measurements. When the most suitable biomarker has been found, one must make sure that all possible sources are located and taken into consideration, in order to provide a sufficient exposure assessment. The next challenge is to gather accurate epidemiologic data, and link this to the exposure in question, and make a reliable risk assessment. As the examples in this paper highlights, within each step are challenges, and possible limitations. For most substances, there are data gaps and incomplete understanding. There is now much work done globally, on how to further improve the process. Based on today's experiences and knowledge, new guidelines are put down. In Europe there was recently launched a program, that will coordinate the cooperation between the member states. Though it is already a...

Abstract A prospective population-based study was conducted to assess the incidence, diagnosis, histology, treatment and survival of lung cancer in northern Finland. The results were compared with those obtained in a similar survey 20 years earlier. In a population of 440,000, altogether 602 lung cancer patients, 510 men and 92 women, were diagnosed during the years 1990 - 92, the annual incidence per 100,000 being 63 for males and 9.5 for females. Lung cancer was confirmed histologically in 381 cases (63%) and in addition, cytologically in 135 cases (23%). Squamous cell carcinoma was the most common histologic type (40%), the proportion of adenocarcinomas being 26%, small-cell carcinomas 24% and large cell carcinomas 4%. The age-standardized incidence of lung cancer had decreased significantly among males (from 87 to 63 per 100 000) compared to the situation 20 years earlier but increased among females (from 4.1 to 9.5), mainly due to adenocarcinoma. The 5-year survival rate had improved during 20 years from 4% to 12% (p < 0.001). The differences in survival between the histological types (χ2logrank = 59.2, p < 0.0001), TNM stages (χ2logrank = 199.6, p < 0.001), symptomatic stages (χ2logrank = 120, p < 0.001) and treatments (χ2logrank = 277, p < 0.001) were also significant. A total of 20% of the patients were operated on in the newer series of patients, the corresponding percentage in the earlier series being 16%. The 5-year survival of the patients who had been operated on had increased from 23% to 48%. The survival of patients with non-small-cell lung carcinoma had increased significantly, even though the patients were older now than earlier.In seventy operated lung cancer patients, the histological tumor types and grades were compared with the etiological factors of lung carcinoma, including cigarette smoking and asbestos exposure. A majority of the patients (93%) were smokers. The incidence of adenocarcinoma among non-smokers had remained the same, 50%. The accumulation of the p53 protein in lung carcinoma was associated with heavy smoking. Exposure to asbestos fibers either by a positive history or by a number of asbestos bodies (AB) in the histological sections of lung tissue was also associated with p53 accumulation. Benign intrathoracic tumors are uncommon, and their occurrence in unselected populations is poorly defined. Thirty-six benign intrathoracic tumors were found. A histologic diagnosis was available for 24 (67%). Hamartoma was the most common benign lung tumor.

Community gardening in cities is increasing, driven by social interaction and food security. City soils are sinks for heavy metals; including neurotoxic lead (Pb). Exposure routes are primarily through inhalation/ingestion of soil, or second by ingestion of plants that have accumulated Pb. This research evaluates soil at three Liberty City, Florida sites estimating risk of Pb exposure through primary and secondary pathways. Soil cores were collected from Liberty City, and red Malabar spinach (Basella rubra) was grown in Pb soil treatments in a greenhouse. Total soil Pb levels and plant tissues were measured after acid digestion, by ICP-OES. In Liberty City, two sites had hotspots with areas of elevated soil Pb levels. Plants grown on Pb contaminated soil all accumulated statistically significant Pb concentrations. Therefore, there is a potential risk of Pb exposure to residents in Liberty City by exposure in hotspot sites through both the primary and secondary pathways.

In British Columbia harvested forests are manually replanted by seasonal workers. Fertilizers contained in perforated paper sachets are often planted with seedlings. There have been anecdotal reports of skin and respiratory illness associated with fertilizer exposure and due to potential metal content in fertilizer source material they may contain metals as contaminants. Workers may also be exposed to pesticide residues on seedlings. This study aimed to characterize fertilizer, metal and pesticide exposure among a sample of B.C. tree planters, and to examine worker respiratory and dermal health. Between May 2006 and April 2007 223 tree planters were interviewed about their respiratory and dermal health, and the exposures of 54 tree planters at five geographically-disperse worksites were monitored. Four worksites were using fertilizer and one was not. The health questionnaire was a modification of the American Thoracic Society standardized questionnaire with questions on dermal health taken from a previous UBC study. Workers were grouped in exposure categories and symptoms analysed using logistic regression. Metals were measured by ICP/MS on post shift hand wipes, full shift air sample filters, in whole blood, bulk soil, seedling root balls, and fertilizer samples. Pesticides were measured on post shift hand wipes and on bulk seedling samples. Using nursery pesticide application records, analyses focused on known pesticides applied to the seedlings at the study sites. Carbamate pesticides were analyzed by HPLC/MS and other pesticides by GC/MS. No evidence was found that tree planters who work with fertilizer are at an elevated risk of exposure to arsenic, lead, cadmium, chromium and nickel relative to other tree planters. Pesticide residues were found on seedlings taken from coastal work sites in April 2007. At coastal worksites the fungicides chlorothalonil and iprodione were found on the skin of workers at low levels (range 0.37 – 106.3 ng.cm² and 0.48 – 15.9 ng/cm² respectively). Work with fertilizer was linked with an increased risk of cough, phlegm, nasal symptoms, nose bleed, and skin irritation. Hygiene conditions at tree planting work sites are very poor. Although measured exposures were low, hygiene conditions should improve to reduce the risk of health symptoms among tree planters. / Medicine, Faculty of / Population and Public Health (SPPH), School of / Graduate

This article focuses on exposure to violence and violence-related activities (i.e., crime and drug use) in 70 children whose mothers are addicted to alcohol or other drugs and explores maternal characteristics associated with violence exposure. Results suggest that exposure to violence is relatively common for these children, with many exposed to repeated violence in both the home and community. Findings also suggest higher levels of exposure to violence among children whose mothers reported fewer symptoms of posttraumatic stress disorder and held beliefs and attitudes about child rearing that have been associated with abusive and neglectful parenting. Levels of violence exposure were also higher when mothers reported more severe drug use in the recent past. These findings point to the need for assessment and treatment for children whose mothers abuse alcohol and other drugs.

Objectives: This study examined the effect of sampling duration, in units of work cycles, on the precision of estimates of exposure to forceful exertion obtained with surface electromyography (EMG). Methods: Recordings of the activity of the flexor digitorum superficialis, extensor digitorum, and upper trapezius muscles over 30 consecutive work cycles were obtained for a random sample of 25 manufacturing workers, each of whom was performing a unique production task representing a portion of the whole job. The mean root-meansquare amplitude and the 10th, 50th, and 90th percentiles of the distribution function of the amplitude probability were calculated for each cycle. Bootstrap analyses were used to examine the precision of the summary measures as the sampling duration increased incrementally from 1 to 30 work cycles. Precision was estimated by calculating the coefficient of variation (CV) of the bootstrap distributions at each sampling duration increment. Results: The average minimum sampling duration for a bootstrap distribution CV of 15% ranged from 2.0 (SD 1.5) cycles to 7.5 (SD 9.6) cycles, depending on muscle and summary measure. For a 5% CV, the average minimum sampling duration ranged from 11.9 (SD 9.0) to 20.9 (SD 10.5) cycles. Conclusions: The results suggest that sampling as few as three work cycles was sufficient to obtain a bootstrap distribution CV of 15% for some of the muscles and summary measures examined in this study. While limited to machine-paced, cyclic manufacturing work, these results will assist the development of exposure assessment strategies in future epidemiologic studies of physical risk factors and musculoskeletal disorders.

There is a debate among researchers and clinicians as to whether the judicious use of safety behaviours (SBs) during exposure therapy is helpful or detrimental. Central to this debate is the premise that SBs may interfere with one’s ability to gather disconfirmatory evidence. However, no study to date has assessed: 1) how SB use may interact with cognitive mechanisms at play during an exposure-like task, or 2) whether it is SBs themselves, or rather, beliefs about SBs that are most important. The two studies outlined in this dissertation sought to investigate the cognitive, emotional, behavioural, and psychophysiological underpinnings and consequences of exposure with SBs. In Study 1, speech anxious participants (N = 111) were randomly assigned to deliver an evaluated speech with or without SBs. Self-reported anxiety ratings and psychophysiological arousal measures were recorded at baseline, in anticipation of the speech, and following the speech. Measures of working memory capacity, ability to gather disconfirmatory evidence, and speech task acceptability were administered. Results demonstrated no differences between conditions on most outcomes. However, condition did influence willingness to deliver future speeches, such that participants in the SB condition were less willing than those in the NoSB condition to deliver a future speech without SBs. In Study 2, speech anxious participants (N = 144) were given divergent information on the helpfulness of SBs. Participants were randomly assigned to one of three conditions and were told either that SBs are: helpful (decrease anxiety), unhelpful (counterproductive and increase anxiety), or were provided with no information on the anxiolytic effects of SBs (control condition). Self-reported anxiety ratings were recorded at baseline, in anticipation of the speech, and following the speech. Similar to Study 1, measures of working memory capacity, ability to gather disconfirmatory evidence, and speech task acceptability were administered. Results demonstrated that participants in the helpful condition perceived the exposure as being more likely to succeed in helping them reduce their anxiety. Moreover, exposure expectancy mediated the relationship between the helpful condition (but not the unhelpful condition) and willingness to engage in future exposure exercises. There were no differences between conditions on most other outcomes. Taken together, these findings suggest that SB use may not necessarily be detrimental to outcomes on an exposure-like task, as individuals were able to gather disconfirmatory evidence (one of the proposed primary mechanisms underlying exposure success) across conditions in both studies. However, clients may believe SBs to be more helpful than they actually are, and clinicians should work collaboratively with clients to identify whether judicious SB use may be appropriate and helpful (or inappropriate and detrimental) in achieving their treatment goals. The current research program has the potential to improve our understanding of the consequences of SB use and identify the ways in which cognitive behavioural therapies could be improved.

The aim of this dissertation is to examine selective exposure theory on Twitter among student users at Kuwait University, and to revisit selective exposure theory’s assumptions in the social media era. Two studies for this dissertation have been conducted among a total of 1391 participants to examine the selective exposure theory among student Twitter users. In both studies, the researcher conducted an online experiment by developing simulated Twitter interface pages and a simulated news app to study selective exposure theory among Kuwait University students. The first study aimed to examine whether the students at Kuwait University tend to be exposed to politicians in Kuwait’s parliament who share the same political ideologies. The second study aimed to examine to what extent student users selectively expose themselves to specific content on Twitter, or more specifically to their like-minded group, and what drives them to do so. Moreover, the effect of Twitter’s social endorsement features on users' news selection has been examined. Each study sample has been drawn from different classes of students at Kuwait University. This study also looked at the role of incidental exposure as a means of encouraging cross-ideological exposure. One noticeable trend in the two experiments conducted for this dissertation is that partisan selective exposure was clear among students participating in both studies, but at different levels. Also, data showed that there was no clear role for the social endorsements on Twitter among students in this experiment to reduce selectivity. Moreover, a person's political leaning is more likely to surpass the impact of the social endorsements when users are browsing Twitter on a daily basis. Results showed that students in the second study read tweets from accounts they did not follow in real life and they asserted that they experienced that on a high basis. Implications of these two online experiment studies are discussed.

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