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- Schenk, Linda, 1980-
(författare)
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Management of chemical risk through occupational exposure limits
- 2009
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Occupational Exposure Limits (OELs) are used as an important regulatory instrument to protect workers’ health from adverse effects of chemical exposures. The OELs mirror the outcome of the risk assessment and risk management performed by the standard setting actor. In paper I the OELs established by 18 different organisations or national regulatory agencies from the industrialised world were compared. The comparison concerned: (1) what chemicals have been selected and (2) the average level of exposure limits for all chemicals. In paper II the OELs established by 7 different national regulatory agencies of EU member states are compared to those of the European Commission (EC). In addition to the same comparisons as performed in the first study a comparison level was introduced (3) the similarity between the OELs of these EU member states and the OELs recommended by the EC. List of OELs were collected through the web-pages of, and e-mail communication with the standard-setting agencies. The selection of agencies was determined by availability of the lists. The database of paper I contains OELs for a total of 1341 substances; of these 25 substances have OELs from all 18 organisations while more than one third of the substances are only regulated by one organisation alone. In paper II this database was narrowed down to the European perspective. The average level of OELs differs substantially between organisations; the US OSHA exposure limits are (on average) nearly 40 % higher than those of Poland. Also within Europe there was a nearly as large difference. The average level of lists tends to decrease over time, although there are exceptions to this. The similarity index in paper II indicates that the exposure limits of EU member states are converging towards the European Commission’s recommended OELs. These two studies also showed that OELs for the same substance can vary significantly between different standard-setters. The work presented in paper III identifies steps in the risk assessment that could account for these differences. Substances for which the level of OELs vary by a factor of 100 or more were identified and their documentation sought for further scrutiny. Differences in the identification of the critical effect could explain the different level of the OELs for half of the substances. The results reported in paper III also confirm the tendency of older OELs generally being higher. Furthermore, several OELs were more than 30 years old and were based on out-dated knowledge. But the age of the data review could not account for all the differences in data selection, only one fifth of the documents referred to all available key studies. Also the evaluation of the key studies varied significantly.
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| 2. |
- Wennberg, Maria, 1974-
(författare)
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Biomarkers of fish consumption and risk of stroke or myocardial infarction
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The effect of fish consumption on the risk of cardiovascular disease has been extensively studied. Omega-3 fatty acids present in fish, namely eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), have been found to have beneficial effects through several mechanisms. In addition, selenium, an antioxidant, may be protective. Fish also represents the main human exposure source to the pollutant methylmercury (MeHg), which is associated with elevated cardiovascular risk in previous studies. The aim of this thesis was to evaluate whether MeHg is associated with the risk of myocardial infarction (MI) or stroke, whether EPA+DHA or selenium (Se) have protective associations, and if the overall association between fish consumption and risk of stroke or MI is detrimental or protective. A prospective incident case-control study design was used to study effects on stroke or MI. Three hundred and sixty-nine cases with twice as many matched controls were included in the study on stroke, while 431 cases with 499 controls participated in the MI study, all from the Northern Sweden Health and Disease Study. The data was collected from health examinations of the population from 1986 until 1999. Also, time trends in burdens of mercury (Hg), lead (Pb) and cadmium (Cd) in erythrocytes (Ery) from 1990 to 1999 were examined. The food frequency questionnaire (FFQ) used in the case-control studies was correlated with measurements of fatty acids in erythrocyte membranes as biomarkers of intake. In this northern Swedish population, levels of Ery-Hg and Ery-Pb decreased during the 1990´s, but Ery-Cd decreased only in smoking men. No significant associations were found between Ery-Hg or levels of EPA+DHA and the risk of stroke. Men reporting fish consumption >3 meals/week had an elevated risk of stroke. In the MI study, higher levels of Ery-Hg were associated with lower risk of MI. No clear associations were found for reported fish consumption, levels of EPA+DHA or Ery-Se. The validated FFQ has a fair reliability in estimating intake of fatty acids EPA and DHA. However, the low variation in fish consumption in the general population in combination with different versions of the FFQ (with pre-defined, multiple choice alternatives) decreased the reliability of self-reported fish consumption in the case-control studies on risk of stroke or MI. In conclusion, MeHg has no harmful association regarding the risk of stroke or MI in this population with generally low exposure levels. The protective association regarding risk of MI is probably due to Ery-Hg being a biomarker for consumption of fish, a source of other beneficial nutrients. Thus, in this population the benefits of the nutrients in fish appear to overcome the potential harm of MeHg. The finding of elevated stroke risk related to high fish consumption in men will be investigated further.
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| 3. |
- Ekblom Bak, Elin, 1981-, et al.
(författare)
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Accelerometer derived physical activity patterns in 27.890 middle‐aged adults : The SCAPIS cohort study
- 2022
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Ingår i: Scandinavian Journal of Medicine and Science in Sports. - : John Wiley & Sons. - 0905-7188 .- 1600-0838. ; 32:5, s. 866-880
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Tidskriftsartikel (refereegranskat)abstract
- The present study aims to describe accelerometer-assessed physical activity (PA) patterns and fulfillment of PA recommendations in a large sample of middle-aged men and women, and to study differences between subgroups of socio-demographic, socio-economic, and lifestyle-related variables. A total of 27 890 (92.5% of total participants, 52% women, aged 50–64 years) middle-aged men and women with at least four days of valid hip-worn accelerometer data (Actigraph GT3X+, wGT3X+ and wGT3X-BT) from the Swedish CArdioPulmonary bioImage Study, SCAPIS, were included. In total, 54.5% of daily wear time was spent sedentary, 39.1% in low, 5.4% in moderate, and only 0.1% in vigorous PA. Male sex, higher education, low financial strain, born in Sweden, and sedentary/light working situation were related to higher sedentary time, but also higher levels of vigorous PA. High BMI and having multiple chronic diseases associated strongly with higher sedentary time and less time in all three PA intensities. All-year physically active commuters had an overall more active PA pattern. The proportion fulfilling current PA recommendations varied substantially (1.4% to 92.2%) depending on data handling procedures and definition used. Twenty-eight percent was defined as having an “at-risk” behavior, which included both high sedentary time and low vigorous PA. In this large population-based sample, a majority of time was spent sedentary and only a fraction in vigorous PA, with clinically important variations between subgroups. This study provides important reference material and emphasizes the importance of a comprehensive assessment of all aspects of the individual PA pattern in future research and clinical practice.
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| 4. |
- Engholm, Albin, 1991-
(författare)
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Driverless trucks in the Swedish freight transport system : An analysis of future impacts on the transport system and the emerging innovation system
- 2021
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A large-scale introduction of driverless trucks could start taking place during the next decade. While this could bring several economic benefits for freight transport actors and society, it may also change the freight transport system and exacerbate the negative effects of road transport. This thesis aims to increase the understanding of how an introduction of driverless trucks could materialize and impact the freight transport system in Sweden. Two overarching issues are addressed. The first is how freight transport patterns will change due to the impacts of driverless trucks on road transport supply. This is addressed in Paper 1 and Paper 2. The second issue, which is studied in Paper 3, is what factors are shaping the ongoing development towards an introduction of driverless trucks in Sweden. In Paper 1, the impact of driverless trucks on the costs for long-distance road freight transport is studied through a total cost of ownership analysis which shows that driverless trucks could enable cost reductions of around 30%-40% per ton-kilometer. A key determinant of the cost reduction is to what extent reduced driver costs will be offset by other forms of human labor that may be required for driverless truck operations. Other factors, including changes to the truck acquisition cost, have marginal importance. The cost-saving potential provides a strong motivation for freight transport actors to develop and adopt driverless trucks. In Paper 2, the impacts of driverless trucks on road transport demand, utilization of different truck types, modal split, and total logistics costs are studied by using the Swedish national freight transport model Samgods. Two scenario types are studied, one in which driverless trucks substitute manually driven trucks and one where driverless trucks capable of operating between logistics hubs are introduced as a complement to manually driven trucks. The analysis shows that in both scenarios, driverless trucks could reduce total costs for Swedish freight transport in the range of billions of SEK per year. Road transport demand and truck traffic volumes may increase significantly through modal shifts from rail and sea. This could lead to increased societal costs through, for instance, increased CO2 emissions and congestion which are, however, not quantified in the study. In Paper 3, an analysis of the innovation system of driverless trucks based on an interview study with actors involved in the development and introduction of driverless trucks in Sweden is presented. The findings suggest that there are several favorable factors for a successful introduction of driverless trucks, but also that the innovation system is characterized by a high degree of uncertainty related to what infrastructure will be required and available, what business models will be emerging, and which actors will be able to capitalize on the development and which actors that become marginalized in a future with driverless trucks. The findings from this thesis can be of interest for policymakers since it highlights potential benefits and challenges associated with driverless trucks from a transport-system perspective and the provided indicative quantitative estimates on system-level impacts offer a glimpse into a future freight transport system with driverless trucks. Also, the thesis highlights critical challenges for the innovation system of driverless trucks which could guide efforts to improve its performance.
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