To Örebro University

Hand-arm vibration is a common occupational exposure that causes neurological impairment, myalgia, and vibration-induced Raynaud's phenomena or vibration white fingers (VWF). The pathological mechanism is largely unknown, though several mechanisms have been proposed, involving both immunological vascular damage and defective neural responses. The aim of this study was to test whether the substances interleukin-33 (IL-33), macrophage-derived chemokine (MDC), interleukin-10 (IL-10), endothelin-1 (ET-1), C-C motif chemokine ligand 20 (CCL20), calcitonin, and thromboxane (TXA2) changed before and after occupational hand-arm vibration exposure. 38 full-time shift workers exposed to hand-arm vibration were recruited. All the participants underwent medical examinations regarding symptoms of Raynaud's phenomena. In 29 of the participants, the concentration of IL-33, MDC, IL-10, ET-1, CCL20, calcitonin, and TXA2 was measured before and after a workday. There was a significant increase in ET-1 and calcitonin concentration and a decrease in the CCL20 concentration after the work shift in all participants. In the group suffering from VWF, but not in the non-VWF group, MDC was statistically significantly lower before the work shift (p = .023). The VWF group also showed a significant increase in MDC after the work shift. Exposure to occupational hand-arm vibration is associated with changes in ET-1, calcitonin, and MDC concentration in subjects suffering from vibration white fingers, suggesting a role of these biomarkers in the pathophysiology of this condition.

BACKGROUND: Chronic kidney disease (CKD) is a growing health issue that is becoming more prevalent globally, increasing financial cost on healthcare systems. The purpose of this study is to investigate the incidence of eye diseases in patients diagnosed with CKD in Sweden and to evaluate which eye diseases are most likely to develop.

METHODS: A longitudinal population-based retrospective case-control study was conducted including all individuals diagnosed with chronic kidney disease during the time period 2001-2019. A total of 19 455 cases and 38 890 controls were included. For each case, two controls were matched with the same sex, age, and county of residence.

RESULTS: CKD patients had a significantly higher risk of contracting any eye disease compared to individuals without kidney disease HR 1.73 (CI 1.67-1.79), with an elevated risk for all blocks of diagnoses except for glaucoma HR 0.95 (CI 0.85-1.06). However, this condition developed earlier in cases than in controls. Subanalyses showed an increased risk for chronic eye disease patients to develop cataract HR 1.70 (CI 1.63-1.78), other retinal disorders HR 1.86 (CI 1.72-2.02), and retinal vascular occlusions HR 2.08 (CI 1.73-2.51). In general, diagnosis of an eye disease occurred earlier in cases than controls.

CONCLUSIONS: The results from this study suggest that CKD patients have an increased risk to develop eye disease. Ocular disease seems to develop considerably earlier in CKD, even without staging the severity of the disease, with particularly high risk of developing retinal diseases and cataracts. Screening for eye disease in CKD should be considered.

The primary aim of this study was to determine if occupational exposure to whole-body vibration (WBV) was associated with reporting neck pain. A cross-sectional study was conducted on a sample of the general population living in northern Sweden, aged 24 to 76 years. Data was retrieved through a digital survey that collected information on exposure to WBV and biomechanical exposures as well as subjectively reported neck pain. The study included 5,017 participants (response rate 44%). Neck pain was reported by 269 men (11.8%) and 536 women (20.2%). There was a statistically significant association between reporting occupational exposure to WBV half the time or more (adjusted OR 1.91; 95% CI 1.22-3.00) and reporting neck pain. In gender-stratified analyses, the same pattern was observed in men, while there were too few women to determine any association. We conclude that occupational exposure to whole-body vibration was associated with neck pain in men.

The literature on Raynaud's phenomenon (RP) in the feet is scarce, especially in the occupational setting. The primary aim of our study was to investigate the occurrence of RP in the feet of miners. As part of the MineHealth project, written surveys and clinical examinations were completed by 260 Arctic open-pit miners working in northern Sweden and Norway (participation rate 53.6%). Data on RP were collected using standardised colour charts and questionnaire items. Clinical examination included assessing the perception of vibration and pain in both feet. There were eight women and three men who reported RP in the feet. Four also had RP in their hands but none acknowledged any first-degree relatives with the condition. Nine reported exposure to foot-transmitted vibration and one to hand-arm vibration. Seven showed signs of neurosensory injury in the feet. To conclude, the occurrence of RP in the feet of miners was 4.4%. Most cases with RP in the feet did not report the condition in the hands and were exposed to vibration transmitted directly to the feet. There were no reports of a hereditary component. Most cases with RP in the feet also had clinical findings suggestive of peripheral neuropathy in the feet.

PURPOSE: To study the risk for eye diseases in individuals with Ulcerative Colitis (UC), and to assess whether silica dust-exposure could contribute to the development of inflammatory eye diseases.

METHODS: A case-control study was conducted using a patient register processed by the National Board of Health and Welfare (NBHW) and Statistics Sweden. Cases were diagnosed with UC between 2007 and 2016. Matching was done with two random controls having the same age, sex and county of residence, without a systemic inflammatory disease. Using a job-exposure matrix, cases and controls were assessed for work-related silica dust exposure. The risk for eye disease was estimated by Cox regression analysis with calculation of Hazard Ratio (HR).

RESULTS: A total of 58 989 individuals were included, comprising 19 663 cases and 39 326 controls. The sex distribution was similar. Overall, individuals with UC had an increased risk for eye disease, specified in ICD 10 chapter VII (H00-H59) with HR 1.25 (CI 1.20-1.32). The highest HR on block-level for cases was 1.52 (CI 1.36-1.70), (H15-H22), which includes episcleritis, keratitis and anterior uveitis. The risk for ocular disease was higher in silica dust-exposed than non-exposed with a HR of 1.44 (CI 1.16-1.78) and 1.25 (CI 1.19-1.31), respectively. Among cases, the risk for iridocyclitis (H20) was further elevated by silica dust exposure, with HR of 3.84 (CI 1.64-8.97) in exposed compared to 1.94 (1.57-2.41) in non-exposed.

CONCLUSION: UC is associated with an increased risk for eye diseases, including inflammatory conditions. Our findings highlight that silica dust-exposure may be of importance in the pathogenesis of uveitis.

Vibration exposure from handheld tools can affect the hands with neurological symptoms and vibration-induced Raynaud's phenomenon (VRP). The underlying pathophysiological mechanisms are not fully known, however, changes in the composition of blood parameters may contribute to VRP with an increase in blood viscosity and inflammatory response. The aim of this study was to examine the effect on blood parameters in capillary blood from fingers that had been exposed to a vibrating hand-held tool. This study involved nine healthy participants who had been exposed to vibration and an unexposed control group of six participants. Capillary blood samples were collected before and after vibration exposure for the exposed group, and repeated samples also from the control group. The exposed groups were exposed to vibration for a 15-min period or until they reached a 5.0 m/s2 vibration dose. Analysis of blood status and differential counting of leucocytes was performed on the capillary blood samples. The results of the blood samples showed an increase in mean value for erythrocyte volume fraction (EVF), hemoglobin, red blood cell count, white blood cell count and neutrophils, as well as a decrease of mean cell volume, mean cell hemoglobin, and mean cell hemoglobin concentration. The increase of EVF and neutrophils was statistically significant for samples taken from the index finger but not the little finger. Even though the study was small it showed that an acute vibration exposure to the hands might increase EVF and neutrophilic granulocytes levels in the capillary blood taken from index fingers.

In this study, we present quantitative exposure-response data on silica exposure in male Swedish iron foundry workers receiving inpatient care for cardiovascular, cerebrovascular, and respiratory morbidity. The study show a significantly increased COPD risk at cumulative silica exposures that correspond to TWA silica below the Swedish OEL of 0.1 mg/m3. ObjectiveWe present quantitative exposure-response data on silica exposure in male Swedish iron foundry workers for cardiovascular, cerebrovascular, and respiratory morbidity.MethodsThis research is a cohort study of 2063 male Swedish iron foundry workers. From the Swedish National Patient Registers, data on morbidity incidence were retrieved. A historical measurement database of 1667 respirable silica exposure measurements from 10 Swedish iron foundries was used to calculate the cumulative exposure dose for each worker.ResultsIncreased morbidity risk for the whole group of foundry workers was determined for ischemic heart disease, cerebrovascular disease, chronic obstructive pulmonary disease (COPD), bronchitis, and pneumonia. In addition, an increased risk for COPD at cumulative silica exposures ranging from 0.11 to 0.84 mg/m3 year is presented.ConclusionsThe study presents a significantly increased COPD risk at cumulative silica exposures below the Swedish occupational exposure limit.

OBJECTIVE: To investigate the increased risk for carpal tunnel syndrome (CTS) in men and women with hand-arm vibration (HAV) exposure.

DESIGN: Case-control study of CTS where 4396 cases was obtained from National Outpatient Register between 2005 through 2016. Cases were matched to controls and exposure was estimated using a job exposure matrix.

RESULTS: Exposure to HAV increased the risk of CTS with an OR of 1.61 (95% CI 1.46-1.77). The risk was highest in men <30 years of age and among women <30 years no increased risk was observed. The risk increased with a mean year exposure above 2.5 m/s2 to OR 1.84 (95% CI 1.38-2.46).

CONCLUSIONS: HAV exposure increase the risk of CTS in both genders, with highest risk increase in younger men. This emphasize identification of HAV exposure in patients with CTS.

Hand-arm vibration (HAV) is a common occupational exposure in Sweden and worldwide that causes both acute transient effects and persistent hand-arm symptoms. The health effects include vibration-induced Raynaud’s phenomenon, neuropathic symptoms, carpal tunnel syndrome (CTS), and musculoskeletal disorders. The overall aim of this thesis was to investigate vascular and neurological effects in the hands of workers exposed to hand-arm vibrations.

Methods: In study 1, the aim was to investigate the risk of CTS from hand-arm vibration. This study was conducted as a register study using the National Outpatient Register and a job exposure matrix to estimate HAV exposure. Study 2 aimed to investigate the acute effects of HAV on the nerve functions of the hands and the impact of grip force. Nerve function was evaluated before and after vibration exposure. In study 3, the aim was to identify low molecular organic biomarkers in blood samples from vibration-exposed workers using a novel metabolomics approach. HAV-exposed workers underwent medical examination and blood samples were collected and analysed before and after a work shift. In study 4, the aim was to investigate if arterial abnormalities in the hands could be identified in patients with VWF which also had a positive Allen’s test. In this case series, Doppler ultrasound and magnetic resonance angiography (MRA) investigations were performed to investigate the arterial status in the hands. 

Results: Study 1 showed that the risk of CTS for HAV exposed individuals increased with an OR of 1.61 (95% CI 1.46-1.77) for the whole population. The risk was highest in HAV exposed younger males. Study 2 showed that HAV exposure with high grip force affect nerve function different than with low grip force. In study 3, workers with VWF had metabolic profiles different from participants without VWF, both before and after vibration exposure. In study 4, ultrasound and MRA identified vascular abnormalities in all participants; these abnormalities were a predominantly missing or not complete superficial arch. 

Conclusion: The overall finding is that HAV exposure, even at levels under legislated values, can give negative health effects. These results add new knowledge about CTS, HAV exposure and gender. Both metabolomics and studies of acute effects of HAV could be further studied to find a level of exposure where no health effects appear. With the findings on MRA, there is the possibility that a subgroup of VWF can be subject for treatment.

BACKGROUND: Cold exposure is an underrecognized occupational hazard that may increase the risk of peripheral nerve entrapment. The aim of this study was to determine if self-reported occupational exposure to contact and ambient cooling was associated with symptoms of carpal tunnel syndrome (CTS).

METHODS: In this mainly cross-sectional study, surveys were conducted on a population-based sample of men and women between 18 and 70 years of age, living in northern Sweden. Cold exposure and presence of symptoms suggestive of CTS were subjectively reported. Associations between exposure and outcome were evaluated using logistic regression.

RESULTS: The study included 2,703 women and 2,314 men, with a median age of 60 years (interquartile range 19). Symptoms of CTS were reported by 453 (9.2%). Being highly occupationally exposed (almost always) to contact cooling of the hands was associated with reporting CTS (OR 3.20; 95% CI 1.62-6.33), as was ambient cooling (OR 2.00; 95% CI 1.03-3.88) and severe ambient cooling (OR 4.02 95% CI 2.09-7.71), after adjusting for age, gender, body mass index, current daily smoking, diabetes mellitus, joint disease, and hand-arm vibration exposure. The point estimates increased with longer daily exposure duration. For workers exposed to severe ambient cooling for more than half of their working hours, in addition to performing heavy manual handling every day, the OR for reporting CTS was 7.25 (95% CI 3.88-13.53), with a positive additive interaction effect (expressed as relative excess risk due to interaction) of 4.67.

CONCLUSIONS: Self-reported occupational exposure to contact and ambient cooling was associated with symptoms suggestive of CTS. There were statistically significant positive exposure-response patterns for time spent exposed to contact and ambient cooling at work in relation to reporting symptoms of CTS. Positive additive interaction effects between cold exposure and heavy manual handling were also found. Since there was important potential uncontrolled confounding regarding repetitive wrist movements and forceful gripping, the results need to be confirmed by other studies, preferably with longitudinal design and more detailed exposure assessment.