Changes in Allostatic Load during workplace reorganization.

OBJECTIVE: Allostatic Load (AL) represents the strain on the body produced by repeated physiologic or allostatic responses activated during stressful situations. Several cross-sectional studies have found empirical substantiation for the relationship between impaired psychosocial work environment and high AL. The aim of this longitudinal study is to investigate changes in AL during workplace reorganization that has been shown to cause impaired psychosocial work environment. Moreover, we aim to investigate the association between changes in AL and changes in psychosocial work environment (job strain, effort-reward imbalance) and psychological distress (stress symptoms and perceived stress). METHODS: A major reorganization of non-state public offices was effectuated in Denmark on 1 January 2007. In 2006 and 2008, we collected clinical and questionnaire data from 359 participants, 265 women and 94 men, employed in seven municipality or county administrations. Four municipalities and one county merged with others, while one municipality and one county remained unmerged. We calculated the AL score based on 13 physiological markers reflecting stress responses of the cardiovascular, metabolic, neuroendocrine and immune systems. We analysed changes in AL from 2006 to 2008. RESULTS: AL increased significantly during workplace reorganization in the whole study group but we observed only a tendency of significant increase in AL in the merger group compared with the control group. Moreover, we observed no association between the changes in AL and changes in psychosocial work environment and psychological distress. CONCLUSIONS: This result leaves the conclusion unclear but contributes to the limited research in this area with a longitudinal design and focus on low-risk levels and small changes in AL in healthy people as predictor of future disease.

The neurobehavioral impact of manganese: results and challenges obtained by a meta-analysis of individual participant data.

Results from a meta-analysis of aggregated data provoked a new analysis using individual data on the neuropsychological performance of occupationally exposed workers. Data from eight studies examining 579 exposed and 433 reference participants were included, 28 performance variables analyzed. The performance scores were adjusted for well-known individual-level covariates; the influence of possible, but unknown study-level covariates was attenuated by means of a z-normalization. Associations between performance and exposure were estimated by ANOVAs and ANCOVAs, the latter representing multi-level models. Four cognitive and motor performance variables each indicated significantly lower performances of exposed individuals when confounding was considered; slowed motor performances and deficits in attention and short-term memory were found. Performance on a single test was significantly related to the biomarker manganese in blood. The outcomes on susceptibility were weak. The slowing of responses was the most distinct feature of performances of exposed workers. It remains unclear, whether this result is related to the employed tests or provides important information about early stages of the neurotoxic impairment. More specific cognitive tests need to be employed to answer this question. The lack of dose-response relationships was related to features of the biomarker: it does not reflect the Mn in brain responsible for changes in performances.

Effort reward imbalance, and salivary cortisol in the morning.

BACKGROUND: Effort reward imbalance (ERI) is suggested to increase risk for stress and is hypothesized to increase cortisol levels, especially the awakening cortisol response, ACR. METHODS: In 2006 and 2008, 480 individuals collected saliva samples at awakening and 30 min post-awakening. Mixed effects models with subject as a random effect and appropriate covariates were used to evaluate associations between the Effort Reward Model, and salivary cortisol at awakening (S0), and ACR. RESULTS: ERI was negatively and significantly associated with S0 for women and positively associated with ACR. S0 and ACR increased significantly from 2006 to 2008. CONCLUSION: ERI was significantly associated with cortisol levels at awakening (inverse association) for women, and positively associated with ACR. The population experienced a significant increase in morning cortisol levels and ACR from 2006 to 2008, which may originate in a re-organization of the included work places.

Statistical means to enhance the comparability of data within a pooled analysis of individual data in neurobehavioral toxicology.

Meta-analyses of individual participant data (IPD) provide important contributions to toxicological risk assessments. However, comparability of individual data cannot be taken for granted when information from different studies has to be summarized. By means of statistical standardization approaches the comparability of data might be increased. An analysis of individual data on the neurobehavioral impact of manganese (Mn) exemplifies challenges and effects of a multilevel statistical procedure. Confounding from individual-level and study-level covariates was shown by analyses of variance, but could be reduced by linear regressions and z-normalization using data of the respective control groups. Fixed models that were used to estimate the impact of the neurotoxic exposure, provided evidence that the employed procedures, especially the z-normalization, effectively reduced variance that was unrelated to the neurotoxic exposure. Even after this statistical treatment the fixed effect models revealed differences among studies that did not seem to be exhaustively explicable by concentration differences obvious from the Mn biomarker at hand. IPD studies using confounded endpoints as effects markers can be reasonably summarized when appropriate statistical operations are employed. For the data at hand the proposed normalization allowed new insights into exposure-effect relationships, in general it appears appropriate to investigate the effect of the independent variable more closely.

Effort reward imbalance is associated with vagal withdrawal in Danish public sector employees.

OBJECTIVES: The current study analyzed the relationship between psychosocial work environment assessed by the Effort Reward Imbalance Model (ERI-model) and heart rate variability (HRV) measured at baseline and again, two years later, as this relationship is scarcely covered by the literature. METHODS: Measurements of HRV during seated rest were obtained from 231 public sector employees. The associations between the ERI-model, and HRV were examined using a series of mixed effects models. The dependent variables were the logarithmically transformed levels of HRV-measures. Gender and year of measurement were included as factors, whereas age, and time of measurement were included as covariates. Subject was included as a random effect. RESULTS: Effort and effort reward imbalance were positively associated with heart rate and the ratio between low frequency (LF) and high frequency power (HF) and negatively associated with total power (TP) and HF. Reward was positively associated with TP. CONCLUSION: Adverse psychosocial work environment according to the ERI-model was associated with HRV, especially in the form of vagal withdrawal and most pronounced in women.

Development of depressive symptoms and depression during organizational change--a two-year follow-up study of civil servants.

OBJECTIVE: On 1 January 2007, Denmark went through a major reorganization, where most of its 275 municipalities and 14 counties merged into larger units. Our study aimed to examine the development of depressive symptoms and incident depression among employees affected by this organizational change. METHODS: A total of 685 civil servants employed in the administration of 5 municipalities and 2 counties participated in the study. They answered a postal questionnaire, 8 months prior to and 16 months after the reorganization, regarding working conditions, psychosocial work environment factors, and depressive symptoms, based on the Major Depression Inventory (MDI). During the follow-up period of 2006-2008, 295 employees had experienced a merger with other workplaces (hereafter the merger group), 259 had got a new job (the new job group), and 131 who experienced no change in workplace served as the control group. The three groups were compared to each other for (i) mean score of MDI and (ii) incident cases of depression using general linear models and logistic regression analyses, separately by gender. RESULTS: After adjustment of the MDI for age, occupation, supervisor function, and department at baseline in 2006, no significant differences in increase in MDI were found between the groups. The incidence of depression in the merger group was not significantly higher than the control group [women: odds ratio (OR) 1.5 (95% confidence interval [95% CI] 0.6-3.9), men: OR 1.7 (95% CI 0.2-18.7)], after adjustment for confounders. CONCLUSION: This study showed no significantly increased risk of depression or increase in depressive symptoms among employees exposed to organizational change as a part of a major local government reform.

[The enzyme papain in industry and food causes allergic sensitization]. / Enzymet papain anvendt i industri og fødevarer giver allergi.

The proteolytic enzyme papain is known to cause allergic sensitization. At a research laboratory several employees developed allergic symptoms after occupational exposure to papain dust and were referred to the local Clinic of Occupational Medicine. 10 out of 22 employees reported work-related ocular itching and symptoms of rhinitis. A Histamine Release Test showed that three employees were sensitized to papain. After the introduction of more stringent hygienic procedures including the use of a fume cupboard and external washing of test tubes during use, all work-related symptoms disappeared.

Cognitive function in a cohort of Danish steel workers.

OBJECTIVE: The aim of this study was to evaluate the level of possible cognitive impairment in a cohort of steel workers occupationally exposed to manganese and lead. MATERIAL: Ninety-two employees from an electro-steel works were examined in 1989 and 1995. Fifty-three were re-examined in 2003. Median age of the participants was 53 years, median duration of employment was 24 years, median blood manganese in 1989 and 1995 was 148 and 171 nmol/l, respectively, and median blood lead in 1989 was 0.79 micromol/l. Non-participants were comparable with participants, although they had a higher level of blood manganese in 1989 (186 nmol/l) and 1995 (186 nmol/l). Manganese level in the air was estimated below 1.9 mg/m3 in the 1970s. In the 1990s, manganese level in the air was below 0.28 mg/m3 in the majority of measurements. METHOD: Cognitive function was examined with the Cognitive Function Scanner, a computer-based neuropsychological test battery. From a published set of norms a subgroup (n=106) matched for gender, age and social status was extracted and used for comparison. RESULTS: Learning and memory, visuomotor and visuospatial function, concentration, attention, perception and vigilance were examined. Despite many statistically significant differences between the groups, it was not possible to interpret the results for the steel workers as being better or worse. In a visuomotor subtest, the pen-to-point test, the steel workers were much less accurate than the comparison group. This could be the result of an impaired ability to make fast accurate movements. There were no associations between pen-to-point test results and duration of employment or blood levels of manganese and lead. CONCLUSION: Intellectual impairment could not be shown with the Cognitive Function Scanner in this cohort of low to moderate manganese and lead exposed steel workers. A slight subclinical impairment of the visuomotor function was possibly found.

Neuromotor function in a cohort of Danish steel workers.

OBJECTIVE: With a longitudinal design to evaluate possible neuromotor impairment in a cohort of steel workers exposed to metal dust. MATERIAL: Ninety-two employees from a steel works were examined in 1989 and 1995. Sixty were re-examined in 2003. A non-matched control group was examined in 1996 (n=19) and in 2003 (n=14). Median blood manganese in 1989, 1995 and 2003 was 149, 171 and 155 nmol/l. Median blood lead in 1989 and 2003 was 0.76 and 0.22 micromol/l. Median air concentration of manganese at the steel works was estimated to be 0.11 mg/m3 in 1970s and was 0.03 mg/m3 in 1990s. Median air concentration of lead was estimated to be 0.13 mg/m3 in 1970s and was 0.01 mg/m3 in 1990s. METHOD: The Catsys 2000 system developed by Danish Product Development is computer-based device for measuring hand tremor, hand coordination and reaction time. RESULTS: Over all there were no statistically significant differences in neuromotor function between the participating steel workers, non-participating steel workers and controls in 1995/1996. Only reaction time for the right hand was slower for the participating steel workers. Compared with the control group the steel workers showed a decline in the ability to perform fast precise hand pronation/supination and finger tapping from 1995 to 2005. Correlation analysis showed no associations between test results for fast hand coordination and blood manganese and lead. Only seniority was associated with deterioration of beat regulation of fast pronation/supination of the hands. DISCUSSION: On a group basis the changes were subclinical, but they should none the less be taken seriously. CONCLUSION: Changes of neuromotor function measured as the ability to perform fast precise pronation/supination of the hands and fast precise finger tapping was shown in this cohort of steel workers. No causal relationships could be shown.