Rita Bast-Pettersen

Neuropsychological Effects of Low Mercury Vapor Exposure in Chloralkali Workers

Neuropsychological effects were examined in 47 mercury vapor exposed male chloralkali workers with current low concentrations of urinary mercury (mean U-Hg 5.9 nmol/mmol creatinine (Cr)). Their average duration of exposure was 13.3 years, and the calculated mean concentration of U-Hg was 9.0 nmol Hg/mmol Cr per year (exposure intensity) during their time of exposure. They were compared with 47 age-matched male referents in a cross-sectional study. The two groups were not statistically significantly different with respect to neuropsychological test performance or number of self-reported subjective symptoms. The test results of the Static Steadiness Test, which assesses tremor, were not associated with exposure to mercury vapor. However current smokers had more hand tremor than non-smokers. Statistically significant associations were found between indices of current exposure (the concentration of inorganic mercury in whole blood) and the results of the WAIS Digit Symbol Test and the Benton Visual Retention Test (number of correct responses). This could indicate a small effect of current exposure on visuomotor/psychomotor speed and attention, and immediate visual memory. Whether the association found between the historical exposure intensity and the Digit Symbol Test results may represent long-term consequences of exposure cannot be determined in this study.

Chronic solvent-induced encephalopathy: European consensus of neuropsychological characteristics, assessment, and guidelines for diagnostics

INTRODUCTION The presence of neuropsychological impairment is a hallmark of chronic solvent-induced encephalopathy (CSE), and using clinical neuropsychological procedures to generate a valid assessment of the condition is crucial for its diagnosis. The goals of this consensus document are to provide updated knowledge of the neuropsychological characteristics of CSE and to provide internationally acceptable guidelines for using neuropsychological assessments in the process of diagnosing patients who are suspected of having CSE. MATERIALS AND METHODS A European working group that was composed of experts in the field of the clinical diagnosis of CSE met at several round-table meetings and prepared this report. The first section of the consensus paper addresses a review of the relevant literature that was published between 1985 and March 2012. The second section addresses recommendations for the clinical neuropsychological assessment of patients who are suspected of having CSE. RESULTS The literature review indicates that the most common neuropsychological impairments in CSE patients are within the domains of attention, particularly the speed of information processing, memory, and motor performance. It appears that the influence of CSE on memory processes mainly involves immediate recall and generally involves verbal, visual and visuospatial material. In the second section, six recommendations are presented regarding important functional domains for the neuropsychological diagnostic process of CSE that relate to the evaluation of neuropsychological impairment, the assessment and evaluation of symptoms, differential diagnostic considerations, the reliability and validity of neuropsychological test results, and the retesting of patients. DISCUSSION AND CONCLUSIONS These recommendations will contribute to the improvement of the process for accurately diagnosing CSE, better counselling for CSE patients, the comparability of epidemiological data between countries, and finally, by raising awareness, these recommendations will contribute to combating the adverse health effects of occupational exposure to solvents.

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.

An epidemiological study of reproductive function biomarkers in male welders

Abstract In a cross-sectional study, the serum concentrations of inhibin B and prolactin of 96 male current welders were compared with the concentrations measured in 96 age-matched referents. Also, 23 patients who were all former welders diagnosed as having welding-related manganism were studied. The current welders’ geometric mean (GM) airborne exposure to manganese (Mn) was 121 µg m−3 (range 7–2320). The serum concentrations of prolactin adjusted for age and smoking habits (GM 193 mIU l−1 vs. 166 mIU l−1; p=0.047) and inhibin B adjusted for alcohol consumption (arithmetic mean (AM) 151 ng l−1 vs. 123 ng l−1; p=0.001) were higher in the welders compared with the referents. The whole blood Mn concentration was associated with the serum prolactin concentrations. Tobacco smoking resulted in lower serum prolactin concentrations. The GM serum prolactin concentrations of the patients did not significantly differ from that of the referents, but their AM serum inhibin B concentration was statistically significantly lower. The results may suggest an effect of Mn on the pituitary that is reversible upon cessation of exposure. Lower inhibin B concentrations in the patients could point to a functional impairment of the testicular Sertoli cells, that may be caused by a welding fume component or other factors in their work environment.

The interaction between manganese exposure and alcohol on neurobehavioral outcomes in welders

Neurobehavioral functions were studied in 137 welders exposed to the geometric mean (GM) air concentration of 214 μg/m(3) (range 1-3230) of manganese (Mn) based on the individual mean from two days of air sampling. Only 22 μg/m(3) (GM) was soluble in the artificial lung fluid Hatch solution. The welders were compared to 137 referents (turner/fitters) recruited from the same plants. The GM concentrations of Mn in whole blood (B-Mn) and urine (U-Mn) were 12.8 μg/L and 0.36 μg/g creatinine versus 8.0 μg/L and 0.07 μg/g creatinine in the referents. Alcohol consumption was assessed by measuring carbohydrate deficient transferrin in serum (sCDT). The welders had poorer performance than the referents on the Grooved Pegboard, Finger Tapping, Simple Reaction Time (SRT) and possibly the Maximum Frequency tests. They also reported more subjective symptoms. Welders with sCDT above the upper reference limit had substantially poorer performances on the Grooved Pegboard test, Finger Tapping test and SRT than welders with sCDT below this level. No effect of high sCDT was observed in the referents, indicating an interaction between high sCDT and exposure to Mn for these tests. Self-reported alcohol consumption had no impact on these neurobehavioral test results. A statistically significant difference in the SRT and Grooved Pegboard test results remained after excluding all subjects with sCDT above the normal level, but the difference in test scores between the groups was smaller. These welders also reported more subjective symptoms than the referents. The results suggest that sCDT should be measured in neurobehavioral studies of occupationally Mn exposed populations for a more precise estimation of high alcohol consumption.

The neuropsychological diagnosis of chronic solvent induced encephalopathy (CSE)―A reanalysis of neuropsychological test results in a group of CSE patients diagnosed 20 years ago, based on comparisons with matched controls

AIMS The aims of the study were to analyze the type and size of deficit scores and the weight attached to symptoms in the diagnostic process for a group of patients diagnosed as having chronic solvent encephalopathy (CSE) at a time when exposure levels were high and financial incentives for CSE-sufferers were almost non-existent. METHODS Forty-eight patients referred for possible CSE and 144 age-matched referents were tested with neuropsychological tests. Symptoms were recorded using the Q16. The WHO 1985 recommendations were used when assessing the outcome of the test results. All the subjects were men in manual occupations. RESULTS Thirty-five patients were diagnosed as having CSE; the remaining 13 not so. The tests for cognitive speed and attention were the ones that discriminated best between the patients with CSE and their referents. The effect sizes of the neuropsychological tests were small to moderate, and the largest effect size (d=0.81) was found for the WAIS Digit Symbol. The effect size of the difference between the CSE-group and their referents in terms of self-reported symptoms was large (d=3.35). For the non-CSE-group the differences between patients and referents were smaller and non-significant. However, the effect size in terms of symptoms was almost as large among the non-CSE-group as among the patients diagnosed as having CSE. CONCLUSIONS The patients reported many symptoms but the neuropsychological tests showed only slight to moderate impairment of function. The similarity of the large effect size for symptoms, but different effect sizes for neuropsychological tests results between the CSE-group and non-CSE-group suggest symptoms were (and still are) not very useful in the diagnostic process of CSE. Objective testing with neuropsychological tests is necessary for diagnosis of CSE.

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.

A follow-up study of neurobehavioral functions in welders exposed to manganese.

Welders may be exposed to high amounts of manganese (Mn). In this study 63 welders and 65 referents were followed up with neurobehavioral tests approximately 6 years after the initial examination at baseline. The welders were exposed to the geometric mean (GM) Mn concentration of 116μg/m(3) at baseline and 148μg/m(3) at follow-up. Their mean duration of employments as welders was 19.5 years at follow-up. Being exposed as a welder was associated with a decline between baseline and follow-up in the performance on the Static Steadiness Test, Finger Tapping Test and Grooved Pegboard Test. However, the decline was also associated with having high concentrations of carbohydrate deficient transferrin in serum (sCDT), indicating high alcohol consumption. When subjects with sCDT above the upper reference limit of the laboratory (≥1.7%) were excluded from the analyses, no difference in the decline in performance was observed between welders and referents for any of the applied neurobehavioral tests. Three welders had developed bradykinesia at follow-up, as assessed by a substantial decline in their Finger Tapping Test performance. They had also experienced a severe decline in Foot Tapping, Grooved Pegboard and Postural Sway Test scores (while blindfolded), while postural tremor as assessed with the CATSYS Tremor 7.0 was normal. Their neurobehavioral test performance at baseline 6 years previously had been normal.

Psychosomatic symptoms and stressful working conditions among Palestinian nurses: a cross-sectional study.

Background: High levels of perceived stressful working conditions have been found to have an adverse effect on physical and mental health. Objectives: To examine the associations between self-reported stressful working conditions and Psychosomatic Symptoms (PSS), and to investigate possible gender differences. Methods: The present cross-sectional study comprises 430 nurses employed in Hebron district, Palestine. Self-reported stressful working conditions were recorded, and a Psychosomatic Symptoms Check list was used to assess prevalence of PSS. Findings: Median score on the psychosomatic symptom checklist for the group was 11, (range 1–21). Women reported more symptoms than men, with medians 11.6 and 10.0, respectively (p = .0001). PSS were associated with more self-reported stressful working conditions for both men (p < .0001) and women (p < .0001). The association was strongest among men. Conclusions: PSS were associated with high self-reported stressful working conditions, and this association was strongest among the men.

Shift work, mental distress and job satisfaction among Palestinian nurses

Background Associations between shift work (SW) schedules, mental distress and job satisfaction have never been completely described. Aims To examine gender-specific associations of SW with mental distress and job satisfaction in nurses in Hebron District, Palestine, in 2012. Methods Detailed information on work schedules (day versus shift), socio-demographic status, mental distress (General Health Questionnaire, GHQ-30) and job satisfaction (Generic Job Satisfaction Scale) in nurses employed in Hebron District, Palestine, was obtained through a questionnaire survey. Associations of SW and outcomes were examined by linear regression analysis. Results Of 372 nurses eligible for the study, 309 and 338 completed surveys regarding mental distress and job satisfaction, respectively. The sample comprised 62% women and 38% men. After adjusting for covariates, women working shifts reported significantly higher levels of mean mental distress [β coefficient 3.6; 95% confidence interval (CI) 0.3–7.0] compared with women working regular day shifts. Men working shifts reported significantly lower levels of job satisfaction (–3.3; 95% CI –6.2 to –0.5) than men working regular day shifts. Women reported higher levels of mental distress than men, but this was unrelated to work schedule. Conclusions In this study, nurses working shifts reported higher levels of mental distress and lower levels of job satisfaction, although these associations were weaker when adjusted for potential covariates. There was no evidence of a gender differential in the association between SW and mental distress and job satisfaction.