Neuropsychological function among workers exposed to aluminum - a mini-review

Aluminum (Al) is the most common element in nature after oxygen and silicon. Aluminum has been proposed to be a causative agent in the development of neurodegenerative diseases. Aluminum made available via the lungs, as it is in occupational settings, is probably better absorbed than that entering the body via the gastrointestinal tract. Neuropsychological tests are sensitive methods for detecting subtle functional impairment of the nervous system. This minireview is based on a systematic literature search for studies on workers occupationally exposed to aluminum. The tests were categorized as belonging to one of 12 different neuropsychological functions. The level of significance was set at p<0.05. Among the 559 papers identified, 24 fulfilled the inclusion criteria. There were no clear, consistent findings of occupational aluminum exposure being correlated with neuropsychological deficits. However, there was a weak tendency toward worse performances on tests related to information processing speed and a slight tendency toward weaker performances on memory tests for workers exposed to aluminum. The limited number of studies in this field makes it difficult to draw a clear conclusion regarding whether occupational exposure to aluminum increases the risk of altered neuropsychological function.

Associations between stressful working conditions and psychosomatic symptoms among Palestinian nurses: a cross-sectional survey

BACKGROUND

Stressful working conditions among nurses have adverse effects on their physical and mental health. We investigated associations between self-reported stressful working conditions and psychosomatic symptoms among nurses in the Hebron district, occupied Palestinian Territory, and whether there are differences the sexes in the perceptions of working conditions and psychosomatic symptoms.

METHODS

We did a cross-sectional survey between Oct 7 and Dec 10, 2012, among registered nurses in all health sectors in Hebron district. A nine-point ordinal scale of working conditions was used to categorise perception of stress as low, medium, or high, and seven psychosomatic symptoms were recorded on a checklist coded as never (0), seldom (1), occasionally (2), or often (3), allowing for a total score between 0 and 21. All analyses were done with STATA (version 10). P values of less than 0·05 were significant. Participation in the study was voluntary, and written informed consent was obtained from each participant. The study was approved by the Regional Committee for Medical and Health Research Ethics, Norway. Permission to do the study was obtained from the Palestinian Ministry of Health.

FINDINGS

Among 372 eligible nurses, ten were on extended leave from work, 16 declined to participate, and four had incomplete data, giving a final sample of 342 nurses (92% response rate). 212 (62%) were women and 130 (38%) were men. Low levels of stress were reported by 42 (12%) nurses, medium levels by 206 (60%), and high levels by 94 (28%). The mean score of psychosomatic symptoms for the group was 10·4 (SD 4·02, range 0-21). Scores did not differ significantly between men and women. Mean symptom scores differed between nurses with self-reported highly stressful working conditions and those with low levels of stress (12.6 vs 8.4, difference 4·1, 95% CI 2·7-5·5; p<0·001). Among male nurses, those with self-reported highly stressful working conditions had a mean psychosomatic symptom score of 13.0, compared with that was 7.7 among those working in low-stress conditions (difference 5·3 units, p<0·001). This effect remained significant after adjustment for the covariates age, education, number of children, work schedule, and years of experience (12·6 vs 7·7, difference 4·9 units, 95% CI 2·6-7·2). Among female nurses, the scores among those with high-stress working conditions was 12.4 and for those with low-stress working conditions was 9.0 (difference 3·4 units, p<0·001). After adjustment the difference remained similar (12·4 vs 9·0, difference 3·5 units, 95% CI 1·7-5·3, p<0·001).

INTERPRETATION

We found that psychosomatic symptoms increased as self-reported perception of stressful working conditions increased, irrespective of sex. The study had a cross-sectional design and both exposure and outcomes were measured using self-report and, therefore, interpretation of the results should be made with caution. Longitudinal epidemiological studies are recommended. Future studies should investigate whether stressful working conditions affect the quality of patients' care in health services.

FUNDING

Norwegian Programme for Development, Research and Education.

Neurosensory component of hand-arm vibration syndrome: a 22-year follow-up study

BACKGROUND

Knowledge about the long-term course of the neurologic component of hand-arm vibration syndrome (HAVS) is scarce.

AIMS

To study the course and prognostic factors of the neurosensory component of HAVS over a period of 22 years.

METHODS

Forty male sheet metal workers, with a mean age of 60 (range 45-78) years at follow-up, were examined with a test battery in 1994 and 2017. At baseline, the sample comprised 27 workers with HAVS symptoms and 13 workers without HAVS symptoms. Among the 27 workers, 25 workers reported work-related hand-arm vibration during follow-up (mean 3639 h). In 2017, the mean time since vibration stopped was 8.4 years.

RESULTS

Among the 27 workers with HAVS in 1994, no overall statistically significant change was observed in hand numbness (Stockholm Workshop Scale), shoulder/arm pain (pain scale) or finger pain from 1994 to 2017. However, vibration exposure during follow-up was associated with increased finger pain. Cotinine, carbohydrate-deficient transferrin, glycosylated haemoglobin and folate were not associated with changes in neurosensory symptoms or manual dexterity (Grooved Pegboard) from 1994 to 2017. A diagnosis of HAVS in 1994 did not predict poor hand strength 22 years later. Isolated hand numbness (without white finger attacks) was more common at baseline than at follow-up.

CONCLUSIONS

This 22-year follow-up study indicates a tendency towards irreversibility of hand numbness and finger pain in workers with HAVS. Continued vibration exposure seems to predict increased finger pain. Our findings highlight the importance of HAVS prevention.

Vascular component of hand-arm vibration syndrome: a 22-year follow-up study

BACKGROUND

Vibration-induced white finger (VWF) is often assessed using the Stockholm Workshop Scale (SWS) and cold challenge plethysmography. However, long-term longitudinal studies using both methods are scarce.

AIMS

To study the long-term course and prognostic factors of VWF assessed with the SWS and photoplethysmography (PPG), and to examine the effects of lifestyle on PPG score, regardless of VWF status.

METHODS

Forty male construction workers were examined with a test battery and clinical examination in 1994 and 2016/17.

RESULTS

At baseline, the sample comprised 27 workers with, and 13 without, symptoms of hand-arm vibration syndrome (HAVS). Thirty-five workers reported vibration exposure during follow-up. The mean age of the workers was 60 years (45-78) at follow-up. The paired t-test showed that PPG scores deteriorated from 1994 to 2017 in the 27 workers with HAVS in 1994 (mean difference 2.7 min, 95% confidence interval (CI) 0.2-5.2). However, there was no statistically significant change in SWS scores in these workers over time. Smoking and age were associated with PPG score deterioration. Vibration exposure during follow-up predicted SWS score deterioration: 1000 h of exposure predicted a deterioration stage of 0.09 (95% CI 0.03-0.16). Analysis of all 40 workers showed that 2017 PPG scores were associated with positive serum cotinine and self-reported smoking during follow-up.

CONCLUSIONS

Whereas age and smoking predicted a PPG deterioration, continued vibration exposure predicted worsening of white finger symptoms. The association of PPG score and smoking should be considered in diagnostic and prognostic factor evaluations.

Psychosomatic symptoms among Palestinian nurses exposed to workplace aggression

BACKGROUND

The study examined associations between workplace aggression (WPA) and psychosomatic symptoms in Palestinian nurses.

METHODS

The 341 nurses, (62% females and 38% males), answered a WHO questionnaire and a psychosomatic symptoms checklist.

RESULTS

A total of 27.3% of the nurses reported exposure to WPA of any kind within the last 12 months. After adjusting for covariates, female nurses exposed to WPA of any kind and those exposed to verbal aggression reported a higher symptom score: (1.5; 95% confidence interval [CI]: 0.3, 2.7), and (1.4; 95%CI 0.2, 2.6), respectively, than unexposed females. Male nurses exposed to bullying reported a higher symptom score: (3.2; 95%CI 1.0, 5.5) than unexposed males.

CONCLUSIONS

Exposure to WPA was associated with higher occurrences of psychosomatic symptoms for both sexes. The female nurses reacted most strongly to verbal aggression or to WPA of any type, while bullying was associated with the male nurses' symptoms.

Job satisfaction and mental health of Palestinian nurses with shift work: a cross-sectional study

BACKGROUND

Shift work is associated with sleep disturbances, mental health problems, and job dissatisfaction. Disparities between male and female nurses in the effect of shift work on mental distress and job satisfaction have been scarcely studied. We aimed to examine differences between female and male nurses in the associations between shift work and job satisfaction and mental health.

METHODS

In this cross-sectional study, male and female nurses were recruited to rate their job satisfaction on the Generic Job Satisfaction Scale and to complete the General Health Questionnaire (GHQ-30). Associations between shift work, mental distress, and satisfaction were estimated from χ² tests and linear regression analyses using Stata/IC10. The study was approved by the ministry of health. Written informed consent was provided by all participants.

FINDINGS

In 2012, we recruited 372 registered nurses from the Hebron governorate in the occupied Palestinian territory. 28 (8%) nurses were excluded, and the final sample (n=344) included 213 (62%) women and 131 (38%) men. 338 nurses rated their job satisfaction, and 309 nurses completed the GHQ-30. After adjusting for covariates, men with shift work reported significantly lower job satisfaction (β-coefficient -3·3, 95% CI -6·2 to -0·5) than men with day schedules. Women with shift work reported significantly higher levels of mental distress (3·6, 95% CI 0·3 to 7·0) than women with day schedules. Distress was reported by more women than men, but this difference concerned only nurses working day shifts. No differences in job satisfaction associated with shift work was seen between men and women. We found no demonstrable interaction between sex and shift work for job satisfaction (β-coefficient -1·6, 95% CI -4·4 to 1·2) or distress (-0·03, 95% CI -5·3 to 5·3).

INTERPRETATION

Shift work was associated with low job satisfaction in male nurses and high distress in female nurses. Because the study had a cross-sectional design and both exposure and outcomes were measured using self-report, the results should be interpreted with caution. Further studies should investigate whether shift work affects the quality of patient care.

FUNDING

The Norwegian Programme for Development, Research and Education (NUFU; NUFU pro x1 50/2002 and NUFUSM-2008/10232) and The National Norwegian State Education Loan Funds.

Tremor and hand-arm vibration syndrome (HAVS) in road maintenance workers

Objectives

The aim of this study was to evaluate postural and rest tremor among workers using vibrating hand tools, taking into account the possible effects of toxicants such as alcohol and tobacco. A further aim was to study workers diagnosed with hand-arm vibration syndrome (HAVS) at the time of examination.

Methods

This study comprises 103 road maintenance workers, 55 exposed to vibrating hand tools (age 41.0 years; range 21–62) and 48 referents (age 38.5 years; range 19–64). They were examined with the CATSYS Tremor Pen^®. Exposure to vibrating tools and serum biomarkers of alcohol and tobacco consumption were measured.

Results

Cumulative exposure to vibrating tools was associated with increased postural (p < 0.01) and rest tremor (p < 0.05) and with a higher Center Frequency of postural tremor (p < 0.01) among smokers and users of smokeless tobacco. Rest tremor Center Frequency was higher than postural tremor frequency (p < 0.001).

Conclusions

The main findings indicate an association between cumulative exposure to hand-held vibrating tools, tremor parameters and consumption of tobacco products. The hand position is important when testing for tremor. Rest tremor had a higher Center Frequency. Postural tremor was more strongly associated with exposure than rest tremor. The finding of increased tremor among the HAVS subjects indicated that tremor might be a part of the clinical picture of a HAVS diagnosis. As with all cross-sectional studies, inferences should be made with caution when drawing conclusions about associations between exposure and possible effects. Future research using longitudinal design is required to validate the findings of the present study.

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.

Workplace aggression, psychological distress, and job satisfaction among Palestinian nurses: A cross-sectional study

BACKGROUND

Nurses can be exposed to aggressive behavior from patients, patient's relatives, colleagues and visitors.

PURPOSE

To determine the prevalence of workplace aggression among Palestinian nurses in the Hebron district and to examine cross-sectional associations between exposure to workplace aggression and the occurrence of psychological distress and job satisfaction.

METHODS

Of 372 nurses eligible for the study, 343 were included (response rate of 92.2%). The sample comprised 62% females and 38% males. The participants responded to questions about their socio-demographic status, workplace aggression (WHO questionnaires), psychological distress (General Health Questionnaire, GHQ-30), and job satisfaction (Generic Job Satisfaction Scale).

RESULTS

Ninety-three (27.1%) of the respondents reported exposure to workplace aggression of any kind. Seventeen (5%) reported exposure to physical aggression, 83 (24.2%) reported exposure to verbal aggression, and 25 (7.3%) reported exposure to bullying. The patients and the patients' relatives were the main sources of physical and verbal aggression, whereas colleagues were the main source of bullying. Males reported a higher prevalence of bullying than females. Younger nurses reported a higher prevalence of exposure to physical aggression, verbal aggression and bullying. Verbal aggression was associated with more psychological distress. Bullying was associated with lower job satisfaction.

CONCLUSIONS

More than a quarter of the nurses reported that they had been subject to some sort of aggression at the workplace. Verbal aggression was associated with higher psychological distress. Workplace bullying was associated with lower job satisfaction. Increased awareness and preventive measures to address this problem among health care workers are warranted.

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.

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.

The bioavailability of manganese in welders in relation to its solubility in welding fumes

Blood and urine samples for determination of manganese (Mn) and iron (Fe) concentrations were collected in a cross-sectional study of 137 currently exposed welders, 137 referents and 34 former welders. Aerosol samples for measurements of personal air exposure to Mn and Fe were also collected. The aerosol samples were assessed for their solubility using a simulated lung lining fluid (Hatch solution). On average 13.8% of the total Mn mass (range 1-49%; N = 237) was soluble (Hatch sol), while only 1.4% (<0.1-10.0%; N = 237) of the total Fe mass was Hatch sol. The welders had statistically significantly higher geometric mean concentrations of Mn in whole blood (B-Mn 12.8 vs. 8.0 μg L (-1)), serum (S-Mn 1.04 vs. 0.77 μg L(-1)) and urine (U-Mn 0.36 vs. 0.07 μg g (-1) cr.) than the referents. Statistically significant univariate correlations were observed between exposure to Hatch sol Mn in the welding aerosol and B-Mn, S-Mn and U-Mn respectively. Pearson's correlation coefficient between mean Hatch sol Mn of two days preceding the collection of biological samples and U-Mn was 0.46 (p < 0.001). The duration of employment as a welder in years was also associated with B-Mn and S-Mn, but not with U-Mn. Statistically significantly higher U-Mn and B-Mn were observed in welders currently exposed to even less than 12 and 6 μg m (-3) Hatchsol Mn, respectively. When using the 95(th) percentile concentration among the referents as a cut-point, 70.0 and 64.5% of the most highly exposed welders exceeded this level with respect to B-Mn and U-Mn. The concentrations of B-Mn, S-Mn and U-Mn were all highly correlated in the welders, but not in the referents.

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.

An epidemiological study of reproductive function biomarkers in male welders

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 microg 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.

Hand tremor related to smoking habits and the consumption of caffeine in male industrial workers

Tremor was measured in 49 smokers/snuffers and in 49 non-smokers/non-snuffers in a cross-sectional study. The Kløve-Matthews static steadiness test and TREMOR 7.0 from the CATSYS test system were used to assess the hand tremor. The creatinine (cr) corrected arithmetic mean concentrations of cotinine in urine were 11 microg/g cr (range 0.1-430) in the non-smokers/non-snuffers compared to 1,417 microg/g cr (range 45-3,780) in the smokers/snuffers. The geometric mean urinary caffeine concentrations were 797 microg/g cr (range 0.5-13,330) in the non-smokers/non-snuffers versus 654 microg/g cr (range 0.9-7,470) in the smokers/snuffers. Increased tremor was found in the group of smokers/snuffers compared to the non-smokers/non-snuffers for several parameters on the tremor measurements, e.g. geometric mean tremor intensity of 0.14 m/s(2) (range 0.09-0.40) in the smokers/snuffers versus 0.11 m/s(2) (range 0.07-0.22) in the non-smokers/non-snuffers for the dominant hand were quantified. Also the mean scores on the static steadiness test were inferior in the smokers/snuffers, in particular for the number of touches. The results further indicate that the frequency dispersion is smaller in the smokers/snuffers compared to the non-smokers/non-snuffers. No systematic association was observed between the biomarkers of nicotine and caffeine exposure and the tremor measurements. However, older age appeared to be an important predictor for the magnitude of tremor in the smokers/snuffers, but not in the non-smokers/non-snuffers.

The Kløve–Matthews Static Steadiness Test Compared with the DPD TREMORComparison of a Fine Motor Control Task with Measures of Tremor in Smokers and Manganese-Exposed Workers

The aim of this study was to compare two tests for tremor/fine motor control as regards their sensitivity in relation to effects on tremor of exposure to manganese and cigarette smoke. One hundred manganese-exposed workers were compared with 100 age-matched referents. The subjects were tested with the Kløve-Matthews static steadiness test (hole tremormeter) and the DPD TREMOR (accelerometer). The manganese-exposed subjects showed increased postural tremor compared to the referents. The tremor had a larger frequency dispersion among the exposed subjects than among the referents as assessed by the TREMOR 7.0 test system, indicating that the tremor had a pattern where the power was burned at a wider spectre of frequencies among the exposed subjects than among the referents. The two tests differed in their ability to demonstrate tremor, depending of the type of exposure (manganese or cigarette smoke). The static steadiness test was better than the TREMOR at discriminating between manganese-exposed subjects and referents while the TREMOR was better at discriminating between smokers and non-smokers than the static steadiness test. The tests also differed in their ability to demonstrate tremor depending on the frequency of tremor. The Tremor Intensity I was higher for subjects with higher tremor frequency, while no such effect was found for the static steadiness test parameters. When studying the effects of exposures where the quality of the tremor is unknown, it is suggested to include at least two tremor tests, one based on acceleration and the other on displacement.

A neurobehavioral study of chloralkali workers after the cessation of exposure to mercury vapor

Neurobehavioral functions were examined in 49 male workers who had been previously exposed to mercury vapor. They were compared with 49 age-matched male referents in a cross-sectional study. The average duration of exposure in the index group was 13.1 years at a calculated mean urinary mercury (U-Hg) concentration of 9.3 nmol Hg/mmol creatinine (Cr.)/year. The exposure had ceased on average 4.8 (range 4.2-10.0) years prior to the examinations. Forty-one exposed participants and 40 referents had also been examined approximately 5 years previously, while they were still under ongoing exposure. The neurobehavioral test scores and the number of subjective symptoms were similar in the previously exposed subjects and the referents. No significant differences in the development of the neurobehavioral test scores were observed between those 41 previously exposed subjects who had also been examined while they were still being exposed when compared to the 40 referents. However, the difference in the Digit Symbol Test scores between the two occasions was associated with the concentration of inorganic mercury in whole blood while they were still under exposure. The results suggest that no long-term effects of mercury vapor exposure are found at the exposure level experienced by these workers. The study may indicate that the test performance on the Digit Symbol Test improves after exposure cessation in the subjects with the highest B-Hg concentrations, and that this test may be quite sensitive to the effects of mercury vapor exposure.

Neuropsychological function in manganese alloy plant workers

OBJECTIVES

The objective was to investigate potential nervous system effects of manganese (Mn) exposure in workers employed in manganese-alloy-producing plants.

METHODS

One hundred male Mn alloy plant workers were compared with 100 age-matched referents. The subjects were examined with a comprehensive neuropsychological test battery. Exposure was assessed by measurement of Mn concentrations in the workroom air, blood and urine.

RESULTS

The geometric mean (GM) concentration of inhalable Mn in workroom air was 301 microg/m(3). The GM concentration of Mn in whole blood (181 nmol/l vs 160 nmol/l) ( P=0.002) and urine (0.9 nmol/mmol creatinine vs 0.4 nmol/mmol creatinine) ( P<0.001) was higher among the exposed subjects than among the referents. The Mn-exposed subjects had increased postural tremor while conducting a visually guided tremor test (static steadiness test) compared with the referents (mean number of contacts 94 vs 59 ( P= 0.001); duration of contacts (in seconds) 5.1 vs 3.5 ( P=0.003)). The tremor had larger frequency dispersion, indicating that the tremor included a wider variety of frequencies, among the exposed subjects than among the referents, assessed by the "TREMOR" test system. Smoking habits (self-reported) influenced the tremor parameters significantly, the Mn-exposed smokers having more tremor than the non-smoking Mn-exposed subjects. No differences between the groups were found in tests for cognitive functions, reaction time or in symptom reporting.

CONCLUSION

The Mn-exposed subjects had increased hand tremor compared with their referents. The tremor was related to exposure parameters. Smoking habits (self-reported) influenced the tremor parameters.

Endocrine and immunologic markers in manganese alloy production workers

OBJECTIVES

The aim of this study was to investigate selected hormones and immunologic markers in manganese alloy production workers with current and long-term manganese exposure.

METHODS

One hundred randomly selected male workers exposed to manganese were compared with 100 male referents (matched for age) from similar process industries in a cross-sectional design.

RESULTS

The geometric mean of the exposed workers' urinary manganese concentration was 0.9 (range 0.1-126.3) nmol/mmol creatinine (Cr) versus 0.4 (range 0.1-13.1) nmol/mmol Cr for the referents. The mean duration of exposure to manganese was 20.0 (range 2.1-41.0) years. The geometric mean of the prolactin serum concentration was higher for the exposed subjects than for the referents (229 versus 197 mIE/l, P=0.06). Serum prolactin was associated with current exposure to "soluble inhalable manganese", duration of exposure, and smoking habits. The subjects with the longest duration of exposure to manganese or the highest current exposure to "soluble inhalable manganese" had a statistically significantly higher serum prolactin concentration than the referents. The smokers had a lower serum prolactin concentration than the nonsmokers. The concentrations of the measured immunologic markers were similar in the groups.

CONCLUSIONS

The study indicates that manganese exposure can increase the serum prolactin concentration. Both duration and current level of exposure are related to the slight increase, which also appears to be modified by current smoking habits. The serum prolactin concentrations were generally within the reference limits of the laboratory and thus not suitable as an exposure marker at these exposure levels.

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.

Neurobehavioral performance in aluminum welders

METHODS

Twenty aluminum welders (mean age 33 years; range 21-52), who had been exposed to aluminum for an average of 8.1 years (range 2-21), were tested for tremor and reaction time and screened for neuropsychiatric symptoms in a cross-sectional study. The welders' median urinary aluminum concentration was 1.5 micromol/L (range 0. 7-4.8). Aluminum in air, measured inside the respiratory protection, was 0.9 mg/m(3) (range 0.6-3.8). The welders were compared with twenty construction workers matched for age.

RESULTS

Welders reported more symptoms than referents did (median 2 vs. 1; P=0.047). Although the welders as a group performed better than the referents on a tremor test, years of exposure, but not age, was predictive of poorer performance. The welders' reaction times were rapid by clinical standards (mean simple reaction time (SRT): 221 milliseconds; mean continuous performance test (CPT): 364 milliseconds). Although, as a group, they performed better than the referents, there was a statistically significant relation between longer reaction times and aluminum in air (air-Al).

CONCLUSIONS

The relations between hand steadiness and years exposed, and between reaction time and air-Al, could indicate slight effects from exposure to aluminum. The possibility of selection of workers with high manual skills into welding work and a possible job-related training effect, might partly serve to explain the good performance among the welders.

Long-term neuropsychological effects in non-saturation construction divers

BACKGROUND

Since the early 1980s, there has been much debate about whether shallow water diving may lead to long-term adverse effects on the nervous system.

HYPOTHESIS

The aim of the study was to investigate possible neuropsychological effects from repeated diving in divers without overt neurological insult.

METHODS

Twenty construction divers recruited from two companies of contractors were tested with a neuropsychological test battery in a cross-sectional study. The divers were on average 40 (range 24-54) yr old. They had worked as divers for an average of 18 (range 5-33) yr. Their mean diving experience was more than 4000 (range 450-13200) dives. A group of younger trainees at a diving school and a group of age-matched construction workers were recruited as controls.

RESULTS

The construction divers did not show clinical signs of mental impairment. However, their neuropsychological test results indicated slight effects in the form of longer reaction time.

CONCLUSIONS

The main finding in this study of non-saturation construction divers was that there was no clear evidence of neuropsychological deficit due to extensive diving experience. However, it is suggested that the prolonged reaction time can be ascribed to extensive non-saturation diving.

[Health care personnel in Norway]

In 1990, the Nordic Council of Ministers initiated the joint Nordic project on "Work and health among health care personnel". The main aims were: To review and evaluate research data concerning the health and work of health care personnel in the Nordic countries, initiate joint Nordic projects and promote collaboration between Nordic researchers. Altogether more than one million people in the Nordic countries are employed in the health care sector, or almost 10% of the labour force. In all the Nordic countries the labour force in the health sector is dominated by women; the proportion of women being between 84 and 87%. In Norway and Sweden a large share of the labour force works part time. When controlled for sex and level of education, sick leave is the same among health personnel as among the general working population. As in the whole population, sick leave is higher among women, and among persons with a lower level of education. In general, workers in the health care sector in the Nordic countries run no greater risk of developing occupationally related injuries than other workers do. In a register-based study of Swedish workers it was found that the risk of being absent from work because of violence or threats is higher among health personnel than in the general working population.

[Treatment with hyperbaric oxygen. Illustrated by the treatment of a patient with retinitis pigmentosa]

A 26 year old man, who was physically fit and occupationally active but had retinitis pigmentosa and a slight hearing impairment, received hyperbaric oxygen treatment for 97 minutes at a pressure of 240 kPA for five days a week over a period of four weeks. After cessation of the treatment his lateral vision was found to be improved. The patient was examined both prior to and after the hyperbaric oxygen treatment to assess possible adverse effects. The examination consisted of a comprehensive neuropsychological test battery, audiometry and spirometry. The patient showed a reversible reduction in gas diffusion for CO (TLCO). No adverse effects on the central nervous system were found. He achieved higher scores in an intelligence test when retested. The gain was greater than usually found as a practice effect. The article discusses possible indications for hyperbaric oxygen treatment.

Neuropsychological deficit among elderly workers in aluminum production

A cross-sectional study was conducted at a Norwegian primary aluminum plant. All workers aged 61-66 years were offered early retirement benefits. Among the workers, 47 met the study criteria and 38 (81%), comprising 14 potroom workers, 8 foundry workers, and 16 controls, volunteered to participate. They were tested with a neuropsychological test battery. Workers in potrooms with Søderberg electrolytic cells were found to show signs of impairment of the nervous system. A test for tremor discriminated significantly between the potroom group and the controls. There was a suggestion of increased risk of impaired visuospatial organization and a tendency to a decline in psychomotor tempo in the potroom workers. We suggest that the above findings may be related to long-term occupational exposure in the potroom, and further to chronic low-dose exposure to aluminum.