Occurrence of cognitive symptoms in dental assistants with previous occupational exposure to metallic mercury.

Previous investigations have presented evidence for an increased prevalence of late cognitive effects in dental personnel exposed to metallic mercury. We wanted to examine if there was a correlation between mercury exposure and cognitive effects in a Norwegian population of dental workers, and if so, to quantify the occurrence. The study group consisted of 608 female dental assistants from central Norway and 425 female controls from the general population, all under the age of 70. They had responded to a standardized postal questionnaire (Euroquest) inquiring about seven symptoms in regard to neurology, psychosomatics, memory, concentration, mood, sleep disturbances, and fatigue. A score was calculated for each symptom based on 4-15 single questions graded on a scale from 1 (seldom or never) to 4 (very often). Dental assistants and controls had a participation rate of 56.4% and 42.9% respectively. Dental assistants reported more cognitive symptoms than the controls, but on average they reported having each of the symptoms "now and then" or less frequently. There were 4.4% of the dental assistants and 2.8% of the controls who reported having three or more of the seven symptoms "often" or more frequently. The corresponding figures for five or more of the seven symptoms were 1.0% and 0.5% respectively. The occurrence of cognitive malfunction may be moderately increased in dental assistants. For dental assistants there was a relative risk of 1.6 of having three or more symptoms "often" or more frequently, and a relative risk of 2.0 of having five or more symptoms as frequently. It can be assumed from our results that the prevalence of possibly work-related cognitive malfunction in dental assistants is between 0.4% and 2.8%, dependent on the applied severity.

Increase in interleukin-6 and fibrinogen after exposure to dust in tunnel construction workers.

OBJECTIVES: To see if there is any change in blood concentrations of interleukin-6 (IL-6) and fibrinogen during a working shift in tunnel construction workers. METHODS: 12 Tunnel construction workers were followed up during a 24 hours period after returning from a 9 day work free period. The first blood sample was taken on Monday afternoon before starting the shift. Another was taken around midnight after 8 hours of work, and another the next afternoon after about 12 hours of rest. Exposure to respirable dust was measured by personal samplers. RESULTS: The exposure of the workers to respirable dust, in terms of an 8 hour time weighted average, varied between 0.3 and 1.9 mg/m(3). For IL-6, there was an increase in the median serum concentration from 1.14 ng/l before starting the shift to 4.86 ng/l after 8 hours of work (p=0.002). For fibrinogen, there was an increase in the median concentration from 3.40 g/l before entering the shift to 3.70 g/l 24 hours later (p=0.044). There was a positive correlation between values of IL-6 at the end of the working shift and the fibrinogen concentrations the next afternoon (Pearson's R=0.73, p=0.007). The observed increase in IL-6 was significant for both smokers and non-smokers. CONCLUSION: The study shows an increase in both IL-6 and fibrinogen concentrations during a working shift for both smoking and non-smoking tunnel construction workers.

Ultra low dose X-ray spinal examinations.

The study and treatment of spinal deformities may lead to excessive doses of radiation for patients (especially children) examined by conventional X-ray radiology apparatus. In order to avoid this very crucial problem, a new X-ray radiology system has been devised. The new apparatus uses a high efficiency linear solid-state detector and highly sensitive electronics, operating in single X-ray counting mode (quantum mode). The scan parameters and image filtering are computer controlled. Data is acquired in real time by a high speed VME system. In this paper, the first images recorded using this new apparatus are shown. The main conclusion of the preliminary comparative dosimetric analysis is that it is possible to divide the patient's dose by a factor of at least ten to one hundred with the quantum X-ray radiology apparatus.

Sign of eye irritation in female hospital workers and the indoor environment.

The relationships between indoor environment factors and signs of eye irritation were studied in a sample of female personnel with (n = 112) and without (n = 64) mucous membrane symptoms working in 36 nursing departments at geriatric hospitals in the municipality of Trondheim, Norway. The indoor climate was characterised by high room temperature (interquartile range 23.0-23.7 degrees C), low relative air humidity (interquartile range 17-26%) and high outdoor airflow rate, as indicated by low indoor levels of carbon dioxide (interquartile range 490-650 ppm). An altered microbial flora was observed in nine of the departments, and Aspergillus fumigatus was found in three of these. Five of the hospitals were situated in urban parts of the municipality near roads with heavy traffic. In the initial analyses decreased tear-film stability (BUT) was observed in subjects working in departments with increased dust settlement rate (P = 0.03), in hospitals situated in urban areas with heavy traffic (P < 0.001), and in subjects working in departments with presence of A. fumigatus (P = 0.04). Increased conjunctival staining (CS) was related to alteration of the microbial flora. In the final multivariate analyses statistically significant relationships were observed between BUT and dust settlement rate and urban vicinity of workplace and between CS and alteration of the microbial flora.

Torsional properties of stainless-steel and nickel-titanium files after multiple autoclave sterilizations.

This study tested the hypothesis that multiple sterilizations of endodontic stainless-steel and nickel-titanium files will lead to a continuous decrease in the resistance of files to separation by torsion. One hundred stainless-steel and 100 nickel-titanium #30 K-type files were divided into 20 groups of 10 and sterilized in increments of 10 cycles, using a full cycle and a fast cycle autoclave. These files were tested by twisting each of them in a clockwise direction until fracture (torque g-cm). Samples of the fractured files were embedded in an epoxy resin and polished for Knoop hardness tests. In addition, the samples were chemically etched to reveal changes in microstructure. The findings of this study indicate that neither the number of sterilization cycles nor the type of autoclave sterilization used affects the torsional properties, hardness, and microstructure of stainless-steel and nickel-titanium files.

[Sick leave while on a waiting list]. / Sykefravaer mens man står på venteliste.

Evidence suggest that waiting for hospital treatment leeds to unnecessary sick leaves. However, we know little about the extent of the problem. During a six-week period, 1,061 patients attending a total of ten hospital departments for the first time for outpatient treatment or examination received a self-administered questionnaire about sick leaves during the waiting period. 901 patients responded. Great variations were found between the ten departments. The average waiting period was 86 days (32-226 days). 26% (8-61%) of the patients had had a sick leave during the waiting period caused by the disease for which they were seeking treatment; average duration was 48 days (17-89 days); total sick leave for all patients responding in this survey was 11,000 days. Of patients with a sick leave during the waiting period, 44% thought that the examination or treatment which they attended would increase their ability to work, while their doctors were somewhat less optimistic (36%). The study shows that a large proportion of patients on waiting lists for hospital treatment are incapable of work and that cost savings achieved by cutting down waiting period may be considerable.

Lung function disturbances and chest X-ray abnormalities among marine engineers.

BACKGROUND: The purpose of the study was to investigate to what extent marine engineers who are exposed to mineral oil mist in the engine rooms of ships have lung function disturbances and chest X-ray abnormalities. METHODS: A previous study examined a cohort of 492 seamen from which we received 169 full-scale (40 x 40 cm) chest radiographs. Among these films were 68 from marine engineers and 101 from seamen who had never worked as engineers (controls). Spirometric data were obtained from 44 engineers and from 71 of the controls. The chest X-rays were classified independently by two certified B-readers, using the ILO classification. RESULTS: Only 7% of the seamen had parenchymal or pleural changes. The only statistically significant difference between the two groups for the chest X-ray findings was for all comments made by the ILO readers which were termed "any symbol" (9.3% for the engineers and 0.6% for the controls; RR = 14.6 (95% CI 1.1-75.5)) and the FEV% (FEV1/FVC x 100) for the spirometric values (82.8 (SD = 10.8) for the engineers and 86.6 (SD = 8.0) for the controls; P = 0.03). CONCLUSIONS: The results of the study indicate a slight lung function impairment and an increase in chest X-ray abnormalities, other than small opacities, among the marine engineers.

Health survey of former workers in a Norwegian coke plant: Part 2. Cancer incidence and cause specific mortality.

OBJECTIVES: A Norwegian coke plant that operated from 1964 to 1988 was investigated to ascertain whether the male workers in this plant had increased morbidities of cancer or increased mortality from specific causes, particularly associated with specific exposures at the coke plant. METHODS: Personal data on all the employees of the plant were obtained from the plant's archives. With additional data from the Norwegian Bureau of Statistics we identified 888 male former workers at the plant. Causes of death were obtained from the Norwegian Bureau of Statistics, and cancer diagnoses from the Norwegian Cancer Registry. The results were compared with national averages adjusted for age. Specific exposures were estimated with records of actual measurements done at the plant and interviews with former workers at the plant. RESULTS: A significant excess of stomach cancer (standardised incidence ratio (SIR) 2.22, 95% confidence interval (95% CI) 1.01 to 4.21) was found. Mortality from ischaemic heart disease and sudden death was positively associated with work in areas which entailed peak exposures to CO. When considering work in such areas the past 3 years before death, the association was significant (p = 0.01). The last result is based on only two deaths. CONCLUSIONS: Considering the short follow up time and the small size of the cohort the results should be interpreted with a certain caution. The positive results would justify a re-examination of the cohort at a later date.

Exposure to mineral oil mist and respiratory symptoms in marine engineers.

The purpose of the study was to see if marine engineers have an increased prevalence of respiratory symptoms, and if so whether it can be related to occupational exposures. A self-administered questionnaire was sent to 700 male seamen from three Norwegian ferry companies. Of the 492 respondents, 169 were currently working as marine engineers and 295 had never worked as marine engineers. The outcomes of cough and wheezing, chronic bronchitis, severe dyspnea, any dyspnea, and mucous membrane irritation (MMI) were defined from the questionnaire. Age and smoking-adjusted prevalences of these respiratory conditions were compared between the groups. Logistic regression was used to further elucidate the explanatory variables. The exposure assessment indicated an exposure (TWAC) to oil mist for marine engineers in the range from 0.12 to 0.74 mg/m3 (mean 0.45 mg/m3) When comparing current marine engineers with those who had never worked as marine engineers, the prevalence ratios were 1.38 (95% CI 1.0-1.9) for MMI, 1.53 (95% CI 1.2-1.9) for any dyspnea, and 1.63 (95% CI 1.0-2.6) for severe dyspnea. The differences remained for some of the symptoms after controlling for self-reported former asbestos exposure in the regression analysis. The increased prevalence of respiratory symptoms found among marine engineers in this investigation may partly be explained be oil-mist exposure, or more probably by a combination of past asbestos exposure and past and present oil-mist exposure.

Smoking intervention in subjects at risk of asbestos-related lung cancer.

A smoking intervention counseling program was applied among asbestos-exposed male smokers younger than 65 years of age to examine the effect of an intervention based on risk communication. Intervention subjects (n = 431) were invited to a health status checkup combined with physician-delivered smoking intervention counseling. Control subjects (n = 141) received no intervention. After 1 year, 5% of the responders in the intervention group, versus 3.4% in the control group, had stopped smoking. Corresponding conservative estimates were 3.5% and 2.6%, respectively. The quitters had been exposed to a higher "dose" of asbestos but had smoked less, and for a shorter period, than had the continuing smokers. Counseling by a general physician increased successful quitting threefold, compared to counseling by a physician in a specialized institution. These results suggest a potential for smoking cessation among subjects at high risk of lung cancer due to asbestos exposure. General practice care may be an appropriate setting both for identification of such subjects and for intervention.

Skin disorders in ship's engineers exposed to oils and solvents.

Ship's engineers are exposed to mineral oil and solvents in their work. This study was intended to investigate if the ship's engineers had an increased prevalence of skin disorders and whether any such increased risk could be linked to exposure to mineral oils and solvents. A self-administered questionnaire was sent to 700 male seamen from 3 Norwegian ferry countries. Of the 492 respondents, 169 were currently working as ship's engineers and 295 had never worked as ship's engineers. The outcomes eczema, acne, dry skin, and dermatitis and hand dermatitis were defined from the questionnaire. Prevalences of these skin disorders were compared between the groups. Logistic regression was used to elucidate explanatory variables further. When comparing current ship's engineers with those who had never worked as ship's engineers, the crude prevalence ratios were 1.7 (95% CI 1.1-2.7) for dry skin, 1.7 (95% CI 1.1-2.5) for any dermatitis, 1.3 (95% CI 0.66-2.67) for acne and 1.2 (CI 0.61-2.27) for eczema. The risk of these symptoms increased for the engineers in the regression analysis, after controlling for age, self-reported use of Stoddard solvent, and the use of fuel oil as hand cleansing agent. The increased prevalence of skin disorders found among ship's engineers in this investigation may be explained by direct contact with mineral oils and solvents.

[Incidence and physicians' registration of assumed occupational lung cancer in Norway]. / Hyppighet og legers registrering av antatt arbeidsbetinget lungekreft i Norge.

About 20% of al lung cancers among men are attributable to occupational exposure. During the years 1991 through 1993, Norwegian doctors reported 161 (4.6%) of 3.510 incidents of cancer in Norwegian men to the Labour Inspection as probably caused by occupational exposure. The proportion of such assumed occupational lung cancer cases varied with geographical region from 0.7% to 6.7%. Notification of an occupational cancer can be justification for economic benefits to the patient and his/her family. The most common assumed causes of the 161 cases notified as occupational lung cancers were asbestos dust exposure (148 cases), exposure to nickel (21 cases), and exposure to stone dust containing crystalline silica (18 cases). The predominating occupations of the patients at the time of the assumed carcinogenic exposure were machinist, industrial worker in metallurgical or chemical industry, mechanic, or metal worker (metal sheet worker, welder).

[Pulmonary function in Norwegian farmers keeping domestic animals]. / Lungefunksjon blant norske husdyrbønder.

In a group of farmers keeping domestic animals, all pulmonary function tests, except for PEF, showed lower values than in a Norwegian reference population. Spirometric values for FVC, FEV1, and PEF were higher among pig farmers than among other farmers. Poultry farmers had lower values of PEF compared to other farmers. One third of all farmers had values of FEF25-75% that were depressed more than 20%, possibly indicating that the smaller, more peripheral airways more frequently are affected than the central airways. No single causal factor for the reduced lung function was found, but farmers that worked in newer cow-stables had a lower lung function than other farmers, especially if the houses were built in the interval 1975-84.

Lung function and respiratory symptoms related to changes in smoking habits in asbestos-exposed subjects.

The purpose of this study was to examine respiratory symptoms and lung function (forced vital capacity [FVC] and forced expiratory volume in 1 second [FEV1]) as related to changes in smoking habits in subjects previously exposed to asbestos. The study was linked to a smoke-ending program among asbestos-exposed males. Subjects were recruited from a population-based survey, and 231 smokers met for the baseline consultation. The baseline prevalences of cough, chronic cough, and dyspnea among smokers were 68.0%, 44.6%, and 42.4%, respectively. Both smoke-ending (n = 10) and tobacco reduction (n = 52) during the 2-year follow-up resulted in remission of cough and chronic cough, whereas dyspnea was unaffected. When the 2-year measurements of FVC and FEV1 were adjusted for the respective baseline measurements, FEV1 tended to improve in subjects who had quit during the study, relative to the continuing smokers. It was concluded that both smoke-ending and reduction of tobacco consumption resulted in reduction of cough and chronic cough, but not of dyspnea. The study further suggests a possible positive effect of smoking cessation on FEV1, but not merely by reduction of tobacco consumption.

[Respiratory tract symptoms among farmers keeping animals in Midt-Norge]. / Luftveissymptomer blant husdyrbønder i Midt-Norge.

In this survey from central Norway, the prevalence of respiratory symptoms in a representative sample of 1,580 farmers who kept domestic animals was compared with the prevalence of such symptoms among 655 controls, both sexes included. The farmer group experienced more symptoms that were exacerbated by work than the controls did (mucous membrane irritation 19% versus 10%, tightness in the chest 7% versus 4%, dyspnoea 4% versus 1% and cough with phlegm 25% versus 22%). No difference could be found between the groups as regards the prevalence of organic dust toxic syndrome or chronic bronchitis. The occurrence of symptoms was correlated to the number of working hours per day, and to the number of years the person had worked with animals. Farmers who kept cattle, pigs or poultry all showed raised prevalence of respiratory symptoms. The results indicate that the working environment of farmers who kept domestic animals may cause respiratory disorders.

Asbestos-related radiographic changes by ILO classification of 10 x 10 cm chest X-rays in a screening of the general population.

A sample of 1388 10 x 10 cm chest X-rays from a previous population screening of males aged 40+ years were reevaluated by use of the ILO classification. There were 1036 films of subjects from an industrialized town, and 352 from a rural community. The observed rates of parenchymal changes (profusion > or = 1/0) at the reevaluation were 1.3% in the urban community and 3.4% in the rural community. The corresponding figures for pleural changes were 5.0% and 0.6%, respectively. Based on additional questionnaire information on asbestos exposure, it was found that the radiographic changes were probably related to past asbestos exposure for 2.3% of the subjects from the urban community and 0.6% from the rural community. In cases of asbestos-related illnesses the mean time since first exposure to asbestos was 35.9 years, whereas the mean duration of the exposures was 11.4 years. The results seem to indicate that the ILO reassessment of the radiographs was more sensitive in detecting pleural changes than the previous clinical screening of both small and large films.

Karyotypic changes in the preclinical and subsequent stages of malignant mesothelioma: a case report.

The karyotypic evolution was evaluated in cells from recurring pleural effusions in a patient previously exposed to asbestos. Pleural malignant mesothelioma (MM) was diagnosed 4 years after the first cytogenetic examination. The primary cytogenetic changes consisted of loss of chromosomes 1p,14,21, Y, both 22, and derivative chromosomes involving 1, 2, and 14. The modal chromosome number was 44. Sixty-seven percent of the cells had a normal karyotype. After 4 years of spontaneous remission, only 6% of the cells had a normal karyotype, 42% had the same karyotypic changes as found previously, whereas 52% had additional derivative chromosomes involving chromosomes 1, 3, 5, 7, 8, and 12, trisomy 7, 7p, and 11, and partial or whole monosomy 3, 8, and 9. The chromosomal changes are in agreement with the main findings in previous reports. The karyotype remained quite stable for 7 months in vitro. After 23 months in culture, all the cells were near-triploid. Cells established in culture were cytokeratin positive. All derivative and marker chromosomes identified in the cultured cells had previously been observed in direct preparations from the pleural effusions. We conclude that chromosomes 1, 14, 21, and 22 may be involved in the preclinical stage of development of asbestos-induced mesothelioma, whereas the later chromosomal changes may be related to progression of the tumor.

[Exposure to asbestos and asbestos-related pulmonary changes among employees at a magnesium plant]. / Asbesteksponering og asbestrelaterte lungeforandringer blant ansatte i en magnesiumfabrikk.

Prevalence of disease related to previous exposure to asbestos was investigated in a cohort of 394 men who had worked for more than a year at a magnesium plant before 1970. Radiography showed lung fibrosis in nine men (2.3%) and pleural plaques in 40 men (9.5%). Prevalence rates varied considerably between sub-groups subjected to different modes of exposure. For the whole cohort there was a positive correlation between prevalence rate of radiographic changes and duration of work entailing exposure to asbestos. Subjects with pleural changes had more dyspnoea than found in an external reference material. Vital capacity and forced expiratory volume in one second was significantly reduced for the whole cohort. A significant reduction in lung function was found among a larger proportion of subjects with pleural changes than among subjects with no radiographic indications of such changes. The results unveil a need for similar surveys among workers in other energy-intensive industries where a similar mode of exposure to asbestos may be assumed.

Chest radiographs in subjects with asbestos-related abnormalities: comparison between ILO categorizations and clinical reading.

The findings of a previous chest X-ray screening, determined without using standardized criteria, were reassessed by means of the ILO classification. Of 470 radiographs that had been determined as showing asbestos-related changes, 430 were categorized according to the ILO Classification. Small opacities with profusion greater than or equal to 1/0 were described in 39 (52%) of 75 participants who, on the original clinical reading, had been determined as having lung fibrosis, and in 45 (12.7%) of 355 who were determined as having pleural changes only. When considering circumscribed pleural thickening at the chest wall or diaphragm, as categorized by the ILO Classification, such changes were present in 401 (93.7%) of 428 subjects with pleural changes as determined on the clinical reading. In addition to the improved sensitivity and specificity achieved, the ILO Classification also allows comparison with other studies. The most apparent disadvantage of the ILO system is that it cannot firmly separate the various types of asbestos-related pleural changes. The study revealed that the previous asbestos exposure of the case subjects had occurred in many different workplaces and occupations.