Prevalence of respiratory disorders among aluminium potroom workers in relation to exposure to fluoride.

In a survey of 370 aluminium potroom workers in western Norway, bronchial responsiveness, lung function, and respiratory symptoms were studied in relation to occupational exposure to air contaminants in the potroom. Increased prevalences of respiratory symptoms, work related asthmatic symptoms, and abnormal lung function were found in subjects exposed to total fluorides above 0.5 mg/m3 when compared with workers exposed to total fluorides at concentrations of less than 0.5 mg/m3. No significant association between bronchial responsiveness and exposure to fluoride was found and the prevalence of respiratory symptoms was independent of the degree of dust exposure. These findings indicate that work related asthmatic symptoms in potroom workers may be related to exposure to fluorides.     

Prevalence of respiratory symptoms and spirometric values in aluminium potroom workers

The goal of this study was to examine the prevalence of chronic respiratory symptoms in potroom workers and to compare these results with changes in spirometric parameters. A modified questionnaire on respiratory symptoms from the British Medical Research Council was used to take the medical history data about respiratory symptoms. Spirometric parameters were determined on the same day (as a part of regular checkups) using the Jaeger spirometer. The study included 215 potroom workers from the aluminium factory in Podgorica, Montenegro. All subjects were men, but they differed in age and duration of work. The group used for comparison consisted of 81 unemployed male applicants for jobs in the factory who had never been exposed to this kind of air pollution before.Potroom workers mostly complained of breathlessness associated with the workplace (56.7 %) or weather changes (rain, cold wind, and humidity) (41.9%) and of dyspnoea when climbing stairs (51.2 %), but only 22.3 % reported using medication to treat these episodes. Most workers reported to have been smoking at the time of the study (62.4 %). Spirometric data showed only insignificant variations compared to the expected values (CECA standards). Chronic obstructive pulmonary disease (COPD), characterised by FEV1/VC % <88 % was found in only 17 (7.9 %) potroom workers, while asthma was identified in 9 (4.2 %). Although the prevalence of chronic respiratory symptoms reported by the examined potroom workers was quite high at the group level, they were not associated with ventilatory impairments.     

Prevalence of respiratory disorders among aluminium potroom workers in relation to exposure to fluoride.

In a survey of 370 aluminium potroom workers in western Norway, bronchial responsiveness, lung function, and respiratory symptoms were studied in relation to occupational exposure to air contaminants in the potroom. Increased prevalences of respiratory symptoms, work related asthmatic symptoms, and abnormal lung function were found in subjects exposed to total fluorides above 0.5 mg/m3 when compared with workers exposed to total fluorides at concentrations of less than 0.5 mg/m3. No significant association between bronchial responsiveness and exposure to fluoride was found and the prevalence of respiratory symptoms was independent of the degree of dust exposure. These findings indicate that work related asthmatic symptoms in potroom workers may be related to exposure to fluorides.     

Respiratory disorders in aluminium potroom workers.

Epidemiological studies of aluminum potroom workers have been in progress in Norway since 1986. The occurrence of work-related asthmatic symptoms and their determinants were studied. Work-related asthmatic symptoms and airflow limitation were closely associated with duration of potroom employment. A significant relationship between current fluoride exposure and work-related asthmatic symptoms was observed in a smaller, cross-sectional population where a detailed exposure classification was carried out. A similar association and also a dose-response gradient was found in a longitudinal study of new employees. The existence of occupational asthma in aluminium potroom workers was confirmed by characteristic patterns of repeated peak flow measurements supported by changes in methacholine responsiveness in workers with suspected work-related asthma. Current smoking as a risk factor for work-related asthmatic symptoms was observed both in cross-sectional and in longitudinal investigations. Similarly to current fluoride exposure, a dose-response gradient was demonstrated in the association between work-related asthmatic symptoms and current amount of tobacco smoked. Allergy was not shown to be a determinant of work-related asthmatic symptoms in any part of the investigation. A family history of asthma and previous occupational exposure may have had some influence on the risk of developing symptoms but the findings were inconsistent and probably of minor importance. Methacholine challenge seemed inappropriate for the screening of aluminium potroom workers in order to detect work-related asthmatic symptoms, but was closely correlated to the severity of symptoms.(ABSTRACT TRUNCATED AT 250 WORDS)     

Bronchial responsiveness decreases in relocated aluminum potroom workers compared with workers who continue their potroom exposure

We have compared the bronchial responsiveness (BR) of 12 aluminum potroom workers (index group) who were relocated due to work-related asthmatic symptoms (WASTH) and 26 subjects (reference group) with WASTH who continued to work in pot-rooms. The subjects were examined at regular intervals during a 2-year follow-up period. BR was expressed as the log-transformed dose-response slope [Ln (DRS + 0.5)]. The monthly change in BR (ΔBR) in the index group was ?4.87 × 10^?2 compared with ?1.58 × 10^?2 in the reference group. After adjustment for potential confounders, the difference between the index group and the reference group was ?2.39 × 10^?2 (95% CI: ?4.07 × 10^?2 to ?0.71 × 10^?2), i.e. 49% of the decrease in BR in the index group could be explained by the removal from exposure. No improvement in lung function was found in the index group compared with the reference group. The results indicate that the removal of potroom workers from exposure causes a decrease in BR.     

Interval censoring in longitudinal data of respiratory symptoms in aluminium potroom workers: A comparison of methods

In a longitudinal study of workers in seven Norwegian aluminium plants, the time to development of asthmatic symptoms could only be determined to lie in the interval between two consecutive health examinations. In a previous paper we analysed the data by survival techniques for interval censored data. In the present paper the data are reanalysed in two ways and compared to the previous analyses. First, it is assumed that occurrence of symptoms coincided with reporting, in which case the data can be analysed as right censored. Secondly, the follow-up times are completely disregarded and the effects of covariates are analysed on the binary outcomes of symptoms. Comparing the estimated effects of the covariates between the three approaches, only minor differences were found. However, the estimates on incidence were strongly influenced by whether the data were analysed as right or interval censored.     

Relation between decline in FEV1 and exposure to dust and tobacco smoke in aluminium potroom workers.

OBJECTIVES: To investigate the relation between pulmonary function and occupational exposure in aluminium pot operators. METHODS: 2795 observations were obtained in 630 workers over six years of follow up. An autoregressive method of analysis was used. RESULTS: After adjustment for FEV1 in the three previous years, the effect of smoking v no smoking on FEV1 was -43.1 ml, 95% confidence interval (95% CI) -72.3 to -13.9. Similarly, an increase in the exposure to particulates by 1 mg/m3 corresponded to a decrease in FEV1 of -11.9 ml, 95% CI -19.9 to -3.9. Age was a significant predictor of both FEV1 and FVC. CONCLUSION: Exposure to particulates in aluminium potrooms seems to increase the decline in FEV15 thereby increasing the risk of development of chronic obstructive lung disease in pot operators.     

Bronchial hyperreactivity in potroom workers and prognosis after stopping exposure

A group of 30 potroom workers who developed an asthma-like syndrome during their work in the electrolytic extraction of aluminium (Alu-Swiss process with prebacked anodes) was followed up after stopping exposure. Subjective respiratory complaints were registered and a non-specific bronchial reactivity test using methacholine was performed once or twice during the follow up period (1984-9). After transfer to other work most workers either had an improvement in respiratory symptoms (60%) or even normalisation (27%); only 13% did not show changes. Bronchial hyperreactivity remained unchanged in 67% of workers, was less pronounced in 13%, normalised in 13%, and deteriorated in 7%. Smoking habits, atopy, and duration of exposure did not seem to have influenced the results obtained. No significant correlation was found between duration of exposure and the speed of onset of respiratory symptoms and the later prognosis of the syndrome. Based on the information collected during the period of observation it appears that reactive airway dysfunction syndrome, once induced, has a tendency to persist. An improvement in subjective complaints may be expected, however, after stopping exposure.     

Are aluminium potroom workers at increased risk of neurological disorders?

OBJECTIVE: To determine whether long term potroom workers in an aluminium smelter are at increased risk of neurological disorders. METHODS: Cross sectional study of 63 current and former aluminium potroom workers first employed before 1970 and with at least 10 years of service. A group of 37 cast house and carbon plant workers with similar durations of employment and starting dates in the same smelter were used as controls. The prevalence of neurological symptoms was ascertained by questionnaire. Objective tests of tremor in both upper and lower limbs, postural stability, reaction time, and vocabulary were conducted. All subjects were examined by a neurologist. RESULTS: No significant differences in age, race, or education were found between the two groups. Although the potroom group had higher prevalences for all but one of the neurological symptoms, only three odds ratios (ORs) were significantly increased; for incoordination (OR 10.6), difficulty buttoning (OR 6.2), and depression (OR 6.2). Tests of arm or hand and leg tremor in both the visible and non-visible frequencies did not show any significant differences between the two groups. Testing of postural stability showed no definitive pattern of neurologically meaningful differences between the groups. There were no significant differences between the two groups in reaction time, vocabulary score, or clinical neurological assessment. CONCLUSIONS: The objective measures of neurological function provided little support for the finding of increased neurological symptom prevalences in the potroom workers, although increased symptoms may be an indicator of early, subtle neurological changes. The results provide no firm basis for concluding that neurological effects among long term potroom workers are related to the working environment, in particular aluminium exposure, in potrooms. These findings should be treated with caution due to the low participation of former workers and the possibility of information bias in the potroom group.     

Annual decline in forced expiratory volume is steeper in aluminum potroom workers than in workers without exposure to potroom fumes

Background

Aluminum potroom exposure is associated with increased mortality of COPD but the association between potroom exposure and annual decline in lung function is unknown. We have measured lung volumes annually using spirometry from 1986 to 1996. The objective was to compare annual decline in forced expiratory volume in 1 s (dFEV1) and forced vital capacity (dFVC).

Methods

The number of aluminum potroom workers was 4,546 (81% males) and the number of workers in the reference group was 651 (76% males). The number of spirometries in the index group and the references were 24,060 and 2,243, respectively.

Results

After adjustment for confounders, the difference in dFEV1 and dFVC between the index and reference groups were 13.5 (P < 0.001) and ?8.0 (P = 0.060) ml/year.

Conclusion

Aluminum potroom operators have increased annual decline in FEV1 relative to a comparable group with non‐exposure to potroom fumes and gases. Am. J. Ind. Med. 59:322–329, 2016. © 2016 The Authors. American Journal of Industrial Medicine Published by Wiley Periodicals, Inc.

     

Bronchial hyperreactivity in potroom workers and prognosis after stopping exposure.

A group of 30 potroom workers who developed an asthma-like syndrome during their work in the electrolytic extraction of aluminium (Alu-Swiss process with prebacked anodes) was followed up after stopping exposure. Subjective respiratory complaints were registered and a non-specific bronchial reactivity test using methacholine was performed once or twice during the follow up period (1984-9). After transfer to other work most workers either had an improvement in respiratory symptoms (60%) or even normalisation (27%); only 13% did not show changes. Bronchial hyperreactivity remained unchanged in 67% of workers, was less pronounced in 13%, normalised in 13%, and deteriorated in 7%. Smoking habits, atopy, and duration of exposure did not seem to have influenced the results obtained. No significant correlation was found between duration of exposure and the speed of onset of respiratory symptoms and the later prognosis of the syndrome. Based on the information collected during the period of observation it appears that reactive airway dysfunction syndrome, once induced, has a tendency to persist. An improvement in subjective complaints may be expected, however, after stopping exposure.     

Follow-up of airway reactivity in potroom workers in relation to exposure.

Two groups of workers were studied: a) 24 workers with respiratory complaints--7 of whom were light and 4 borderline hyper-reactors--who continued to work on the electrolytic reduction of aluminium for up to two years; b) 30 workers with increased bronchial reactivity who ceased to work in potrooms for 3.7 years on average (range 2-11 years) because of respiratory complaints. Subjective respiratory complaints were recorded and a non specific bronchial reactivity test was performed one or two times during the follow-up period. A sustained level of airway reactivity was recorded in both groups of workers regardless of exposure conditions. In workers with dyspnoea and airway obstruction, bronchial reactivity did not worsen in spite of continued exposure. On the other hand cessation of exposure was not followed by normalization of bronchial reactivity. The potential role of atopy, smoking habits and length of previous exposure was analyzed. It appears that increased bronchial reactivity, once induced, has a tendency to persist. An improvement in subjective complaints may be expected after cessation of exposure.     

Characteristics of alveolar cells and soluble components in bronchoalveolar lavage fluid from non-smoking aluminium potroom workers

Aluminium potroom workers have been reported to develop severe pneumoconiosis and bronchial hyperreactivity. The influence of inhalation of aluminium oxide and fluorides on the alveolar milieu was studied by bronchoalveolar lavage (BAL) in 14 male non-smoking potroom workers; 28 non-smoking healthy volunteers served as controls. The total numbers, concentrations, and proportions of various alveolar cells did not differ between the groups. The concentrations of albumin and fibronectin in BAL fluid were significantly higher (p less than 0.01 for both) in the exposed workers, reflecting an increased alveolar capillary permeability and an activation of alveolar macrophages (AMs). The concentration of angiotensin converting enzyme, another AM marker, was, however, decreased (p less than 0.01) in the workers. The concentration of hyaluronan, a fibroblast marker, did not differ between the groups. AMs from workers had a decreased capacity (p less than 0.05) to interact with yeast C3b particles but not to ingest them. The expression of HLA-DR and OKM1 on the cell surfaces of AMs were equal in the two groups. The BAL findings were not accompanied by restrictive lung disease in the workers. The fact that only a discrete alveolitis was found in the potroom workers may be due to a low grade of exposure to alumina and fluorides and to frequent use of respiratory protection equipment.     

Eosinophil-related respiratory disease in aluminium workers.

We carried out a nested case-control study in an aluminium producing plant, using the results of pre-employment examination to identify workers with an increased risk of developing work-related obstructive respiratory symptoms. Cases (n=49) are those who had become unable to work because of work-related respiratory disease. They were compared with 49 matched controls. Pre-employment eosinophil count was strongly related to the occurrence of work-related obstructive respiratory disease. This finding is interesting in the light of a possible pathogenesis.     

Dust exposure and respiratory health effects in cement production

Dust can be produced by almost all production processes in Portland cement factory. Dust exposure potentially can affect respiratory function. But evidence for respiratory effect of cement dust exposure has not been conclusive. In this study we assessed effect of cement dust exposure on respiratory function in a cement production factory. A respiratory symptoms questionnaire was completed and pulmonary function tests were carried out on 94 exposed and 54 non exposed workers at a cement factory in the east of Iran. Additionally, respirable dust level was determined by the gravimetric method. X-ray fluorescence (XRF) technique was performed to determine the silica phases and the SiO(2) contents of the bulk samples. The arithmetic means (AM) of personal respirable dust were 30.18 mg/m(3) in the crushing, 27 mg/m(3) in the packing, 5.4 mg/m(3) in the cement mill, 5.9 mg/m(3) in the kiln and 5.48 mg/m(3) in the maintenance that were higher than threshold limit value (TLV) of the American Conference of Governmental Industrial Hygienists (ACGIH) which is 5 mg/m(3). This value in the unexposed group was 0.93 mg/m(3). In this study cough, sputum, wheezing and dyspnea were more prevalent among exposed subjects. Exposed workers compared to the unexposed group showed significant reduction in Forced Expiratory Volume in one second (FEV(1)), Forced Vital Capacity (FVC), and Forced Expiratory Flow between 25% and 75% of the FVC (FEF(25-75%)) (P<0.05). It can be concluded that in our study there was close and direct association between cement dust exposure and functional impairment among the cement factory workers.     

Characteristics of alveolar cells and soluble components in bronchoalveolar lavage fluid from non-smoking aluminium potroom workers.

Aluminium potroom workers have been reported to develop severe pneumoconiosis and bronchial hyperreactivity. The influence of inhalation of aluminium oxide and fluorides on the alveolar milieu was studied by bronchoalveolar lavage (BAL) in 14 male non-smoking potroom workers; 28 non-smoking healthy volunteers served as controls. The total numbers, concentrations, and proportions of various alveolar cells did not differ between the groups. The concentrations of albumin and fibronectin in BAL fluid were significantly higher (p less than 0.01 for both) in the exposed workers, reflecting an increased alveolar capillary permeability and an activation of alveolar macrophages (AMs). The concentration of angiotensin converting enzyme, another AM marker, was, however, decreased (p less than 0.01) in the workers. The concentration of hyaluronan, a fibroblast marker, did not differ between the groups. AMs from workers had a decreased capacity (p less than 0.05) to interact with yeast C3b particles but not to ingest them. The expression of HLA-DR and OKM1 on the cell surfaces of AMs were equal in the two groups. The BAL findings were not accompanied by restrictive lung disease in the workers. The fact that only a discrete alveolitis was found in the potroom workers may be due to a low grade of exposure to alumina and fluorides and to frequent use of respiratory protection equipment.     

Effects of pre- and postnatal exposure to parental smoking on early childhood respiratory health

Compelling evidence suggests a causal relation between parental smoking during and after pregnancy and adverse effects on respiratory health in the offspring. The authors' aim in this study was to disentangle the effects of prenatal and postnatal smoking on early childhood respiratory health. Most parents who smoke during pregnancy continue to smoke postpartum, and it is difficult to identify sufficiently large subgroups of children who were exclusively exposed in utero or after birth. This study was based on the first 22,390 children born between 2000 and 2004 in the Norwegian Mother and Child Cohort, a pregnancy cohort designed to eventually include 100,000 pregnancies. Data were collected through detailed questionnaires administered at various stages of pregnancy, starting in early pregnancy. Because of the large study population, the authors were able to disentangle the pre- and postnatal effects of parental smoking on wheeze and lower respiratory tract infection in the children's first 18 months of life. They found maternal smoking in pregnancy to be an independent risk factor for wheeze and respiratory infection. Postnatal paternal smoking was also associated with these outcomes, independently of maternal smoking in pregnancy.     

Factors affecting FEV1 in workers with potroom asthma after their removal from exposure

OBJECTIVE: In this study the relationship has been studied between exposure time and potential prognostic factors and FEV1 percent predicted (FEV1-% pred) in workers with potroom asthma, after their transfer from exposure to exposure-free departments. METHODS: Between 1970 and 1990 in a Dutch aluminium-production plant, 179 workers had been diagnosed as having potroom asthma. We carried out a follow-up study (n = 122) in the population still present at the factory 5 years after their relocation to an exposure-free department. In this study population, we examined the relationship between FEV1-% pred at follow-up, and exposure time: the time interval between start of exposure and diagnosis. To correct for confounding factors, we included age, pre-employment FEV1-% pred, allergy, medical treatment, and smoking in the analysis. RESULTS: The mean FEV1-% pred at follow-up was within the normal range (90.3, SD 13.5). Long exposure time was significantly associated with a low FEV1-% pred at follow-up (P = 0.0046). Adjustment was necessary for pre-employment FEV1-% pred and current smoking as confounding factors. CONCLUSION: Long duration of exposure is a factor affecting FEV1 in workers with potroom asthma. The results of this study give support for additional preventive measures to be taken, such as early recognition of work-related respiratory complaints and repeated education.     

Factors affecting FEV1 in workers with potroom asthma after their removal from exposure

Objective: In this study the relationship has been studied between exposure time and potential prognostic factors and FEV₁ percent predicted (FEV₁-% pred) in workers with potroom asthma, after their transfer from exposure to exposure-free departments. Methods: Between 1970 and 1990 in a Dutch aluminium-production plant, 179 workers had been diagnosed as having potroom asthma. We carried out a follow-up study (n=122) in the population still present at the factory 5 years after their relocation to an exposure-free department. In this study population, we examined the relationship between FEV₁-% pred at follow-up, and exposure time: the time interval between start of exposure and diagnosis. To correct for confounding factors, we included age, pre-employment FEV₁-% pred, allergy, medical treatment, and smoking in the analysis. Results: The mean FEV₁-% pred at follow-up was within the normal range (90.3, SD 13.5). Long exposure time was significantly associated with a low FEV₁-% pred at follow-up (P=0.0046). Adjustment was necessary for pre-employment FEV₁-% pred and current smoking as confounding factors. Conclusion: Long duration of exposure is a factor affecting FEV₁ in workers with potroom asthma. The results of this study give support for additional preventive measures to be taken, such as early recognition of work-related respiratory complaints and repeated education. Received: 2 August 1999 / Accepted: 10 June 2000