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4.  Pre-employment lung function at age 16 years as a guide to lung function in adult life. 
BACKGROUND--A study was conducted to find out if pre-employment lung function at age 16 improved the estimation of that between ages 25 to 27 compared with the use of reference values based on smoking history, stature, body mass index, and other concurrent anthropometric variables. METHODS--Apprentices attending a shipyard training school were assessed on six occasions from entry during their 17th year to age 25 to 27; results for 114 such men were analysed. The measurements were of stature, body mass, fat free mass and body fat, thoracic dimensions, forced expiratory volume and indices of forced expiratory flow, total lung capacity, and its subdivisions, transfer factor and KCO. RESULTS--At best about half the variance in the final lung function could be accounted for with the concurrent reference variables. For each lung function index the proportion of explained variance was substantially increased by also including in the prediction equation the pre-employment lung function expressed in standard deviation units. CONCLUSION--Estimation of the longitudinal decline in lung function during adult life should be based on initial and final measurements of which the first should ideally be at age 25 but those at age 16 can be used instead: such measurements have long term value and should be preserved.
PMCID: PMC1012160  PMID: 8507594
5.  Longitudinal respiratory survey of shipyard workers: effects of trade and atopic status. 
A respiratory sample survey of 609 shipyard workers was conducted in 1979: the men were reassessed an average of 7.2 years later. The 53 deaths between the surveys were related to age, level of lung function and smoking but not to trade as a welder or caulker/burner. Of the survivors, 488 (88%) were seen, including 425 men who had retired or been made redundant. Redundancy was related to age, smoking, and respiratory symptoms; the average reduction in duration of employment per symptom was 0.44 years. Changes in respiratory symptoms included onset of chronic bronchitis and wheeze on most days (numbers respectively 77 and 109) and increased breathlessness on exertion (n = 89); significant related factors included smoking, previous metal fume fever or pneumonia, and, for breathlessness, trade as a welder or caulker/burner. Electrocardiographic evidence for myocardial ischaemia was also associated with increased breathlessness. The annual declines in FEV1 and other spirometric indices were related to age, to being a smoker at the time of the initial survey, and to trade as a welder or caulker/burner compared with trades that did not involve welding or burning. There was significant interaction between these effects. In a subsample of 124 redundant workers there was also significant interaction between the effects of fumes and atopy (skin test positive to common antigens) or a raised serum IgE concentration. It was concluded that welding fumes interacted with smoking and an atopic constitution to cause respiratory impairment. The results related mainly to exposures in the past and were not necessarily relevant for present day conditions in the industry.
PMCID: PMC1035106  PMID: 2310720
6.  Respiratory symptoms and impairment in shipyard welders and caulker/burners. 
All 607 men, aged 17 to 69, comprising a stratified sample of workers from one shipyard completed a respiratory questionnaire, clinical examination, and detailed spirometry. Chest radiographs were available on 332 men. Among the men aged 50-69 the prevalence of persistent cough and phlegm (chronic bronchitis) was 40%, of wheeze on most days 25%, and undue breathlessness on exertion 25%. After allowing for age the relative risk of welders and caulker/burners having these symptoms were respectively 2.8, 2.2, and 3.1 compared with other shipyard tradesmen. The effects were of comparable magnitude to and interacted with those of current smoking. Among the welders and caulker/burners who smoked, the relative risk of developing chronic bronchitis or undue breathlessness was related to the average fume exposure; the relative risk of wheeze was related to the average fume exposure in all smoking categories, with the strongest association in the ex-smokers. The occurrence of wheeze was also associated with a history of previous metal fume fever. A history of pleurisy but not of pneumonia was related to the fume exposure in the welders. After allowing for age and stature, forced expiratory volume (FEV1) was on average higher in young welders (age less than 30) than other tradesmen. In welders and caulker/burners who were current or ex-smokers, FEV1 and PEF were reduced in relation to the average fume exposure (mean reductions respectively 0.25 l and 0.99 l s-1). The FEV1% (of forced vital capacity), the flow rates at small lung volumes (MEF50%FVC and MEF25%FVC), the mean transit time, and its standard deviation were also reduced by fume exposure or the declines with age were increased, or both. No impairment was demonstrable in the non-smokers and many men had given up smoking with apparently beneficial results. The occupational component of the respiratory impairment related mainly to exposures in the past; information was needed on the effects of present conditions in the industry.
PMCID: PMC1009771  PMID: 2751927
7.  Indirect estimation of maximal oxygen uptake for study of working populations. 
A total of 345 shipyard workers (aged 23 to 47) volunteered to perform progressive exercise on a cycle ergometer (15 W/min increments) up to the symptom limited maximum. The results were used to obtain maximal oxygen uptake (nO2 max), the oxygen uptake at a respiratory exchange ratio of unity (nO2 at R1.0), and cardiac frequency at an oxygen uptake of 45 mmol/min (fC45). In this group 156 men (45% of initial population) attained nO2 max as defined, 108 (31%) withdrew or did not exercise maximally, and 49 (14%) had transient electrocardiographic abnormalities. For the 156 men extrapolation of the relation of cardiac frequency on oxygen uptake to the predicted maximal cardiac frequency resulted in overestimation of nO2 max by 9.6%. nO2 Max per kg body mass was negatively correlated with body mass. nO2 Max (mean value 130.6 mmol/min) was described in terms of age, fat free mass, smoking (yes or no), and level of habitual activity (rated 1 to 4): the standard error of the estimate (SEE) was 17.3 mmol/min (R2 0.42); the equation was suitable for reference values. For estimating the nO2 max of individual men an empirical relation based on nO2 at R1.0, fC45, fat free mass, and % body fat had an SEE of 12.1 mmol/min (R2 0.67). Seventy six per cent of men (88% of those who exercised) attained nO2 at R1.0 (oxygen uptake approximately 73% of maximum). Thus the nO2 max could be estimated in a higher proportion of men than could achieve nO2 max. The estimate is appropriate for assessing exercise capacity in relation to employment.(ABSTRACT TRUNCATED AT 250 WORDS)
PMCID: PMC1009646  PMID: 3415918
8.  Respiratory effects of a single saturation dive to 300 m. 
Lung function and the response to exercise were monitored in seven diver/welders who took part in a test saturation dive to 300 m for an average duration of 12 days; decompression took an average of nine days. Immediately after the dive the forced vital capacity was increased above base line by on average 0.51, the forced expiratory volume by 0.281 and peak expiratory flow rate by 0.71 s-1. There was no change in flow rate at small lung volumes (FEF 75% FVC). Recovery was complete and appeared to have a half time of 28 days. Transfer factor of the lungs for carbon monoxide (TlCO) was reduced by on average 9.6% after the dive but while partial recovery occurred, the values at one year were on average lower than those observed initially. The reason is unclear. One subject developed transient oxygen toxicity with stiff lungs and increased ventilation and cardiac frequency during submaximal exercise; a second subject developed similar changes but without accompanying symptoms. There is need for detailed physiological surveillance of people undertaking deep dives; this should be undertaken in circumstances that permit accurate measurements and full subject cooperation.
PMCID: PMC1007786  PMID: 3814548
9.  Lung mechanics in relation to radiographic category of coalworkers' simple pneumoconiosis 
ABSTRACT The maximal expiratory flow/static transpulmonary pressure relationship and the maximal expiratory flow response to breathing oxyhelium were used to distinguish between loss of elastic recoil and narrowing of small airways in 36 lifelong non-smoking non-bronchitic South Wales coalminers. On average the miners showed significantly (p < 0·05) reduced lung elastic recoil when compared with 10 healthy similarly aged non-miners. The mean forced expiratory volume in one second and the forced expiratory flow response to oxyhelium at 50% of the vital capacity were significantly (p < 0·05) lower in 12 miners with radiographic categories 2 or 3 when compared with 24 similarly aged miners with radiographic categories 0 or 1. The miners with categories 2 or 3 coalworkers' simple pneumoconiosis (CWP) had worked underground for 10 years longer, and their mean residual volume, residual volume/total lung capacity ratio, volume of isoflow and critical transmural pressure were significantly higher (p < 0·05). The results indicate that in the prodromal and early stages of simple CWP (categories 0 and 1), the dominant pathophysiological abnormality is loss of elastic recoil suggesting the presence of “focal emphysema.” As simple CWP progresses to categories 2 and 3, the loss of recoil is maintained, and the small airways become narrower. These findings are consistent with the hypothesis that progression of simple CWP is associated with the development of both centrilobular emphysema and intrinsic narrowing of small airways.
PMCID: PMC1009113  PMID: 6824596
10.  A long-term follow-up of workers exposed to beryllium 
ABSTRACT The relationship of features of beryllium disease to the estimated exposure to beryllium has been investigated over a 30-year period at a factory manufacturing beryllium products. The factory opened in 1952. Of the 146 men who had worked there for more than six months up to 1963, 89% were seen at that time and were followed up in 1973. The nine who continued to work in the factory and those who were engaged subsequently were examined in 1977. On each occasion a clinical interview, occupational history, chest radiograph, and assessment of lung function were carried out. The findings of the main survey were related to the beryllium content of the dust measured by mass spectrometry for 1952-60 when over 3000 determinations were made. In no part of the plant did the estimated average daily exposure exceed 2 μg m-3, and only 9% of individual determinations exceeded this level. Twenty determinations exceeded 25 μg m-3. During the period under review, four men developed the clinical, radiographic, and physiological features of beryllium disease. Two men acquired abnormal chest radiographs consistent with beryllium disease but without other features, and one developed probable beryllium disease despite the diagnosis not being confirmed at necropsy. The affected men were all exposed to beryllium oxide or hydroxide but in a wide range of estimated doses. In six the changes developed after exposure had ceased; trigger factors including patch testing may have contributed to their illness. Seventeen men recalled episodes of brief exposure to high concentrations of dust, two developed pneumonitis from which they recovered completely, and one developed chronic beryllium disease after a further 23 years' exposure. In subjects without clinical or radiographic evidence of disease no convincing evidence was obtained for any association between the lung function and the estimated exposure to beryllium.
PMCID: PMC1009111  PMID: 6824594
11.  Relationship between type of simple coalworkers' pneumoconiosis and lung function. A nine-year follow-up study of subjects with small rounded opacities. 
One hundred and twenty-five men who were identified in 1968 as having the simple pneumoconiosis of coalworkers were re-examined nine years later when their mean age was 59.6 years. On both occasions the lung function and response to exercise were assessed. There was no evidence for progression of simple pneumoconiosis between the surveys, but 14 had developed small irregular opacities on their chest radiographs and 28 showed early changes of progressive massive fibrosis (PMF). After allowing for the effects of smoking and of exposure to coal dust, subjects with both p and r types of simple pneumoconiosis exhibited a reduced transfer factor compared with subjects having q-type opacities; subjects with r-type opacities also showed an increased pulmonary elastic recoil pressure. The presence of irregular opacities, independent of rounded opacities, was associated with a low transfer factor and decreased slope of phase III of the single breath oxygen test. Subjects who developed PMF between 1968 and 1978 had p or r opacities more often than q opacities: these subjects had an increase pulmonary elastic recoil pressure. The development of PMF was also associated with physiological evidence of airways obstruction. The changes in subjects with r opacities are consistent with the presence of space occupying lesions that may progress to PMF. Subjects with p opacities have physiological evidence of emphysema as do some subjects with established PMF. Irregular opacities may reflect the presence of both emphysema and diffuse fibrosis. There is need for more morbid anatomical evidence on the underlying pathology.
PMCID: PMC1069280  PMID: 7317293
12.  Lung function of office workers exposed to humidifier fever antigen. 
Office workers who became sensitised to antigens derived from humidifier sludge developed episodes of fever, malaise, and other symptoms, including polyuria and mild chest tightness. The episodes usually occurred on a Monday evening and were to some extent dose-related. Lung function was assessed over a day shift on two occasions, including one after which almost all the susceptible subjects developed symptoms. The symptoms were preceded by a 6% reduction in forced expiratory volume and vital capacity, a corresponding increase in residual volume, and a reduction in flow rate after 75% vital capacity had been expired. There were no changes in peak expiratory flow, forced expiratory flow at 50% of vital capacity, or transfer factor. In some subjects the transfer factor was apparently reduced 36 hours later, but for this there may have been another explanation. The physiological features were considered to reflect narrowing of small airways in the lung. The changes, however, were minimal and not the main cause of the symptoms. A feature of the episode was the severity of the constitutional symptoms despite the low airborne dust levels.
PMCID: PMC1008795  PMID: 7470402
13.  Effects of exposure to slate dust in North Wales. 
In a study of slate workers in four areas in North Wales 725 workers and ex-workers who had been exposed to slate and to no other dust were seen, together with 530 men from the same area who had never been exposed to any dust. Evidence of pneumoconiosis was found in one-third of the slate workers, and 10% had degrees of pneumoconiosis that would attract compensation (category 2 or higher). The prevalence of respiratory symptoms was high, and there was evidence of an effect of both simple and complicated pneumoconiosis on lung function additional to that of age. There was a high prevalence (40-50%) of radiological lesions suggestive of healed tuberculosis in men aged over 55. Either pneumoconiosis or old tubercular lesions (or both together) could account for the current symptomatology and disability of the men.
PMCID: PMC1008683  PMID: 7426466
14.  The ventilatory cost of activity. 
The energy cost of activity, depending on its intensity, varies between 6 and 50 kJ min-1 with average values for essential daily tasks and for hard work respectively of 12 and 28 kJ min-1. The levels of ventilation required to sustain these activities are, on average, 15 and 33 1 min-1 with an overall range of +/- 30%. Additional ventilation is needed for speech. The requirements for individual activities are reviewed.
PMCID: PMC1008062  PMID: 1156570

Results 1-14 (14)