A survey of dust exposure, respiratory symptoms, lung function, and response to skin prick tests was conducted in a modern British bakery. Of the 318 bakery employees, 279 (88%) took part. Jobs were ranked from 0 to 10 by perceived dustiness and this ranking correlated well with total dust concentration measured in 79 personal dust samples. Nine samples had concentrations greater than 10 mg/m3, the exposure limit for nuisance dust. All participants completed a self administered questionnaire on symptoms and their relation to work. FEVy and FVC were measured by a dry wedge spirometer and bronchial reactivity to methacholine was estimated. Skin prick tests were performed with three common allergens and with 11 allergens likely to be found in bakery dust, including mites and moulds. Of the participants in the main exposure group, 35% reported chest symptoms which in 13% were work related. The corresponding figures for nasal symptoms were 38% and 19%. Symptoms, lung function, bronchial reactivity, and response to skin prick tests were related to current or past exposure to dust using logistic or linear regression analysis as appropriate. Exposure rank was significantly associated with most of the response variables studied. The study shows that respiratory symptoms and sensitisation are common, even in a modern bakery.Occupational asthma and rhinitis occur in bakers' and the environmental agents responsible appear to be components of the grain itself" or grain contaminants, such as mites, weevils, and moulds"7 The relative importance of these potential allergens may vary according to the source of the flour, conditions of storage, and intensity of exposure. Recent papers describing grain components as important allergens have come from Australia,24 where grain has a low moisture content. A higher moisture content, or storage ofgrain or flour for long periods, may promote the growth of contaminant micro-organisms, mites, and insects. Materials added to flour before baking, such as yeast and amylase, derived from Aspergillus species,' may also be allergenic. As many as a third ofbakers and grain workers may show evidence of sensitisation,9" which appears to be related to intensity and duration of exposure in the industry as well as to host factors, such as atopy." 12 Mechanisms involving IgE and the mast cell have been implicated,'2 13 but precipitins to components of flour have also been identified' and non-immunological processes, such as direct activation of complement pathways, may be involved.'4Apart from case reports, there is little information about asthma and sensitisation in British bakers. This study was designed to (a) describe the levels of exposure to bakery dust in a modern British bakery, (b) estimate the prevalence of symptoms and sensitisation in the workforce of the bakery, and (c) explore relations between indices of exposure and response. Methods STUDY DESIGN AND SUBJECTSThe study was a cross sectional survey of current employees conducted over six consecutive days and nights. All current...

Background There is a need for a new respiratory symptoms questionnaire for use in epidemiological research in asthma. Method A questionnaire was designed following a pilot study in 78 subjects. It contains nine questions on symptoms such as wheeze and difficulty with breathing in defined circumstances such as exercise and sleep. It was completed by 211 adults and validated by comparison with a self reported history of asthma and with bronchial hyperresponsiveness to histamine. Its short term reproducibility was measured by three repeat administrations over two weeks. Results Subjects with asthma (n = 33), particularly those having had an asthma

After identification of a case of extrinsic allergic alveolitis due to exposure to wood dust at a sawmill, all employees at the sawmill where he worked were studied with an occupational, environmental, and symptom questionnaire, spirometry, skin prick tests, and serum specific IgG measurements. Ninety five of current and 14 of 17 ex-sawmill workers were studied. As a basis for comparison, a group of 58 workers from a nearby light engineering factory were also studied. Few women (6) were employed and they were excluded from the analysis. Workers at the sawmill were stratified into high and low exposure groups depending on their place of work. This division was supported both by their subjective assessment of the dustiness of their environment and the results of personal dust samples. There were no significant differences between the three groups in age, height, smoking habits, exposure to other causes of extrinsic allergic alveolitis, forced expiratory volume in one second, forced vital capacity, atopic state, or cutaneous reactivity to moulds. In the high exposure group the prevalence of work related cough and nasal and eye symptoms was higher than in the low exposure and comparison groups. The prevalence of work related wheeze was similar in both the high exposure and comparison groups, but was lower in the low exposure group. The prevalences of chronic bronchitis and symptomatic bronchial hyper-reactivity were similar in the high and low exposure groups but were lower in the comparison group. Serum concentrations of specific IgG against extracts of sawdust and Trichoderma koningii were significantly higher in the high exposure group than in the other two groups. The prevalence of symptoms suggestive of extrinsic allergic alveolitis was 4 4% in the high exposure group, greater than in the low exposure group (0%), and the comparison group

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Background: Oasys-2 is a validated diagnostic aid for occupational asthma that interprets peak expiratory flow (PEF) records as well as generating summary plots. The system removes inconsistency in interpretation, which is important if there is limited agreement between experts. A study was undertaken to assess the level of agreement between expert clinicians interpreting serial PEF measurements in relation to work exposure and to compare the responses given by Oasys-2. Method: 35 PEF records from workers under investigation for suspected occupational asthma were available for review. Records included details of nature of work, intercurrent illness, drug therapy, predicted PEF, rest periods, and holidays. Simple plots of PEF and the Oasys-2 generated plots were available. Experts were advised that approximately 1 hour was available to review the records. They were asked to score each work-rest-work (WRW) period and each rest-work-rest (RWR) period for evidence of occupational effect. At the end of each record scores of 0-100% were given for evidence of "asthma" and "occupational effect" for the whole record. Kappa values were calculated for each scored period and for the opinions on the whole record. The scores were converted into four groups (0-25%, 26-50%, 51-75%, 76-100%) and two groups (0-50% and 51-100%) for analysis. This is relevant to scores produced by Oasys-2. Agreement between Oasys-2 scores and each expert was calculated. Kappa values for the median expert score v Oasys-2 were 0.75 for two groups and 0.67 for four groups. Agreement was poor for records with intermediate probability, as defined by Oasys-2. Conclusion: Considerable variation in agreement was seen in expert interpretation of occupational PEF records which may lead to inconsistencies in diagnosis of occupational asthma. There is a need for an objective scoring system which removes human variability, such as that provided by Oasys-2.

A 34 year old sawmill maintenance engineer developed a dry cough that was associated with widespread wheezes and crackles in his lungs. His symptoms worsened, with work related lethargy, fever, and breathlessness, and the loss of a stone in weight. At that time, while still at work, he had a neutrophil leucocytosis and increased concentration of y globulins. When seen subsequently some two months after stopping work, his chest radiograph and lung function tests were normal, but the cells recovered at bronchoalveolar savage showed an increase in lymphocytes and mast cells, a pattern consistent with extrinsic allergic alveolitis. Serum precipitins were identified to extracts of sawdust, wood chips, and bark from the sawmill, and to eight species of mould grown from these samples. Specific IgG binding inhibition studies suggested that a common epitope present on Trichoderma koningii might be responsible for the cross reactivity of the patient's serum with the wood and fungal extracts. A diagnosis of wood associated extrinsic allergic alveolitis was made and since changing his job the patient has remained well. Wood associated allergic alveolitis has not previously been described in British sawmill workers, but has been reported in Sweden, with a prevalence of 5%-10% in exposed workers. A review of published data suggests extrinsic allergic alveolitis in wood workers is primarily caused by inhalation of the spores of contaminating fungi, but inhaled wood dust may exert a synergistic effect. (Occup Environ Med 1994;51:160-164) Royal Brompton Hospital, Sydney Street, London SW3

We have studied asthma caused by inhaled acid anhydrides as a model of hapten-induced airway hyperresponsiveness. Inhalation tests with the relevant anhydride in sensitised individuals reproducibly provoked a significant increase in non-specific airway responsiveness identifiable 3 h after the test and prior to the development of the late asthmatic reaction. Seven cases of asthma caused by tetrachlorophthalic anhydride (TCPA) had specific IgE in their serum to a TCPA-human serum albumin conjugate. RAST inhibition studies showed the anhydride to be involved in the antibody-combining site. Survey of the factory population where these 7 cases worked allowed investigation of the determinants of the specific IgE response: its presence was associated with intensity of exposure and current cigarette smoking; in addition smoking interacted with atopy to increase the prevalence of specific IgE. During a 5-year period of avoidance of exposure to TCPA specific IgE declined exponentially with a half-life of one year, suggesting continuing IgE secretion. Five years after avoidance of exposure, airway hyperresponsiveness remained increased in several cases.

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