Peak flow rate records in the diagnosis of occupational asthma due to isocyanates.

Peak expiratory flow rate (PEFR) has been recorded hourly or two-hourly from waking to sleeping in workers with respiratory symptoms who were exposed to isocyanate fumes at work. Twenty-three recordings averaging 33 days duration were recorded in 20 workers. Each worker was also admitted for bronchial provocation testing to toluene di-isocyanate (TDI) or diphenylmethane di-isocyanate (MDI) fumes or both. A final assessment of work-related asthma made from subsequent work exposure was compared with the results of bronchial provocation testing and a subjective assessment of the peak flow records. Both techniques were specific and sensitive. Physiological patterns of occupational asthma were defined from the records of PEFR. The most striking finding was the slow recovery from work-induced asthma. This commonly took several days to start and in one worker took 70 days to complete after leaving work. Several workers developed a pattern resembling fixed airways obstruction after repeated exposure at work. The consequences of these findings for the recording of symptoms of occupational asthma are discussed and recommendations are made for the recording of PEFR in workers in general.

Toluene di-isocyanate-induced asthma. I. Reactions to TDI, MDI, HDI and histamine.

A group of twenty four workers handling di-isocyanates and with respiratory disease were investigated by occupational-type bronchial provocation tests for sensitivity to toluene di-isocyanate (TDI), to which all were exposed, and to diphenylmethane di-isocyanate (MDI) and hexamethylene di-isocyanate (HDI). Sixteen gave asthmatic reactions to TDI and eight of these also reacted to MDI. Four of the eight TDI and MDI reactors had histories of exposure only to TDI, and of them two reacted also to HDI. Of nine subjects tested with HDI, three gave asthmatic reactions, and all three also reacted to TDI and MDI. Thus reactions to MDI and HDI were elicited only in the TDI reactors. The possibility of specific sensitivity to these and other di-isocyanates requires tests in subjects exposed to them and not to TDI.

Occupational asthma in an electronics factory.

Workers in a modern electronics factory were surveyed by questionnaire and lung function testing to see if there was evidence of widespread work-related respiratory symptoms. Of the responding workers exposed to solder flux fumes on the shop floor, 22% had work-related breathlessness or wheeze or both. Exposed workers had a lower FEV1 and FVC than unexposed workers. Work-related rhinitis was also present in 22% of exposed workers. The most likely cause for these results is sensitivity to colophony fumes, released from solder flux during soldering. Levels of solder flux fume were below the threshold limit value in this factory during the survey.

Occupational type bronchial provocation tests: testing with soluble antigens by inhalation.

Thirty-seven patients with asthma or alveolitis thought to result from exposure to materials commonly encountered at their work were tested by inhalation of an aerosol of these materials. Twenty-four (65%) developed an immediate asthmatic reaction, which was followed by a non-immediate reaction in 10, of whom six developed the signs and symptoms of alveolitis. Eighteen (76%) patients with asthmatic reactions to test material were prick test positive to that material while only two our of 13 with a negative inhalation test were prick test positive (15%). Precipitating antibody to test material was measured in 23 and was present in nine (39%) of those with positive inhalation tests, and one (12%) of those with negative tests. It was present in five of the six with a reaction in the gas exchanging portions of the lung.

Effects of orally administered sodium cromoglycate in asthma and urticaria due to foods.

Out of twenty patients with a history of asthma or urticaria attributed to food substances, ten reacted on oral challenge: seven with asthma, one with asthma and urticaria and two with urticaria alone. In five of the eight asthmatic reactors, the symptoms developed within a few sec and there was no associated rise in free venous plasma histamine. In those remaining, two with asthma, two with urticaria and one with both, the symptoms developed only after 20-30 min. A rise in free plasma histamine occurred only in the two subjects with urticaria alone. The third with urticaria and asthma did not have blood estimations performed. Sodium cromoglycate in a dosage of 800 mg a day for 1 week, or a single dose of 1.0 g by mouth, did not block any of the reactions. By inhalation it blocked the asthmatic reactions which developed within a few sec of challenge.

Respiratory disease in workers exposed to solder flux fumes containing colophony (pine resin).

Twenty-one patients are described who developed asthma, or evidence of a peripheral airways reaction, while working in the electronics industry and exposed to solder flux fumes containing colophony (pine resin). This selected group contained five patients with pre-existing asthma. Fourteen patients had never smoked. Prick-testing with common environmental antigens gave one or more positive reactions in nine patients. The diagnosis was confirmed by occupational-type provocation tests in all workers with colophony-based cored solder, and reproduced by exposure to the fumes of heated colophony alone. Control subjects did not react to the test with colophony. The clinical findings and provocation test reactins have features of a hypersensitivity reaction, although so far specific antibodies have not been found.

Peak flow rate records in the diagnosis of occupational asthma due to colophony.

Peak expiratory flow rate (PEFR) has been measured hourly from waking to sleeping in 29 workers with respiratory symptoms exposed to the fumes of soft soldering fluxes containing colophony (pine resin). Thirty-nine records of mean length 33 days have been analysed, and the results compared with the occupational history and bronchial provocation testing in the same workers. From plots of daily mean, maximum, and minimum PEFR, recurring physiological patterns of asthma emerge. The most common pattern is for asthma to increase with each successive working day. Some workers have an equivalent deterioration each working day. Regular recovery patterns taking one, two, and three days are described. The combination of a three-day recovery pattern and a late asthmatic reaction on Monday results in Monday being the best day of each week. Assessment of these records has shown them to be specific and sensitive, provided the worker was not taking corticosteroids or sodium cromoglycate during the period of the record and that bronchodilator usage was kept constant on days at home and at work. The results of the PEFR records correlate well with bronchial provocation testing, and provide a suitable alternative to this for the diagnosis of mild to moderate occupational asthma. The records are of particular use for screening symptomatic workers whose symptoms appear unlikely to be related to work.

Occupational asthma due to inhaled carmine.

Two patients are described with occupational asthma due to carmine, a natural dye extracted from the insect Coccus cactus. Both had dual asthmatic reactons after carmine inhalation. Oral challenge provoked gastrointestinal symptoms in one patient, and asthma in them both, perhaps accounting for their continuing symptoms. One patient worked extracting carmine from the insects and the other used carmine as a cosmetic colouring agent.

Occupational asthma in a research centre breeding locusts.

The prevalence of work-related asthma, rhinitis and urticaria was measured in a scientific establishment working with locusts. Twenty-six percent of those handling the locust in the research centre had work-related wheeze or breathlessness, and one-third had work-related rhinitis and urticaria. Work-related symptoms were uncommon in scientists exposed to locusts in the field, and in other employees at the centre. Antigens were prepared from the locusts, Schistocerca gregaria and Locusta migratoria, as well as the moth, Chilo partellus, which was also bred at the centre. Skin prick testing with the locust antigens showed positive reactions in 55% of the atopic workers at the centre, but were also present in 43% of unexposed atopic workers. In this latter group there was a correlation between positive reaction to locust and dermatophagoides antigens. Atopic workers handling the locusts developed occupational asthma more often and more quickly than similarly exposed non-atopic workers. IgG and IgE antibodies to the locust antigens were found to correlate significantly with both the degree of exposure and the presence of disease.

Asthma and extrinsic allergic alveolitis due to Merulius lacrymans.

A teacher with breathlessness of insidious onset developed acute symptoms on return home following his discharge from hospital. His flat was found to have extensive dry rot (Merulius lacrymans). Precipitins and specific IgE and IgG antibody against M. lacrymans were present and intracutaneous testing gave a typical dual skin reaction. Pulmonary physiology demonstrated airflow obstruction with a low DLCO and KCO, and a chest X-ray showed diffuse micronodular shadowing, maximal in the mid-zones. Inhalation challenge testing provoked a combined asthmatic reaction without a change in DLCO. Rapid clinical recovery and more gradual radiographic and physiological improvement followed cessation of exposure to the antigen.

Occupational asthma due to formaldehyde.

Bronchial provocation studies on 15 workers occupationally exposed to formaldehyde are described. The results show that formaldehyde exposure can cause asthmatic reactions, and suggest that these are sometimes due to hypersensitivity and sometimes to a direct irritant effect. Three workers had classical occupational asthma caused by formaldehyde fumes, which was likely to be due to hypersensitivity, with late asthmatic reactions following formaldehyde exposure. Six workers developed immediate asthmatic reactions, which were likely to be due to a direct irritant effect as the reactions were shorter in duration than those seen after soluble allergen exposure and were closely related to histamine reactivity. The breathing zone concentrations of formaldehyde required to elicit these irritant reactions (mean 4.8 mg/m3) were higher than those encountered in buildings recently insulated with urea formaldehyde foam, but within levels sometimes found in industry.

Toluene di-isocyanate-induced asthma. II. Inhalation challenge tests and bronchial reactivity studies.

In sixty-three workers exposed to toluene di-isocyanate (TDI), no overall differences in bronchial reactivity to histamine inhalation and to exercise testing were found between the total groups of positive and negative TDI reactors to provocation tests. A subgroup of TDI highly sensitive subjects reacting to very low concentrations (less than or equal to 0.001 p.p.m.) were more sensitive to both histamine and exercise than the group who were less sensitive to TDI, and who reacted to higher concentrations (0.002--0.02 p.p.m.) than the group of non-reactors. There were, however, in the last group a number of subjects with high degrees of histamine reactivity who did not react to the TDI. These findings suggest that, on the one hand, the asthmatic reactions to TDI cannot be attributed solely to non-specific mechanisms and, on the other, that in subjects with high degrees of specific sensitivity non-specific mechanisms may also be playing a part.

Sequential brush biopsy and conventional biopsy: direct comparison of diagnostic sensitivity in lung malignancy.

One hundred and sixteen patients with suspected lung malignancy who were referred for bronchoscopy were examined using both the flexible fibreoptic bronchoscope and the rigid bronchoscope. Both instruments were used sequentially under the same general anaesthetic. Brush biopsies were obtained through the fibreoptic bronchoscope and conventional biopsies, for histological examination, through the rigid bronchoscope. Both specimens were taken from the same area. Eighty-two per cent of those in whom there was a final clinical diagnosis of malignancy were found to have abnormal cytology via the fibreoptic bronchoscope, while abnormal histology was found in 50% by means of the rigid bronchoscope. For those in whom malignancy was confirmed, 16.9% showed disagreement between the two methods in cell typing. Brush biopsy through the flexible fibreoptic bronchoscope under general anaesthesia is confirmed as a sensitive method for diagnosing lung malignancy.