A J Newman Taylor

CADMIUM FUME INHALATION AND EMPHYSEMA

Lung function and chest radiographs of 101 men who had worked for 1 or more years manufacturing copper-cadmium alloy were compared with those of a referent group matched for age, sex, and employment status. Cigarette consumption was similar in the two groups. The cadmium workers had an excess of abnormalities of lung function and of radiographic changes consistent with emphysema. Classification of the cadmium workers by exposure categories based on either estimated cumulative cadmium exposure or liver cadmium measured by neutron activation analysis showed that abnormalities of lung function were greatest in those with the highest cumulative cadmium exposure or liver cadmium. The difference in the transfer coefficient (KCO) between cadmium workers and referents increased linearly with increasing cumulative exposure without evidence for a threshold. The estimated mean decrement in KCO for a cadmium worker employed 5 or more years with a cumulative exposure of 2000 yr.microgram.m-3 (exposure to the current UK control limit of 50 micrograms.m-3 for a working lifetime of 40 yr) lies between 0.05 and 0.3 mmol.min-1.kPa-1.l-1 (95% confidence interval). This decrement is consistent with the functional and radiological changes of emphysema observed in this group of workers.

Work related symptoms, sensitisation, and estimated exposure in workers not previously exposed to laboratory rats

Findings are presented from the initial cross sectional phase of a cohort study of employees exposed to laboratory rats. Of 366 eligible workers at four sites 323 (88%) were surveyed; symptoms assessed by self completed questionnaire and sensitisation measured by the response to skin prick tests were related to intensity of exposure both to total dust and to rat urinary aeroallergen. Among 238 workers, without previous occupational exposure to rats, work related symptoms, which started after first employment at the site were related to exposure intensity (expressed either in terms of dust or of aeroallergen) at the time of onset of symptoms. These relations were stronger in atopic subjects but were unrelated to smoking. Positive skin tests to rat urinary extract were also more frequent with increased exposure, a relation found in both atopic subjects and in smokers. There was a strong association between work related symptoms and specific sensitisation.

Work related symptoms, sensitisation, and estimated exposure in workers not previously exposed to flour

Findings are presented from the initial cross sectional phase of a cohort study of employees exposed to flour in bakeries or mills. Of 401 eligible workers in seven sites 344 (86%) were surveyed; symptoms assessed by self completed questionnaire, and sensitisation measured by the response to skin prick tests, were related to intensity of exposure both to total dust and to flour aeroallergen. Among 264 subjects without previous occupational exposure to flour, work related symptoms which started after first employment at the site were related to exposure intensity, especially when exposure was expressed in terms of flour aeroallergen. The relations with eye/nose and skin symptoms were independent of atopic status and cigarette smoking. Positive skin test responses to mixed flour and to alpha amylase were also more frequent with increasing exposure intensity, although this was confounded by atopic status. There was only a weak association between symptoms and specific sensitisation.

Laboratory animal allergy in a pharmaceutical company

A cross sectional survey was carried out on 138 workers exposed to laboratory animals. Sixty (44%) had symptoms in a self completed questionnaire that were consistent with laboratory animal allergy (LAA) of whom 15 (11%) had chest symptoms. There was a positive skin prick test to one or more animal urine extracts (rat, mouse, guinea pig, rabbit) in 13% and 38% had a positive radioallergosorbent test to urine extract. LAA chest symptoms were almost five times more common in atopic than non-atopic subjects (who were distinguished by skin test response to common, non-animal aeroallergens). A positive skin test to animal urine was associated with LAA chest symptoms and with atopy. Nose, eye, or skin symptoms without chest symptoms were not associated with atopy. There was an inverse relation between duration of employment at the firm and LAA chest symptoms, suggesting selection of affected people out of employment with animals.

Smoking, atopy, and laboratory animal allergy

This study examined data from three cross sectional surveys of 296 laboratory workers exposed to small mammals. Four indices of laboratory animal allergy were studied: symptoms suggestive of occupational asthma, symptoms suggestive of any occupational allergy, skin weals to animal urine extracts, and serum binding in radioallergosorbent tests with urine extracts. Pooled data from the three surveys showed an association between smoking and all indices except radioallergosorbent tests; the association was significant for symptoms of occupational asthma. One of the three surveys consistently showed a stronger association of allergy indices with smoking than with atopy (defined on skin tests with non-animal aeroallergens). Associations with smoking persisted after stratifying by atopic status, suggesting that smoking may be a risk factor for laboratory animal allergy.

Is lung cancer associated with asbestos exposure when there are no small opacities on the chest radiograph

This study was designed to test the hypothesis that the risk of lung cancer from asbestos exposure is confined to persons with radiographic evidence of pulmonary fibrosis. Occupational and smoking histories were obtained from 271 patients with a confirmed diagnosis of primary lung cancer and 678 referents (279 with other respiratory disease and 399 with cardiac disease). Histories were reviewed blind to assess the timing, duration, and probability of exposure to asbestos. To allow for a lag between asbestos exposure and the development of lung cancer, subjects were classified by the time they had spent in an occupation entailing definite or probable exposure more than 15 years before diagnosis. The presence and extent of fibrosis was assessed blindly from chest radiographs by three readers and scored for small opacities with the ILO 1989 International Classification of Radiographs of the Pneumoconioses. 93 (34.3%) cases had worked in an occupation with definite or probable asbestos exposure compared with 176 (25.8%) referents (crude odds ratio for lung cancer 1.49, 95% CI 1.09-2.04). After adjustment for age, sex, smoking history, and area of referral, the odds ratio (95% CI) was 2.03 (1.00-4.13) in the subgroup of 211 with a median ILO score for small parenchymal opacities of 1/0 or more, and 1.56 (1.02-2.39) in the 738 with a score of 0/1 or less (ie, those without radiological evidence of pulmonary fibrosis). These results suggest that asbestos is associated with lung cancer even in the absence of radiologically apparent pulmonary fibrosis.

Occupational asthma due to methyl methacrylate and cyanoacrylates.

Five patients had asthma provoked by cyanoacrylates and one by methyl methacrylate, possibly because of the development of a specific hypersensitivity response. Acrylates have wide domestic as well as industrial uses, and inhalation of vapour emitted during their use can cause asthma.

Respiratory symptoms questionnaire for asthma epidemiology: validity and reproducibility.

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 attack in the last year (n = 23), were more likely to report any symptom and to report a greater number of symptoms than those without asthma. The same relationship was found for bronchial hyperresponsiveness and symptoms. Either two or more, or three or more, symptoms appeared to be good indices of self reported asthma and bronchial hyperresponsiveness, or both, with a high sensitivity (65-91%) and specificity (85-96%). Reproducibility was good, with few subjects changing the number of symptoms reported by more than one symptom and none by more than four symptoms. The results compared favourably with those from questions on phlegm production from the MRC questionnaire and were better than those reported for the MRC wheeze questions. CONCLUSIONS: The questionnaire will be useful for epidemiological research on asthma and could form part of a new standardised questionnaire with wide applications.

Risk factors for sensitisation and respiratory symptoms among workers exposed to acid anhydrides: a cohort study.

OBJECTIVES: To examine the relation between exposure to acid anhydrides and the risk of developing immediate skin prick test responses to acid anhydride human serum albumin (AA-HSA) conjugates or work related respiratory symptoms; to assess whether these relations are modified by atopy or smoking. METHODS: A cohort of 506 workers exposed to phthalic (PA), maleic (MA), and trimellitic anhydride (TMA) was defined. Workers completed questionnaires relating to employment history, respiratory symptoms, and smoking habits. Skin prick tests were done with AA-HSA conjugates and common inhalant allergens. Exposure to acid anhydrides was measured at the time of the survey and a retrospective exposure assessment was done. RESULTS: Information was obtained from 401 (79%) workers. Thirty four (8.8%) had new work related respiratory symptoms that occurred for the first time while working with acid anhydrides and 12 (3.2%) were sensitised, with an immediate skin prick test reaction to AA-HSA conjugates. Sensitisation to acid anhydrides was associated with work related respiratory symptoms and with smoking at the time of exposure to acid anhydride. When all subjects were included and all three acid anhydrides were taken into account there was no consistent evidence for an exposure-response relation, but with the analysis restricted to a factory where only TMA was in use there was an increased prevalence of sensitisation to acid anhydrides and work related respiratory symptoms with increasing full shift exposure. This relation was apparent within the current occupational exposure standard of 40 micrograms.m-3 and was not modified significantly by smoking or atopy. CONCLUSIONS: Intensity of exposure and cigarette smoking may be risk factors for sensitisation to acid anhydrides. Exposure is also a risk factor for respiratory symptoms. As there was evidence for sensitisation to TMA at full shift exposures within the occupational exposure standard this standard should be reviewed.

Recurrent nocturnal asthmatic reactions to bronchial provocation tests

Introduction Nocturnal symptoms were described by Salter as an important feature of bronchial asthma in 1882 (Salter, 1882), and lung function measurements in asthmatic patients have confirmed the tendency for airflow obstruction to increase during the night and early morning (Clark & Hetzel, 1977). In a recently reported case, airflow obstruction was found to recur on several nights following a single exposure to the provoking agent, with maintenance of relatively normal lung function during the intervening days (Davies, Green & Schofield, 1976). Episodes of wheezing confined to the night-time have been reported in workers handling Western Red Cedar (Gandevia & Milne, 1970; Mitchell, 1970). Nevertheless, asthma recurring on several successive nights after a single short exposure to the provoking agent has only recently been recognized, and its mechanism is unknown.