Endotoxin exposure in asthmatic children and matched healthy controls: results of IPEADAM study.

UNLABELLED: Children spend increasing time indoors. Exposure to environmental factors may contribute to the development or exacerbation of the asthmatic phenotype. Inter-relationships between these factors might influence the manifestation of asthma. Endotoxin exposure has been shown to have pro-inflammatory and protective effects in different situations. We investigated the exposure to several indoor pollutants (endotoxin, Der p 1, damp, ETS, PM2.5) in asthmatic and healthy children. The children were recruited from two primary care centers according to their response to a validated questionnaire. Asthmatic children were matched for sex, age and sib-ship size with children living in asthma free households. Of 90 matched pairs, higher levels of endotoxin were found in the living room carpets, but not the bedroom carpet or mattresses of the asthma compared with the control homes (STATA analysis OR: 1.88 (1.11-3.18); P=0.018). Asthmatic children were also more likely to live as part of a single parent family, in a house where the parents self-reported the presence of damp, and where the living room had been redecorated in the 12 months prior to the sampling visits. This study suggests that endotoxin in urban homes is a risk factor for the development of asthma. Moreover, this study found that there were no statistically significant interactions between environmental factors. PRACTICAL IMPLICATIONS: This study has demonstrated that the home environments of English children (4-17) with asthma and without the disease do not differ greatly. With the exception of endotoxin, the parameters examined in this study, including house dust mite allergens, nitrogen dioxide, ETS and damp are unlikely to be related to the development of asthma. Avoidance of these pollutants may not be beneficial in preventing asthma in this age group.

Survey of symptoms, respiratory function, and immunology and their relation to glutaraldehyde and other occupational exposures among endoscopy nursing staff.

OBJECTIVES: To find the nature and incidence of symptoms experienced by a large sample of hospital endoscopy nurses. To find whether nurses in endoscopy units develop asthma under current working conditions in endoscopy units. To obtain analytically reliable data on exposure concentrations of glutaraldehyde (GA) vapour in endoscopy units, and to relate them to individual hygiene and work practices. To characterise any exposure-response relations between airborne GA and the occurrence of work related symptoms (WRSs). Due to the growing concern about the perceived increase in WRSs among workers regularly exposed to biocides, all of whom work within a complex multiexposure environment, a cross sectional study was designed. METHODS: Current endoscopy nurses (n=348) from 59 endoscopy units within the United Kingdom and ex-employees (who had left their job for health reasons (n=18) were surveyed. Symptom questionnaires, end of session spirometry, peak flow diaries, skin prick tests (SPTs) to latex and common aeroallergens, and measurements of total immunoglobulin E (IgE) and IgE specific to GA and latex were performed. Exposure measurements included personal airborne biocide sampling for peak (during biocide changeover) and background (endoscopy room, excluding biocide changeover) concentrations. RESULTS: All 18 ex-employees and 91.4% of the current nurses were primarily exposed to GA, the rest were exposed to a succinaldehyde-formaldehyde (SF) composite. Work related contact dermatitis was reported by 44% of current workers exposed to GA, 56.7% of those exposed to SF composite, and 44.4% of ex-employees. The prevalence of WRSs of the eyes, nose, and lower respiratory tract in current workers exposed to GA was 13.5%, 19.8%, and 8.5% respectively and 50%, 61.1%, and 66.6% in the ex-employees. The mean percentage predicted forced expired volume in 1 second (ppFEV(1)) for ex-employees (93.82, 95% confidence interval (95% CI) 88.53 to 99.11) was significantly lower (p<0.01) than that of current workers exposed to GA (104.08, 95% CI 102.35 to 105.73). Occupational peak flow diaries completed by current workers with WRSs of the lower respiratory tract showed no evidence of bronchial asthma (<15% variation). Six per cent of the population had positive latex SPTs. Positive indications of one GA specific IgE and 4.1% latex specific IgE occurred. There was no conformity between the latex specific IgE and positive SPTs. Positive SPTs to latex were associated with WRSs of dermatitis and ocular WRSs, but no other WRSs. Exposures were above the current maximum exposure limit (MEL) of 0.2 mg/m(3) (0.05 ppm) in eight of the units investigated. A significant relation existed between peak GA concentrations and work related chronic bronchitis and nasal symptoms (after adjustment for types of local ventilation) but not to other WRSs. Peak GA concentrations were significantly higher in units that used both negative pressure room and decontaminating unit ventilation. CONCLUSION: This study documents a significant level of symptoms reported in the absence of objective evidence of the physiological changes associated with asthma. Ex-employees and current workers with WRSs warrant further study to elucidate the cause and mechanisms for their symptoms. Ventilation systems used for the extraction of aldehydes from the work area may be less effective than expected and due to poor design may even contribute to high peak exposures.

Attempting to control mite allergens with mechanical ventilation and dehumidification in British houses.

BACKGROUND: Allergen avoidance is of considerable interest in the treatment and even prevention of asthma. Attempts to control house dust mites have included environmental manipulation in homes in an attempt to reduce humidity below a level that favors mite survival. This appears to have some benefit in Scandinavia, but a previous attempt with mechanical ventilation heat pump recovery (MVHR) units in the UK failed to achieve the desired results. OBJECTIVE: We report a study using an additional central dehumidification modification of the MVHR (MVHRcd) in an attempt to reduce allergen levels in houses of asthmatic subjects. METHODS: Ten houses of asthmatic patients allergic to dust mites and 10 architectural control houses were studied. The active houses were fitted with an MVHRcd unit in November/December 1994 and activated in January 1995. The active and control houses were monitored continuously for internal temperature and humidity by using digital sensors in the asthmatic and control bedrooms. Dust samples were collected to determine allergen levels at baseline (January 1994) and 3, 6, 9, and 15 months after switching on the units. RESULTS: The winter seasonal average humidity fell from 50% relative humidity (RH) in control bedrooms to 37% RH in asthmatic bedrooms compared with 72% RH in the ambient air as measured on the intake of the MVHRcd systems. There was no corresponding change in seasonal mean temperature within the houses. Although the temperature and humidity weekly and seasonal means remained below the study target of 45% RH or 7 g/kg absolute humidity at 21 degrees C, there were transient rises in humidity detected by the sensors in the houses with MVHRcd systems. Allergen levels fell both in active and control houses during the study period, but there was no significant advantage gained from the installation of MVHRcd systems. CONCLUSION: The MVHRcd system failed to confer a benefit in terms of mite allergen reduction despite apparently adequate control of temperature and humidity.

Comparative personal exposures to organic dusts and endotoxin.

The aims of the study were to provide valid comparative data for personal exposures to dust and endotoxins for different occupations and to calculate comparative data for the contamination of organic dusts with endotoxin. Nine different occupational settings were studied, drawn from the textile, agricultural and animal handling industries. Samples were collected by personal sampling techniques, using the Institute of Occupational Medicine (IOM) sampling head, glass fibre filters and rechargeable sampling pumps. The dust exposures were calculated by gravimetric analysis and using the calculated volume of air sampled were expressed as mg/m3. Endotoxin exposures were measured using a simple water extraction from the collected dusts, followed by a quantitative turbidimetric assay. Results were expressed as ng/m3, using the calculated volume of air sampled. In addition, the levels of the contamination of dusts with endotoxin for individual industries were expressed as ng/mg of collected dust. Two hundred and fifty-nine samples, collected from 9 different industries and across 36 different sites were analysed. This represented a sampling rate of 25% for the total work force. The average sampling time was 4.62 h. For all the dusts collected, a significant correlation between the collected dust and endotoxin was seen (r = 0.7 and p < 0.001). The highest dust exposures occurred during cleaning activities (grain handling: 72.5 mg/m3). The individuals exposed to the highest median level of dust and endotoxin were the animal handlers (poultry handlers, dust: 11.53 mg/m3, endotoxin: 71,995 ng/m3). Weaving and mushroom cultivation had the lowest exposures for dust and endotoxins. The mostly highly contaminated dusts (median values expressed as ng of endotoxin per mg of collected dust) were found in the animal handling (poultry: 1,030 ng/mg, swine: 152 ng/mg) and cotton spinning (522 ng/mg) industries. Processing of cotton and wool fibres was found to reduce the levels of contamination of dusts with endotoxin. In the study, valid comparative data for personal exposures to organic dusts and endotoxins have been presented. The highest exposures were found amongst animal handlers and during cleaning activities. The results highlight that dust exposures are greater in a number of industries than the set exposure standards. In addition, endotoxin exposures are found to be greater than levels at which harmful effects have been demonstrated.

A comparison of performance of two personal sampling heads for cotton dust.

Cotton dust sampling for monitoring worker exposure was traditionally performed by work area sampling. A change to an exposure limit based on personal sampling has recently been agreed. The choice of sampling head for personal monitoring exposure was hampered by the use of two different sampling heads in the major epidemiological studies of textile workers which had incorporated personal sampling techniques. The purpose of this study was to compare the results of exposure measurements using these two sampling heads. This study has examined the performance of the two sampling heads, by performing dual sampling on cotton operatives during normal working activities. Each operative included wore two samplers randomly allocated to left or right side. A minimum of 200 minutes of sampling was accepted and the relative concentrations calculated. The IOM total dust sampler produced repeatedly higher measurements than the Manchester head. The ratio overall was 1.33 (95% C.I. 1.20-1.49). The performance was similar across the ranges of dust exposure from low (< 1 mg/m3-ratio 1.28), medium (1-3 mg/m3-ratio 1.43) to high exposure (> 3 mg/m3-ratio 1.24). The two heads give reproducibly proportionate dust measurements with approximately 30% greater results obtained with the IOM total dust sampler. Either dust sampling head could be used for worker monitoring and the results adjusted accordingly for reference to the Maximum Exposure Limit.

Prevalence and predictors of work related respiratory symptoms in workers exposed to organic dusts.

OBJECTIVES: The aims of this study were to document the prevalence of work related upper and lower respiratory tract symptoms in workers exposed to organic dusts and to identify variables predictive of their occurrence. METHODS: A cross sectional survey with an administered questionnaire (a previously validated adaptation of the Medical Research Council (MRC) respiratory questionnaire) was performed. Symptoms were classified as work related by their periodicity. Demographic data, smoking habits, and occupational histories were recorded. Personal exposures to dust and endotoxin were measured and individual subjects ascribed an exposure value specific to occupation, site and industry. Cox's regression techniques were used to identify variables predictive of work related upper and lower respiratory tract symptoms. Information was stored using Dbase 3 and analysed with SPSS. RESULTS: 1032 Workers (93% of the target population) were studied in nine different industries. The highest prevalences of work related lower respiratory tract symptoms (38.1%), upper respiratory tract symptoms (45.2%), and chronic bronchitis (15.5%) were found among poultry handlers. White workers were significantly more likely to complain of upper and lower respiratory tract symptoms. An individual in the swine confinement industry had a symptom complex compatible with byssinosis. Increasing current personal exposures to dust or endotoxin were found to be predictive of upper and lower respiratory tract symptoms, chronic bronchitis, and byssinosis. In a univariate analysis a relation between current exposures and the organic dust toxic syndrome was found. Present smoking and previously documented respiratory tract illness were significantly predictive of work related lower respiratory tract symptoms. Women were more likely to report work related upper respiratory tract symptoms. CONCLUSIONS: People exposed to organic dusts may have a high prevalence of work related respiratory tract symptoms which are related to dust exposures and smoking habits. Action should be taken to reduce exposures to dust and endotoxin and stopping smoking should be promoted among workers exposed to organic dusts to reduce morbidity.

Chronic bronchitis in textile workers.

BACKGROUND: Exposure to cotton is known to produce a specific occupational disease known as byssinosis. A large population of textile workers was investigated to determine whether such exposure was also associated with chronic bronchitis once other possible aetiological factors had been accounted for. METHODS: A total of 2991 workers were investigated for the presence of symptoms compatible with chronic bronchitis. An MRC adapted respiratory questionnaire and MRC definition of chronic bronchitis were used for diagnostic labelling. Current and lifetime exposure to dust was estimated by personal and work area sampling, and the use of records of retrospective dust levels previously measured over the preceding 10 years. Airborne endotoxin exposure was measured using a quantitative turbidometric assay. Lung function tests were performed to measure forced expiratory volume in one second (FEV1) and forced vital capacity (FVC). A control group of workers exposed to man-made fibre textiles was identified. The comparative prevalence of chronic bronchitis in the two populations was assessed, allowing for sex, age, smoking habit, and ethnic origin. Two case referent studies were also performed; cases of chronic bronchitis were separately matched with controls from the cotton and control populations to determine the effect of the symptomatic state on lung function. RESULTS: After controlling for smoking (pack years), workers in a cotton environment were significantly more likely to suffer from chronic bronchitis and this was most marked in workers over 45 years of age (odds ratio 2.51 (CI 1.3 to 4.9); p < 0.01). Regression analysis of all possible influencing parameters showed that cumulative exposure to cotton dust was significantly associated with chronic bronchitis after the effects of age, sex, smoking, and ethnic group were accounted for (p < 0.0005). In the intra-cotton population case control study a diagnosis of chronic bronchitis was associated with a small decrement in lung function compared with controls: percentage predicted FEV1 in cases 81.4% (95% CI 78.3 to 84.6), controls 86.7% (84.9 to 88.5); FVC in cases 89.9% (95% CI 87.0 to 92.9), controls 94.6% (92.8 to 96.4). After controlling for cumulative past exposure and pack years of smoking the effect of the diagnostic state remained significant for both FEV1 (p < 0.01) and FVC (p < 0.05). CONCLUSIONS: Chronic bronchitis is more prevalent in cotton workers than in those working with man-made fibre and exposure is additive to the effect of smoking. The diagnosis of chronic bronchitis is associated with a small but significant decrement in lung function.