This study aimed to examine the relationship between exposure to rat urinary allergens, atopic status, smoking and the development of allergic symptoms and specific sensitization.It is a case-referent analysis of a cohort of 342 newly employed laboratory animal workers. Cases comprised persons developing symptoms of laboratory animal allergy or a positive skin prick test to rat urinary allergens; each was matched with up to two asymptomatic referents. Subjects were assigned to categories of exposure based on measurements of airborne rat urinary allergens.Of the cases, 80% reported that their symptoms started within 2 yrs of employment. The odds ratio (OR) for development of each symptom type (respiratory, eye or nose and skin) and of an immediate skin test reaction was increased in those with direct contact with rats. A gradient of increasing OR for the development of any such symptom across exposure categories was found; for respiratory symptoms and skin test reactions the OR for subjects in the highest exposure category were lower than those in intermediate categories, a pattern attenuated when the analysis was confined to outcomes developing within 2 yrs of first exposure. Atopy increased the OR of most outcomes as did cigarette smoking, although there was no evidence of a relationship between smoking and the development of a specific skin test reaction.In conclusion, allergen exposure was confirmed as the most important determinant of laboratory animal allergy; by implication, measures to reduce exposure may be the most effective means to reduce its incidence. Eur Respir J 1999; 13: 1139±1143. Allergy to inhalable, animal-derived proteins is a common occupational health problem among employees working with small laboratory animals. In a prospective study of new staff at a large toxicological laboratory with several animal species, the incidence of clinically-diagnosed laboratory-animal allergy in the first year was 9% and that of specific immunoglobulin (Ig)E development~22% [1].Figures from the surveillance of work-related and occupational respiratory disease (SWORD) national surveillance scheme indicate that laboratory animal proteins are the commonest high molecular weight cause of occupational asthma seen by chest and occupational physicians in the UK [2]; the annual incidence of new cases of laboratory animal asthma in the UK, estimated from the same source, is at least 188 per million exposed employees [3].With the development of immunoassays [4] it has become possible to measure directly the relationship between intensity of exposure to airborne animal allergens and sensitization and allergic disease. This relationship has been studied in a cohort with occupational exposure to laboratory rats; in a previous report of the initial, cross-sectional phase [5] weak associations between allergic symptoms and rat urinary aeroallergen exposure, modified by atopic status were described. The present study describes the findings of a full longitudinal study, analysed using a nested case-referent approa...

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 eyelnose and skin symptoms were independent of atopic status and cigarette smoking. Positive skin test responses to mixed flour and to a 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.

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...

This study supports the view that patients with specific IgE to grass pollen are at risk of thunderstorm-related asthma. The details of the causal pathway from storm to asthma attack are not clear. Case-control and time series studies are being carried out.

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 expo--sure 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. ( information; the current cohort study was designed to correct these deficiencies. We report findings of the initial phase. Subjects and methods SURVEY METHODSFour institutions specialising in small animal research in the United Kingdom were identified: three use a variety of animals including rats; the fourth uses almost exclusively mice and is not described in this paper. All full time employees in occupational groups where exposure to laboratory rats or mice was probable and a group of non-exposed office workers, who had started work at the site from 1 January 1986 onwards and had worked for at least one month, were invited to participate.Members of the cohort still employed at the sites have been surveyed at six-monthly intervals since 1990. We describe the findings from the initial survey. Two visits to each site were made, the second to collect information from those missed at the first visit. Of 366 eligible subjects 323 (88%) were surveyed, with no difference in response rates between the three workforces. Questionnaires were completed by 315 subjects (84%) and skin prick tests by 295

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Objectives: To estimate the incidence of specific IgE sensitization and allergic respiratory symptoms among UK bakery and flour mill workers; and to examine the roles of flour aeroallergen and total dust exposures in determining these outcomes.Methods: A cohort of 300 new employees, without previous occupational exposure to flour, were followed prospectively for a median (range) of 40 (1-91) months. Cases-defined as those developing work-related symptoms or a positive skin prick test to flour or a-amylase during follow up-were compared with controls, matched for duration of employment. Exposures to flour aeroallergen and total inhalable dust were estimated using a questionnaire and personal sampling techniques. Results: Incidence rates for work-related eye/nose and chest symptoms were 11.8 and 4.1 cases per 100 person years (py), respectively. Fewer employees developed positive skin prick tests to flour (2.2 cases per 100 py) or a-amylase (2.5 cases per 100 py). Positive skin tests to occupational allergens were more common among those with new work-related symptoms. There were clear relationships between the risks of developing work-related symptoms or a positive skin prick test and three categories of estimated exposure to total dust or flour aeroallergen. Atopic employees were more likely to develop a positive skin prick test-but not work-related symptoms. These findings were unaffected by age, sex or cigarette smoking. Conclusions: In this population, many work-related symptoms which develop after first employment in modern UK bakeries or flour mills were not accompanied by evidence of IgE sensitization to flour or a-amylase. Although average dust exposures were within current occupational standards, the risks of development of upper and lower respiratory symptoms and of specific sensitization were clearly related to total dust and/or flour aeroallergen exposure. The incidence of work-related chest symptoms in the presence of a positive skin test to flour or a-amylase in this setting was approximately 1 case per 100 py.

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.