Preventing baker's asthma: an alternative strategy

BACKGROUND: Although baker's asthma has attracted considerable research interest over the last 30 years, success in its prevention has been slow to achieve. This paper describes the results of an alternative preventive strategy, based on an observation that the excess of sensitization in bread bakers is largely due to IgE-mediated allergy to fungal amylase, contained in bread improvers. The practical application of the strategy has been to limit bread improver exposures to <1 mg/m3 [8 h time-weighted average (TWA)], whilst exposures to all other ingredients, including flour, have been limited to <10 mg/m3 (8 h TWA). METHOD: The paper describes the findings of in-house respiratory health surveillance and dust sampling programmes, from a UK food company whose primary interests are milling and baking, over the period following the introduction of the strategy to target the reduction in bread improver exposure. RESULTS: Over the 10 year period of surveillance, the incidence of symptomatic sensitization in the bread baking sector (2240 per million employees per annum) was greater than for the other flour-using groups (330 per million employees per annum), despite broadly similar total inhalable dust exposures. There was an overall reduction in the incidence of new cases of symptomatic sensitization, from 2085 per million employees per year in the first 5 years of the surveillance programme, to 405 per million employees per year in the subsequent 5 years. CONCLUSION: The strategy of targeting bread improver exposure is an effective approach for the prevention of new cases of symptomatic sensitization in bread bakeries.     

Respiratory symptoms and sensitization in bread and cake bakers

This purpose of this study was to examine the relationship betweenexposure to wheat flour, soya flour and fungal amylase and thedevelopment of work-related symptoms and sensitization in breadand cake bakery employees who have regular exposure to thesesubstances. The study populations consisted of 394 bread bakeryworkers and 77 cake bakery workers whose normal jobs involvedthe sieving, weighing and mixing of ingredients. The groupswere interviewed with the aim of identifying the prevalence,nature and pattern of any work-related respiratory symptoms.They were also skin-prick tested against the common bakery sensitizingagents, i.e., wheat flour, soya flour, rice flour and fungalamylase. The results of personal sampling for sieving, weighingand mixing operations at the bakeries from which the study groupswere taken were collated in order to determine typical exposuresto total inhalable dust from the ingredients, expressed as 8hour time-weighted average exposures. Data from the health surveillanceand collated dust measurements were compared with the aim ofestablishing an exposure-response relationship for sensitization.The prevalence of work-related symptoms in bread bakery andcake bakery ingredient handlers was 20.4% and 10.4% respectively.However, in a large proportion of those reporting symptoms inconnection with work, the symptoms were intermittent and ofshort duration. It is considered that the aetiology of suchsymptoms is likely to be due to a non-specific irritant effectof high total dust levels, rather than allergy. None of thecake bakers and only 3.1% of the bread bakers had symptoms whichwere thought to be due to allergy to baking ingredients. Usingskin-prick testing as a marker of sensitization, the prevalenceof positive tests to wheat flour was 6% for the bread bakersand 3% for the cake bakers. Comparable prevalences for soyaflour were 7% and 1 % respectively. However, the prevalenceof positive skin-prick tests to fungal amylase was 16% amongstthe bread baking group with only a single employee (1 %) inthe cake baking group having a positive test. Furthermore, thisemployee had previously worked in a bread bakery. The differencein rates of sensitization to wheat flour between the bread andcake bakers is not statistically significant, whereas the differencefor soya flour is at the borderline of statistical significance(p=0.045). In contrast, the difference in fungal amylase sensitizationis significant at the 0.1% level. For both bread and cake bakers,the 8 hour time-weighted average exposures for each of the activitiesshowed a wide variation with mixing having the lowest averageexposure and sieving the highest. Out of the allergens studiedin this investigation, fungal amylase is the principal sensitizerin large scale bread bakeries, with the main source of exposurebeing the handling of bread improvers. In contrast, the riskof sensitization to wheat flour is low in both bread and cakebakeries. The absence of positive skin-prick tests in the subgroupof cake bakery employees who regularly handle fungal-amylase-containingflour suggests that their levels of exposure are below the thresholdfor sensitization to amylase.     

Work-Related Asthma in a Population Exposed to Grain, Flour and Other Ingredient Dusts

The purpose of the study was to determine the prevalence andcausation of work-related asthmatic symptoms in a populationexposed to grain, flour and other ingredient dusts. Where workerscomplained of asthmatic symptoms which were the result of dustexposure, follow-up aimed to identify whether the symptoms werethe result of sensitisation or of non-specific irritation. Aquestionnaire was presented to 3,450 workers who had exposureto dust during the course of flour milling (528), bread baking(1,756), cake baking (209) and other activities in food preparation(957). Those with positive responses were followed-up by takinga formal history, examination, skin prick testing and serialpeak flow measurement. The overall prevalence of work-relatedasthmatic symptoms was 4.4% (153 out of 3,450). In the groupwho were followed-up (128 out of 153), non-specific respiratoryirritation was thought to be the cause in 90 (2.6%), whilstsensitisation was responsible for symptoms in 12 (0.3%). Ofthe 12 cases due to sensitisation, the agents responsible were:fungal amylase (10 cases, all associated with bread baking),flour (one case, associated with flour packing), and grain (onecase, associated with flour milling). Non-specific irritationis considerably more common than sensitisation as the causeof work-related asthmatic symptoms in flour milling, bakingand other flour-based industries. The prevalence of sensitisationto flour is very low (less than 1 in 1,000) in all these industries.The principal sensitiser encountered in modern plant bakeriesappears to be fungal amylase. The most important source of exposureto fungal amylase is probably the debagging, sieving, weighingand mixing of bread improvers.     

Latent period for symptomatic sensitization in bakeries

AIM: To describe the latent period for symptomatic sensitization in bread bakery workers. METHODS: Data on the latent period for symptomatic sensitization, resulting in either asthma or rhinitis, were obtained from an in-house health surveillance programme in a single large organization. RESULTS: Over a period of 10 years, 90 employees were identified with symptoms attributable to sensitization. The mean latent period was 7.3 years, with three employees describing the onset of symptoms in their first year of exposure. CONCLUSIONS: The long latent period, typically more than 1 year, suggests that health surveillance on appointment and then at annual intervals thereafter should be adequate to identify affected individuals in a bakery environment.     

Incidence of occupational skin conditions in a food manufacturing company: results of a health surveillance programme

BACKGROUND: The food industry has been associated with a high risk of work-related skin problems. Aim To examine the incidence of work-related skin conditions and the likely causative agents in a single large food company. METHOD: Analysis of a health surveillance programme, conducted over a 7 year period, in a food company with 21 000 employees working in diverse manufacturing processes. RESULTS: The mean incidence of skin conditions, taking all of the different food manufacturing operations together, was 1310 per million employees per annum. The mean incidence was greatest in the manufacturing sector whose operations involved chilled or frozen product (3180 per million employees per annum). Most of the cases reported (184/192 = 96%) were due to primary irritant dermatitis. The two commonest suspected causes of the dermatitis were contact with ingredients and hand washing. Taken together, these factors accounted for 58% of all cases. Although the wearing of gloves is often considered necessary to prevent dermatitis from exposure to ingredients and to lessen the need for hand washing, this factor itself was responsible for 9% of all cases. CONCLUSION: Analysis of a company health surveillance scheme showed the average incidence of work-related skin problems to be lower than previously reported in the food industry.     

Respiratory symptoms and wheat flour exposure: a study of flour millers

The objective of this study was to determine the prevalence of respiratory symptoms and their relationship to sensitization to wheat flour allergens and fungal amylase, in a group of workers from the UK flour milling industry. A cross-sectional study was used to evaluate symptoms, using a structured interview technique, and sensitization, using skin prick test findings, from 679 employees in flour milling and packing operations at 18 flour mills. A total of 147 workers (147/679, 22%) described upper respiratory tract symptoms of some kind. In the majority (139/147, 95%) these symptoms were of an occasional or transitory nature and were related to short-term exposures to high levels of dust. Three individuals (3/679, 0.4%) were identified whose symptoms were thought to be the result of allergy to wheat flour. The prevalence of positive skin prick tests to wheat flour allergens and to fungal amylase was 1.2% (8/678) and 0.9% (6/678), respectively. Measurements of total inhalable dust exposure for personnel exposed to flour dust were taken at 10 of the sites (116 samples). For production personnel the levels were typically between 1 and 10 mg/m3 (8-h time weighted average), with a median of 6.2 mg/m3. Hygiene operatives had appreciably higher exposure than production personnel, with a median of 18.7 mg/m3. Overall, 43% (50/116) of all samples exceeded 10 mg/m3 (8-h time weighted average). The findings suggest that the risk of sensitization to wheat flour allergens from current dust exposures in flour mills is very low. Wheat allergy was responsible in only a small proportion of the total who had respiratory symptoms. The principal causation of symptoms experienced by the workforce was considered to be a non-specific irritant effect related to short-term exposures to high levels of total inhalable dust.     

Allergy to flour and fungal amylase in bakery workers

The purpose of this study was to describe the prevalence ofrespiratory symptoms and skin prick test findings in a groupof 383 employees in a plant bakery population who had the greatestregular exposure to ingredient dusts. The prevalence of positiveskin prick tests to fungal amylase was 16%, in contrast to 6%to wheat flour, suggesting that the principal sensitiser isfungal amylase and not flour. Furthermore, the findings suggestthat symptomatic allergy to bread-baking ingredients is uncommon(3.1%). In comparison, occasional short-lived symptoms whichdo not appear to have an allergic aetiology are relatively prevalent(17.2%). Where sensitisation to ingredients arises, fungal amylasepresent in bread improvers is the principal allergen.     

Concerns for asthma at pre-placement assessment and health surveillance in platinum refining--a personal approach

Platinum, a noble metal, is inert in the body and has an important use in medical applications. It is used in autocatalysts to control harmful vehicular emissions and the catalytic effects improve efficiencies of pharmaceutical and petrochemical processes. The refining process involves exposure to halogeno complex salts of platinum which are potent allergens. They induce symptoms typical of a type I allergy, the most significant of which is asthma. Platinum refining not only exposes employees to the risk of sensitization to these salts but also to respiratory irritants. Inhalation of these aggravates pre-existing asthma. The increasing incidence of asthma in the community requires that prospective employees for platinum refining be assessed carefully to establish their respiratory health status in relation to the risk of sensitization or aggravation of pre-existing asthma. Routine medical surveillance has been shown to reduce persistence of asthma in sensitized workers who cease exposure to the platinum salts upon diagnosis. Skin prick test using dilute platinum salt solutions can detect sensitization at an early stage and this has become the mainstay of surveillance programmes as it is objective and reproducible as well as predictive for the development of symptoms when exposure is allowed to continue. Symptoms are not sensitive or specific. Smoking is a significant risk factor.     

Occupational asthma prevention and management in industry--an example of a global programme

Isocyanates are widely used in the manufacture of polyurethane foams, plastics, coatings and adhesives, and are known to cause occupational asthma in a proportion of exposed workers. Substitution as a prevention strategy is not currently a feasible option. For this reason, health and safety professionals working together in an automotive coatings business created a proactive global programme to address the known potential effects of isocyanates on its workers. The goals of the programme are prevention, early detection and mitigation of effect of key endpoints, especially asthma and to a lesser degree dermatitis, in people who are occupationally exposed, or potentially exposed, to isocyanates and products containing isocyanates. The surveillance programme for isocyanates has several important components, which include assessment of exposure, pre-placement questionnaire and spirometry, training and education of employees, regularly administered periodic questionnaires, medical assessment for abnormal questionnaire responses, process for early reporting and investigation of symptomatic employees and incidents, group data review and management reporting. Although regional differences exist regarding availability of specialized services, we have successfully implemented this programme in parts of North America, Europe and Latin America, and are currently implementing elsewhere. These simple control measures are relatively inexpensive and can be applied in even small business settings. It is recommended that all employers who manufacture, handle or use isocyanate-containing products consider such a strategy.     

Current best practice for the health surveillance of enzyme workers in the soap and detergent industry

This study defines current best practice for the health surveillance of workers who are potentially exposed to enzymes in the manufacture of enzymatic detergent products. It is recommended that health surveillance is performed 6-monthly for the first 2 years and annually thereafter. The health surveillance programme should include a respiratory questionnaire to detect symptoms, assessment of lung function to detect pre-symptomatic changes and an immunological test to detect specific immunoglobulin E (IgE) to enzymes. The International Union Against Tuberculosis and Lung Disease respiratory questionnaire should be used since it has been validated extensively for detecting asthma. Operators should observe the American Thoracic Society performance criteria for spirometers and standardized procedures for conducting spirometry. Since current airborne monitoring techniques for enzymes do not detect short-duration peak exposures, the incidence of employee sensitizations remains the most reliable measure of the integrity of environmental control. The Pepys skin prick test has been validated as a sensitive, specific and practical test for detecting specific IgE to many inhalant allergens including enzymes. For newly sensitized workers, a multi-cause investigation should be conducted to identify potential sources of exposure. Group results of immunological test results assist in the evaluation of workplace control measures, and should be used to monitor the effectiveness of hygiene and engineering programmes and to help prioritize areas for improvement. Positive responses to a questionnaire or abnormal spirometry should be assessed further. Occupational asthma should be excluded in any case of adult-onset asthma that starts or deteriorates during working life. This is particularly important because an accurate diagnosis of occupational asthma with early avoidance of exposure to its cause can result in remission of symptoms and restoration of lung function.     

Supermarket baker's asthma: how accurate is routine health surveillance?

Background: Regular health surveillance is commonly recommended for workers exposed to occupational antigens but little is known about how effective it is in identifying cases.

Aims: To report one large company's surveillance and compare its findings with those of a standard cross-sectional survey in the same workforce.

Methods: A supermarket company with 324 in-store bakeries producing bread from raw ingredients conducted a three-stage health surveillance programme in around 3000 bakery employees. The first stage involved the administration of a simple respiratory questionnaire. If chest symptoms were present a second questionnaire focusing on their work relationship was administered. If positive a blood sample was requested for the measurement of specific IgE to flour and fungal α-amylase. The results were compared to an independent cross-sectional survey of employees in 20 of the company's stores.

Results: Two hundred and ninety nine (92%) of the company's bakeries took part in surveillance. The overall employee response for the first stage was 77%; a quarter of those with respiratory symptoms reported that they were work related. Seventy four (61%) of those with work related chest symptoms had a measurement of specific IgE to either flour or fungal α-amylase, of whom 30 (41%) had a positive result. Surveillance estimated that 1% of bakery employees (1% bakers, 2% managers, 0.6% confectioners) had work related symptoms with specific IgE. This compared with 4% (7.5% bakers, 3.3% managers, 0% confectioners) in the cross-sectional survey (n = 166, 93% response).

Conclusion: Comparison with a standard cross-sectional survey suggests that routine surveillance can underestimate the workplace burden of disease. The reasons may include technical or resource issues and uncertainties over confidentiality or the perceived consequences of participation. More research needs to be done looking into the design and efficacy of surveillance in occupational asthma.

     

Implementation of statutory occupational respiratory health surveillance

Health surveillance is required by UK regulations in certain circumstances, and is usually provided through an occupational health organization. Although there are studies assessing the provision of health surveillance across the country, there are no published studies addressing the practical application of legislation, guidelines and medical research to respiratory health surveillance programmes. An audit of a multidisciplinary health surveillance programme was carried out, using review of occupational health records, occupational hygiene reports and managers' risk assessments, to compare the implementation of health surveillance in different organizations and under different contractual relationships. Sixty-six per cent of National Health Service (NHS) and 56% of industrial workplaces were able to provide risk assessments but were unable to link these with appropriate health surveillance. Twenty-seven per cent of NHS employees potentially exposed to respiratory sensitizers had baseline surveillance, compared with 87% in industry. Fifty-five per cent of Medical Research Council questionnaires were inappropriately administered by the employee themselves, rather than an interviewer as recommended. Other follow-up questionnaires in use had not been formally validated. Non-regular lung function assessment using spirometry was the predominant tool used for follow-up surveillance. There was no overall strategic approach to respiratory health surveillance in the organization studied. Health surveillance programmes should focus on disease prevention without becoming a repetitious application of unvalidated tools. Clinical governance demands quality assurance standards that will effectively implement a coordinated approach to health surveillance.     

The impact of the COSHH regulations on workers with occupational asthma

In the UK, the COSHH Regulations give specific guidance thatemployers have duties to inform, instruct and train their employeesabout occupational risks and provide them with suitable healthsurveillance. The aim of the study was to evaluate the impactof the Regulations on employees with occupational asthma. Onehundred consecutive patients attending an occupational lungdisease clinic completed a questionnaire assessing the implementationof the COSHH Regulations in their workplace. Twenty-eight percent had a pre-employment inquiry about asthma, 31% had regularhealth surveillance by questionnaires and 19% had regular lungfunction assessment at work. Pre-employment spirometry was carriedout in 44% of the workers who were exposed to one of the originalseven prescribed agents, significantly more than those who wereexposed to other agents (19%) (p < 0.05). Moreover, figuresfor spirometry during employment were 31% and 8% respectively(p < 0.05). The patients who worked after ‘COSHH’but before ‘MS25’ had a tendency to be providedwith health surveillance more than those who worked after both‘COSHH’ and ‘MS25’. Ninety-one per centof the patients had never been informed about the risks of gettingasthma at work and 73% had never seen the safety data sheets.The workers who (1) worked after ‘COSHH’ introduction;(2) worked in larger firms and (3) were exposed to one of theoriginal seven prescribed agents, had a tendency to be informed,instructed and trained more than the rest. However, there wereonly significant statistical differences (p<0.05) in termsof the safety data sheet provision between the cases who workedbefore the time of the legislation and those employed afterwards.     

Absenteeism and mortality of workers exposed to electromagnetic fields in the French Electricity Company

The objective of this study was to describe the health status of electricity workers exposed to electromagnetic fields during their job. Two groups of exposed workers were studied from 1978 to 1993: the live line workers (n = 121) and the substation workers (n = 232.7) of the French Electricity Company (EDF). A control group was randomly selected from all the company non-management male employees; one control for each exposed subject was matched for the first year of employment. Absenteeism indices and mortality rates were computed and compared in the exposed and control groups. The absence rates were 1.98% in the substation workers and 2.5% in the control group (p < 0.001) and 2.7% in the live-line workers and 2.8% in the control group (NS). No effect of the length of exposure was found. However the medical causes of sickness absence were different: exposed employees had less psychiatric and respiratory diseases but more accidents at work than their control group. Relative risks of accidents at work were 1.2 95% confidence interval (CI) = 1.08-1.33[ for substation workers and 3.22 (CI = 1.78-5.88) for live line workers. EDF electromagnetic field exposed workers seemed not to be affected by any specific health problems except for an excess of accidents at work.     

Small bakeries--a cross-sectional study of respiratory symptoms, sensitization and dust exposure.

This cross-sectional study investigated the prevalence of respiratory symptoms and sensitization to dust components in 224 individuals in 18 small bakeries in Scotland. Each work practice in the bakeries was characterized by an assessment of dust exposure and assigned to a category with either a direct exposure to flour dust of an indirect exposure to flour dust. We found that work-related respiratory symptoms were significantly associated with specific IgE to wheat flour and amylase but not to exposure category (except for nasal/eye symptoms). However, specific IgE to wheat flour was significantly associated with exposure category. There was a higher prevalence of immunological sensitization, reporting of work-related respiratory symptoms and exposure to dust than in other studies and of the 144 personal dust sample results taken, 21 (14.6%) of the total exceeded 10 mg/m3, the substantial dust concentration as outlined by the COSHH Regulations. Follow-up of those with work-related asthma symptoms (questionnaire response) was inconclusive of the work-relatedness of their symptoms, although it did confirm respiratory morbidity.     

A cross-sectional study of employer and employee occupational health needs and priorities within the Irish Civil Service

BACKGROUND: This study aimed to establish how important an occupational health unit (OHU) is to its clients, and to identify the perceived needs and priorities for such a service. METHODS: A cross-sectional postal survey of a stratified, randomly selected group of employees (n = 760) and all human resources (HR) managers (n = 34) was conducted in the Irish Civil Service. Each participant was requested to rate the overall importance of the OHU and to prioritize eight proposed functions for the unit: medical surveillance, general health education, pre-employment/promotion medical assessments, ill-health retirement assessments, return-to-work (after sick leave) assessments, occupational health education, research, and general medical screening. The results were analysed according to age group, gender, grade and occupation. RESULTS: There was a response rate of 69% from employees and 74% from personnel managers. Significantly more HR managers than employees (92 versus 81%) thought an occupational health service was either important or very important. There were also differences in prioritization of functions by employees and HR managers. HR managers prioritized those functions concerned with assessing individuals' fitness for work, notably pre-employment/promotional health assessments, whereas employees consider group-directed 'preventative' functions to be more important, i.e. general medical screening, health education and medical surveillance. Both sets of opinions are not mutually exclusive, and considerable overlap exists, notably in the areas of occupational and general health education.     

Seafood processing in South Africa: a study of working practices, occupational health services and allergic health problems in the industry

The work practices, occupational health services and allergic health problems among workplaces which process seafood in Western Cape province of South Africa were examined. A cross-sectional study was conducted among 68 workplaces that were sent a self-administered postal survey questionnaire. Workplaces reporting a high prevalence of work-related symptoms associated with seafood exposure were also inspected. Forty-one (60%) workplaces responded to the questionnaire. The workforce consisted mainly of women (62%) and 31% were seasonal workers. Common seafoods processed were bony fish (76%) and rock lobster (34%). Major work processes involved freezing (71%), cutting (63%) and degutting (58%). Only 45% of workplaces provided an on-site occupational health service and 58% of workplaces conducted medical surveillance. Positive trends were observed between workplace size and activities such as occupational health service provision (P = 0.002), medical surveillance programmes (P = 0.055) and reporting work-related symptoms (P = 0.016). None of the workplaces had industrial hygiene surveillance programmes to evaluate the effects of exposure to seafood. Common work-related symptoms included skin rashes (78%), asthma (7%) and other non-specific allergies (15%). The annual prevalence of work-related skin symptoms reported per workplace was substantially higher for skin (0-100%) than for asthmatic (0-5%) symptoms. The relatively low prevalence of employer-reported asthmatic symptoms, when compared to epidemiological studies using direct investigator assessment of individual health status, suggests likely under-detection. This can be attributed to under-provision and under-development of occupational health surveillance programmes in workplaces with less than 200 workers. This is compounded further by the lack of specific statutory guidelines for the evaluation and control of bio-aerosols in South African workplaces.     

The suitability of teff flour in bread,layer cakes,cookies and biscuits

Abstract

A niche market in alternative foods has emerged in response to interest in a health conscientious diet. The purpose of this study was to evaluate the baking characteristics of teff to determine whether teff could produce satisfactory baked products. Cakes, cookies, biscuits and bread were made in triplicate from composites of wheat flour with 0, 10, 20, 30, 40 and 100% teff flour. Objective tests on size, shape, color and texture were used to evaluate the quality of the baked products. Increases in percent teff resulted in decreases in bread and cake volume (p?>?0.05). The fracture strength of the cookies were not significantly different (p?>?0.05) but spread was significantly greater for cookies made with 40% and 100% teff flour (p?≤?0.05). There was also significant difference (p?≤?0.05) in biscuit height and color among teff treatments. Overall, this study showed that teff flour is best suited for use in cookies and biscuits.     

Respiratory symptoms and ventilatory performance in workers exposed to grain and grain based food dusts

A health surveillance study of male grain food manufacturingworkers used a respiratory health questionnaire and spirometryto assess the prevalence of work-related respiratory symptomsand impaired ventilatory performance. The prevalence of cough,breathlessness, wheeze and chest tightness was between 8–13%but was 20% for rhinitis. Rhinitis was the most common symptomwith 37% of those reporting rhinitis describing this as work-related.A case-control analysis of workers reporting rhinitis did notidentify any specific occupational activities associated withincreased risk of rhinitis. Smoking habit and all respiratorysymptoms apart from rhinitis had a significant effect upon ventilatoryperformance. Occupational exposure to raw grains, flour, ingredientsand finished food was categorized as high, medium or low ineither continuous or intermediate patterns. Multiple regressionanalysis confirmed the effects of height, age and smoking uponventilatory performance. However, occupational exposure to grain,flour, food ingredients and cooked food dusts had no effectupon ventilatory performance. It is concluded that smoking habitis the major determinant of respiratory symptoms and impairedventilatory function. The excess complaints of rhinitis warrantfurther study but it would appear that the current occupationalexposure limits for grain, flour, food ingredients and cookedfood dusts are adequate to protect workers against impairmentof ventilatory performance.