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01-10-2009 | Respiratory | Article

Occupational asthma is most common asthma phenotype in bakers


Free abstract

MedWire News: Occupational asthma (OA) is the most common asthma phenotype among supermarket bakery workers, research shows.

“While baker's asthma has been well described in various workplaces, phenotypes of asthma among bakery workers in a common workplace setting have yet to be characterized,” write Mohamed Jeebay (University of Cape Town, South Africa) and team in the European respiratory Journal.

“Defining various clinical phenotypes using specific clinical criteria is important for decisions regarding medical surveillance and clinical management of this high-risk group,” they explain.

The researchers therefore studied 517 bakery workers employed by a supermarket chain in the Western Cape province of South Africa.

Between 2003 and 2004 the participants completed the standard European Community Respiratory Health Survey (ECRHS) questionnaire, which is designed to assess asthma symptoms. Additional questions relating to current and previous employment, and degrees of exposure to flour dust and tobacco smoke were also included.

The participants also underwent skin prick tests, spirometry, and methacholine challenge testing, and their levels of specific immunoglobulin E antibodies to wheat, rye and fungal α-amylase were also assessed.

The presence of asthma was defined by an asthma attack or use of asthma medication in the past 12 months, or the presence of nonspecific bronchial hyperresponsiveness.

In addition to these criteria, atopic asthma (AA) was defined by the presence of atopy and the absence of sensitization to bakery dust allergens, while nonatopic asthma (NAA) was defined by being nonatopic and the absence of sensitization to bakery dust allergens. Work-aggravated asthma (WAA) was defined by work-related chest symptoms and the absence of sensitization to bakery dust allergens, and probable OA was defined as sensitization to bakery dust allergens.

The researchers found that the prevalence of probable OA (13%) among the bakery workers was significantly higher than the AA (6%), NAA (6%), and WAA (3%) phenotypes.

High levels of previous exposure to dust, fumes and vapors that caused respiratory symptoms were more strongly associated with WAA (odds ratio [OR]=5.8) than OA (OR=2.8), while work-related ocular–nasal symptoms were significantly associated with both WAA (OR=4.3) and OA (OR=3.1).

The researchers also found that adverse reactions to ingested grain products were significantly associated with OA (OR=6.4).

Jeebay and team conclude: “Our study has demonstrated that OA is the most common asthma phenotype among supermarket bakery workers in this region and is an important globally evolving trend. Analysis of risk factors contributes towards differentiating between these various phenotypes.

“Medical surveillance programs in bakeries can therefore use these criteria to identify persons at risk at an early stage and intensify surveillance and other workplace interventions. Furthermore, in view of the increase in baking activities in supermarkets globally, measures to monitor and reduce exposures remain an important priority.”

MedWire ( is an independent clinical news service provided by Current Medicine Group, a part of Springer Science+Business Media. © Current Medicine Group Ltd; 2009

By Mark Cowen

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