Asthma is a common lung disease that makes breathing difficult. When it is caused by breathing in hazardous substances in the workplace, it is called occupational asthma.

Baker’s asthma is an occupational asthma that bakery employees develop after being exposed to cereal grains such as wheat, rye and yeast. The allergy can be life-threatening and eventually affect their ability to work.

Globally, research shows between 12% and 26% of bakers suffer from allergic rhinitis (itchy eyes) or conjunctivitis (runny nose), and between 15% to 21% have bakers asthma.

In South Africa, between 17% and 31% suffer work-related respiratory and ocular-nasal symptoms, and about 13% eventually develop baker’s asthma.

But at least double the number of employees show symptoms of wheat flour sensitivity. With continued exposure this can lead to them developing baker’s asthma.

To tackle the challenge of flour dust, various countries have proposed exposure limits for flour dust. In the US industrial hygienists’ bodies have adopted a threshold of flour dust per cubic metre. In Holland, the Dutch Expert Committee of the Health Council also have a grain dust limit.

Although South Africa has a general dust standard level ten times higher than international norms for flour dust, it has no legislation with specific exposure limits for flour dust allergens such as wheat, rye and yeast.

The high sensitisation potential of grain dust makes the South African standard unacceptable in protecting the health of workers. It is a source of concern.

How the allergy develops

If bakery employees who are sensitive to flour dust continue to be exposed to elevated levels of dust, they first develop eye or nose symptoms before they develop asthma.

The frequency of the sensitisation to wheat flour and yeast or other raising agents increases with the intensity of their exposure. The longer the person is exposed or the higher the dust levels, the greater the risk of developing allergy and asthma due to allergens in the flour dust.

International reviews show that between 5% and 28% of bakery workers have a wheat flour sensitivity while between 2% and 16% have a reaction to yeast or other raising agents.

In South Africa, 26% are wheat-flour-sensitive; about 24% are also sensitive to rye flour; and another 4% show a yeast reaction.

Workers with bakers asthma and/or allergic symptoms require medical treatment and workplace remediation. They are treated in the same way as non-occupational asthma sufferers. The most important medication is inhaled bronchodilators and regular use of inhaled corticosteroids. Nasal and eye symptoms are similarly treated with antihistamine medication and local corticosteroid.

Symptoms can be controlled with the appropriate medication and less exposure, but some workers require chronic treatment.

In addition, redeploying workers to minimise further exposure to bakery allergens is strongly advised. Preventative measures should be aimed at reducing workplace exposure and reducing airborne dust generated by baking processes.

Changing practises

International research shows there is a direct relationship between occupational asthma and exposure to airborne allergens. The intensity of the exposure to sensitising agents is the most important risk factor for occupational asthma.

This suggests that reducing allergen exposure levels may reduce the number of sensitised bakery workers.

Despite the overwhelming evidence that workplace exposures to flour dust should be controlled, there are sub-optimal prevention strategies in bakeries.

Primary prevention strategies aimed at reducing workplace exposure to sensitising agents would be the most rational approach for reducing the burden of occupational asthma.

Our study introduced various interventions to reduce the possibility of baker’s asthma. It includes introducing lids on mixer tubs, dust masks for “dusty” tasks, and better housekeeping routines to minimise flour dust exposure.

As part of our study we introduced techniques for bakery employees that would reduce flour dust. These formed part of dust control manual and a training DVD that was developed to educate bakers on how to reduce the dust levels in their workplaces. These included:

using a sieve instead of throwing flour around;

using oil instead of flour to prevent dough sticking to the kneading board during bread baking; and

using a vacuum cleaner or sprinkling the floor with water when sweeping, to prevent the flour dust becoming airborne.

The overall effect of the intervention – evaluated one year later – revealed a 50% decrease in mean flour dust, wheat allergen and rye exposures in bakeries.

It also resulted in a supermarket chain implementing the use of mixer tub lids as a standard feature in bakeries, and using the DVD to train all new bakers as part of their induction programme.

New laws are needed

The challenge with many of the measures introduced internationally are that they are not totally protective and there has been very little implementation beyond general requirements.

Considering South Africa’s high levels of flour dust a guideline on the workplace management of baker’s allergy and asthma should be adopted.

But South Africa’s National Department of Labour should also consider revising the “grossly inadequate” flour dust exposure standard to bring it in line with international best practice.