• cereal manufacture;
  • occupational asthma;
  • thiamine

We describe occupational asthma related to breakfast cereal manufacture. Anaphylaxis to thiamine has been previously reported (1–5).

A 46-year-old man worked manufacturing breakfast cereal enriched with vitamins. The vitamins in solution were atomized and sprayed across conveyer belts of the cereal. For 6 years prior to his symptoms he worked on a rotating programme where for 1 week in seven he was responsible for the spraying of breakfast cereal with vitamins.

His first attack of asthma occurred during a night shift when he was performing this process. He commenced bronchodilator treatment. He improved rapidly away from work. Over the next 5 months he developed progressive breathlessness. He improved on days off and on holiday.

Skin prick testing to common environmental allergens including wheat were negative. Lung function testing showed airways obstruction (FEV1 2.95–85% predicted; FVC 4.12–97% predicted). He kept 2 hourly serial peak flow recordings for a period of 6 weeks, which were analysed by OASYS-2 (6). This shows a severe deterioration in his asthma during the week he was working with the vitamins. Recovery took 8 days, the first six of which he was off work. There was no clinical respiratory infection at this time. He was admitted for occupational broncho-provocation testing. After a control day with no exposure he had an exposure to 10 min of powdered thiamine preparation supplied by his employer. The powder was transferred between two bags for 10 min with no obvious reaction. A second challenge day, involving a 30 min exposure resulted in a late asthmatic reaction, maximal at 8 h (Fig. 1). His IgE RAST to thiamine was negative.


Figure 1. Case A challenge to powdered thiamine supplied by employer. Control challenge and exposure to 30 min of powder pouring.

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He has now changed job within the factory, and drives forklift trucks in the warehouse department. He experiences no work related symptoms, but his asthma remains difficult to control.

A 43-year-old production worker at the same cereal production plant had mild background asthma for 8 years. Over a 6-month period he developed symptoms of increased cough and wheeze. Symptoms coincided with his work shifts where he atomized the vitamin mixture supplement on to breakfast cereal products. He had performed this work for 4 years before onset of symptoms.

Symptoms resolved on holidays and improved on days off.

Initial investigations showed an obstructive defect (FEV1 59% predicted, FVC 88% predicted) and severe bronchial hyper-reactivity with a PC20 to histamine of less than 0.25 mg/ml. Occupational Peak flow recordings were performed and were suggestive of occupational asthma, but he failed to keep sufficient readings on days off work.

An occupational challenge was performed in blinded fashion. Histamine reactivity was performed on the day preceding the occupational challenge (0.78 mg/ml). Control challenge was with aerosolized saline. Aerosolized vitamin mix was generated in the challenge labortory on active days. On the first day of active challenge, exposure was for three periods of 30-s exposure to the aerosolized vitamin. On the second challenge day, the exposure was increased to two periods of 2 min exposure.

On the higher exposure challenge a 24% fall in FEV1 occurred at 5 h postexposure (Fig. 2). Blood gases demonstrated a significant hypoxia (pO2 45 mmHg, pH 7.46, pCO2 38.4 mmHg). Histamine reactivity on the day after the challenge had deteriorated to 0.28 mg/ml.


Figure 2. Case B challenge with aerosolized vitamin mixture. Control challenge aerosolized saline. Two active challenge days represent low and high exposure to the aerosolized solution containing raw vitamin as provided by the cereal company.

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The individual has not returned to work since and symptoms have progressively improved.

We believe these two cases are the first reports of occupational asthma related to the use of thiamine in an industrial setting. The production of a fine aerosol of vitamin mixture facilitates the pulmonary deposition. Both cases are confirmed by occupational challenge, which demonstrated predominantly late asthmatic reactions.


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