- Top of page
- Material and methods
Background: Vegetable pollen is a rare source of occupational allergens. Occupational allergy has only been described in the case of paprika pollen and tomato pollen. We describe a new source of occupational pollen allergy.
Aim: To study the incidence and the impact of broccoli and cauliflower pollen allergy in employees involved in classical plant breeding.
Methods: Fifty-four employees of five companies working with cauliflower (Brassica oleracea botrytis) and broccoli (B. oleracea italica/cymosa) pollen were eligible for complete evaluation. Allergy to cauliflower and broccoli pollen was evaluated by questionnaire and determination of sensitization by radioallergosorbent test (RAST) and skin-prick tests (SPT). SPT and RAST were performed with a panel of commercial and homemade extracts from cauliflower and broccoli pollen.
Results: Work-related symptoms such as rhinitis, conjunctivitis, asthma and urticaria caused by B. oleracea pollen were reported by 44% of the participants (24/54), of whom all but one had positive SPT for cauliflower- and/or broccoli-pollen/flower extracts and 58% (14/24) had positive RAST results. Symptoms had developed within the first 2 years in 33% of the patients. Six patients had to stop or change work.
Conclusions: Brassica oleracea pollen is a new source of occupational allergen with strong allergenic potential leading to symptoms in almost half of the exposed employees.
Cauliflower (Brassica oleracea botrytis) is one of the most important vegetable crops in the Netherlands. Both cauliflower and broccoli (B. oleracea italica/cymosa) belong to the Brassicaceae family (Cruciferae). Flowers of Brassica plants develop after the crop and are pollinated by insects. They produce small amounts of airborne pollen of 19–24 μm diameter.
Shoots of B. oleracea develop out of a full-grown crop and give rise to yellow or white flowers. During growth and production of cauliflower and broccoli as vegetables, the workers do not come into contact with the flowers because the vegetables are harvested before flowering. However, in plant improvement and seed production activities there is scope for close contact. Classical plant breeding has become very important in horticulture in the Netherlands. For crossbreeding of different species, pollen of the filament of one flower is placed on the pistil of another, requiring the close contact of the employees with the flowers. An IgE-mediated inhalant allergy can be expected, as has been described for paprika pollen (1).
A visit of an employee, working in B. oleracea, to our outpatient department with progressive rhino-conjunctival symptoms and shortness of breath in the last 3 years, raised the question about the prevalence of work-related symptoms to cauliflower and broccoli pollen. As the employee had positive SPT to cauliflower and Brussels sprouts pollen, a type I allergy was likely.
Allergy to vegetable pollen has been reported only rarely. In a study of sweet bell pepper workers in a greenhouse, symptoms were reported in 54% (1). The only other case is a patient with tomato pollen allergy (2). The aim of this study was to evaluate the allergenic potential of B. oleracea pollen among classical plant breeders and to analyse possible risk factors.
- Top of page
- Material and methods
In this study, we found a high percentage (44%) of allergy to cauliflower and broccoli pollen. A positive history with rhinitis as the main work-related symptom followed by conjunctivitis was supported by sensitization to cauliflower and/or broccoli pollen by SPT (96%) and RAST (58%). The high percentage found in this study could be an overestimation because employees with symptoms might be more willing to participate. On the other hand an underestimation is also possible, as most of the workers in this industry are seasonal workers who tend to change their job when symptoms occur. Groenewoud et al. (1) reported an even higher percentage of 54% (254/472) of allergy to sweet bell pepper pollen.
Allergy caused by vegetable pollen seems to be very rare. The only other example in the literature was occupational asthma by a woman working in a tomato glasshouse (2). Occupational asthma among greenhouse employees working with (flowering) vegetables is more frequently reported, but in relation to allergy for predatory mites or thrips (10–12). In our study, three persons reported the presence of mildew (Erisyphe cruciferarum) or false mildew (Peronospora parasitica) as a cause of their symptoms. All three however were sensitized to cauliflower and/or broccoli pollen as well and two of them reported symptoms around the flowering season. So the symptoms are most probably the result of exposure to B. oleracea pollen, although a role of mildew cannot be fully excluded.
Differences between the severity of symptoms caused by various varieties of B. oleracea pollen (white cabbage, Savoy cabbage, Brussels sprouts) were only reported in a minority of cases. Symptoms caused by cauliflower and broccoli pollen were very similar. It seems therefore likely that B. oleracea pollen of various varieties have a more or less similar allergenic potential.
Skin-prick test was highly sensitive in contrast to the RAST. Of the 24 persons with work-related symptoms, 96% (23/24) had positive SPT for broccoli and/or cauliflower pollen and 58% (14/24) had a positive RAST. Therefore, homemade extracts for SPT are a reliable alternative when no commercial extract is available (1).
The low correlation between the SPT and RAST results can be explained by the fact that the amount of allergens present in the extracts was overestimated due to residual HSA, which in turn led to the detection of lower allergen content in the RAST.
Atopy appeared to be a risk factor for allergy to B. oleracea pollen. This was previously described for other Brassica species pollen (13). This high prevalence of respiratory allergy caused by B. oleracea pollen has major consequences for the health of the employees. Some were forced to search for a different job because of progressive respiratory symptoms. Others were able to reduce symptoms by avoidance measures (1). Theoretically, by using gloves and dust masks the exposure can be reduced. One employee reported relief of symptoms by using a dusk mask and gloves, whether others mentioned a decrease of symptoms by restricting the contact with the flowering plants. However, in practice, such measures are not very easy to realize. Antihistamines can improve rhino-conjunctivitis. Sensitization to B. oleracea pollen tends to be persistent for many years. Often, especially in case of asthma not responding to medication, the search for another profession is the best solution.
In conclusion, we have demonstrated that B. oleracea pollen is a highly potent occupational allergen causing work-related symptoms in almost half of the exposed employees.