Occupational asthma, rhinitis and contact urticaria from greenhouse work.

Background: The current knowledge about occupational allergic diseases among greenhouse workers is scant.

Aims: To describe greenhouse workers' occupational allergic diseases.

Methods: We identified 28 greenhouse workers with occupational allergic diseases in 2002-2020 by conducting a systematic search in the patient register of the Finnish Institute of Occupational Health. All the patients worked in tomato- or cucumber-growing greenhouses and showed immunoglobulin-E-mediated sensitization to occupational agents. Specific inhalation challenges or workplace peak expiratory flow monitoring confirmed occupational asthma (OA), nasal allergen challenges confirmed occupational rhinitis (OR) and open skin tests confirmed occupational contact urticaria (OCU).

Results: Most patients had more than one occupational disease and were sensitized to several workplace agents. Tomato plants were the most common cause of occupational diseases and induced 22 allergic diseases in 14 patients. Cucumber plants caused occupational diseases in 10 patients (3 OA, 7 OR and 6 OCU). The pest control mite Amblyseius swirskii and a mixture of parasitic wasps Encarsia formosa and Eretmocerus eremicus both induced two OA cases. Three patients had an occupational disease caused by storage mites and three others had a work-related systemic reaction to a bumblebee sting.

Conclusions: The greenhouse workers typically suffered from several occupational allergic diseases and were sensitized to cultivated plants, various pest control organisms and storage mites. All these can cause OA and OR, but in this study, OCU was only induced by cultivation plants. Cucumber plant is a novel cause of OA and OR, and A. swirskii is a novel cause of OA.