Occupational contact dermatitis caused by “Chrysal flower food”
Sylvie M. Franken  Rutger I.F. van der Waal  Thomas Rustemeyer
First published: 07 July 2019 https://doi.org/10.1111/cod.13350
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Contact dermatitis in florists and flower handlers is a common problem. The best‐known causes are plant allergens such as sesquiterpene lactones, primin, tulipalin, and irritant contact factors such as plant sap and fibers.1-7

CASE REPORT
A 38‐year‐old man presented in the outpatient clinic of the dermatology department with swelling and redness of the face and the hands. His skin problems had started a year and a half before and seemed to be work‐related. The patient had been working as an all‐round machine operator in the same “flower food” (fertilizer) factory for 14 years, but had changed position 2 years before. Since then he was involved in mixing the different components of flower food. Since he started working with protective clothing, including long sleeves with elastic bands at the wrists, the symptoms had gradually diminished. The patient had not consulted his occupational physician. He mentioned that several co‐workers also experienced similar skin problems.

Patch testing was performed with the European baseline series, 2‐bromo‐2‐nitropropane‐1,3‐diol 0.25% pet., 2‐n‐octyl‐4‐isothiazolinone 0.1% pet., ethylenediaminetetraacetic acid (EDTA) 1% pet., and the separate ingredients of the flower food supplied to us by the patient. These were dissolved in our laboratory according to concentrations listed by de Groot.8 Allergens were tested using Van der Bend test chambers (Brielle, The Netherlands) applied on the back and covered with Fixomull stretch (BSN Medical, Hamburg, Germany). Readings were performed on day (D) 2, D3, and D7 according to ESCD criteria.9

Patch test readings showed positive results (D2/D3/D7) for methylchloroisothiazolinone/methylisothiazolinone (+/+/+), 2‐n‐octyl‐4‐isothiazolinone (+/++/+), cetylpyridinium chloride monohydrate 0.1% aq. (−/+/−), and the mix “Chrysal TV21” 2% pet. (?+/+/+). The Chrysal mix originally contained <5% octylisothiazolinone, resulting in an octylisothiazolinone concentration of 0.1%.

The patient was advised to contact his occupational physician to evaluate and adapt the working process. This seemed of great importance for himself and his employer in view of other colleagues also having similar symptoms. For secondary prevention, he was advised to wear protective clothing, gloves, and a face mask when working with isothiazolinone‐containing products. Moreover, the patient was advised to check his cosmetic products and toiletries for isothiazolinones and if present, to avoid these. The protective clothing, however, was insufficient to prevent recurrences beyond the borders of the mask, that is, on unprotected skin. He therefore avoided entering the room where the raw materials were poured in containers, and his symptoms subsided after this adjustment. The reaction to cetylpyridinium chloride monohydrate, a quaternary ammonium salt, was deemed to be an irritant as lower concentrations and the same concentration in pet., respectively, evoked no reactions.

DISCUSSION
We describe a patient working in a factory preparing “flower food” with contact sensitization to isothiazolinones. The small bags containing powder or a liquid are often added to a bouquet of cut flowers to preserve them. The presence of isothiazolinone in “flower food” was suspected to be the cause of the work‐related dermatitis. All other ingredients of the product were negative in our tests. To the best of our knowledge, isothiazolinone allergy has never been reported before as a cause of occupational dermatitis in florists or flower handlers, although this is not uncommon in our experience.

In this case we suspect that the change of work tasks 2 years before has contributed to sensitization. Florists and handlers of cut flowers should be aware of the possible allergens in “flower food” and in other professional products used in transport and handling of cut flowers. As isothiazolinones are omnipresent, at home as well as at work, they can be overlooked as a cause of persisting dermatitis.

CONFLICT OF INTEREST
None to declare.

REFERENCES