An outbreak of phytophotodermatitis due to celery.

BACKGROUND

Celery is known to contain psoralens, a group of substances that cause a toxic dermal reaction on exposure to ultraviolet A rays (UVA). An outbreak of phytophotodermatitis amongst 11 workers in a celery harvest in southern Israel is reported.

METHODS

Analysis of the trigger factors was carried out. The patients were questioned regarding their working conditions. Samples of the celery that the workers had been harvesting were analyzed for levels of total psoralens by means of high performance liquid chromatography (HPLC). Levels of UVA were measured.

RESULTS

It was found that the celery harvested in the south of the country contained 84 micrograms/g fresh weight (f.wt.) total psoralens as compared to 35 micrograms/g f.wt. in celery harvested in the north of the country at the same time. The following year the celery harvested in the south contained only 26 micrograms/g f.wt. total psoralens. Other risk factors noted were that the subjects had fair skin, wore no protective clothing, and worked with moist hands. In addition, the days were clear and sunny thus ensuring maximal UV radiation for that time of the year.

CONCLUSIONS

Multiple factors contributed to the outbreak of phytophotodermatitis. A late harvest in the south of the country is incriminated as the cause of the unusually high levels of psoralens in the celery of that year.