An outbreak of phototoxic dermatitis due to limes

During the week beginning July 29, 1984, 12 children in a day camp in a suburb of Baltimore, Maryland, were noted to have skin eruptions consistent with phototoxic dermatitis. These eruptions were confined to the hands, wrists, and forearms, and appeared as discrete and confluent polymorphous patches and linear streaks. These eruptions were also macular, hyperpigmented, and nonpruritic. Clinical examination revealed that 97 (16%) of 622 children, seven (7%) of 104 counselors, and no adult staff members had a similar rash. Onsets of the rash ranged from July 19-August 11, with peak occurrence on July 25-27. All camp members were white. Sex did not vary significantly between those affected and not affected. The mean age (5.3 years) of affected children was significantly different from the mean age (6.9 years) of unaffected children (p less than 0.001). Attack rates for the eight camp units were highest in two units (57% and 74%, respectively) and ranged between 0-6% for the other six units. Activities involving work with hands by various camp units were investigated. Only exposure to making pomander balls (sachets) in arts and crafts class (when other activities were controlled for) was significantly associated with illness (p less than 0.03). In making pomander balls, children punctured the skin of limes (the principal component) with scissors, releasing oils known to contain photoreactive furocoumarin (psoralen) compounds. These compounds evidently coated the children's skin and, upon exposure to the sun, caused a phototoxic dermatitis. An environmental and botanical survey of the camp did not reveal other phototoxic agents with which campers may have had contact. This is one of the largest reported outbreaks of phototoxic dermatitis and the first in which a citrus fruit was implicated on a large scale.