Botanical Dermatology

Occupational exposure to plants occurs in various professions, most commonly in florists, horticulturists, grocery store workers, and outdoor workers, especially farmers, loggers, and foresters. Of course, members of any profession in which workers contact plants may contract plant-induced dermatoses. Other commonly affected professions include gardeners, food handlers, pharmaceutical workers, and botanists.15,126 In the United States, agriculture workers have the greatest incidence of occupational skin disease due to plants.127 They had a 35.9% annual prevalence of dermatitis. The manufacturing industry was second with a 14.8% annual prevalence. Half of these were due to non-cash plants, trees, and naturally occurring vegetation, and only 10% were due to contact with food products (fruits and vegetables) being harvested.127


The true prevalence of dermatitis among florists is unknown.117 Irritant dermatitis outweighs allergic contact dermatitis in frequency and probably importance. Two studies in the United States estimate an 8% point prevalence of hand dermatitis among retail florists.128,129 A Portuguese study found a 29.8% annual prevalence of hand dermatitis in florists 130 and they commented on its similarity to an American study demonstrating a 26% annual prevalence.131 A United Kingdom survey found that 46% of retail florists had hand dermatitis at some time during their employment.132 No study demonstrated any relationship between atopy and dermatitis. Most importantly, most cases of hand dermatitis were mild, periodic, and self-limiting. Floral designers appear to be at highest risk among all floral workers.128 A study of four Italian floriculture centers found that 25% of 200 workers had mechanical irritant dermatitis, 12% irritant dermatitis from chemical agents, 8% had pseudophytodermatitis from pesticides, insecticides, and fungicides, and only 5% had allergic contact dermatitis to plants.126

The most frequent allergen among retail florists varies by study. Clearly, the big three sensitizers are, in alphabetical order, primin, sesquiterpene lactones, and tulipalin A. One study of 71 patients (market gardeners and wholesale florists) found that sesquiterpene lactones (Compositae) caused more allergic contact dermatitis than tulipalin A (tulips and alstroemeria) or primin (primula).133 Other studies found tulips and Alstroemeria (tulipalin A) to be the more common causes than Compositae.131 One survey found that the most common plant suspected to be the cause of allergic contact dermatitis was primrose (Primula obconica).132 Primula has been an uncommon cause of allergic contact dermatitis in some studies of retail florists because workers know how to properly handle the plant, or because, as I discovered while trying to photograph one in Denver, none of the greenhouses or flower shops in the yellow pages carried them. Most cases of primula dermatitis probably occur in non-occupational settings.117 Even though nitrile rubber gloves protect against tuliposide A penetration, few, if any, floral workers wear them because of severe limitations in dexterity.128, 132

Daffodil itch (due to Narcissus spp., Amaryllidaceae) from handling stems, is one of the most common causes of irritant contact dermatitis in florists. The plant contains calcium oxalate in its sap.15


Phytophotodermatitis from contact with celery seems to be the main cause of plant-related occupational dermatitis in grocery store workers.15, 50, 134 The risk for phytophotodermatitis increases based on two factors: amount of exposure to fresh produce (especially celery) and the use of tanning salons (UVA exposure). One study found that the prevalence ratio of phytophotodermatitis was 41 for those with both risk factors compared to those with neither risk factor.134


Among that diverse group of the work force who spend most of their time outdoors, poison ivy and poison oak (Toxicodendron spp.) are the main causes of occupational contact dermatitis.135 It is estimated that 0.11% of all workmen's compensation is due to poison ivy and poison oak dermatitis due to its significant effect on those in agriculture.71 Toxicodendrons account for 10% of all lost-time injuries for the United States Department of Agriculture Forest Service.136 Poison oak causes great problems in California, Oregon, and Washington, while poison ivy is a scourge to foresters in Illinois, Kentucky, West Virginia, and Mississippi.136 Poison sumac typically is not a problem because of its predilection for rural areas, however, it plagued the workers who built Disney World in Orlando, Florida.135

Foresters, especially when fighting forest fires, have virtually no control over avoiding these plants. Up to 25% of firefighters may need to leave the fireline because of severe toxicodendron dermatitis.136 This group would benefit most from a successful preventative skin protectant. In fact, the U.S.D.A. Forest Service performed some of the earliest studies on organoclay compounds.

Forestry workers often suffer from 'Woodcutter's Eczema,' an allergic reaction due to airborne sesquiterpene lactones in Frullania (liverworts) growing on tree trunks in the American and Canadian Pacific Northwest.102 In Portugal, Frullania and lichen dermatitis accounts for 12% of occupational dermatitis in outdoor workers.137 The dermatitis is worse in wet winter months. It presents in a pseudo-photo distribution involving the upper eyelids but sparing the submental area. This suggests dispersal of oleoresin by rainwater.91


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