**3.2.5 Plants**

Plants, particularly those of the Rhus family, are often thought of in the context of allergic contact dermatitis, though they are infrequently within the top five allergens detected in children (Table 1). Up to 85% of the population is sensitized to plants within the Toxicodendron genus, which includes poison ivy, and most patients are sensitized between ages 8 and 14 years old (Koo et al., 2010). Plant allergy can often be identified by history and distribution generally at exposed sites. *Rhus verniiciflua* (Japanese lacquer tree) has been reported in children to cause severe allergic contact dermatitis, which can be mistaken for cellulitis. Many reported patients required systemic steroids due to severity of rash (Gach et al., 2006; Rademaker & Duffill, 1995).

Compositae (Asteraceae) is the second largest plant family and is a well-recognized cause for contact allergy in gardeners, florists and farmers due to the sesquiterpene lactone component. For some time, it was rarely considered a clinically relevant allergen in children. However, there are several cases described in the literature. Flohr and colleagues described hand dermatitis in three children aged 3-8 years old, each of whom had frequent exposure to plants and tested positive to Compositae (Flohr et al., 2008). Paulsen et al. suggest that this particular allergy may be more common in atopic patients (Paulsen et al., 2008.) and Belloni Fortina et al. propose it should be added to the pediatric screening series when investigating airborne dermatitis in atopic children. They made this recommendation after finding 12 of 641 children sensitized to this antigen (Belloni Fortina et al., 2005).

### **3.2.6 Henna tattoos with para-phenylenediamine (PPD)**

Henna (*Lawsoniainermis*) is a plant from the Lythraceae family. Henna dye is a dark green powder made from the leaves of this plant and used for hair dyeing and for temporary body tattooing. PPD is added to henna dye in order to make the color darker and speed the dyeing process (Jovanovic & Slavkovi-Jovanovic, 2009). This tattooing practice is becoming more popular in the pediatric population. PPD is a potent sensitizer and the literature is peppered with case reports regarding sensitization to PPD after henna tattooing in children (Jovanovic & Slavkovi-Jovanovic, 2009; Sidwell et al., 2008). As this exposure is becoming more prevalent in the pediatric population, some are calling for increased regulations (Sidwell et al., 2008).
