urushiol poison ivy allergen molecule. also present in poison oak, lacquer tree and poison sumac. urushiol is a mixture of closely

urushiol allergy allergen allergic contact skin sensitiser sensitizer sensitisation sensitization patch test dermatology dermatologist anacardiaceae toxicodendron poison oak ivy sumac oleoresin itch itching hapten hydrogen carbon oxygen molecule atoms atomic model molecular compound composition chemical chemistry 3d rendering science scientific