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Urushiol-induced contact dermatitis (also called Toxicodendron dermatitis and Rhus dermatitis) is the medical name given to allergic rashes produced by the oil urushiol, which is contained in various plants, including the plants of the genus ''Toxicodendron'' (including poison ivy, poison oak, and poison sumac), other plants in the sumac Anacardiaceae family (mango, pistachio, Rengas tree, Burmese lacquer tree, India marking nut tree, and the shell of the cashew nut), and unrelated plants such as ''Ginkgo biloba''.〔Lepoittevin, J.-P., Benezra, C., Asakawa, Y. 1989. Allergic contact dermatitis to Ginkgo biloba L.: retationship with urushiol. Arch. Dermatol. Res., 281: 227-230.〕 Symptoms of the rash include itching, inflammation, oozing, and in severe cases, a burning sensation. The American Academy of Dermatology estimates there are up to 50 million cases of urushiol-induced dermatitis annually in the United States alone, accounting for 10% of all lost-time injuries in the United States Forest Service. Poison oak is a significant problem in the rural western and southern United States, while poison ivy is most rampant in the eastern United States. Dermatitis from poison sumac is less common. == Exposure == Urushiol-induced contact dermatitis is contracted by contact with a plant or any other object containing urushiol oil. The oil adheres to almost anything with which it comes in contact, such as towels, blankets, clothing and landscaping tools. Clothing or other materials that contact the plant and then, before being washed, contact the skin are common causes of exposure. For people who have never been exposed, or are not yet allergic to urushiol, it may take 10 to 21 days for a reaction to occur the first time, once allergic to urushiol, however, most people break out 48 to 72 hours after contact with the plant. Typically, individuals have been exposed at least once, if not several times, before they break out with a rash. For individuals already allergic to urushiol, it normally takes about 24 hours for the rash to first appear; for those with severe reactions, it will worsen during the next few days. For severe reactions, a prednisone prescription is necessary to stop skin damage, especially if the eyes are involved. The rash persists typically one to two weeks and in some cases up to five weeks. At least 25% of people have very strong responses resulting in severe symptoms. Since the skin reaction is an allergic one, people may develop progressively stronger reactions after repeated exposures. Urushiol is primarily found in the spaces between plant cells beneath the outer skin of the plant, so the effects of urushiol rash are less severe if the plant tissue remains undamaged on contact. Once the oil and resin are thoroughly washed from the skin, the rash is not contagious. Urushiol does not always spread once it has bonded with the skin, and cannot be transferred once the urushiol has been washed away. Although simple skin exposure is most common, ingestion can lead to serious, more systemic reactions. Burning plant material is commonly said to create urushiol-laden smoke that causes systemic reaction as well as rash inside the throat and on the eyes. Firefighters often get rashes and eye inflammation from smoke-related contact.〔(【引用サイトリンク】title=FIREFIGHTERS BATTLE HIDDEN DANGERS THIS WILDFIRE SEASON: POISON OAK, IVY AND SUMAC PLANTS TOP CAUSE OF DISABILITY, SICK TIME )〕 A high-temperature, fully inflamed bonfire may incinerate the urushiol before it can cause harm, while a smoldering fire could vaporize the volatile oil and spread it as white smoke. However, some sources dispute the danger of burning urushiol-containing plant material. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Urushiol-induced contact dermatitis」の詳細全文を読む スポンサード リンク
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