Poisonous Plants

Poison Ivy, Oak, and Sumac – these plants all belong to a plant genus called Toxicodendron. They contain a toxic resin called urushiol that causes pathological effects in humans. Interestingly, the urushiol compound is not a defensive measure for the plant, but instead helps it to retain water.

In general, poison ivy grows east of the Rocky Mountains, poison oak grows west of the Rocky Mountains, and poison sumac grows in the southeastern United States. Of note, the plants may look different depending on the season and the area where they are growing.

The most common reaction from exposure to this resin is an itchy red rash on the skin. The rash often includes fluid-filled vesicles.  The vesicles do not contain urushiol, and the rupture of the vesicles does not spread the rash. The rash is not contagious. In a first-time exposure, the appearance of skin lesions is common within 24 to 48 hours. For someone who has a previous exposure the rash generally appears sooner and is often more severe. 

Urushiol is very heat stable and can aerosolize and affect the lungs if the plant is burned. If present in an area with large amounts of these plants, plan to avoid them, especially during combustion.

Once exposed, the area should be washed. A person with an average allergic response can prevent an immune reaction by washing off the resin within 20 minutes with room temperature water and mild soap if available. The efficacy of rinsing the affected area seems to diminish as time passes. Clothing should be carefully removed and washed thoroughly. The urushiol on clothes can last for days and cause repeated exposure until removed (laundered). (See 6 Minutes for Safety – Dirty Nomex).

Further treatment can include over-the-counter anti-itch creams and keeping the area clean. Try to avoid scratching as much as possible to reduce the chance of infection from bacteria on your hands and nails. For severe reactions or large portions of the skin, seek an evaluation by a medical professional.

Discussion Topics:

• In what local and geographic areas are you likely to encounter poisonous plants?

• What is your crew policy for engaging fire or reevaluating tactics when poisonous plants are present?

• Have a conversation: Who on you crew has a serious reaction to poisonous plants? Who has never been exposed? What soaps and treatment do you carry?

• What are some trigger points for seeking medical attention or taking time off the fireline to wash and heal. ...Location of the rash? ...Size of blisters? ...All of crew’s clothing covered in oils?

References:

• Video on poison oak

• Details on Identification