Poisonous plants to humans

Many native and exotic plants are poisonous to humans when ingested or if there is skin contact with plant chemicals. However, the most common problems with poisonous plants arise from contact with the sap oil of several ever-present native plants that cause an allergic skin reaction—poison ivy, poison oak, and poison sumac.

Poison ivy, poison oak, and poison sumac release oil, urushiol, when the leaf or other plant parts are bruised, damaged, or burned. When the oil gets on the skin an allergic reaction, referred to as contact dermatitis, occurs in most exposed people as an itchy red rash with bumps or blisters. When exposed to 50 micrograms of urushiol, an amount that is less than one grain of table salt, 80 to 90 percent of adults will develop a rash. The rash, depending upon where it occurs and how broadly it is spread, may significantly impede or prevent a person from working. Although over-the-counter topical medications may relieve symptoms for most people, immediate medical attention may be required for severe reactions, particularly when exposed to the smoke from burning these poisonous plants. Burning these poisonous plants can be very dangerous because the allergens can be inhaled, causing lung irritation. Outdoor workers may be exposed to poisonous plants.

Prevention
Workers can prevent contact with poisonous plants by taking these steps:
• Wear long sleeves, long pants, boots, and gloves.
o Wash exposed clothing separately in hot water with detergent.
• Barrier skin creams, such as a lotion containing bentoquatum, may offer some protection before contact.
o Barrier creams should be washed off and reapplied twice a day.
• After use, clean tools with rubbing alcohol (isopropanol or isopropyl alcohol) or soap and lots of water. Urushiol can remain active on the surface of objects for up to 5 years.
o Wear disposable gloves during this process.

First Aid
• Immediately rinse skin with rubbing alcohol, specialized poison plant washes, degreasing soap (such as dishwashing soap) or detergent, and lots of water.
• Rinse frequently so that wash solutions do not dry on the skin and further spread the urushiol.
• Scrub under nails with a brush.
• Apply wet compresses, calamine lotion, or hydrocortisone cream to the skin to reduce itching and blistering.
• Follow the directions on any creams and lotions. Do not apply to broken skin, such as open blisters.
• Oatmeal baths may relieve itching.
An antihistamine such as diphenhydramine (Benadryl) can be taken to help relieve itching.