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Healthy
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Poisonous Plants
Allergic reactions to materials as varied as nickel, latex, and poison ivy are evidenced by a rash where the offending substance touched a person’s skin. This is known as “contact dermatitis.” Three widespread weeds--poison ivy, poison oak, and poison sumac--are among the most common causes of allergic reactions in the U.S. Annually, as many as 50 million people develop rashes after contact with one of these plants.
The three plants differ in appearance, but they are all related. All contain the same allergy-causing material, urushiol, a clear, oily substance found throughout the plants. It is an unbelievably powerful allergen--you need only one billionth of a gram to cause a rash, and it has been calculated that just a 1-1/2 teaspoons of urushiol would be enough to cause everyone in the world to break out! Because this is such a common allergic reaction, it is a good idea for childcare programs to learn more about it.
Leaves of Plants
Poison ivy and poison oak generally have three leaves. In botanical terms, these are actually three leaflets that comprise one leaf, but they are clearly in groups of three. A generations-old saying warns, “Leaves three, let it be.”
Poison ivy flowers and produces white waxy berries. If the leaves are bruised, even very slightly, the released urushiol makes a black spot on the leaves. These tiny black irregular spots occurring on the leaves are very characteristic of poison ivy. Poison ivy also can appear as a brown, hairy-looking vine, climbing trees to 10 or more feet in height. Contact with the vine can produce the same allergic reaction as contact with the leaves. In the U.S., poison ivy typically grows in the East, Midwest, and South.
Poison oak is not as common as poison ivy. Again, “leaves three, let it be.” In the case of poison oak, the leaves are shaped somewhat like oak leaves. They are shiny, without prickers, and the middle leave has a distinct stalk. It is harder to identify poison oak in the winter, when it loses its leaves and only the stalk shows. The plant usually grows as a small shrub in the southern U.S. but can grow as a large standing shrub or climbing vine in the West.
Poison sumac has leaves with as few as seven to as many as 13 leaflets. It also is shrub-like and tends to grow in standing water. Poison sumac is most common in the peat bogs of the northern U.S. and in swampy southern regions of the country. Whereas sumac that is not poisonous will have fruit growing from the ends of its branches, poisonous sumac has fruit that grows between the leaf and the branch. In addition, the leaves have a brilliant orange or red color in the fall.
Despite their different appearances, all three of these plants have the same poison, urushiol, and produce the same allergic reaction in those who touch it. It is important to remember that all parts of the plants contain urushiol--leaves, stems, even roots--and the poison exists in the plants throughout the year, whether they have leaves or not. The plants are more readily recognized in the spring and summer, but they are always a hazard.
Killing Poisonous Plants
To rid your playground or yard of these pests, first be sure that you are wearing long pants, long-sleeved clothing, and gloves. A powerful herbicide such as glyphosate (the ingredient found in RoundupTM) will kill the plants. If poison ivy has climbed far up a tree, cut the stem a few inches above the ground and dose the stem with the herbicide, repeating weekly as necessary. As always, never apply a herbicide or other chemical when children are present, and carefully follow label directions.
A few days after they are killed, the plants can be pulled up and eradicated. Again, wear protective clothing, and carefully dispose of the collected plants carefully using plastic trash bags. Never run a mower or a bush hog over these plants. The fragments of poisonous plants can present a serious hazard. The most important caution of all is to not burn the weeds! The poisonous oil is carried in smoke and can cause head-to-toe allergic reactions in people on whom the poisonous smoke blows.
Skin Reactions
After the poisonous oil-like urushiol gets on skin, it is fairly quickly inactivated--within 30 minutes--by binding itself to skin cells. Thoroughly washing the affected areas with soap and warm water, and even perhaps just simply running them under water within five minutes of contact may prevent an allergic response. If washing occurs within 30 minutes, the reaction will be reduced. After about 30 minutes, the oil cannot be passed on by touching another part of the body or by touching someone else.
Urushiol quickly becomes inactive on skin; however, it can hang around on clothing, animal fur, and garden tools for months. Acquiring this reaction from touching a pair of gloves, garden shears, or a pet’s fur is termed “indirect contact.” Clothing that has come in contact with the weeds should be kept separate from other clothing items and washed in hot water and detergent.
About 85 percent of people are allergic to urushiol and will have some type of reaction, although the onset of the reaction may vary. An allergic reaction does not usually begin until a day or so after contact, and the reaction may continue to worsen for several days. If a child has never had a previous reaction to urushiol, the rash may not show up for a week or l0 days. Itching occurs, then swelling, redness, and finally watery groups of blisters on the skin. There are often streaks in the reacting area, indicating that the foliage was dragged along the skin.
The rash appears first where the contact was greatest, later in areas with briefer contact occurred and where the skin is thicker. A common misconception is that the rash can be spread by contact with the blister fluid, but there actually is no urushiol in the blister fluid, and the rash cannot be spread by scratching or by any other kind of contact at this stage. Scratching is to be avoided if possible, because it can lead to secondary bacterial infection. After a week or two, the allergic symptoms usually subside, although occasionally the rash may last for weeks.
Treating the Rash
Treatment consists first in finding relief from the itching. A doctor or pharmacist may suggest an over-the-counter remedy and a course of steroids is frequently prescribed for the worst cases. Allergic reactions will occur each time you are exposed to poison ivy, poison oak, or poison sumac. Having a reaction once does not make you immune, and unfortunately, there is no “shot” that can be given to produce immunity to poison ivy and its friends.
If you think a child has touched poison ivy, poison oak, or poison sumac, whether in your yard or while on a field trip, immediately wash the child’s exposed skin. Then notify the child’s parents.
Play Area Check
On a regular basis, check the play area for signs of any of these plants. Identify these three weeds; and once identified, eradicate them in areas where they may be accessible to children. Childcare providers can educate children about these poisonous plants, or warn them about the hazards of playing in bushes in general--especially if you do not know what the bush is!
If any of these poison plants are growing on your childcare program’s property, you may already have encountered more than a few rashes. By learning about poison ivy, poison oak, and poison sumac, you can make sure it does not threaten your outdoor play time.
Don Palmer, MD
Alabama Chapter, American Academy of Pediatrics
Internet Resources
Pictures, fast facts, and treatment options, poisonivy.aesir.com
For more information on Integrated Pest Management alternatives for poison ivy control, see the University of CT Extension website at www.hort.uconn.edu/ipm/homegrnd/htms/poisivy2.htm
Resources
American Academy of Dermatologists, PO Box 4014, Schaumburg, IL 60168; 847-330-0230; www.aad.org/public/Publications/phamphlets/PoisonIvyOakSumac.htm
Local County Extension Services can provide pamphlets, posters, and general information on poisonous plants.
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