Through experience, many people know that they are susceptible to poisoning by poison-ivy, poison-oak, or poison sumac, while some others either have escaped contamination or have a certain degree of immunity. The extent of immunity appears only relative, and absolute immunity to the toxic principle apparently does not exist. Persons who have shown a degree of immunity upon repeated contact with the plants may develop poisoning on subsequent exposure.
The skin irritant of poison-ivy, poison-oak, and poison sumac is the same toxic agent. It is a nonvolatile phenolic substance called urushiol and is found in all parts of the plant, including roots and fruit. It occurs in great abundance in the plant sap. The danger of poisoning is greatest in spring and summer, when the sap is abundant, and least late in fall or in winter.
Poisoning is usually caused by contact with some part of the plant. A very small quantity of the poisonous substance is capable of producing severe inflammation of the skin and can easily be transferred from one object to another. Clothing may become contaminated and is often a source of such prolonged infection that it is likely to be judged as a case of poisoning difficult to cure. Dogs and cats frequently touch the plants and transmit the poison to unsuspecting persons. The poison may remain on the fur of animals for a considerable period after they have walked or run through poison-ivy plants. Smoke from burning plants will carry the toxin and has been reported to cause severe cases of poisoning. Cases of poisoning of children from eating the fruit have been reported. A local belief that eating a few leaves of these plants will develop immunity in the individual is unfounded. It never should be attempted. No part of the plant should ever be taken internally, as it is a violent irritant and poisonous to man.
Cattle, horses, sheep, hogs, and other livestock apparently do not suffer from skin irritation caused by these plants, although they have been observed to graze upon the foliage occasionally. Bees collect honey from the flowers, though no reports are on record of any ill effects from the use of the honey.
The time between contamination of the skin and the first symptoms varies greatly with individuals and probably with conditions. The first symptoms of itching or burning sensation may develop in a few hours or after 5 days or even more. The delay in development of symptoms is often confusing in attempting to determine the time or location when contamination occurred. The itching sensation and subsequent inflammation, which usually develops into water blisters under the skin, may continue for several days from a single contamination. Persistence of symptoms over a long period is likely to be due to new contacts with plants or with previously contaminated clothing or animals. Severe infection may produce more serious symptoms, which result in much pain through abscesses, enlarged glands, fever, or complicated constitutional malfunction. Secondary infections are always a possibility in any break in the skin, such as is produced by breaking vesicles that have formed as large water blisters.
PRECAUTIONS AGAINST POISONING
The most effective way to prevent poisoning from the plants is to avoid contact with them. If it is necessary to work among them, some measure of prevention can be gained by wearing protective clothing, but it is necessary to remember that the active poisonous principle can easily be transferred. Some protection also may be obtained in advance by the use of protective creams or lotions. They prevent the poison from touching the skin, or make the active principle easily removed, or neutralize it to a certain degree.
Various formulas containing ferric chloride and glycerin have been used more or less effectively as a preventive measure, although there may be some danger of pigmentation of the skin from the ferric chloride. A common formula is ferric chloride, 5 parts; glycerin, 25 parts; alcohol, 25 parts; water. 50 parts.
A lotion of this formula applied to the exposed skin prior to contact with poisonous plants gives effective protection for many people. It is especially effective if followed by thorough washing with soap and water. Such washing, even if no protective lotion has been used, is often effective in preventing poisoning. Proper precaution should be taken by repeated lathering with a strong alkali soap, followed by thorough rinsing and repeating the process several times. The water should be frequently changed, and a shower or flowing water bath is preferable. The soap probably only emulsifies the active principle, and thorough rinsing is necessary to avoid spreading the poison to other parts of the body.
The United States Public Health Service reports successful chemical protection against ivy poisoning by use of an oxidizing agent—sodium perborate prepared and used fresh as an ointment. Following is a formula given for the ointment: Cetyl alcohol, 35.1 percent; stearyl alcohol, 5.3; ceresin, 3.5; castor oil. 20.8; mineral oil, 21.9; Duponol WA pure, 1.7; sodium perborate. 10.0; and boric acid, 1.7 percent.
A more recent less oily formula recommended for both mechanical and chemical protection is given as follows: Shellac, 13 parts; isopropanol, 31; linseed oil, 4; titanium oxide, 12; sodium perborate, 13; talcum, 20; and carbitol, 3 parts.
Sometimes cottonseed oil, olive oil, or petrolatum is applied as a protective ointment when contamination is anticipated. Later the oil must be completely removed by repeated washing.
Clothing, wearing apparel, and tools that have been contaminated are often difficult to handle without further danger of poisoning. Some who are more or less immune to poisoning often contaminate others by carelessness. Contamination on automobile door handles or on a steering wheel after a trip to the woods often causes prolonged cases of poisoning of persons who have not been near the plants. One of the most effective ways for decontaminating articles is by thorough washing through several changes of strong soap and water. Contaminated clothing should not be worn again until thoroughly washed. It should not be washed with other clothes, and care should be taken to rinse thoroughly any implements used in washing.
Dogs and cats can be decontaminated in the same manner; precaution should be taken, however, to avoid being poisoned in doing the washing. It is likely that most “dry cleaning” processes will remove any contaminant; but there is always danger that clothing sent to commercial cleaners may cause poisoning to unsuspecting employees.
Certain prophylactic inoculations for the prevention of ivy poisoning have been developed and used with limited success; such treatment, however, should be administered by a physician only. The theory that eating a few leaves of these poisonous plants will confer immunity is without foundation; it should not be attempted even as an experiment, because very serious poisoning is likely to result.
TREATMENT FOR POISONING[1]
[1] For a fuller description of treatments for poisoning see: United States Public Health Service, ivy and sumac poisoning. Pub. Health Rpts. Sup. 161 (rev.), 8 pp., 1943. For sale by the Superintendent of Documents, Government Printing Office, Washington 25, D. C. Price, 10 cents.
There seems to be no absolute quick cure for ivy poisoning for all individuals, even though many studies have been made to devise effective remedies. Remedies may be helpful in removing the poisonous principle or rendering it inactive and for giving some relief from the irritation. Mild poisoning usually subsides within a few days, but if the inflammation is severe or extensive a physician should be consulted. Self-treatment also has other dangers, as the symptoms of ivy poisoning may be confused with those of other conditions and harm may be done by improper treatment. In all cases the safest procedure is to consult a physician.
Some tried remedies are effective on certain individuals and ineffective on others. Sometimes a person will find one remedy effective and later, to his surprise, get very little relief from it. A large number of patent medicine remedies of doubtful value are commonly offered for sale. The following are more or less standard measures that have been advocated by different individuals and found helpful in certain cases.
The United States Public Health Service recommends a 10 percent alcoholic solution of tannic acid applied as a lotion. It is stated that in using it the tops of the blisters should be rubbed off with sterile gauze saturated with the solution and that any large blisters should be opened with a sterile instrument. The treatment should be repeated three or four times at 6-hour intervals. A modified form of this treatment recommends vigorous rubbing of the lesions with alcohol-soaked gauze to remove the tops of blisters, followed by application of a 10 percent aqueous solution of tannic acid as a lotion. Any treatment involving opening of blisters and the application of alcohol is severe, and many cases requiring such treatment should be handled by physicians.
One of the oldest well-established remedies is a fresh solution of one 5-grain tablet of potassium permanganate dissolved in 1 quart of water; concentrations as much as 5 percent, however, have been used. The potassium permanganate is apparently active in neutralizing any poison that may remain on the surface of the skin and it has some therapeutic properties. This solution may be applied freely to the irritated or contaminated skin, but the skin should be rinsed with water a few minutes after the stronger solutions are used. Applications should be repeated every hour or two. The brown stain it causes on the skin will in time wear off, or it may be removed with lemon juice. It more or less permanently stains clothing.
Ferric chloride in combination with several other substances has been used effectively by many people. One of the most common formulas is that given under the discussion of precautions against poisoning (p. 22). To this formula 1 to 3 percent of phenol is frequently added to reduce the itching; however, not more than 1 percent of phenol should ever be used without the advice of a physician, on account of the danger of systemic absorption and poisoning. The solution should be freely applied to the irritated or contaminated skin every hour or two. Some instances of persistence of the brown discoloration of the skin have been reported. For this reason its use is limited, but for most individuals the discoloration completely disappears after a few days. Stain on clothing is usually permanent.
Photographer’s hypo solution has been used with good results in many cases. This is a 10-percent solution of sodium thiosulfate in water. The irritated or contaminated skin should be bathed in it every hour or two. It does not stain skin or clothing.
A calamine lotion with the addition of about 2 percent of phenol is often used and in many cases is effective. Frequent applications are necessary. For some people it is effective in relieving the itching. The pink stain is not permanent.
It is better to leave inflamed areas exposed to the air rather than cover them with dressings. If poisoning is so severe that dressings appear necessary, a physician should be consulted before any home remedies are applied.
