Poisoning

Encyclopedia of Medicine, Apr 06, 2001 by Tish Davidson

Poisoning occurs when any substance interferes with normal body functions after it is swallowed, inhaled, injected, or absorbed.

Poisonings are a common occurrence. About 10 million cases of poisoning occur in the United States each year. In 80% of the cases, the victim is a child under the age of five. About 50 children die each year from poisonings. Curiosity, inability to read warning labels, a desire to imitate adults, and inadequate supervision lead to childhood poisonings.

The elderly are the second most likely group to be poisoned. Mental confusion, poor eyesight, and the use of multiple drugs are the leading reasons why this group has a high rate of accidental poisoning. A substantial number of poisonings also occur as suicide attempts or drug overdoses.

Poisons are common in the home and workplace, yet there are basically two major types. One group consists of products that were never meant to be ingested or inhaled, such as shampoo, paint thinner, pesticides, houseplant leaves, and carbon monoxide. The other group contains products that can be ingested in small quantities, but which are harmful if taken in large amounts, such as pharmaceuticals, medicinal herbs, or alcohol. Other types of poisons include the bacterial toxins that cause food poisoning, such as Escherichia coli; heavy metals, such as the lead found in the paint on older houses; and the venom found in the bites and stings of some animals and insects. The staff at a poison control center and emergency room doctors have the most experience diagnosing and treating poisoning cases.

The effects of poisons are as varied as the poisons themselves; however, the exact mechanisms of only a few are understood. Some poisons interfere with the metabolism. Others destroy the liver or kidneys, such as heavy metals and some pain relief medications, including acetaminophen (Tylenol) and nonsteroidal anti-inflammatory drugs (Advil, Ibuprofen). A poison may severely depress the central nervous system, leading to coma and eventual respiratory and circulatory failure. Potential poisons in this category include anesthetics (e.g. ether and chloroform), opiates (e.g. morphine and codeine), and barbiturates. Some poisons directly affect the respiratory and circulatory system. Carbon monoxide causes death by binding with hemoglobin that would normally transport oxygen throughout the body. Certain corrosive vapors trigger the body to flood the lungs with fluids, effectively drowning the person. Cyanide interferes with respiration at the cellular level. Another group of poisons interferes with the electrochemical impulses that travel between neurons in the nervous system. Yet another group, including cocaine, ergot, strychnine, and some snake venoms, causes potentially fatal seizures.

Severity of symptoms can range from headache and nausea to convulsions and death. The type of poison, the amount and time of exposure, and the age, size, and health of the victim are all factors which determine the severity of symptoms and the chances for recovery.

There are more than 700 species of poisonous plants in the United States. Plants are second only to medicines in causing serious poisoning in children under age five. There is no way to tell by looking at a plant if it is poisonous. Some plants, such as the yew shrub, are almost entirely toxic: needles, bark, seeds, and berries. In other plants, only certain parts are poisonous. The bulb of the hyacinth and daffodil are toxic, but the flowers are not; while the flowers of the jasmine plant are the poisonous part. Moreover, some plants are confusing because portions of them are eaten as food while other parts are poisonous. For example, the fleshy stem (tuber) of the potato plant is nutritious; however, its roots, sprouts, and vines are poisonous. The leaves of tomatoes are poisonous, while the fruit is not. Rhubarb stalks are good to eat, but the leaves are poisonous. Apricots, cherries, peaches, and apples all produce healthful fruit, but their seeds contain a form of cyanide that can kill a child if chewed in sufficient quantities. One hundred milligrams (mg) of moist, crushed apricot seeds can produce 217 milligrams of cyanide.

Common houseplants that contain some poisonous parts include:

• Aloe
• Amaryllis
• Cyclamen
• Dumbcane (also called Diffenbachia)
• Philodendron.

Common outdoor plants that contain some poisonous part include:

• Bird of paradise flower
• Buttercup
• Castor bean
• Chinaberry tree
• Daffodil
• English ivy
• Eucalyptus
• Foxglove
• Holly
• Horse chestnut
• Iris
• Jack-in-the-pulpit
• Jimsonweed (also called thornapple)
• Larkspur
• Lily-of-the-valley
• Morning glory
• Nightshade (several varieties)
• Oleander
• Potato
• Rhododendron
• Rhubarb
• Sweet pea
• Tomato
• Wisteria
• Yew.

Symptoms of plant poisoning range from irritation of the skin or mucous membranes of the mouth and throat to nausea, vomiting, convulsions, irregular heartbeat, and even death. It is often difficult to tell if a person has eaten a poisonous plant because there are no tell-tale empty containers and no unusual lesions or odors around the mouth.