Toxic Plants

Abstract

More than 60,000 calls are made annually to poison control centers (PCCs) for cases of suspected plant toxicity. Children younger than age 6 years comprise two thirds of cases, due to their natural curiosity and limited judgment. Most of these exposures are benign; fewer than 10% result in treatment by a health professional. The PCC is a valuable source of information to assist in management. Most ingestions of plant material by young children are of small quantity, and symptoms, if present, typically are short-lived and self-limited. Gastrointestinal effects are common and may be a clue to seek other, more subtle signs of poisoning. Plant ingestions in older children and adolescents generally are intentional and of larger quantity, the result of either substance experimentation or attempted self-harm.Autonomic toxidromes can be seen in many plant poisonings. Deadly nightshade (Atropa belladonna) and Jimson weed (Datura stramonium) produce atropine, scopolamine, and hyoscyamine, all anticholinergic toxins. Victims can present with classic symptoms of flushing, hyperthermia, blurred vision, dry mouth, and hallucinations. Common garden vegetables in the Solanum genus, including tomatoes, potatoes, and eggplants, also can cause anticholinergic symptoms when blossoms or unripe buds are ingested. Physostigmine may be indicated to treat severe or persistent symptoms.A variety of central nervous system (CNS) responses follow plant ingestion. Hallucinations are common with marijuana ingestion by children and with ingestion of nutmeg or morning glory seeds by teenagers. Tobacco plant exposure results in parasympathetic symptoms (miosis, bronchorrhea, gastrointestinal distress) as well as neuromuscular derangement due to unchecked nicotinic receptor response.Cardioactive glycosides are produced by foxglove (Digitalis), but they also are found in lily of the valley (Convallaria) and oleander (Nerium and Thevetia). Symptoms cannot be distinguished from those of digoxin toxicity and include hyperkalemia, CNS depression, and cardiac conduction abnormalities. Treatment with digoxin-specific antibody fragments can be lifesaving.Potentially dangerous toxins can show up in unexpected sources. Berries of the holly and mistletoe plants, common in holiday decorations, carry a risk of significant gastrointestinal distress. Amygdalin, contained in seeds and pits of Prunus species fruits (cherries, apricots, peaches, apples, plums), generates cyanide when metabolized. The resulting inhibition of cellular respiration can be lethal.Ingestion of mushrooms also may have fatal consequences. Species that harbor amatoxins (Amanita) and related compounds typically cause delayed onset (6 hours) of nausea, vomiting, and diarrhea. A second latent period is followed by acute and possibly fulminant hepatitis beginning 48 to 72 hours after ingestion. Effective decontamination and therapies directed at the toxins generally are ineffective, and supportive care, including liver transplant if necessary, is the mainstay of therapy. Other species of mushrooms can cause hallucinations, muscarinic toxicity, or general gastrointestinal irritation. Although most mushroom species are nontoxic, caretakers of a child who has eaten or who is suspected of eating any wild mushroom should call the PCC for guidance.The PCC can be an important aid in medical decision making, particularly with symptomatic patients for whom the identity of the plant is unknown. Electronic transmission of digital images may allow the PCC and expert botanists to identify the offending plant quickly and confidently and provide data on managing the exposure.Management of a potentially lethal exposure always should include communication with a toxicologist. In these situations, establishing control of airway, breathing, and circulation should be priorities. Aggressive decontamination, with gastric emptying, activated charcoal, and possibly whole bowel irrigation, may be warranted.Parents should be aware of the types of plants kept inside the home as well as in any landscaping in the yard or neighborhood. Unknown plants or shrubs, especially those that have bright colors or other features that might seem inviting to the curious child, can be identified with the help of a local nursery.Comment: Although pediatricians may consider drug ingestion readily in the differential diagnosis for certain signs and symptoms, I dare say we do not consider toxic plant exposures as often as we should, especially in younger children. Plant exposures in children 6 years of age and younger accounted for 4.6% of calls to PCCs, and this figure only represents instances when exposure was considered. The prevalence, therefore, is probably underestimated. Another important aspect to consider is the overlap of presentations between herbal remedies and plant exposures, another area where we need to expand our questioning. Consideration of toxic plant exposures in our patients reinforces the importance and value to parents and pediatricians of PCCs and the vast knowledge of diagnosis and treatment their staff impart. The website http://www.aapcc.org contains useful information about poison centers.Janet R. Serwint, MDConsulting Editor, In Brief