Introduction
Background
Plants have evolved highly complex systems of defense against most of their natural enemies (eg, insects, animals). At the very least, these defenses make many plants unpalatable; however, some can be fatal to the inexperienced forager.
Throughout human history, plants have played pivotal roles as medicines and poisons. Our medical predecessors may not have known the exact mechanisms involved, but they did recognize various plants as instrumental for medical treatment and as instruments of murder. With current technology, we finally are able to peer into plants and see their vast arsenal of chemicals, including glycosides, alkaloids, oxalates, and resins.
When considering poisoning by plant resin, always be aware of possible co-intoxicants, which may blur the clinical picture. Such co-intoxicants include pharmaceutical and illicit drugs, herbicides, fungicides, insecticides, fertilizers, and artificial plant hormones.
Examples of unintentional toxic plant ingestion include the following:
- Hikers who mistake poisonous plants for nutritious ones
- Herbalists who seek natural remedies or natural highs and end up with poisonous concoctions
- Children who are attracted to brightly colored fruits and leaves of poisonous plants (This group accounts for the most calls to poison centers regarding plant toxicity.)
Pathophysiology
Resins are a diverse group of chemical compounds that share chemical characteristics, such as insolubility in water, solidity at room temperature, and lack of nitrogen group. Resin compounds formed with sugars are called glycoresins; those formed with oils are called oleoresins. Latex is a term used to describe these toxins when found in emulsions (ie, urushiols, which are catechol derivatives) in ducts of plants. They are released and activated when structural damage to the plant occurs.
Frequency
United States
While some individuals ingest toxic plants to attempt suicide, most present to the ED after unintentional toxic plant ingestion.
The 2006 Annual Report of the American Association of Poison Control Centers' National Poison Data System (NPDS) documented 64,236 plant exposures (2.7% of total human exposure).1 This figure is lower than that of 2004 (documented 74,811); however, the overall number of all types of human exposures remain little changed in the past 6 years.2
Pediatric (children <5 years old) plant exposures in 2006 were noted to be 44,710 or 3.7% of pediatric exposures reported.
The following is a list of the 25 most commonly reported plant involved in a reported exposure in 2006 NPDS:
- Spathiphyllum species - 2,133
- Euphorbia pulcherrima - 1,615
- Ilex species - 1,572
- Philodendron species - 1,514
- Phytolacca americana - 1,358
- Toxicodendron radicans - 1,194
- Schlumbergera bridgesii - 705
- Ilex opaca - 608
- Crassula argentea - 604
- Plants-cardiac glycosides - 583
- Malus species - 582
- Taraxacum officinale - 581
- Pepper mace - 566
- Epipremnum areum - 566
- Plants, cyanogenic glycosides - 555
- Plants, pokeweed - 543
- Mold - 538
- Caladium species - 533
- Nandina domestica - 530
- Narcissus pseudonarcissus - 474
- Spinacia oleracea - 467
- Cactus (unknown type or name) - 460
- Rosa species - 450
- Quercus species - 447
- Hedera helix - 446
Mortality/Morbidity
Five deaths were reported in 2004, which represents 0.007% of all plant exposures.
- Of all plant exposures reported, only 30% had outcomes reported. Sixty-six percent of the reported outcomes were asymptomatic.
- Ninety-five percent of all plant exposures reported were unintentional.
Age
Approximately 74% of plant exposures reported to poison centers in 2004 involved children younger than 6 years.
Clinical
History
Most plants involved in exposures reported to poison control centers are identified. However, plants often remain unidentified when patients come to the ED because of concern regarding plant ingestion or symptoms following plant ingestion or exposure.
Because toxic principles of plants may vary greatly by season and geography, systematic evaluation is invaluable for determining the etiology of the patient's symptoms and identifying the potential plant toxin. Generally, this is the case when describing circumstances surrounding the toxicity to the poison center or consulting toxicologist over the telephone.
Emergency physicians must obtain accurate history to determine extent of exposure and subsequent risk of disease. The following items may provide important information:
- Name of plant (note that common names vary considerably by region)
- Actual plant (if available, allows for detailed description of features)
- Amount ingested or exposed
- Duration of time since exposure
- Initial symptoms and time between exposure and symptom onset
- Past medical history, current medication, and allergies (These may alter host response and risk.)
Physical
A thorough examination focusing on existence or development of toxidromes (eg, anticholinergic syndromes, nicotinic syndromes) may be helpful in identifying the general class of toxin(s). It is very important to repeat this evaluation over time (generally several hours) to follow the evolution of symptoms and response to treatment.
- Many plants cause nonspecific gastrointestinal upset. Possible poison hemlock ingestion is suggested when gastrointestinal upset is accompanied by early onset of increased secretions followed by nicotinic syndromes such as respiratory difficulty, altered mental status, and possibly seizures (see Media file 1).
- Plant ingestion alone is unlikely to cause isolated altered mental status.
- Physicians must always consider other causes of acute altered mental status, such as hypoglycemia, co-ingestants, concomitant trauma, or infection.
Hemlock. Photo by Cornell University Poisonous Plants Informational Database.
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References
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Further Reading
Keywords
plant poisoning resins, resins, plant resins, poison ivy, poison oak, poison sumac, contact dermatitis, glycoresins, oleoresins, urushiols, poisonous plants, poisonous plant exposures, plant toxin, Toxicodendron species, Cicuta maculata, water hemlock, cicutoxin, chinaberry, Melia azedarach, tetranortriterpene, daphne, daphnetoxin, toxic plant ingestion, resin skin exposure
