Nicotine poisoning describes the symptoms of the toxic effects of consuming nicotine,
which can potentially be deadly. Historically, most cases of nicotine poisoning have been
the result of use of nicotine as an insecticide. More recent cases of poisoning typically appear
to be in the form of Green Tobacco Sickness or due to accidental ingestion of tobacco
or tobacco products or ingestion of nicotine containing plants.
The estimated lower limit of a lethal dose of nicotine has been reported as between 500
and 1000 mg. Historical data as between 40 and 60 milligrams in adults and about 1 mg/kg
in children . Children may become ill following ingestion of one cigarette; ingestion of more
than this may cause a child to become severely ill. In some cases children have become poisoned
by topical medicinal creams which contain nicotine.
People who harvest or cultivate tobacco may experience Green Tobacco Sickness, a type
of nicotine poisoning caused by dermal exposure to wet tobacco leaves. This occurs most commonly
in young, inexperienced tobacco harvesters who do not consume tobacco.
Toxicology The LD50 of nicotine is 50 mg/kg for rats
and 3 mg/kg for mice. 0.5-1.0 mg/kg can be a lethal dosage for adult humans, and 0.1 mg/kg
for children. However the widely used human LD50 estimate of 0.5–1.0 mg/kg was questioned
in a 2013 review, in light of several documented cases of humans surviving much higher doses;
the 2013 review suggests that the lower limit causing fatal outcomes is 500–1000 mg of
ingested nicotine, corresponding to 6.5–13 mg/kg orally. Nicotine therefore has a high toxicity
in comparison to many other alkaloids such as Caffeine, which has an LD50 of 127 mg/kg
when administered to mice. It is unlikely that a person would overdose
on nicotine through smoking alone, the US Food and Drug Administration states in 2013
"There are no significant safety concerns associated with using more than one OTC NRT
at the same time, or using an OTC NRT at the same time as another nicotine-containing product—including
a cigarette." Ingestion of nicotine pharmaceuticals, tobacco products, or nicotine containing plants
may also lead to poisoning. Smoking excessive amounts of tobacco has also led to poisoning;
a case was reported where two brothers smoked 17 and 18 pipes of tobacco in succession and
were both fatally poisoned. Spilling an extremely high concentration of nicotine onto the skin
can result in intoxication or even death since nicotine readily passes into the bloodstream
following skin contact. Signs and symptoms
Nicotine poisoning tends to produce symptoms that follow a biphasic pattern. The initial
symptoms are mainly due to stimulatory effects and include nausea and vomiting, excessive
salivation, abdominal pain, pallor, sweating, hypertension, tachycardia, ataxia, tremor,
headache, dizziness, muscle fasciculations, and seizures. After the initial stimulatory
phase, a later period of depressor effects can occur and may include symptoms of hypotension
and bradycardia, central nervous system depression, coma, muscular weakness and/or paralysis,
with difficulty breathing or respiratory failure. Pathophysiology
The symptoms of nicotine poisoning are caused by excessive stimulation of nicotinic cholinergic
neurons. Nicotine is an agonist at nicotinic acetylcholine receptor which are present in
the central and autonomic nervous systems, and the neuromuscular junction. At low doses
nicotine causes stimulatory effects on these receptors, however, higher doses or more sustained
exposures can cause inhibitory effects leading to neuromuscular blockade.
It is sometimes reported that people poisoned by organophosphate insecticides experience
the same symptoms as nicotine poisoning. Organophosphates inhibit an enzyme called acetylcholinesterase,
causing a buildup of acetylcholine, excessive stimulation of all types of cholinergic neurons,
and a wide range of symptoms. Nicotine is specific for nicotinic cholinergic receptors
only and has some, but not all of the symptoms of organophosphate poisoning.
Diagnosis Increased nicotine or cotinine is detected
in urine or blood, or serum nicotine concentrations increase.
Treatment The initial treatment of nicotine poisoning
may include the administration of activated charcoal to try to reduce gastrointestinal
absorption. Treatment is mainly supportive and further care can include control of seizures
with the administration of a benzodiazepine, intravenous fluids for hypotension, and administration
of atropine for bradycardia. Respiratory failure may necessitate respiratory support with rapid
sequence induction and mechanical ventilation. Hemodialysis, hemoperfusion or other extracorporeal
techniques do not remove nicotine from the blood and are therefore not useful in enhancing
elimination. Acidifying the urine could theoretically enhance nicotine excretion, although this
is not recommended as it may cause complications of metabolic acidosis.
Prognosis The prognosis is typically good when medical
care is provided and patients adequately treated are unlikely to have any long-term sequelae.
However, severely affected patients with prolonged seizures or respiratory failure may have ongoing
impairments secondary to the hypoxia. It has been stated that if a patient survives nicotine
poisoning during the first 4 hours, they usually recover completely.
References
External links How Stuff Works:Nicotine
Nicotine Poisoning In Pets