For clinicians, a more practical way of categorizing hazardous chemicals is by toxic syndrome or toxidrome.47 Each toxidrome describes the characteristic toxic effects elicited by the chemicals within a group, serving as a set of clinical “fingerprints.” Illnesses from exposure to any of the chemicals associated with a given toxidrome are treated similarly. Common toxidromes with example chemicals that cause them are defined in Table 6. It should be noted that a chemical incident likely could involve a mixture of chemicals which can complicate the identification of the substances causing the health effects and/or environmental contamination.
Table 6: Common Toxic Syndromes or Toxidromes
| Name | Description | Examples |
|---|---|---|
| Acute exposure to solvents, anesthetics, or sedatives (SAS) | Central nervous system depression leading to a decreased level of consciousness (progressing to coma in some cases), depressed respirations, and in some cases ataxia (difficulty balancing and walking) | gasoline, benzene, toluene, xylene, carbon tetrachloride, methylene chloride, freon, nitrous oxide, benzodiazepines, barbiturates |
| Anticholinergic | Under-stimulation of cholinergic receptors leading to dilated pupils (mydriasis), decreased sweating, elevated temperature, and mental status changes, including characteristic hallucinations | BZ (3-quinuclidinyl benzilate), atropine, hyoscyamine, scopolamine |
| Anticoagulants | Alteration of blood coagulation that results in abnormal bleeding indicated by excessive bruising, and bleeding from mucous membranes, the stomach, intestines, urinary bladder, and wounds, as well as other internal (e.g., intracranial, retroperitoneal) bleeding | coumadin, brodifacoum, bromodialone, diphacinone |
| Cholinergic | Overstimulation of cholinergic receptors leading to hyperactivity of target tissues, including hypersecretion ("leaking all over," with tearing, increased nasal secretions, increased salivation, copious bronchial secretions, and sweating) from exocrine glands and miosis (pinpoint pupils), bronchospasm (wheezing), and hyperperistalsis (leading to nausea, vomiting, cramping, and diarrhea) from smooth muscle in the eye, the respiratory tract, and the gastrointestinal tract, respectively. Activation and subsequent fatigue of skeletal muscle produce initial twitching, progressing to weakness and usually flaccid paralysis, and activation and subsequent fatigue of neurons in the brain, which are responsible for initial agitation, tremors, choreoathetoid (dancing and writhing) movement, seizures and convulsions, progressing to paralysis of the respiratory center in the medulla and cessation of breathing. | tabun, sarin, soman, VX, aldicarb, methomyl, chlorpyrifos, parathion, Novichok agents |
| Convulsant | Central nervous system excitation (GABA antagonism and/or glutamate agonism and/or glycine antagonism) leading to generalized convulsions | hydrazines, tetramethylenedisulfotetramine, picrotoxin, strychnine |
| Irritant/Corrosive | Immediate effects range from minor irritation of exposed skin, mucous membranes, pulmonary, and GI tract to coughing, wheezing, respiratory distress and more severe GI symptoms that may progress rapidly to systemic toxicity | ammonia, chlorine, phosgene, riot control agents, mustard agents, Lewisite, hydrofluoric acid, methylene chloride |
| Knockdown | Disrupted cellular oxygen delivery to tissues may be caused by simple asphyxia due to oxygen displacement by inert gases, hemoglobinopathies (e.g., carbon monoxide, methemoglobin inducers), impairment of oxygen transport by the red blood cell, and/or impairment of the cell’s ability to use oxygen (e.g., mitochondrial inhibitors such as cyanide). All these situations lead to altered states of consciousness, progressing from fatigue and lightheadedness to seizures and/or coma, with cardiac signs and symptoms, including the possibility of cardiac arrest. | cyanides, hydrogen sulfide, azides, rotenone, sodium monofluoroacetate, carbon monoxide, aniline, arsine, nitrogen |
| Opioid | Opioid agonism leading to pinpoint pupils (miosis) and central nervous system and respiratory depression | fentanyl and fentanyl derivates, diacetylmorphine |
| Stress Response/Sympathomimetic | Stress- or toxicant-induced catecholamine excess or central nervous system excitation leading to confusion, panic, and increased pulse, respiration, and blood pressure | mephedrone, amphetamines |