Freons (fluorocarbons and chlorofluorocarbons [CFCs]) historically have been widely used as aerosol propellants, in refrigeration units, in the manufacture of plastics, in foam blowing, and as degreasing agents. Under provisions of the Montreal Protocol of 1987, the use of CFCs is being phased out to avoid further depletion of stratospheric ozone. Nevertheless, freons remain in older refrigeration and air conditioning systems, and illicit importation of freons occurs. Most freons are gases at room temperature, but some are liquids (freons 11, 21, 113, and 114) and may be ingested. Specialized fire extinguishers contain closely related compounds known as halons, which contain bromine, fluorine, and chlorine.
Mechanism of toxicity
Freons are mild CNS depressants and asphyxiants that displace oxygen from the ambient environment. Freons are well absorbed by inhalation or ingestion and are usually rapidly excreted in the breath within 15–60 minutes.
Like chlorinated hydrocarbons, freons may potentiate cardiac arrhythmias by sensitizing the myocardium to the effects of catecholamines.
Direct freezing of the skin, with frostbite, may occur if the skin is exposed to rapidly expanding gas as it escapes from a pressurized tank.
Freons and halons are mild irritants and may produce more potent irritant gases and vapors (eg, phosgene, hydrochloric acid, hydrofluoric acid, and carbonyl fluoride) when heated to high temperatures, as may happen in a fire or if a refrigeration line is cut by a welding torch or electric arc.
Some agents are hepatotoxic after large acute or chronic exposure.
Inhalation. The toxic air level is quite variable, depending on the specific agent (see Table IV–4). Freon 21 (dichlorofluoromethane; TLV, 10 ppm [42 mg/m3]) is much more toxic than freon 12 (TLV, 2000 ppm). In general, anesthetic or CNS-depressant doses require fairly large air concentrations, which can also displace oxygen, leading to asphyxia. The air level of dichloromonofluoromethane considered immediately dangerous to life or health (IDLH) is 5000 ppm. Other TLV and IDLH values can be found in Table IV–4.
Ingestion. The toxic dose by ingestion is not known.
Skin or mucous membrane exposure can cause pharyngeal, ocular, and nasal irritation. Dysesthesia of the tongue is commonly reported. Frostbite may occur after contact with rapidly expanding compressed gas. Chronic exposure may result in skin defatting and erythema.
Respiratory effects can include cough, dyspnea, bronchospasm, hypoxemia, and pneumonitis.
Systemic effects of moderate exposure include dizziness, headache, nausea and vomiting, confusion, impaired speech, tinnitus, ataxia, and incoordination. More severe intoxication may result in coma or respiratory arrest. Ventricular arrhythmias may occur even with moderate exposures. A number of deaths, presumably caused by ventricular fibrillation, have been reported after freon abuse by “sniffing” or “huffing” freon products from plastic bags. Hepatic injury may occur.
Diagnosis is based on a history of exposure and clinical presentation. Many chlorinated and aromatic hydrocarbon solvents may cause identical symptoms.
Specific levels. Expired-breath monitoring is possible, and blood levels may be obtained to document exposure, but these procedures are not useful in emergency ...