Formaldehyde is a gas with a pungent odor that is used commonly in the processing of paper, fabrics, and wood products and for the production of urea foam insulation. Low-level formaldehyde exposure has been found in stores selling clothing treated with formaldehyde-containing crease-resistant resins, in mobile homes, and in tightly enclosed rooms built with large quantities of formaldehyde-containing products used in construction materials. Formaldehyde aqueous solution (formalin) is used in varying concentrations (usually 37%) as a disinfectant and tissue fixative. Stabilized formalin may also contain 6-15% methanol.

1. Formaldehyde causes precipitation of proteins and will cause coagulation necrosis of exposed tissue. The gas is highly water soluble. When inhaled, it produces immediate local irritation of the upper respiratory tract and has been reported to cause spasm and edema of the larynx.
2. Metabolism of formaldehyde produces formic acid, which may accumulate and produce metabolic acidosis if sufficient formaldehyde was ingested.
3. Formaldehyde has been listed by the International Agency for Research on Cancer (IARC) as a known human carcinogen associated with nasal sinus and nasopharyngeal cancer. NIOSH also considers formaldehyde a carcinogen.

1. Inhalation. The OSHA workplace permissible exposure limit (PEL) is 0.75 ppm (8-hour TWA) and the short-term exposure limit (STEL) is 2 ppm. The NIOSH-recommended exposure limit (REL) is 0.016 ppm (8-hour TWA); the ceiling for a 15-minute exposure is 0.1 ppm. The air level considered immediately dangerous to life or health (IDLH) is 20 ppm.
2. Ingestion of as little as 30 mL of 37% formaldehyde solution has been reported to have caused death in an adult.

1. Formaldehyde gas exposure produces irritation of the eyes, and inhalation can produce cough, wheezing, and noncardiogenic pulmonary edema.
2. Ingestion of formaldehyde solutions may cause severe corrosive esophageal and gastric injury, depending on the concentration. Lethargy and coma have been reported. Metabolic (anion gap) acidosis may be caused by formic acid accumulation from metabolism of formaldehyde or methanol.
3. Hemolysis has occurred when formalin was accidentally introduced into the blood through contaminated hemodialysis equipment.

Is based on a history of exposure and evidence of mucous membrane, respiratory, or GI tract irritation.

1. Specific levels
   1. Formaldehyde levels are available in plasma, but formate levels may better indicate the severity of intoxication. Neither are readily available in typical hospital laboratories.
   2. Methanol and formate levels (available in some toxicology laboratories) may be helpful in cases of intoxication by formalin containing methanol.
2. Other useful laboratory studies include arterial blood gases, chest imaging, electrolytes, glucose, BUN, creatinine, osmolality, and calculation of the osmol gap.

1. Emergency and supportive measures
   1. Maintain an open airway and assist ventilation if necessary.
   2. Inhalation. Treat bronchospasm and pulmonary edema if they occur. Administer supplemental oxygen and observe for at least 4-6 hours.
   3. Ingestion
      1. Treat coma and shock if they occur.
      2. Administer IV saline or other crystalloids to replace fluid losses caused by gastroenteritis. Avoid fluid overload in patients with inhalation exposure because of the risk for pulmonary edema.
      3. Treat metabolic acidosis with sodium bicarbonate.
2. Specific drugs and antidotes
   1. If a methanol-containing solution has been ingested, evaluate and treat with ethanol or fomepizole as for methanol poisoning.
   2. Formate intoxication caused by formaldehyde alone should be treated with folic acid. Ethanol and fomepizole are not effective.
3. Decontamination. Rescuers should wear self-contained breathing apparatus and appropriate chemical-protective clothing when handling a heavily contaminated patient.
   1. Inhalation. Remove victims from exposure and give supplemental oxygen if available.
   2. Skin and eyes. Remove contaminated clothing and wash exposed skin with soap and water. Irrigate exposed eyes with copious tepid water or saline; perform fluorescein examination to rule out corneal injury if pain and lacrimation persist.
   3. Ingestion. Give plain water to dilute concentrated solutions of formaldehyde. Perform aspiration of liquid formaldehyde from the stomach if large quantities were swallowed. Depending on the concentration of solution and patient symptoms, consider endoscopy to rule out esophageal or gastric injury. Activated charcoal is of uncertain benefit and may obscure the endoscopist's view.
4. Enhanced elimination
   1. Hemodialysis is effective in removing methanol and formate and in correcting severe metabolic acidosis. Indications for hemodialysis include severe acidosis and an elevated osmol gap.
   2. Alkalinization of the urine helps promote excretion of formate.