Formaldehyde and Formalin (HCHO)
Quick Reference
What is HCHO?
A toxic colorless gas with a strong odor. Highly flammable. Vapors are heavier than air. Dissolved in water in concentrations between 4 – 40% and called formalin. Used to preserve tissue samples, to synthesize resins and plastics and in agriculture as a fertilizer and disinfectant. Commonly transported in 20 L jugs, 200 L drums, 1000 L bulk tanks, and rail cars. Paraformaldehyde is the crystallized form.
Crew Safety
- Staging/Perimeter
- No risk of fire: 50 m, uphill/upwind.
- Large tank involved with fire or risk of fire: 800 m, uphill/upwind.
- Additional Resources
- Fire department or on-scene response team for rescue, clean-up, and risk of fire.
- PPE requirements
- Contact requires butyl rubber gloves and chemical protective clothing and SCBA for vapors.
- Exhaust fan during transport even after decontamination.
- Safely initiating patient contact
- Large spills/exposures: Patients decontaminated and brought to paramedics in a safe location.
- Small spills/exposures: Paramedics may coach decontamination from a distance provided no risk of exposure to fumes.
Effect on the Patient
Inhalation can cause significant bronchospasm or stridor, and ingestion causes significant corrosive injury. Readily absorbed by both inhalation and ingestion. Disrupts activity of multiple transport proteins leading to widespread physiologic dysfunction. Also metabolized to formic acid, leading to severe acidosis.
Patient Decontamination
Remove contaminated clothing, avoid pulling over head. Flush exposed or irritated eyes for 15 minutes and exposed skin with water/soap for 3 – 5 minutes. Contaminated clothing will give off toxic vapors. Paramedics should not directly contact patient during initial decon due to risk of inhalational exposure. If ingestion occurred any emesis should be double-bagged and care provided in a well-ventilated area.
Patient Treatment
Treat as per CPGs. Do not induce vomiting. If upper airway stridor is present in a child, consider nebulized epinephrine. Consider having patient drink 125 – 250 mL water or milk if ingestion occurred.
Safe Transfer of Care
After initial decontamination the primary concern for secondary exposure is from emesis in patients who ingested formaldehyde. These patients should be cared for in a well-ventilated area, emesis should be double bagged, and contact/splash precautions taken.
Paramedic and Equipment Decontamination
Ambulance to be aired out for 20 minutes with doors open. Small quantities of emesis cleaned with contact/splash precautions. If excessive quantities are present, paramedics should not decontaminate themselves due to the need for respiratory protection.
Quick Access Resources
DPIC Monograph
Paramedic Specialist Safety Data Sheet
No SDS available.
Emergency Response Guidebook
US CDC Medical Management of Formaldehyde
<a href="/ps/chemical/other/other_Formaldehyde.pdf" target="_blank"US CDC Medical Management of Formaldehyde (PDF)
Revision History
| Version | Date | Changes | Author |
|---|---|---|---|
| 1.0 | 2026-05-01 | Initial version | Clinical Hub |