Formaldehyde

Chemical and Physical Properties

Formaldehyde is a colorless, flammable gas with a pungent odor. It is commonly used in liquid form as a 37% aqueous solution known as formalin, which is primarily used as a fixative for biological tissue specimens. To prevent polymerization of formaldehyde solution, 10 - 15% of methanol is added. Formalin can release formaldehyde gas, especially when poured or spilled over a large surface area, creating a potential inhalation exposure.

Paraformaldehyde is a solid polymer of formaldehyde that comes as a fine white powder. When heated paraformaldehyde depolymerizes back to formaldehyde gas. If it is added to water and heated, the resulting gas immediately dissolves, making an uninhibited formalin solution. 

Health Hazards

Formaldehyde, formalin, and paraformaldehyde are potential human carcinogens, irritants, and chemical sensitizers.   

Acute effects 

  • Ingestion can cause nausea, vomiting, loss of appetite, gastrointestinal irritation and/or diarrhea. 
  • Inhalation can cause irritation of the respiratory tract, tightening of the chest, headaches, palpitations of the heart. 
  • Dermal exposure may cause allergic reactions or drying, cracking, and scaling. 
  • Eyes may become irritated, burn, water, and changes or loss of vision. 

Chronic effects 

  • Sensitization to formaldehyde can cause allergy symptoms to develop and worsen in certain individuals, potentially leading to dermatitis and occupational asthma.
  • Long-term exposure to formaldehyde is linked to nasopharyngeal cancer and has been associated with an increased risk of myeloid leukemia.

Exposure Limits

The University of Minnesota manages formaldehyde under OSHA Standard 29 CFR 1910.1048. The legal Permissible Exposure Limit (PEL) is 0.75 ppm as an 8-hour average, with a Short-Term Exposure Limit (STEL) of 2.0 ppm for any 15-minute period. Crucially, OSHA defines an Action Level (AL) of 0.5 ppm; exceeding this concentration triggers mandatory periodic air monitoring and medical surveillance.

To maintain safety, all formaldehyde work should be performed inside a certified chemical fume hood, downdraft table, or other localized exhaust system. If a protocol requires handling formaldehyde or formalin on an open benchtop, an exposure assessment must be performed to ensure airborne concentrations remain below the AL and to determine if additional controls or respiratory protection are necessary.

Training

Annual training is required for any workers exposed to formaldehyde concentrations of 0.1 ppm or greater. A Formaldehyde training module (UHS654) for annual training is available through Lab and Research Safety.

Safe Handling and Storage

  • Operations involving the pouring, dispensing, or heating of paraformaldehyde or formalin must be carried out in a fume hood or with another form of localized exhaust.
  • Gloves must be worn whenever paraformaldehyde, formalin or tissues preserved or fixed with formalin are handled. While latex gloves provide some protection against formaldehyde liquids, butyl or nitrile gloves are recommended and should be used when contact is anticipated.
  • Eye protection must be used.
  • Eye washes must be provided in the immediate work area where there is any possibility that an employee's eyes may be splashed with solutions containing 0.1% formaldehyde or greater.     

Accidental Exposure

  • Inhalation: Move the victim to fresh air immediately and give artificial respiration if not breathing. 
  • Skin Contact: Remove contaminated clothing immediately and wash the affected body area with soap or mild detergent and large amounts of water until no evidence of the chemical remains (15 to 20 min).
  • Eye Contact: Wash the eyes immediately with large amounts of water, occasionally lifting lower and upper lids, until no evidence of chemical remains (15 to 20 minutes). Get medical attention immediately.
  • Accidental Ingestion: Do not induce vomiting. Seek emergency medical attention. 

Spill Response

Please review the Chemical Spills Fact Sheet for details regarding emergency and non-emergency spill cleanup. 

Waste Disposal

Review the University’s hazardous waste disposal procedures for proper waste disposal.

Exposure Monitoring & More Information 

To schedule exposure monitoring or for more information contact Health, Safety & Risk Management at [email protected]. 

References

29 CFR 1910.1048 Formaldehyde Standard

OSHA Substance Technical Guidelines for Formalin (29 CFR 1910.1048 Appendix A)