Yi-Chun LinPh.D.Taiwan
Laser Materials ProcessingPublished
Dec 24, 2025
Formaldehyde (CH₂O)
Chemical Properties
Chemical Identity
CAS Number
50-00-0
Formula
CH₂O
Molecular Weight
30.03 g/mol
Exposure Limits Comparison
OSHA PEL
0.75 ppm
NIOSH REL
0.016 ppm
Health Effects
Respiratory Irritation
Yes
Eye Irritation
Yes
Skin Sensitization
Yes
Nasopharyngeal Cancer
Yes
Leukemia
Yes
Formaldehyde (CH₂O) safety information
Comprehensive safety and handling requirements
Detection Monitoring
- Electrochemical
- Photoionization detector (PID)
- Colorimetric
- Dräger Formaldehyde 0.2/a
- Gastec 91L
- Kitagawa 710
| Sensor Types | |||||||||||||
| Detection Range | 0-10 ppm typical | ||||||||||||
| Alarm Setpoints |
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| Colorimetric Tubes | |||||||||||||
| Analytical Methods |
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| Odor Threshold | 0.05-1 ppm - provides early warning but olfactory fatigue occurs. Do not rely on odor alone. |
Environmental Impact
| Aquatic Toxicity | Toxic to aquatic life. LC50 (fish, 96h): 7-45 mg/L depending on species. | ||||
| Biodegradability | Readily biodegradable (>70% in 28 days). Oxidizes to formic acid then carbon dioxide. | ||||
| Bioaccumulation | Very low bioaccumulation potential. BCF <10. Log Kow: 0.35. | ||||
| Soil Mobility | High mobility. Does not adsorb significantly. Volatilizes from soil and water surfaces. | ||||
| Atmospheric Fate | Photolyzes rapidly via hydroxyl radicals. Atmospheric half-life: 1-2 days. Forms formic acid. | ||||
| Ozone Depletion | false | ||||
| Reportable Releases |
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Ppe Requirements
| Respiratory | Full-face NIOSH-approved respirator with organic vapor and formaldehyde cartridges for concentrations <0.75 ppm. SCBA required for >0.75 ppm or unknown concentrations. |
| Eye Protection | Chemical safety goggles or full-face respirator. Face shield for splash hazard. |
| Skin Protection | Nitrile or butyl rubber gloves (breakthrough time >8 hours). Chemical-resistant suit for high exposure or liquid contact. |
Reactivity
- Strong oxidizers
- Strong acids
- Strong bases
- Phenols
- Aniline
- Nitrogen dioxide
- Performic acid
- Perchloric acid
- Carbon monoxide
- Carbon dioxide
- Formic acid
- Heat
- Light
- Contamination
- Acids
- Bases
- Cold temperatures (polymerization)
| Stability | Pure formaldehyde unstable. Solutions polymerize on standing, especially without stabilizer (methanol). |
| Polymerization | Polymerizes to paraformaldehyde, especially with impurities, acids, bases, or on cooling. Exothermic reaction. |
| Incompatible Materials | |
| Hazardous Decomposition | |
| Conditions To Avoid | |
| Reactivity Hazard | Reacts violently with strong oxidizers. Reacts with phenols forming heat-sensitive explosive compounds. Reacts with nitrogen dioxide forming explosive nitro compounds. |
Regulatory Classification
- Carcinogenicity
- Acute toxicity
- Respiratory sensitization
- Skin sensitization
- Aquatic toxicity
| Un Number | UN1198 (solution, flammable), UN2209 (solution, ≥25%) | ||||||
| Dot Hazard Class | 3 (Flammable liquid) or 8 (Corrosive) | ||||||
| Dot Label | Flammable Liquid, Corrosive (depending on concentration) | ||||||
| Nfpa Codes |
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| Epa Hazard Categories | |||||||
| Sara Title Iii | true | ||||||
| Cercla Rq | 100 pounds (45.4 kg) | ||||||
| Rcra Code | U122 |
Storage Requirements
- Strong oxidizers
- Strong acids
- Strong bases
- Phenols
- Aniline
- Perchloric acid
- Nitromethane
| Temperature Range | Store below 25°C (77°F). Refrigeration recommended for solutions to prevent polymerization. |
| Ventilation | Local exhaust ventilation mandatory. Fume hood for small quantities. Outdoor storage for large quantities. |
| Incompatibilities | |
| Container Material | Stainless steel, glass, or polyethylene. NOT copper or copper alloys (catalyzes oxidation). |
| Segregation | Separate from oxidizers, acids, and bases. Flammable storage if concentration >30%. |
| Quantity Limits | Minimize quantities. OSHA requires <100 gallons or 1,000 lbs inside buildings. |
| Special Requirements | Stabilized with methanol (10-15%) to prevent polymerization. Label as carcinogen with appropriate warnings. Post carcinogen work area signs. Secondary containment required. Emergency eyewash and shower within 25 feet. |
Produced From Contaminants
Produced From Materials
Exposure Limits
Regulatory exposure thresholds and safe concentration levels
- Osha Pel Ppm
- 0.75
- Osha Pel Mg M3
- 0.92
- Niosh Rel Ppm
- 0.016
- Niosh Rel Mg M3
- 0.02
- Acgih Tlv Mg M3
- 0.3
- Workplace Exposure
- Osha Peltwa_8hr: 0.75 ppmstel_15min: 2 ppmceiling: nullNiosh Reltwa_8hr: nullstel_15min: nullceiling: 0.016 ppm (0.02 mg/m³) - 15 minute ceilingidlh: 20 ppmAcgih Tlvtwa_8hr: nullstel_15min: nullceiling: 0.3 ppm (A2 suspected human carcinogen designation)Biological Exposure Indices0: [object Object]
Physical Properties
Physical characteristics and state information
- Boiling Point
- -19°C (-2°F) for pure gas
- Melting Point
- -92°C (-134°F)
- Vapor Pressure
- 1 atm @ -19°C
- Vapor Density
- 1.03 (Air=1)
- Specific Gravity
- 0.815 @ -20°C (liquid)
- Flash Point
- 85°C (185°F) for 37% solution (formalin)
- Autoignition Temp
- 430°C (806°F)
- Explosive Limits
- LEL: 7%, UEL: 73%
- Appearance
- Colorless gas or clear solution (formalin)
- Odor
- Pungent, irritating odor @ 0.05-1 ppm (provides warning)
Reactivity
Chemical reactivity and compatibility with other substances
- Stability
- Pure formaldehyde unstable. Solutions polymerize on standing, especially without stabilizer (methanol).
- Polymerization
- Polymerizes to paraformaldehyde, especially with impurities, acids, bases, or on cooling. Exothermic reaction.
- Incompatible Materials
- Strong oxidizers
- Strong acids
- Strong bases
- Phenols
- Aniline
- Nitrogen dioxide
- Performic acid
- Perchloric acid
- Hazardous Decomposition
- Carbon monoxide
- Carbon dioxide
- Formic acid
- Conditions To Avoid
- Heat
- Light
- Contamination
- Acids
- Bases
- Cold temperatures (polymerization)
- Reactivity Hazard
- Reacts violently with strong oxidizers. Reacts with phenols forming heat-sensitive explosive compounds. Reacts with nitrogen dioxide forming explosive nitro compounds.
Synonyms & Identifiers
Alternative names and chemical identifiers (CAS numbers)
- Synonyms
- Methanal
- Methylene oxide
- Oxymethylene
- Formalin (37% solution)
- Formol
- Common Trade Names
- Formalin
- Formalith
- Formaldehyde solutions
- Other Identifiers
- Rtecs NumberLP8925000Ec Number200-001-8Pubchem Cid712
