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Flame Retardants in Insulation

What problematic flame retardants are used?

See the table below to learn more about the most common three flame retardants used in foam plastic building insulation.

Flame Retardant Name and CAS # HBCDD


CAS RN: 25637-99-4

Tris (1-chloro-2-propyl) phosphate

CAS RN: 13674-84-5
Poly FR

Brominated styrene butadiene copolymer

Also known as BLUEEDGE, Emerald Innovation 3000, GreenCrest, and FR-122P
Use in Insulation Older expanded and extruded (EPS and XPS) foam board insulation Polyurethane and polyisocyanurate insulation (foam spray and boards) Expanded and extruded (EPS and XPS) foam board insulation
Chemical Class Brominated flame retardant Chlorinated organophosphate flame retardant Brominated flame retardant
Health & Environmental Concerns Persistence and long-range transport


Neurodevelopmental toxicity

Aquatic toxicity

Accumulation in liver and kidneys

Potential carcinogen, endocrine disruptor, reproductive toxin, and neurotoxin

Degrades into smaller, likely toxic compounds

Poorly studied
Legal Restrictions Banned or phased out in Japan, the European Union, and Canada

Recommended for global elimination by the Stockholm Convention
European Union: Regulated under Toy Safety Directive

Under study at U.S. Environmental Protection Agency and National Toxicology Program

Listed on the California Safer Consumer Products Candidate List

Do they provide a fire safety benefit?

Our peer-reviewed paper, Flame retardants in building insulation: a case for re-evaluating building codes, concluded that flame retardants in building insulation do not provide a fire safety benefit for many applications.

What We Found

  • Since 1961, building codes have required foam plastic insulation materials to meet flame spread requirements as measured by the Steiner Tunnel test.
  • The Steiner Tunnel test does not accurately measure the flame spread of foam plastics.
  • Flame retardants are added to foam plastic materials to pass the Steiner Tunnel test, but they do not provide fire safety benefits in many building applications.
  • Fire safety for foam plastics is provided instead by code provisions requiring firestopping and thermal barriers.