Which flame retardants are toxic and harmful to health?

What are flame retardants and what are they used for?

Flame retardants are chemical or mineral substances that make plastics, textiles, building materials and electronic devices difficult to ignite or delay the spread of fire in the event of an incident. They play a central role in product safety and are used in numerous everyday products. Whether in cable insulation, seat padding, carpets, insulation materials or electrical device housings—wherever fires can occur, flame retardants are intended to help minimise flammability.

However, despite their protective function, many traditional flame retardants are now under scrutiny. Numerous compounds are considered hazardous to health, persistent in the environment and in some cases toxic. The debate about toxic and health-damaging flame retardants has stirred the industry—and rightly so.

What makes flame retardants harmful to health?

Flame retardants pose a health risk when they are toxic, do not break down easily in the environment, and accumulate in the human body. Brominated or chlorinated compounds are particularly problematic: When heated or exposed to fire, they can release toxic substances such as dioxins and are suspected of causing hormonal disorders, nerve damage or even cancer.

There is also a daily exposure risk, as many of these substances migrate from products, enter the body via household dust, inhalation or skin contact, and have already been detected in blood and breast milk. This makes the use of safe, halogen-free alternatives such as expandable graphite all the more important.

These flame retardants are considered toxic and hazardous to health

Flame retardants are intended to save lives in the event of a fire, but not all deliver this benefit without risks. Some of the most commonly used substances have faced criticism for years.

Brominated flame retardants – widespread, highly controversial

Brominated flame retardants are among the most widely used halogenated flame retardants. They are effective and comparatively inexpensive, but their health and environmental side effects are significant.

Studies have shown that brominated flame retardants can have neurotoxic effects, disrupt hormone processes and are associated with an increased likelihood of developmental disorders. Especially problematic: Many of these compounds are very stable and degrade poorly in the environment. As a result, they enter the food chain and ultimately our bodies.

Examples of problematic brominated flame retardants:

• Polybrominated diphenyl ethers (PBDE): Already banned in many countries but still present in older products. They can affect thyroid function and have been detected in breast milk.
• Hexabromocyclododecane (HBCD): Was commonly used in insulation materials and is now considered of very high concern (SVHC under REACH).

Chlorinated flame retardants – hazardous to health and persistent

Chlorinated flame retardants are also valued for their effectiveness—in particular, in foams, textiles or electronics. Like their brominated counterparts, however, they are considered dangerous.

Chlorinated flame retardants can release toxic dioxins and furans when heated, both of which are considered carcinogenic and immunotoxic. They can also have hormone-like effects, especially regarding oestrogen receptors.

A well-known example:

• TCPP (Tris(1-chloro-2-propyl)phosphate): Mainly used in polyurethane foams. Suspected of affecting the nervous system and being carcinogenic. Despite the risks, TCPP is still widely used.

Melamine – a double-edged alternative?

Melamine is often marketed as a halogen-free substitute, but this nitrogen compound also has a questionable reputation. Since January 2023, melamine has been classified as a substance of very high concern and is on the SVHC list.

The health concerns relate to potential impacts on the kidneys, bladder and fertility. Furthermore, toxic gases can be generated when burning melamine-containing materials, making its use in enclosed spaces problematic.

Organophosphorus compounds – not halogen-free means not harmless

Organophosphorus compounds are often seen as an alternative to brominated and chlorinated substances. However, many representatives in this class are also toxicologically concerning. Some organophosphorus compounds have neurotoxic properties, while others are suspected of affecting hormonal systems or being carcinogenic.

A particular problem is the wide variety of different organophosphorus compounds, which makes regulation difficult. While some are regarded as harmless, others have been associated in studies with developmental disorders and impaired fertility.

Regulations and bans in the EU

The European Union has been pursuing a consistent strategy for years to identify and regulate chemicals that are hazardous to health and the environment—and to ultimately replace them with safer alternatives. This shift is also evident in the field of flame retardants.

Numerous brominated, chlorinated and organophosphorus compounds have already been added to the list of substances of very high concern (SVHC) or are now strictly regulated or banned completely by EU regulations such as REACH and RoHS. Examples include:

• Polybrominated diphenyl ethers (PBDE)
  Already banned for years, but these compounds are still found in old electronic devices and furniture.
• HBCD (Hexabromocyclododecane)
  Classified as persistent, bioaccumulative and toxic—now banned in insulation and packaging materials.
• Melamine
  Listed since 2023 as a substance of very high concern, making its use and marketing significantly more difficult.
• TCPP (Tris(1-chloro-2-propyl)phosphate)
  Still permitted but under observation—its health risks are now well documented.

Safe alternatives: Mineral & halogen-free

Thanks to increasing regulation of halogenated flame retardants, mineral and halogen-free alternatives are coming into focus, especially expandable natural graphite (expandable graphite). These additives are based on natural raw materials, are non-toxic, non-volatile, and at the same time meet the highest requirements for flame protection.

What makes expandable graphite so special?

When exposed to heat, expandable graphite expands to many times its original volume, forming a protective intumescent barrier. This physical shield reliably protects the underlying materials from flames and heat, and prevents the formation and spread of smoke gases—all without using health-hazardous chemicals.

Advantages of halogen-free flame retardant systems:

• REACH-compliant & harmless to health
  Not listed on SVHC lists, no risk to humans or the environment.
• Environmentally friendly & resource-efficient
  Expandable graphite is produced from natural flake graphite, entirely without halogen additives.
• Effective at low dosage
  Even small amounts are sufficient to meet critical flame retardancy standards (e.g. UL 94 V-0, DIN EN 45545, DIN 1402 or DIN EN 13501).
• Synergistically combinable
  Particularly effective in combination with other additives such as APP (ammonium polyphosphate) or ATH (aluminium hydroxide).