Abbreviations – What Means What?
Chemicals used in Fire Retardants.
More than 175 different types of FRs exist, and they are usually divided into 4 main groups:
- Inorganic FRs
- Organophosphorous FRs
- Nitrogen-containing FRs
- Halogenated organic FRs.
Here is a list of some of the most widely used ones:
|Additive FRs.||These are numerous and frequently used especially in furniture and fabrics. They are blended with the polymers and are thus more likely to leach out of products eg HBCD, aluminium trihydrate, magnesium hydroxide and phosphate esters.
|Aluminium Trihydrate.||Aluminium hydroxide is used as a fire retardant filler for polymer applications. It decomposes at about 180 °C (356 °F), absorbing a considerable amount of heat in the process and giving off water vapour. In addition to behaving as a fire retardant, it is very effective as a smoke suppressant in a wide range of polymers, most especially in polyesters, acrylics, ethylene vinyl acetate, epoxies, PVC and rubber.|
|Antimony oxide by itself is not a fire retardant, and the halogens by themselves, mainly bromine and chlorine, are weak fire retardants. However, when they are combined they become synergistic and are the most effective and most widely used flame retardant system for plastics. Usually three to four parts of halogenated flame retardants are used to one part of antimony oxide on a weight basis.|
|BFRs: Brominated Flame Retardants.||The largest market group of FRs is the brominated flame retardants. Many of the BFRs are considered toxic, persistent and bio-accumulate in the environment. It is estimated that more than 200,000 tonnes of BFRs are produced each year globally. The main ones are TBBPA, HBCD and polybromodiphenyl ethers (PBDE). Since the early 1970’s increasing evidence as to the presence of different BFRs in the environment at various locations, far from where they are produced or used (even in the Arctic) has amassed, causing enormous environmental concern. They have been measured in indoor and outdoor air and dust samples, in water, in soil and sediment, and in sewage sludge. They are detected in plants and wildlife throughout the food chain, in human tissues, blood serum and breast milk in the general population. Also toxic (acute and chronic) and eco-toxic effects of some BFRs have been observed in human health including endocrine disruption and carcinogenicity. Despite these observations, only limited information is available on many BFRs, especially concerning the effects on wildlife and man, their environmental fates and bio-degradability potential.
|Brominated Tris.||This was used in children’s sleepwear in the 1970’s until it was banned as a mutagen – it was then replaced by a known carcinogen, chlorinated tris.|
|Bromine is a chemical Halogen. Brominated flame retardants(BFRs) represent the largest commercial use of bromine. When the brominated material burns, the flame retardant produces hydrobromic acid which interferes in the radical chain reaction of the oxidation reaction of the fire. BFRs are not only persistent in the environment; they are also persistent in living tissues. Similar to PCBs, BFR concentrations have been found to increase up the food chain,
indicating that these chemicals are readily absorbed by the body where
they accumulate in fatty tissues.
|C14-17 Alkanes Chlorinated.
|Also known as Short-Chain Chlorinated Parrifins (SCCPs) SCCPs, used as a flame retardant are found world-wide in the environment, wildlife and humans. They are bioaccumulative in wildlife and humans, are persistent and transported globally in the environment, and toxic to aquatic organisms at low concentrations.|
|CFRs: Chlorinated Flame Retardants
|Chlorinated flame retardants (CFRs) are used in textiles, paints and
coatings, plastics, and insulation foams. Like BFRs, some chlorine-containing
flame retardants persist in the environment, and may accumulate in
the tissues of humans and other animals.1 Tris(2-chloroisopropyl
phosphate) (TCPP) and Tris(2-chloroethyl) phosphate (TCEP), and
chloroparaffins are some examples of chlorinated flame retardants.
|Chlorinated Tris, or Tris (1,3-dichloro-2-propyl) phosphate is a chlorinated phosphate ester. Chlorinated Tris (TDCPP) is a flame retardant currently used in many applications including polyurethane foam found in upholstered furniture. Chlorinated Tris can escape from foam and attach to house dust or remain in the air. Common names for chlorinated Tris include Fryol FR 2 and Antiblaze 195. No human studies have been conducted, but evidence suggests that TDCPP may impact fertility by influencing hormone levels and semen quality in men. According to studies conducted in rats, chlorinated Tris is associated with increased tumor rates in kidneys and testes, some of which were cancerous. A recently published study found that TDCPP was a neurotoxin to brain cells.|
|decaBDE: decabromodiphenyl ether.||Most commonly found in UK furniture, decaBDE has been made a Substance of Very High Concern under the EU’s chemical legislation called REACH. It is likely that furniture made with this chemical will still be in use and will need to be disposed of safely. DecaBDE has now been replaced with a new Brominated FR – which is also likely to be found to be a substance of concern over time.|
|· Formaldehyde has been classified as a known human carcinogen (cancer-causing substance) by the International Agency for Research on Cancer and as a probable human carcinogen by the U.S. Environmental Protection Agency. Research studies of workers exposed to formaldehyde have suggested an association between formaldehyde exposure and several cancers, including nasopharyngeal cancer and leukemia.|
|Halogenated organic FRs||These are usually based on chlorine and bromine and can be divided into three classes – aliphatic, sysloaliphatic and aromatic (dibromoneopentyl glycol (DBNPG), hexabromocyclododencane (HBCD) and tetrabromobisphenol A (TBBPA).|
|Hexabromocyclododecane (HBCDD) has been identified as a substance of very high concern (SVHC) and is included in Annex XIV of the REACH Regulation. This means that the substance is subject to authorisation
for specific uses under the REACH Regulation. The Annex XIV entry for this substance sets a sunset date of 21st August 2015. Substances cannot be placed on the market or used after this date unless the company
has applied for and is granted an authorisation. REACH also places responsibilities on industry to provide information in response to requests from consumers, (usually in the form of a safety data sheets) on the safe
use of these SVHC substances on their own or in preparations and in articles.
|Inorganic FRs.||These comprise of metal hydroxides (eg aluminium hydroxide and magnesium hydroxide), ammonium polyphosphate, boron salts, inorganic antimony, tin, zinc and molybdenum compounds as well as elemental red phosphorous. They are added as fillers into the polymers and are considered immobile, in contrast to the organic additive FRs.
|Nitrogen-containing FRs.||These inhibit the formation of flammable gases and are primarily used in polymers containing nitrogen, such as polyurethane and polyamide. The most important nitrogen-based FRs are melamine and melamine derivatives.|
|Organohalogens||Many flame retardants are organohalogens. They are compounds in which carbon is bonded to bromine or chlorine. Organohalogens are often toxic, lipophilic (fat-loving), and/or resistant to degradation, leading to their persistence and bioaccumulation in our bodies and in the environment. Bio-monitoring studies find organohalogen flame retardants in the blood and body tissues of nearly all Americans tested, with the highest levels in young children. US citizens have much higher levels of these chemicals in their house dust and body fluids than in Europe where most flammability standards do not lead to the use of fire retardants in consumer products.
|Organophosphorus FRs||These are primarily phosphate esters that may also contain bromine or chlorine. Organophosphorus FRs are widely used in both textile fibres and polymers.|
|PBB: polybrominated biphenyl||The International Agency for Research on Cancer (IARC) classified PBBs as “possibly carcinogenic to humans”. EPA has not classified PBBs for carcinogenicity. Studies on mice and rats have shown that exposure to PBDEs and PBBs cause neurodevelopmental toxicity, weight loss, toxicity to the kidney, thyroid, and liver, and dermal disorders.|
|PBDE: polybrominated diphenyl ether||EPA (Environmental Protection Agency) is concerned that certain PBDE congeners are persistent, bioaccumulative, and toxic to both humans and the environment. The critical endpoint of concern for human health is neurobehavioral effects. Various PBDEs have also been studied for ecotoxicity in mammals, birds, fish, and invertebrates. In some cases, current levels of exposure for wildlife may be at or near adverse effect levels.|
|PentaBDE||This was used in furniture and baby product foam until it was banned as a Persistent Organic Pollutant (POP), after which it was also replaced with chlorinated tris.|
|Persistent Organic Pollutants (POP).||Under the Stockholm Convention 22 chemicals are globally banned as Persistent Organic Pollutants.|
|Phosphate esters.||The main phosphate esters are
· Tris (monochloropropyl) phosphate (TMCP or TCPP)
· Tris (dichloropropyl) phosphate (TDCPP)
· Bis (chloromethyl) trimethylenebis(bis(chloromethyl) phosphate (BTMCP or V6)
During the burning of the material containing a phosphorous based flame retardant, phosphorus is converted into phosphoric acid which extracts water from the pyrolising substrate causing it to char. This results in a protective layer that shields the combustible material from the gas phase. Without the fuel the combustion is stopped.
|Reactive FRs||These are chemically bonded into plastics e.g. HET acid (chlorendic acid), TBBPA, DBNPG or different organophosphorus compounds.|
|TBBPA||Tribromoneopentyl alcohol is a reactive brominated flame retardant, which combines a high bromine content with high stability. It is often used in combination with TCPP for polyurethanes. TBBP-A, which has been linked to breast cancer, and has been shown in mice and rats to disrupt the thyroid hormone system, which plays a crucial role in the development of the brain and body.|
|TCEP: tris(2-chloroethyl)phosphate||In a study examining reproductive health in mice, TCEP impaired the sperm quality of males, and exposed mating mice had fewer pups and fewer litters. Another study found that exposure to TCEP increased tumors in the kidneys, and brain damage was observed. Brain damage was observed in another experiment. The researchers also found that the exposed rats had learning impairments as well.|
|Several studies suggest that TDCPP may be carcinogenic. Rodents that were fed TDCPP over two years showed increased tumor formation in the liver and brain. Men living in homes with high concentrations of TDCPP in house dust were more likely to have decreased sperm counts and increased serum prolactin levels.|
Glossary of Regularly Used Terms
|Acute Toxicity||Toxic effects after a short, normally high dose exposure.
|Bioaccumulation.||Accumulation of a chemical in wildlife or humans. There is increasing evidence that some BFRs, like PBDE and HBCD, bioaccumulate in the food chain, as increasing concentrations of these BFRs are found in species higher in the food chain such as zooplankton, invertebrates, fish and sea mammals. Bioaccumlation of BFRs in the food chain is one of the ways that humans can be exposed to BFRs, through diet, eating contaminated fish, meat, eggs and dairy products etc.
|The natural breakdown of a chemical or other substance; the breakdown may only be partial. If a substance is fully biodegradable then it will break down into natural chemicals.|
|Chemical modification or alteration such as (but not limited to) nutrients, amino acids, toxins, and drugs in the body.|
|Carcinogenicity||Ability to cause cancer.|
|Continuously Migrate.||Many flame retardants are semi-volatile and continuously migrate out of products and into dust, humans and animals.|
|Chronic Toxicity||Toxic effects after a long, usually low dose exposure.|
|Dermal Toxicity||Toxic effects when the chemical is applied to the skin.|
|Endocrine Disrupting Chemical||A chemical which disrupts the endocrine or hormonal system|
|Inhalation Toxicity||Toxic effects when the chemical is inhaled into the lungs|
|The ability of a chemical to dissolve in fat, oil and lipids.|
|Off-gas.||Off-gassing is the tendency of many chemicals to volatilize or let off molecules in a gas form into the air.|
|Oral Toxicity||Toxic effects when the chemical is given through the mouth in food or drink.|
|A chemical that doesn’t break down well in the environment, so sticks around.|
|Persistent Organic Pollutant (POP)||An organic chemical which is persistent and pollutes the environment.|
|The brominated and chlorinated flame retardants commonly found in consumer goods belong to a class of chemicals called semi-volatile organic compounds. Because they are not chemically bound to material but incorporated during manufacturing or sprayed on afterward, they routinely escape as vapour or airborne particles that tend to stick to surfaces or settle in dust. Friction and heat generated through normal use of a product — sitting on a couch, for example, or watching TV — can accelerate their release.
They can also escape during production or when treated products are recycled or disposed of in landfills or incinerators. Once released, they can build up in sewage sludge, soil and sediments. Scientists have detected flame retardants hundreds of miles from human sources, including in the tissue of sperm whales, which spend most of their time in deep ocean waters, and of Arctic marine mammals, suggesting long-distance transport by water and air currents.
|Toxicity||The degree to which a substance (a toxin or poison) can harm humans or animals. Acute toxicity involves harmful effects in an organism through a single or short-term exposure. Subchronic toxicity is the ability of a toxic substance to cause effects for more than one year but less than the lifetime of the exposed organism. Chronic toxicity is the ability of a substance or mixture of substances to cause harmful effects over an extended period, usually upon repeated or continuous exposure, sometimes lasting for the entire life of the exposed organism.|
|VOCs: Volatile Organic Compounds.||These are chemicals that become a gas at room temperature. They are harmful to health. Formaldehyde is a common VOC.|