Flame retardants delay the ignition of flammable materials such as plastic, polymer foams and textile and hinder the flame propagation. Numerous organic chemicals are used as flame retardants including brominated or chlorinated flame retardants and phosphorous-based flame retardants. A range of inorganic chemicals are also used as flame retardants.
Brominated flame retardants (BFRs) can be used in a broad range of polymers and are relatively inexpensive. Between the years 2001 and 2008, the volume of BFRs produced worldwide doubled from approximately 200,000 to 410,000 tonnes annually and between 2005 and 2008, Chlorinated Flame Retardants (CFRs) increased from 82,000 to 190,000 tonnes. The BFRs that have been used most extensively are tetrabromobisphenol A (TBBPA), hexabromocyclododecane (HBCD), and commercial mixtures of polybrominated diphenyl ethers (PBDEs). However, many BFRs are persistent in the environment and do not break down easily while others have the potential to bioaccumulate. In addition, CFRs such as chlorinated paraffins and certain halogenated phosphorus compounds have also been detected. Exposure to different halogenated flame retardants (HFRs) is associated with a range of adverse biological effects in animals and humans including endocrine disruption, immunotoxicity, reproductive toxicity, effects on fetal/child development, thyroid and neurologic function, and cancer. Due to their properties and global contamination, some BFRs (PBDEs, HBB and HBCD) have been listed as POPs in the Stockholm Convention and the short chain chlorinated paraffins are currently being evaluated in the POPs Review Committee for possible listing.
BFRs are the major source of brominated dioxin and furan (PBDD/F) contamination ,,. PBDD/F is unintentionally produced at different stages of the life cycle of these flame retardants and are relevant to dioxin-like contaminants in house dust, sewage sludge or food.
Substitution of flame retardants can take place at three levels: Chemical substitution, resin/material substitution or product redesign. All three levels are great business opportunities for green design and green chemistry. Comprehensive assessments of flame retardants are conducted under the framework of an EU project on alternative flame retardants and the US EPA partnership program Design for the Environment, which evaluate a wide range of flame retardants.