The term ‘flame retardants’ includes hundreds of substances, the majority of which contain bromine, such as polybrominated biphenyls (PBB), deca, octa and penta diphenyl ether (PBDE), polybrominated diphenyl ethers (PBDEs), hexabromocyclododecane (HBCD) and brominated bisphenols e.g. tetrabromobisphenol A.
A huge variety of household items can be contaminated with flame retardants as they are used to make these products difficult to catch fire. However, there is some concern about these chemicals, as they can also increase the toxicity of fire. In some of the products in which they are found, these retardants can make up between 5 and 30% of the total weight. Thousands of tonnes of flame retardants are used every year around the world, most of which ends up in our homes.
These substances can therefore be emitted into the air inside our homes from plastics, electrical and electronic devices, cables, furniture, fabrics, mattresses, polyurethane foam, rugs and carpets. They are often found, for example, as pollutants in household dust. We have to bear in mind that some of these chemicals are used as additives in materials but there is no chemical bond between them.
Some of these substances are extremely worrying for scientists due to their toxicity, strong persistence and the fact that they disperse in the air. They also pollute the food chain e.g. in fish. They are found in most humans (in blood, fat, the liver, breast milk, foetuses etc.) and can enter our bodies through various routes including inhalation.
The European Union has established standards to eliminate or reduce the presence of some of these chemicals. Some of them have also been included in the Stockholm Agreement on organic pollutants to help reduce their usage. Because of these measures, amongst others, some flame retardants which have been identified as problematic are being substituted for other chemicals. However, even though many products in our homes contain them, it is not uncommon for some of the substitute chemicals to end up also being identified as problematic.
A large number of scientific studies carried out on animals to help foresee possible damage to humans have linked the exposure to PBDE with health issues such as: thyroid hormone imbalance, permanent learning difficulties and memory problems, changes in behaviour, hearing loss, delayed onset of puberty, lowered sperm count, foetal deformities and possibly cancer (e.g. thyroid cancer).
The damage shown was worse at lower levels of concentrations (similar levels as the ones detected in the general public) when they were exposed during pregnancy or childhood.
Studies on humans have shown, for example, that having somewhat higher levels of PBDE is linked to women having difficulty conceiving. There is also a link between a high exposure to certain PBDEs and pregnant women having lower levels of the thyroid stimulant hormone (TSH), which could have serious effects on the child’s development. Other studies showed that high levels of PBDE in the umbilical cord was linked to having poor mental and motor development as children and that having slightly higher levels of some PBDEs in breast milk (an indicator of prenatal exposure) is associated with an increased risk of male babies having an undescended testicle later in life.
Bear in mind that these results follow exposure levels similar to those detected in the general public from daily exposure to these chemicals.
To conclude, different studies conducted on animals, cell cultures or humans have shown a possible link between various flame retardants and problems with the kidneys, liver (including hepatic cancer), immunosuppression etc. Some research suggests that certain chemicals of this kind can encourage the growth of breast, ovarian or uterine tumour cells and also suggest potential links with other health issues including obesity and type 2 diabetes. However, a lot more research needs to be done regarding these chemicals and their possible effects.
We should also add that the effects of some flame retardants can be exacerbated by the presence of other pollutants such as PCBs which are found in most of our bodies.