Up in flames

Flame retardants are supposed to stop fires

On 19 October 2012, the European Food Safety Authority (EFSA) published the last of a series of six opinions covering brominated flame retardants (BFRs). Since 2010, the Panel on Contaminants in the Food Chain (CONTAM) has reviewed the available toxicological data and sparse information in relation to dietary exposure for the BFRs. Three of the BFRs belong to the “nasty nine” chemicals added to the previous “dirty dozen” list of restricted or banned toxic chemicals by a United Nations treaty. They are all persistent organic pollutants or POPs. But first a bit of background.

Collusion to introduce flame retardants

Of course fire should be avoided at all cost, or should it? In an interesting piece of investigative journalism, the Chicago Tribune revealed in mid 2012 how tobacco companies, worried about cigarettes causing fires, championed the treatment of furniture with fire retardants. With couches, chairs and many other products packed with fire retardants, it has been shown that American babies carry the highest levels of flame retardants among infants in the world. But flame retardants can be found all over the world. In 1999, Swedish researchers reported that flame retardant levels in women’s breast milk had increased 60-fold between 1972 and 1997. And some of the chemicals have been linked to cancer, neurological disorders and developmental problems, whilst not even providing effective fire protection according to the Chicago Tribune story.

Since the 1970s manufacturers have repeatedly withdrawn flame retardants amid health concerns. Some have been banned by the United Nations treaty that seeks to eliminate the worst chemicals in the world (the “dirty dozen” and “nasty nine”). Although demand for brominated and chlorinated flame retardants in North America and the European Union is declining, it is still rising in many other regions.

What are flame retardants?

Electronics, furniture and clothes can all be treated with BFRs

There are numerous chemicals that manufacturers use to try to reduce the flammability of all sorts of products, including furniture, textiles, electronics, baby car seats and carpets. Based on their chemical structures, flame retardants can fit into one of several categories, with some categories raising more health concerns than others. Mineral and organophosphate flame retardants have raised less concerns while halogenated compounds, like chlorinated and brominated flame retardants, are the most worrying because they accumulate in human tissues and have a long half-life.

Brominated flame retardants are mixtures of a large range of man-made organobromide compounds that are supposed to inhibit the ignition of combustible materials. Of the commercialised chemical flame retardants, the brominated varieties are the most widely used. They are most effective in plastics and textile applications, e.g. electronics, clothes and furniture.

Actions taken to reduce risks

The earliest flame retardants, polychlorinated biphenyls (PCBs) were banned in 1977 when it was discovered that they were toxic. That’s when industries shifted to using brominated flame retardants instead, but then these started to receive closer scrutiny. Now several brominated flame retardants have been gradually banned in the European Union from 2006 and some have been excluded from the US market by an agreement between the government and industry to be fully implemented by the end of 2013.

Aquatic animals contaminated with BFRs

So has the problem disappeared? The simple answer is no since due to their persistence in the environment there are still concerns about the risks these chemicals can pose to public health. BFR-treated products from the past, whether still in use or discarded, leach BFRs into the environment. At home, house dust can become contaminated by the chemicals from treated foam in furniture and other household objects and pose a particular risk to young children. In nature, contamination of water can lead to accumulation of BFRs in aquatic organisms in particular. Studies have found that these chemicals can be found in fish and other seafood as well as in human blood, urine and breast milk.

Monitoring the situation in Europe

In order to assess the need for further regulatory measures for BFRs, the European Commission asked EFSA to assess the risks related to the presence of brominated bisphenols (PBBs), diphenyl ethers (PBDEs), cyclododecanes (HBCDDs), tetrabromobisphenol A (TBBPA), phenols and phthalic acid derivatives in food.

In October 2010, the CONTAM Panel concluded that the risk to the European population from exposure to PBBs through food was of no concern. Since PBBs are no longer produced or used in Europe and taking into account low and declining environmental concentrations, the CONTAM Panel concluded that PBBs are a low priority for further research or monitoring efforts.

In May 2011, the Panel in assessing the risk related to the presence of PBDEs in food, considered that there might be a potential health concern for young children for one of the compounds in the group. However, other compounds were unlikely to raise health concerns. Nevertheless, since numerous products containing PBDEs are still in use, the Panel recommended that the surveillance of PBDEs should continue.

In July 2011, in its third opinion on BFRs, the Panel concluded that current dietary exposure to HBCDDs in the EU does not raise a health concern. Furthermore, additional exposure, particularly of young children, to HBCDDs from house dust is unlikely to raise a health concern.

In December 2011, the CONTAM Panel published its review of TBBPA and its derivatives in food. These compounds are widely used as flame retardants and can influence thyroid hormone homeostasis. TBBPA is primarily used as reactive flame retardant covalently bound to epoxy and polycarbonate resins. TBBPA derivatives are used as either reactive or additive intermediates in polymer manufacture. Samples tested for TBBPA in fish and other seafood were all negative.  The CONTAM Panel concluded that current dietary exposure to TBBPA in the European Union does not raise a health concern. Equally, other exposure sources for young children like house dust was unlikely to raise a health concern.

In April 2012, the Panel published an opinion on a complex group of compounds called brominated phenols that are used as reactive as well as additive flame retardants in a large range of resins and polyester polymers. The opinion focused on 2,4,6-TBP, but even for this compound there were limitations in the current knowledge. The CONTAM Panel concluded that even for high consumers of fish, molluscs and crustaceans a health concern was unlikely. Due to lack of data a risk assessment of other brominated phenols or their derivatives was not possible.

In October 2012, the Panel finally considered emerging and novel BFRs. Information on 17 emerging and 10 novel BFRs was collected. The information varied widely for these BFRs. Due to the very limited information on occurrence, exposure and toxicity, the CONTAM Panel could not perform a risk characterisation for any of the BFRs considered. Instead, an attempt was made to identify those BFRs that could be a potential health concern and should be considered first for future investigations. There was convincing evidence that tris(2,3-dibromopropyl) phosphate (TDBPP) and dibromoneopentyl glycol (DBNPG) are genotoxic and carcinogenic, warranting further surveillance of their occurrence in the environment and in food. Based on the limited experimental data on environmental behaviour, 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE) and hexabromobenzene (HBB) were identified as compounds that could raise a concern for bioaccumulation. A modelling exercise identified ten additional BFRs that should be subjected to further in-depth studies.

What about the rest of the world?

Europe might be a little better off than the rest of the world (Photo: shaire productions)

Although not completely off the hook, the situation in Europe in relation to BFRs seems to be under control. There are some new BFRs that might be a problem, but the current information is insufficient to be able to draw any conclusions. But the rest of the world is much more vulnerable. Some efforts in the USA might improve their situation. The US Environment Protection Agency is concerned that certain PBDE congeners are persistent, bioaccumulative, and toxic to both humans and the environment. They state that 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.

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