Brominated Organic Pollutants

Question 1

What are brominated flame retardants?

Answer 1

• The term ”brominated flame retardants” is a combination of a structure (Br) and use (FR)
  definition.

• Brominated flame retardants, BFR, cover a wide group of chemicals.

• BFRs do not have a specific or particular structure which is why these compounds can be found
as aliphatic, cyclo-aliphatic, aromatic, and polymeric compounds.

BFRs can be divided into subgroups.

• Polybrominated biphenyls (PBBs)
• Polybrominated diphenyl ethers (PBDEs)
• Hexabromocyclododecane (HBCDD)
• Tetrabromobisphenol A (TBBPA)
• ”Novel” BFRs (NBFRs) - see figure 5.

Increased use of plastics: petroleum-based, flammable materials.

– Present in a lot of synthetic materials that need to be able to be heated up.

– BFRs are used in consumer electronics, IT electronics and white goods as to avoid the
products to overheat. Thus, the function of BFRs is to suppress and inhibit combustion.

– During combustion, free radicals are formed, in which bromine or halogens in general,
have the ability to trap and, thereby, inhibit potential fire.

Only Cl- and Br-compounds are used as FRs.
– Halogens are very effective in catching free radicals.
– Flourinated compounds are very stable and need high temperatures to decompose in
order to make the flourine available as a retardant. This is not possible in a typical fire.
– Iodinated compounds are not very stable.

Question 2

Talk a bit about BFR in relation to transport.

Answer 2

BFRs are prone to have long-range transport, which is also known as ”grass-hopping”.
– Indicated by detections at remote locations such as Arctic regions (far from the source
of use).
– Persistence makes long-range transport possible.
– Four different transport modes: Compounds are classified according to their log Koa and
log Kaw values.
∗ Fliers: volatile compounds.
∗ Multiple hoppers
· Exchanging with the oceans: relatively volatile
· Exchanging with terrestrial surfaces: very hydrophobic, semi-volatile
· Multimedia hoppers
∗ Single hoppers: particle-bound compounds.
∗ Swimmers: water-soluble compounds.

PBDEs and HBCDD are semi-volatile compounds (SVOCs).
• Gas and particle phase partitioning.
• Wash-out with rain and show.
• Temporary deposition and re-volatilization.
• The polar regions are cold traps.
• Other ways of long-range transport:
- Biological transport with migratory animals.
– Plastic additives: Additives are not bound to the polymer. They can be released to the
surrounding environment, e.g. leach into the marine environment.
The following additives are mentioned in the order of decreasing weight percent:

Question 3

Talk a bit about BFR in relation to distribution.

Answer 3

• BFRs are a very large, diverse group of chemicals. PBDEs and HBCDD are considered semi-
  volatile organic chemicals (SVOCs) i.e., that they neither want to stay in water nor in air,
  they are quite in the middle. This means that these compounds can distribute to both com-
  partments, i.e. air and water.
  • These compound have shown to have a very high log Kow, meaning that they are lipophilic
  can, therefore, distribute into biota. There is great evidence that these compounds have been
  found in organisms.
  • Which leads to the bioaccumulation of these compounds. Concentrations of BFR have been
  found zooplankton, shrimp, to fish and up to whales meaning the don’t just bioconcentrate in
  one type of biota but they biomagnify for several trophic levels.
  • PBDEs are detectable in Arctic biota, but concentrations are relatively low.
  • Concentrations of NFRs are lower than those of PBDEs and HBCD. It is unknown whether
  this is due to lower emissions, lower uptake, or degradation.
  • Biomagnification: Increasing concentrations of BDE-47 with increasing trophic level in food
  webs.

Question 4

Talk a bit about BFR in relation to transformation.

Answer 4

• Some of the flame-retardants are considered PBT and some are even on the Stockholm con-
  vention list. So, they are generally rather persistent.
  • These compound have shown to have a very high logkow meaning that they are lipophilic, which
  means that they can distribute into biota. There is great evidences that these compounds have
  been found in organisms.
  • Which leads to the bioaccumulation of these compounds. Concentrations of BFR have been
  found zooplanktion, shrimp, to fish and up to whales meaning the don’t just bioconcentrate
  in one type of biota but they biomagnify for several trophic levels.
  • However, one way they have been analyzed is by making an enantiomer-specific analysis.
  • They are mirror images of the molecules. They are identical mirror-images. This means that
  they behave identically in physical processes, but different in biological e.g. enzymes might
  favor a specific kind over another.