Flame-retardant chemicals are useful in preventing fires, but they can also travel long distances in the air and damage the growth of animals.
OPAL Water Centre research has discovered flame retardants in a number of English lakes, and a significant concentration of one particular flame retardant in some fish.
Chemicals released from industrial sources can pollute freshwaters such as lakes, ponds and rivers either in waste water or by being transported in the air and then deposited.
Brominated flame retardants (BFRs) are one type of chemical that can be carried a long way in the air. Widely used on furniture, clothing and electricals to prevent fires, BFRs can also build up in the bodies of animals and affect the development of embryos and the young. They can also affect the action of hormones.
Before OPAL Water's research, very few studies had been carried out on BFRs in freshwaters in the UK. Scientists from the OPAL Water Centre at University College London and at the University of Birmingham worked together to find out more about BFRs in lakes and ponds across England.
They took samples of surface mud and a small number of fish from nine lakes across the country. They also collected water samples every three months from each lake.
Flame retardants found in all samples
Our scientists found BFRs in all the samples analysed. Concentrations in the mud samples are at the low end of the range reported for rivers in parts of Europe, but this may be because our lakes are only affected by BFRs arriving from the air and not by waste water being pumped directly into them.
There are many types of BFRs and they all have long names that are usually abbreviated. Two important types of brominated flame retardant are called HBCDs and TBBP-A. TBBP-A was only detected in four fish samples (from three different lakes) while HBCDs were found in all 30 fish samples.
Are fish changing the chemicals in their bodies?
One type of HBCD, called δ-HBCD, was found in some fish but, importantly, not in the water or mud of the same lakes. The amount of δ-HBCD that was found in the fish was also higher than in the original manufactured HBCD mixture. This finding had never been reported before.
It is possible that the fish are making δ-HBCD in their bodies by changing other HBCDs they have taken in. Another possibility is that they are getting rid of other compounds more efficiently, leaving δ-HBCD behind. This has important implications for the way that some of these harmful brominated flame retardants move up the food chain and transfer from one animal to another.
Interested in finding out more?
This work was published in the scientific journal Environmental Science and Technology.
Stuart Harrad, Mohamed Abou-Elwafa Abdallah, Neil Rose, Simon Turner and Tom Davidson (2009): Current-use brominated flame retardants in water, sediment and fish from English lakes. Environmental Science and Technology, volume 43, pages 9077-9083.
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