A common fireproof material used in TVs and furniture can mimic female hormones and disrupt the body's natural balance, research shows.
Of a family of fireproof materials known as brominated flame retardants (BFRs), TBBPA is one of the most widely used.
It is added to a wide range of items such as furniture and computer circuit boards, to slow or prevent the growth of a fire.
But research shows that it can also mimic the female hormone oestrogen and disrupt the body's endocrine system, which regulates hormones.
Scientists used electronic 3D modelling techniques to look at the chemical at the atomic level, reports journal Environmental Health Perspectives.
Dr Linda Birnbaum and her team focused their attention on TBBPA, which has previously been shown to cause tumours in rats and mice.
In the EU,TBBPA has been the subject of years of protracted safety reviews and is currently still under evaluation.
Dr Birnbaum, of America's National Insitute of Health, said: 'We're beginning to have a better understanding of flame retardants and their effect on human health.
'This particular study helps us literally see what brominated flame retardants do when they get in the body - they interfere with the body's natural hormones.
'Using the 3D imaging capabilities, we can see the flame retardants binding, or attaching, to proteins like oestrogens do.'
She added: 'Having chemicals act like oestrogen or other hormones disrupts how the endocrine system works.
'In this case, the ability of flame retardants to bind to and inhibit an enzyme that metabolises oestrogen, called oestrogen sulfotransferase, could result in the body having too much oestrogen.'
For the study, the researchers used X-ray crystallography to build a 3D model of the protein binding to flame retardants.
Dr Lars Pedersen said: 'Using crystallography allows us to visualize exactly how these compounds can interact with the body's enzymes.
'Although there is much more to be learned about how these chemicals and their metabolites impact different systems in the body, every piece of the puzzle helps increase our understanding of the effects they may have.'
The researchers say they hope the study will be used by companies to develop safer alternatives to current flame retardants.