The flame retardants TBBPA and TCBPA are commonly used in devices with electrical chips, including cell phones, computers, tablets, televisions and video game consoles.
Maria Bondesson, a research assistant at the Center for Nuclear Receptors and Cell Signaling (CNRCS) at the University of Houston, and colleagues found that zebrafish exposed to the flame retardants tetrabromobisphenol A (TBBPA) and tetrachlorobisphenol A (TCBPA) gained much more weight and had a higher body mass index (BMI) and fat cell build up than those not exposed to them.
TBBPA and TCBPA are commonly used in devices with electrical chips, including cell phones, computers, tablets, televisions and video game consoles. If these chips overheat, they could catch fire. TBBPA and TCBPA stop this from happening.
However, the researchers point out that these compounds are released from electronic devices and can settle in the dust that we inhale. "It's been shown that young children, who spend a lot of time on the floor, have higher levels of these compounds in their blood than adults. It has also been found to be passed through breast milk," says Bondesson.
Both TBBPA and TCBPA are a form of bisphenol A (BPA), which past studies have suggested is an obesogen - a compound that causes obesity. As such, Bondesson and colleagues set out to see whether TBBPA and TCBPA could also be deemed potential obesogens.
Exposure to TBBPA and TCBPA led to accumulation of fat cells
The team used sibling zebrafish for their study. One sibling in each pair was exposed to low concentrations of TBBPA and TCBPA for 11 days and fed egg yolks as their primary source of fat. The other siblings were fed the same diet but were not exposed to the flame retardants.
Because zebrafish are transparent, this allowed the researchers to visually identify any accumulation of lipids, or fat cells, during the study period.
After 1 month of observation, the team found that the zebrafish that had been exposed to TBBPA and TCBPA were much heavier and had a much higher BMI, compared with those that were not exposed to these flame retardants.
The team also found that the fish exposed to the compounds had a much higher build up of fat cells. "We could see the lipids accumulated in the liver, the heart region, the head and very obviously in the blood vessels. We also could see it subcutaneously along the side of the fish," notes Bondesson.
Because all zebrafish were fed the same diet, this indicates that the fat cell accumulation and rise in weight and BMI is down to exposure to the flame retardants, according to the researchers.
They hypothesize that TBBPA and TCBPA activates a hormone receptor called PPARgamma, which previous studies have suggested has the ability to convert stem cells into fat cells, potentially explaining their findings.
It is estimated that almost 35% of adults and 17% of children and adolescents in the US are obese. Bondesson believes their findings may aid the fight against obesity by bringing us closer to identifying chemicals that may cause it. She adds:
"Given the growing obesity epidemic and the serious health conditions it often leads to, our research shows that it's important to study if chemicals are obesogens. Our goal is to find the worst ones and then replace them with safer alternatives."
The study was supported by a $375,209 grant from the National Institute for Environmental Health Sciences - a part of the National Institutes of Health.
In February 2014, Medical News Today reported on a study suggesting people who are overweight or obese inhale up to 50% more air each day, making them more vulnerable to air pollutants.