The retardants, along with pesticides sprayed on parks and farms, have caused a decline in IQ and cognitive abilities in more than a million children in the US between 2001 and 2016, say researchers at New York University's Grossman School of Medicine.
Over that time, retardants—PDBEs (polybrominated diphenyl ethers)—and organophosphate pesticides were responsible for 81 percent of the cognitive decline, while the damage caused by lead from car exhausts and mercury had fallen dramatically as a result of improved environmental controls.
The researchers analysed the impact of toxins and heavy metals found in furniture upholstery, tuna, pesticides and car exhausts by analysing blood samples from young women and from five-year-old children. From that, the researchers have estimated that the cognitive abilities and IQs of 1,190,230 children had been impaired, and some had suffered from learning disabilities, autism and behavioural problems.
The toxins can disrupt brain and kidney function, and flame retardants and pesticides interfere with the thyroid glands, which secrete hormones that help the brain develop.
There's also been an economic toll. Each case of intellectual disability costs society around $1,272,000, and so the total cost from lost economic productivity and other societal costs amounted to $7.5 trillion.
"Although people argue against costly regulations, unrestricted use of these chemicals is far more expensive in the long run, with American children bearing the largest burden," said researcher Leonardo Trasande.
Simple solutions include opening windows in the home to stop the build-up of chemicals and eating more organic produce, while government needs to introduce tighter federal controls of the toxins, he added.