The chemicals we've long feared the most – heavy metals like lead and mercury – are less of a threat to kids' developing brains than they were two decades ago. But two new menaces may be taking their place: pesticides and flame retardants.
According to new research from New York University, flame retardants resulted in a loss of 162 million IQ points among children in the US between 2001 and 2016.
The study, published Tuesday in the journal Molecular and Cellular Endocrinology, looked at the four chemicals known to impact the brain of a developing child most: lead, mercury, pesticides, and polybrominated diphenyl ethers (otherwise known as flame retardants).
Leo Trasande, a paediatrician and public-health researcher at NYU who co-authored the study, described these pollutants as "hit-and-run" chemicals: Once a child is exposed to them, there's no reversing the damage.
"Kids' brain development is exquisitely vulnerable," Trasande told Business Insider. "If you disrupt, even with subtle effects, the way a child's brain is wired, you can have permanent and lifelong consequences."
The study found that lead cost US kids 78 million IQ points during the 15-year period studied, while pesticides caused a loss of nearly 27 million IQ points during those years. Mercury, meanwhile, caused a loss of 2.5 million IQ points.
Children's' lower IQs are costing the US trillions of dollars
The researchers found that among kids exposed to toxins from 2001 to to 2016, the proportion of IQ loss due to exposure to flame retardants and pesticides increased from 67 percent to 81 percent. Flame retardants can be found in household furniture and electronics, while pesticides can be consumed when they linger on produce.
"What we found was quite striking," Trasande said.
"We know that there is no safe level of lead exposure. The same is true for methylmercury, pesticides, and flame retardants."
The study also found that there is an economic cost to childhood brain damage: Trasande said that each individual IQ point is worth roughly 2 percent of a child's lifetime economic productivity. So if a child could potentially make US$1 million over the course of their lifetime, they would lose US$20,000 for every IQ point lost.
"A kid's brain power is the engine of our economy," Trasande said.
"If a child comes back from school with one less IQ point, maybe mum or the parent might not notice. But if 100,000 children come back with one less IQ point, the entire economy notices."
According to the researchers, IQ loss due to lead, mercury, flame retardants, and pesticide exposure combined cost the US around US$6 trillion from 2001 to 2016.
Regulations on flame retardants and pesticides are more lax than heavy metals
For decades, scientists have understood that exposure to lead and mercury can result in childhood brain damage. So many of the main hideouts for these chemicals – leaded gasoline, lead paint, and mercury emissions from coal-fired power plants – have been phased out.
As early as the 1970s, the Environmental Protection Agency required lead to be phased out of gasoline and paint (though lead paint can still be found in homes built before 1978).
The agency also set standards to reduce mercury emissions from coal-fired power plants in 2011, though some power plants still do not meet these requirements.
But there have been fewer efforts to regulate pesticides and flame retardants.
The EPA has banned around 37 pesticides, though more than 500 have been used in the US. Another 97 have been voluntarily withdrawn by pesticide manufacturers.
More than a dozen states have adopted legislation that restricts the use of flame retardants in products like furniture, carpeting, and children's toys, but none of the chemicals are banned federally.
Ways to reduce kids' exposure
Many factors can influence a kid's exposure to a chemical, Transande said.
"The science has really evolved such that the dose is not the only thing that makes the poison," he said. Other factors to consider could include the timing and frequency of exposure.
Trasande added that regulating all of these chemicals has a far lower long-term economic cost than the cost of kids' lost IQ points due to exposure.
To minimise personal risk in one's own home, Trasande suggested simple steps like opening windows so that dust laced with flame retardants can escape. He also suggested vacuuming frequently and using a wet mop to sop up chemicals on the floor.
In addition, parents should avoid mattresses and children's toys that contain polyurethane foam (which often carries flame retardants).
Trasande also said households should avoid spraying pesticides on their lawns or backyards and recommended switching to organic foods (though organic produce can also contain pesticides).
"We've made less progress in phasing out or banning some of the pesticides of greatest concern," Trasande said. "But there are steps we can take proactively as consumers."
This article was originally published by Business Insider.
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