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‘Safer’ Chemicals Still Linked to Neurotoxicity, Developmental Effects

Sleeping newborn
Photo by Angela Duxbury on Unsplash

A class of chemicals commonly found in everything from children’s toys to home furnishings may pose more of a risk to brain development in children than previously thought.

The chemicals in question are organophosphate esters, which have been used as replacements for banned flame retardants in electronics, car seats and other baby products, furniture, and building materials. These newer organophosphate esters were thought to be less toxic than their predecessors, primarily because they didn’t interfere with a particular neurotransmitter-related enzyme called acetylcholinesterase, or AChE.

However, in a new commentary published in Environmental Health Perspectives, a team including researchers from NC State, the National Institute of Environmental Health Sciences, and Duke University’s Nicholas School of the Environment provides evidence that these “safer” organophosphate esters are also neurotoxic, even though they do not act on AChE.

“The current thinking by some regulators is that these chemicals are safe because they were designed not to interfere with AChE,” says Heather Patisaul, a neuroendocrinologist at NC State and lead author of the work. “But the evidence points to organophosphate esters still causing developmental neurotoxic effects, likely through action on other neurotransmitter systems.”

The team looked at over three decades worth of toxicity studies on organophosphate esters done in vitro as well as in rodent and human studies. They found evidence across all models that these chemicals disrupt a number of neurotransmitters and are associated with adverse behavioral outcomes such as hyperactivity, delayed language and fine motor skill development, and even lowered IQs.

Organophosphate esters “gas out” of products and get into the dust in our homes, leading to human exposure. They are routinely found in human urine, blood, placental tissue and breast milk. Babies and young children are most at risk of exposure.

“Even though the effects we’re seeing are more subtle than those associated with halogenated flame retardants or organophosphate pesticides, the evidence shows that organophosphate esters are neurotoxic,” Patisaul says. “The evidence from us and other research teams points to disruption of neurotransmitter systems. They could even be hitting a different part of the acetylcholine pathway other than AChE. That hasn’t been well investigated yet but is something we are actively exploring.”

The researchers hope their commentary will lead to more comprehensive assessment of organophosphate ester neurotoxicity by regulators and a reduction in use, even as they work to determine the mechanisms by which these chemicals affect neurologic development.

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