Summary: Exposure to even low levels of common chemicals called organophosphate esters can harm IQ, memory, learning, and brain development overall in young children.
Source: Green Science Policy Institute
Chemicals increasingly used as flame retardants and plasticizers pose a larger risk to children’s brain development than previously thought, according to a commentary published today in Environmental Health Perspectives.
The research team reviewed dozens of human, animal, and cell-based studies and concluded that exposure to even low levels of the chemicals—called organophosphate esters—may harm IQ, attention, and memory in children in ways not yet looked at by regulators.
The neurotoxicity of organophosphate esters used as nerve agents and pesticides is widely recognized, but the neurotoxicity of those used as flame retardants and plasticizers has been assumed to be low. As a result, they are widely used as replacements for some phased-out or banned halogenated flame retardants in electronics, car seats and other baby products, furniture, and building materials. However, the authors’ analysis revealed that these chemicals are also neurotoxic, but through different mechanisms of action.
“The use of organophosphate esters in everything from TVs to car seats has proliferated under the false assumption that they’re safe,” said Heather Patisaul, lead author and neuroendocrinologist at North Carolina State University. “Unfortunately, these chemicals appear to be just as harmful as the chemicals they’re intended to replace but act by a different mechanism.”
Organophosphate esters continuously migrate out of products into air and dust. Contaminated dust gets on our hands and is then inadvertently ingested when we eat. That’s why these chemicals have been detected in virtually everyone tested. Children are particularly exposed from hand-to-mouth behavior. Babies and young children consequently have much higher concentrations of these chemicals in their bodies during the most vulnerable windows of brain development.
“Organophosphate esters threaten the brain development of a whole generation,” said co-author and retired NIEHS Director Linda Birnbaum. “If we don’t stem their use now, the consequences will be grave and irreversible.”
The authors call for a stop to unnecessary uses of all organophosphate esters. This includes their use as flame retardants to meet ineffective flammability standards in consumer products, vehicles, and building materials.
For uses where organophosphate esters are deemed essential, the authors recommend governments and industry conduct alternatives assessments and make investments in innovative solutions without harmful chemicals.
“Organophosphate esters in many products serve no essential function while posing a serious risk, especially to our children,” said Carol Kwiatkowski, co-author and Science and Policy Senior Associate at the Green Science Policy Institute. “It’s urgent that product manufacturers critically reevaluate the uses of organophosphate ester flame retardants and plasticizers—many may be doing more harm than good.”
Beyond Cholinesterase Inhibition: Developmental Neurotoxicity of Organophosphate Ester Flame Retardants and Plasticizers
To date, the toxicity of organophosphate esters has primarily been studied regarding their use as pesticides and their effects on the neurotransmitter acetylcholinesterase (AChE). Currently, flame retardants and plasticizers are the two largest market segments for organophosphate esters and they are found in a wide variety of products, including electronics, building materials, vehicles, furniture, car seats, plastics, and textiles. As a result, organophosphate esters and their metabolites are routinely found in human urine, blood, placental tissue, and breast milk across the globe. It has been asserted that their neurological effects are minimal given that they do not act on AChE in precisely the same way as organophosphate ester pesticides.
This commentary describes research on the non-AChE neurodevelopmental toxicity of organophosphate esters used as flame retardants and plasticizers (OPEs). Studies in humans, mammalian, nonmammalian, and in vitro models are presented, and relevant neurodevelopmental pathways, including adverse outcome pathways, are described. By highlighting this scientific evidence, we hope to elevate the level of concern for widespread human exposure to these OPEs and to provide recommendations for how to better protect public health.
Collectively, the findings presented demonstrate that OPEs can alter neurodevelopmental processes by interfering with noncholinergic pathways at environmentally relevant doses. Application of a pathways framework indicates several specific mechanisms of action, including perturbation of glutamate and gamma-aminobutyric acid and disruption of the endocrine system. The effects may have implications for the development of cognitive and social skills in children. Our conclusion is that concern is warranted for the developmental neurotoxicity of OPE exposure. We thus describe important considerations for reducing harm and to provide recommendations for government and industry decision makers.