Common chemicals put brain at risk

Research shows chemicals found in countless household items can harm specialised cells in the brain.

A team of researchers from the Case Western Reserve University School of Medicine in Ohio looked at the dangers some common household chemicals pose to brain health, suggesting that chemicals found in a wide range of items, from furniture to hair products, may be linked to neurological diseases like multiple sclerosis and autism spectrum disorders. 

The new study, published in Nature Neuroscience, found some chemicals specifically affect the brain’s oligodendrocytes, which generate the protective insulation around nerve cells.  

Lead author Dr Paul Tesar said that while neurological problems affected millions of people, only a fraction of cases could be attributed to genetics alone, indicating that unknown environmental factors were important contributors to neurological disease. 

“Loss of oligodendrocytes underlies multiple sclerosis and other neurological diseases; however, few environmental chemicals have been assessed for potential risks to oligodendrocytes,” Dr Tesar said.  

“We’ve now shown that specific chemicals in consumer products can directly harm oligodendrocytes, representing a previously unrecognised risk factor for neurological disease. 

“Exposure to environmental chemicals can impair neurodevelopment, and oligodendrocytes may be particularly vulnerable, as their development extends from gestation into adulthood.” 

The researchers looked at environmental chemicals in two classes that disrupt oligodendrocyte development through distinct mechanisms: quaternary compounds, ubiquitous in disinfecting agents and personal care products, were potently and selectively cytotoxic to developing oligodendrocytes; while organophosphate flame retardants, commonly found in household items such as furniture and electronics, prematurely arrested oligodendrocyte maturation. 

They used cellular and organoid systems in the laboratory to show that quaternary ammonium compounds cause oligodendrocytes to die, while organophosphate flame retardants prevented the maturation of oligodendrocytes. 

“Chemicals from each class impaired oligodendrocyte development postnatally in mice and in a human 3D organoid model of prenatal cortical development,” Dr Tesar said. 

“Our library contained diverse chemicals with the potential for human exposure, including industrial chemicals, pesticides, and chemicals that are of interest to regulatory agencies. In a primary screen, we treated OPCs with chemicals at a concentration of 20 μM and allowed oligodendrocytes to develop for 3 days before analysis. 

“Of the 1,823 chemicals in the primary screen, more than 80% had no effect on oligodendrocyte development or cytotoxicity, 292 were identified as cytotoxic to developing oligodendrocytes, 49 inhibited oligodendrocyte generation, and 22 stimulated oligodendrocyte generation. 

“Analysis of the epidemiological data showed that adverse neurodevelopmental outcomes were associated with childhood exposure to the top organophosphate flame retardant identified.”  

Lead author and graduate student in the School of Medicine’s Medical Scientist Training Program Erin Cohn said that the association between human exposure to these chemicals and effects on brain health required further investigation to track the chemical levels in the brains of adults and children to determine the amount and length of exposure needed to cause or worsen disease. 

“Understanding human exposure to these chemicals may help explain a missing link in how some neurological diseases arise,” she said. 

“Our results and the likelihood of organophosphate flame-retardant exposure in children raise potential health concerns as these chemicals may reach higher concentrations in cerebrospinal fluid than blood.”