By Erika Edwards -
NBC News
Chemicals emanating from vehicle exhaust and used to make a variety of common products — from elastane to memory foam mattresses — may cause childhood eczema, according to research from the National Institutes of Health (NIH, for its acronym in English).
"We have strong data that contaminants are very likely behind the increase in atopic dermatitis cases," said Dr Ian Myles, head of the Epithelial Research Unit at the Clinical Immunology and Microbiology Laboratory at the National Institute of Allergy. and Infectious Diseases.
(Note: I participated in a clinical trial led by Myles in 2018.)
Doctors at a hospital in France examine a baby with eczema.BSIP/Universal Images Group via Getty Images
Atopic dermatitis, more commonly known as eczema, is an incredibly itchy and inflammatory skin condition that affects 31.6 million people in the United States.
It almost always begins in the first year of life, peaking in early childhood, according to the National Eczema Association.
Allergens, such as pets, perfumes, dyes, and foods, can cause an unexpected flare-up, even in adults.
The causes of eczema have long been a mystery.
Genetics play an important role, but the incidence of eczema has doubled or tripled in industrialized countries since the 1970s, so experts are convinced that something in the environment is behind this dramatic increase.
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Myles and his team searched for explanations for this skin rash in clinics across the country - where they treated large numbers of eczema patients - and studied toxins in the environment.
They found that the most prevalent chemicals were diisocyanates and isocyanates.
Diisocyanates are used in the manufacturing process of many polyurethane products, such as adhesives, flexible foams, carpets, and weather-resistant or elastic fabrics.
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Aside from the exposure of factory workers, the Agency for Toxic Substances and Disease Registry, part of the Centers for Disease Control and Prevention (CDC), says it is unlikely that Chemicals are toxic in polyurethane products, provided they have been properly cured or dried by the manufacturer.
But it's the exhaust fumes from modern vehicles that may have skyrocketed eczema rates in the last 50 years.
Catalysts remove many of the harmful chemicals in gasoline, but in the process they produce isocyanates as a byproduct.
Catalytic converters became mandatory on all vehicles in the United States in 1975, coinciding with the start of the rise in eczema cases.
The results were published in Science Advances in January.
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Dr. Jessica Hui, a pediatric allergist and immunologist at National Jewish Health in Denver, called the research "exciting."
“I think these authors hit the nail on the head in acknowledging that the incidence of allergic conditions is increasing at the same time as the various pollutants in our environment are increasing,” Ella Hui said.
"We finally understand better why people have eczema."
The NIH team didn't just link diisocyanates and isocyanates to eczema foci.
They brought the chemicals back to their lab and, using mice and bacterial cultures, found that they directly affect the skin microbiome in two ways.
They force healthy, protective bacteria to stop producing oils that hydrate the skin.
And "as they do so, they also activate a specific receptor in the skin, sending signals to the brain to induce itching and inflammation," Myles explained.
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Demonstrating that chemicals cause atoptic dermatitis reactions in the skin could help find new treatments.
The research team then studied whether spraying a type of healthy bacteria called Roseomonas mucosa on a person's skin would reduce eczema flare-ups.
These bacteria are found in the microbiome of healthy people who do not have eczema.
The study found that most people experienced modest, sustained improvement.
The effect was even more dramatic if these people lived in areas where diisocyanate levels were higher.
What can people prone to eczema flare-ups do?
Avoiding car exhaust and even the wide variety of products that contain polyurethane is not reasonable for most people.
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“It's a very interesting study, but we don't have any evidence that anything can be done” to reduce exposure to diisocyanates and isocyanates, said Dr. Peck Ong, a pediatric allergist and immunologist at Children's Hospital Los Angeles.
“A lot of this is out of our control.
You can't close the freeways,” Myles said.
Some air filtration systems may be able to remove diisocyanates and isocyanates.
According to Myles, there is a need to investigate which ones might do this effectively to reduce the risks of eczema.