CHEMICAL POLLUTANTS CAN CHANGE YOUR SKIN BACTERIA AND INCREASE YOUR ECZEMA RISK NEW RESEARCH EXPLORES HOW
Chemical Pollutants Can Change Your Skin Bacteria and Increase Your Eczema Risk New Research Explores How
April 22nd, 16PM April 22nd, 16PM(The Conversation is an independent and nonprofit source of news, analysis and commentary from academic experts.)
Ian Myles,
National Institute of Allergy and Infectious Diseases
(THE CONVERSATION) "We haven't had a full night's sleep since our son was born eight years ago," said Mrs. B, pointing to her son's dry, red and itchy skin.
Her son has had eczema his entire life. Also known as
atopic dermatitis, this chronic skin disease affects about
1 in 5 childrenin the industrialized world. Some studies have found
rates ofeczema indeveloping nationsto be over thirtyfold lower compared with industrialized nations.
However, rates of eczema didn't spike with the
Industrial Revolution, which began around 1760. Instead, eczema in countries such as
the U.S.,
Finlandand
other countriesstarted rapidly rising around 1970.
What caused eczema rates to spike?
I am an
allergist and immunologistworking with a team of researchers to study trends in U.S. eczema rates. Scientists know that factors such as diets rich in
processed foodsas well as exposure to
specific detergents and chemicalsincrease the risk of developing eczema. Living near
factories, major roadwaysor
wildfiresincrease the risk of developing eczema. Environmental exposures may also come from
inside the housethrough paint,
plastics, cigarette smoke or synthetic fabrics such as spandex, nylon and polyester.
While researchers have paid a lot of
attention to genetics, the best predictor of whether a child will develop eczema
isn't in their genesbut the
environment they livedin for theirfirst few yearsof life.
There's something in the air
To figure out what environmental changes may have caused a spike in eczema in the U.S., we began by looking for potential eczema hot spots – places with eczema rates that were much higher than the national average. Then we looked at databases from the U.S. Environmental Protection Agency to see which chemicals were most common in those areas.
For eczema, along with the allergic diseases that
routinely develop with it– peanut allergy and asthma – two chemical classes leaped off the page:
diisocyanatesand
xylene.
Diisocyanates were first manufactured in the U.S.
around 1970for the production of spandex, nonlatex foam, paint and polyurethane. The manufacture of xylene also increased around that time, alongside an increase in the
production of polyesterand other materials.
The chemically active portion of the diisocyanates and xylene molecules are also found in
cigarette smokeand wildfires. After 1975, when all new cars became outfitted with a new technology that converted exhaust gas to less toxic chemicals, isocyanate and xylene both became
components ofautomobile exhaust.
Research has found that exposing mice to isocyanates and xylene can
directly cause eczema,
itch and inflammationby
increasing the activity of receptorsinvolved in itch, pain and temperature sensation. These receptors are also more active in mice placed on
unhealthy diets. How directly exposing mice to these toxins compares to the typical levels of exposure in people is still unclear.
How and why might these chemicals be linked to rising rates of eczema?
Skin microbiome and pollution
Every person is coated with millions of microorganisms that live on the skin, collectively referred to as the
skin microbiome. While researchers don't know everything about how friendly bacteria help the skin, we do know that people need these organisms to
produce certain types of lipids, or oils, that keep the skin sealed from the environment and stave off infection.
You've probably seen moisturizers and other skin products containing
ceramides, a group of lipidsthat play an important role in protecting the skin. The amount of ceramides and related compounds on a child's skin during their
first few weeks of lifeis a
consistent andsignificant predictorof whether they will go on to
develop eczema. The less ceramides they have on their skin, the more likely they'll develop eczema.
To see which toxins could prevent production of the beneficial lipids that prevent eczema, my team and I used skin bacteria as canaries in the coal mine. In the lab, we exposed bacteria that directly make ceramides (such as Roseomonas mucosa), bacteria that help the body make its own ceramides (such as Staphylococcus epidermidis) and bacteria that make other beneficial lipids (such as Staphylococcus cohnii) to isocyanates and xylene. We made sure to expose the bacteria to levels of these chemicals that are similar to what people might be exposed to in the real world, such as the standard levels released from a factory or the fumes of polyurethane glue from a hardware store.
We found that exposing these bacteria to isocyanates or xylene led them to stop making ceramides and instead make amino acids such as lysine. Lysine helps
protect the bacteriafrom the harms of the toxins but doesn't provide the health benefits of ceramides.
We then evaluated how
bed sheets manufactured using isocyanates or xyleneaffect the skin's bacteria. We found that harmful bacteria such as Staphylococcus aureus proliferated on nylon, spandex and polyester but could not survive on cotton or bamboo. Bacteria that help keep skin healthy could live on any fabric, but, just as with air pollution, the amount of beneficial lipids they made dropped to less than half the levels made when grown on fabrics like cotton.
Addressing pollution's effects on skin
What can be done about the connection between pollution and eczema?
Detectors capable of sensing low levels of isocyanate or xylene could help track pollutants and predict eczema flare-ups across a community. Better detectors can also help researchers identify air filtration systems that can scrub these chemicals from the environment. Within the U.S., people can use the
EPA Toxics Trackerto look up which pollutants are most common near their home.
In the meantime, improving your microbial balance may require avoiding
products thatlimit the growthof healthy skin bacteria. This may include certain skin care products, detergents and cleansers. Particularly for kids under 4, avoiding cigarette smoke, synthetic fabrics, nonlatex foams, polyurethanes and some paints may be advised.
Replacing bacteria that has been overly exposed to these chemicals may also help. For example, my research has shown that
applying Roseomonas mucosa, a ceramide-producing bacterium that lives on healthy skin, can lead to a monthslong reduction in typical eczema symptoms
compared with placebo. Researchers are also studying
other potentialprobiotic treatmentsfor eczema.
Evaluating the environmental causes of diseases that have become increasingly common in an increasingly industrialized world can help protect children from chemical triggers of conditions such as eczema. I believe that it may one day allow us to get back to a time when these diseases were uncommon.
This article is republished from The Conversation under a Creative Commons license. Read the original article here:
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