- Researchers are increasingly interested in the health risks from chemical additives in microplastics.
- A new study used 3D human skin-equivalent models to examine how flame retardant additives in microplastics are absorbed by the skin.
- The findings demonstrate that several flame-retardant additives passed through the skin barrier.
Research is moving forward in exploring the potential dangers of microplastics and how people may be exposed and affected.
A study published in Environment International examined how certain flame retardants that can be added to plastic can be absorbed through the skin.
Researchers found that the skin could absorb up to 8% of the exposure dose but that specific amounts varied.
However, the amount of additives that became available to circulate in the bloodstream did not exceed 0.14% of what was initially present in the microplastics.
Researchers noted that sweaty skin was more likely to absorb some flame retardants than dry skin.
The study’s results suggest the need to address microplastic additives that people could be exposed to and the concern that skin absorption can be an exposure route.
Microplastics are tiny plastic particles that are smaller than 5 millimeters.
Humans are commonly exposed to microplastics, so experts are seeking to understand the potential health dangers this poses to people. However, a significant concern is not the microplastics but the related chemical additives.
The study authors noted the following:
“Many of these additives, particularly in the flame retardant and plasticizer categories, such as polybrominated diphenyl ethers (PBDEs), have been found to cause adverse health effects including: endocrine disruption, reproductive toxicity, neurotoxicity, hepatotoxicity and cancer.”
The study authors note that several countries have banned the commercial formulation of PBDEs but their environmental contamination could be a problem for decades.
To investigate the potential implications of these substances on human health, researchers used 3-dimensional human skin equivalent models. They examined how exposure to microplastics and related flame retardants affected absorption and whether these chemicals could potentially pass through the skin to enter the bloodstream.
Researchers also applied a special film liquid to the skin models to get an idea of how sweaty skin impacted absorption compared to dry skin. They exposed the models to polyethylene and polypropylene microplastics and thus, several flame retardants.
Researchers detected the presence of several flame retardant chemicals in the skin and found that five of the flame retardants they tested (BDE 47, 99, 100, 153, and 183) got through the skin barrier to reach the equivalent of the human bloodstream. However, they also note that only a tiny amount actually made it into the bloodstream.
The study authors found the microplastic type had a small but not significant effect on the amounts of flame retardant chemicals in the skin.
Exposure to polyethylene microplastics led to more accumulation in the skin. BY comparison, exposure to polypropylene microplastics led to slightly less accumulation.
However, the microplastic type did not significantly impact the amounts of flame retardant chemicals that made it into the bloodstream.
Researchers also observed how skin hydration impacted the absorption of flame-retardant chemicals. In general, sweatier skin increased dermal bioavailability, except for BDE 47, where absorbed concentrations were higher when the skin was dry.
“This skin-model study with lab-made microplastics gets us thinking about the permeability of the skin barrier to plastic’s additives — in this case flame retardants that might be in the microplastics shedding off our electronic devices and certain textiles,” non-study author Heather Leslie, PhD, a scientist specializing in the impact of microplastics in humans and ecosystems based in Amsterdam, told Medical News Today.
“The objective was to study the transfer of the chemical additives from microplastic to skin, but for me it was especially interesting that the researchers did not observe any microplastic particles themselves penetrating through the artificial skin. Such studies are rare so far. It gives hope that real skin is an effective barrier at least to the fine and ultrafine plastic particles that are shedding from synthetic clothes, sheets and upholstery textiles.”
— Heather Leslie, PhD, scientist
Despite the compelling findings, this research does have certain limitations.
Skin models may provide a helpful equivalent to human skin, but they cannot account for additional factors that may be involved in real-world exposures.
“They tested polyethylene and polypropylene — these aren’t typically the polymers that you would find in, say, a couch or clothing,” said non-study author Hanno Erythropel, PhD. lecturer at the Yale School of the Environment.
“It doesn’t diminish the work… [but] you rarely wear polyethylene on your skin. Polyethylene is more of like your shopping bag,” Erythropel told MNT.
Researchers also note they were only able to exmaine a small number of flame retardant types. Future studies could look at other types of flame retardants and additional chemicals.
Other areas of research could explore the dangers of exposure to microplastics through the skin barrier and what action steps could help minimize potential health risks.
The results of this study indicate a growing need to address the health implications of exposure to dangerous chemicals found in microplastics.
In their conclusion, the study authors note the following:
“These results provide important experimental evidence for regulators and policy makers to legislate for microplastics and safeguard public health against such exposure, which contributes to the human body-burdens of toxic additive chemicals linked with causing cancer, and disruption of the endocrine system.”
As more information comes to light about the dangers of microplastics, there may be a number of strategies to address the problem.
Scientists and researchers could develop flame retardants that are not dangerous and explore how to address the buildup of microplastics.
“Flame retardants are these wonderful compounds that we need to make sure that things don’t burst into flames,” Erythropel explained.
“They have a use. They have a function — but what we’ve learned over the years is a lot of these brominated flame retardants… have really hazardous traits. There are all kinds of efforts to find other flame retardants that do the job of making things not ignite but that don’t come with certain health hazards. When we make additives, we want to make sure that they do the job — but it would be really good if we could make these additives to be non-problematic.”
— Hanno Erythropel, PhD. lecturer
Leslie also noted that efforts could also focus on using less-flammable materials.
“Designing out the hazardous chemicals from products can be achieved in many ways, for instance by functional substitution, which asks: how do we achieve equivalent product performance and function without the hazardous chemicals?” she questioned.
“In the case of flame retardants, a question might be, can we use materials that are simply not that flammable in the first place? Some polymeric building materials are highly flammable, while there are alternatives. Never underestimate the power of human ingenuity,” Leslie said.
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