Scientists have uncovered surprisingly high levels of a little-known silicone pollutant floating in the atmosphere. This discovery is raising fresh concerns about possible risks to human health and the climate. The chemicals, called methylsiloxanes, are commonly found in cosmetics, industrial products, transportation, and household items. Researchers detected these compounds across a wide range of environments, from busy cities to quiet rural villages and remote forests.

The study, led by experts from Utrecht University and the University of Groningen, was published in the journal Atmospheric Chemistry and Physics. It adds to a growing body of research about synthetic chemicals that are now present almost everywhere on Earth.

What Are Methylsiloxanes and Why Should You Care?

You may already know about pollutants like PFAS (often called “forever chemicals”) and microplastics. These substances have received a lot of attention for their widespread presence in the environment. But methylsiloxanes, a class of water-repelling silicone compounds often used as lubricants, have flown under the radar for years.

These chemicals are in many products you might use daily. Think about shampoos, deodorants, makeup, skin creams, and even some cleaning products. They are also added to industrial lubricants, engine oils, and materials used in transportation. Because they are so common, scientists have long suspected they end up in the environment. But the new research shows just how much is out there — and it is far more than expected.

How These Pollutants Get Into the Air

For years, scientists believed that the methylsiloxanes found in the atmosphere came mainly from evaporation. When you apply a personal care product, some of the chemicals can evaporate into the air. The same happens with certain industrial materials.

However, researchers recently discovered that ships and motor vehicles release a different form of methylsiloxanes. These are made up of much larger molecules that do not evaporate easily. Instead, they are released directly into the air through exhaust gases.

Here is how it works: Methylsiloxanes are added to lubricants like engine oil to help with lubrication. But during engine operation, moving parts such as pistons need constant oiling. This makes it unavoidable that small amounts of engine oil enter the combustion chamber. Because methylsiloxanes are highly heat resistant and do not fully break down during combustion, some survive the intense temperatures inside engines and are released into the atmosphere through exhaust.

Just How Widespread Are These Chemicals?

The new research shows these larger methylsiloxanes are not limited to traffic-heavy locations. Scientists detected them in urban, coastal, rural, and forest environments. This suggests the chemicals are truly widespread in the atmosphere.

“The findings also suggest that concentrations of methylsiloxane in the atmosphere are much higher than expected,” says Rupert Holzinger, associate professor at Utrecht University who co-supervised the study.

According to the researchers, these large molecular methylsiloxanes account for between 2 and 4.3 percent of the total mass of organic aerosols in the atmosphere. That makes them among the most abundant synthetic compounds detected in airborne particles. To put that in perspective, atmospheric concentrations of PFAS are typically more than a thousand times lower.

Where Were the Highest and Lowest Levels Found?

The highest concentrations were measured in urban regions. Samples collected in the São Paulo metropolitan area in Brazil reached 98 nanograms per cubic meter. The lowest levels appeared in forest locations, including Rugsteliskis, Lithuania, where concentrations measured just 0.9 nanograms per cubic meter.

Researchers also collected air samples in Cabauw, a small rural village in the Netherlands. There, concentrations reached 2 nanograms per cubic meter.

The measurements came from sites in the Netherlands, Lithuania, and Brazil. This gave researchers data from different climates, hemispheres, and economic regions, including both developed and emerging economies.

What Does This Mean for Your Health?

Because methylsiloxanes appear to be present almost everywhere in the atmosphere, researchers say people are likely inhaling them continuously. Scientists still do not know what long-term health effects this exposure could have. This is a major gap in our understanding.

“However, we estimate that the daily inhalation dose of methylsiloxanes may exceed that of other synthetic compounds, such as PFAS and micro- and nanoplastics,” says Holzinger. “We therefore underscore the urgent need for the evaluation of these health impacts.”

In other words, you might be breathing in more of these silicone pollutants every day than you are of better-known chemicals like PFAS. Experts say this makes it critical to study what these compounds do inside the human body over time.

Could These Chemicals Affect the Climate?

Researchers also warn that methylsiloxanes could influence climate and atmospheric processes. These chemicals can change the properties of aerosols, which play an important role in cloud formation and climate behavior.

For example, the compounds may alter aerosol surface tension, affecting how clouds form. They could also interfere with ice nucleation, an important step in atmospheric cloud processes. Small changes in how clouds form can have big effects on weather patterns and global temperatures.

Where Do These Pollutants Come From?

The study found that more than half of the detected large molecular methylsiloxane particles likely come from traffic emissions. Researchers believe the source is connected to lubricants such as engine oil.

Scientists reached this conclusion after finding that methylsiloxanes spread through the atmosphere in a similar way to long-chain hydrocarbons commonly found in engine oil. The matching dispersion patterns strongly suggest they come from the same source.

Interestingly, the long-chain hydrocarbons decreased significantly as they traveled through the atmosphere and became diluted. Methylsiloxanes, however, remained far more stable. Large amounts continued to persist in the atmosphere even after long-distance transport. According to the researchers, this stability means the compounds can likely travel great distances through the air.

What Experts Generally Say About This Type of Pollution

Health and environmental experts have long been concerned about synthetic chemicals that persist in the environment. The term “persistent organic pollutants” describes chemicals that do not break down easily and can accumulate in living organisms. While methylsiloxanes are not yet classified as persistent organic pollutants by major regulatory agencies, their stability in the atmosphere raises red flags.

Many experts agree that more research is urgently needed on the health effects of inhaling these compounds. Some studies in animals have suggested that certain siloxanes may affect hormone function or cause liver damage, but human studies are limited. Because these chemicals are so widespread, even small health effects could have large public health consequences.

Practical Takeaways for Readers

While scientists work to understand the full picture, here are some things you should know:

• Check product labels: Methylsiloxanes often appear on ingredient lists as “cyclomethicone,” “dimethicone,” or specific names like “cyclotetrasiloxane” and “cyclopentasiloxane.” These are common in cosmetics and personal care products.
• Ventilate indoor spaces: Since these chemicals can evaporate from products in your home, opening windows and using exhaust fans may help reduce indoor concentrations.
• Reduce personal care product use: Using fewer products containing silicones may lower your personal exposure, though experts note that outdoor air is a major source.
• Support further research: This study highlights how much we still do not know about everyday chemicals. Advocating for more research funding can help close these gaps.
• Stay informed: As more studies emerge, health recommendations may change. Following trusted health news sources can help you make informed decisions.

The Bottom Line

This new research reveals that methylsiloxanes are far more common in the air than anyone realized. They come from traffic, industrial sources, and everyday products. They travel long distances and persist in the atmosphere. And people are likely breathing them in constantly.

Until scientists understand the health effects, the best approach is awareness. Knowing that these chemicals exist and are widespread is the first step. The researchers behind this study are calling for urgent evaluation of health impacts. For now, the public should pay attention to this emerging issue and take reasonable steps to reduce exposure where possible.

Source: ScienceDaily