Microplastics in the Air You Breathe and the Food You Eat

Microplastics can be found in many different items that we’re exposed to over the course of a day. Plastic water bottles, synthetic carpet, and even beauty products can all increase our exposure to these tiny plastic particles. Microplastics can also be inhaled and ingested with foods or beverages.

While the exact effect microplastics may have on our health in the long term is not yet clear, we do know they are capable of affecting human cells and also have a negative effect on the environment and the organisms within it.

By knowing where you might come across microplastics in your day-to-day life, you can better understand how you can identify and then reduce your exposure.

What Are Microplastics?

Microplastics are tiny pieces of plastic, usually less than 5 millimeters (0.2 inches) in size. Microplastics can come from two main sources:

• Primary microplastics. These microplastics are manufactured to be smaller than 5 millimeters in size. They include things like glitter, the microfibers used in the production of synthetic fabrics like fleece, and microbeads used in personal care products like face scrubs and toothpaste. 
• Secondary microplastics. These originate from large pieces of plastic pollution like bags or water bottles that break down into smaller pieces, eventually becoming microplastics. Plastic containers can also shed microplastic particles over time or when heated.

Microplastics can eventually break down into even smaller particles, known as nanoplastics. These are smaller than 0.001 millimeters in size.

Microplastics in Humans 

Because plastics are such a durable material, once they’re small enough to form microplastics they can easily be ingested or inhaled as we’re exposed to them over the course of our lives. While the exact effect of these microplastics is unclear, research indicates that they may lead to increased inflammatory response, toxicity, and disrupt the gut microbiome.

In 2020, scientists detected microplastics in the placentas of healthy women. It’s thought that the particles probably derived from personal care products, paints, cosmetics, and packaging. The size of the microplastics meant that once ingested or inhaled, they were small enough to be carried through the bloodstream. Microplastics were not detected in all participants, meaning some lifestyle factors may be at play.    

So we know that microplastics can be found in the human body, but how do they get there? 

Microplastics in Foods, Beverages, and Air

Despite the ubiquity of microplastics in our everyday life, there isn’t that much research into the impact of microplastics on our well-being. What we do know is that they can easily be found in a variety of everyday foods and beverages.

Scientists estimate that the annual ingestion of microplastics for the average American falls somewhere within the range of 39,000 to 52,000 particles. 

One study found that some brands of bottled water are contaminated with microplastics. The most common microplastics found were polymer plastics like the polypropylene used to manufacture bottle caps. The primary source of contamination is thought to be from both the manufacturing process and the packaging.

In contrast, while tap water has been found to contain microplastics, the levels are far lower compared to bottled water.

Microplastics have also been found in beer, packaged sea salt, and seafood. Exposure to microplastics in seafood will usually be higher in bivalves or small fish that are eaten whole. 

Some tea bags are made using plastics, with research showing that steeping one plastic teabag can release 11.6 billion microplastic particles into one cup of tea. The same study also found that 3.1 billion nanoplastic particles were released. Higher temperatures of water seem to encourage the release of more plastic particles, and this study seems to suggest that far higher levels of microplastics could be consumed than indicated by previous studies.

As well as ingesting microplastics with our food and drink, they can also be inhaled. One study in Australia found that the dust within indoor air can contain a wide range of microparticles, some of which are plastic-based. Homes with carpeted floors had almost twice the number of petrochemical-based fibers like polyethylene and polyacrylic, while homes with hard floors had more polyvinyl fibers.  

The rates of inhalation and ingestion of these microplastics were 12,891 ±4472, with the highest rates found in young children. This is because young children have a higher breathing rate, combined with lower body weight. They also spend more time playing on floors, and frequently put their hands in their mouths, making it more likely they will be exposed to microplastics in dust.  

To put the amount of microplastics ingested or inhaled into context—the above study estimated that children under 6 ingest around 6.1 milligrams of microplastics per kilogram of body weight, per year. For a 5-year-old, this amount equals the size of a pea. While over the course of a year this seems like a small amount, we still don’t fully understand the cumulative effects these microplastics may have on our bodies.

Impact on Human Health 

While we know microplastics are everywhere, more research needs to be done to better understand their long-term impact on our well-being.

Scientists have been working on developing methods to help detect the presence of microplastics in human tissue. These methods will be key in determining whether microplastics are a health hazard, or if their accumulation shouldn’t worry us too much.

So far, research has shown that microplastics are indeed capable of affecting human cells, leading to oxidative stress, immune responses (such as allergic reactions), and cell death in toxicology tests. However, further research is needed to understand how microplastics accumulate and are excreted from the body.

In the meantime, many people choose to try and avoid microplastics where possible, especially given we know they can have negative impacts on the environment and wildlife.