The widespread production and use of plastics began around the 1950s, but the production of plastics has also increased steadily. It's estimated that about 2 million metric tons of plastic were generated in 1950, but more than 400 million metric tons were being produced in 2015 alone. About half of all of the plastics ever made were produced in the past twenty years, and most of that is just disposable, with about half of plastic materials being discarded after less than four years of use.
Plastic is a useful material because it is cheap to produce and extremely durable. But that durability means that instead of breaking down naturally, it just turns into ever smaller bits. Microplastic and nanoplastic particles have made their way into seemingly everything, with the stuff being found in plants, the human placenta, the oceans, and maybe even clouds.
Scientists are still learning about how that plastic exposure may threaten human health, but research has suggested that microplastics may be causing damage to the genome; organ, immune and metabolic dysfunction; neurotoxicity; and harmful impacts on reproduction and development. Microplastic exposure has also been associated with the development of various chronic diseases.
A study has now shown that microplastics that can be found in commercial tea bags that are polymer-based, are able to enter human intestinal cells. The study noted that these particles could then move into the bloodstream, and throughout the body. The findings have been reported in the journal Chemosphere.
In this study, the researchers brewed various types of polymer-based tea bags were used to steep tea, and massive amounts of nanoparticles and nanofilamentous structures were released into the water. The team used many different tools to analyze these brews, including dynamic light scattering (DLS), laser Doppler velocimetry (LDV), nanoparticle tracking analysis (NTA), infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM).
As tea brewed, around 1.2 billion particles of microplastics per milliliter were released by polypropylene bags; cellulose bags released around 135 million particles per milliliter; and nylon-6 released 8.18 million particles per milliliter.
The microparticles were also stained by the researchers, and human intestinal cells were exposed to the stained particles. This showed that intestinal cells that produce mucous absorb high levels of microplastics and nanoplastics. Some of the particles even entered the nucleus of the cells, which houses the genome.
The researchers suggested that microplastics and nanoplastics may be having a major impact on human health, and more research is urgently needed to determine how this exposure may be affecting us.
"We have managed to innovatively characterize these pollutants with a set of cutting-edge techniques, which is a very important tool to advance research on their possible impacts on human health," said co-corresponding study author and UAB researcher Alba Garcia.
The use of plastics in food packaging is continuing to expand, and the scientists noted that we must ensure the safety of these materials to protect public health.
Sources: Autonomous University of Barcelona (UAB), Chemosphere