Tiny fragments of plastic have been detected in our lungs, liver, kidneys, and even our brain. While studies confirm plastic in our bodies, researchers struggle to measure its health effects. An international treaty to reduce plastic pollution is underway in Busan, South Korea.
The image released in 2019 by the NGO WWF left a lasting impression: a credit card dipped like a buttered slice of toast into a cup of coffee, symbolizing the 5 grams of plastic we allegedly consume each week without realizing it. Although scientists agree this figure is exaggerated, the ingestion of tiny plastic fragments through food and drinking water is a well-established phenomenon.
“Nano and microplastics can enter the body due to their very small size. They pass through the intestinal barrier, the blood-testis barrier, and even the placental barrier,” explained Dr. Pierre Souvet, founder of the French Environmental Health Association. “We’ve found them in the blood, lungs, liver, kidneys, and even in the brain, as a recent American study demonstrated through brain autopsies,” added Dr. Souvet, who is also part of a coalition of scientists advocating for an effective plastics treaty. Delegates from 175 countries are convening in Busan, South Korea, from November 25 to December 1 to finalize an international treaty on plastics.
Foreign bodies
Plastic particles traveling throughout our bodies? It’s not a comforting thought, but what about their health impacts? “These are foreign bodies; their mere presence in our system is already a problem,” Dr. Souvet noted. Beyond their physical presence, there is a “chemical effect” linked to substances that give plastics their durability, flexibility, or color. “About 16,000 chemical compounds are used in plastic manufacturing,” the doctor said. “Among them, 25% are potentially hazardous, such as phthalates and bisphenol, known endocrine disruptors, yet only 6% are regulated.”
The precise health impacts remain uncertain. “We’re still at the stage of suspicions, but experimental studies have highlighted harmful effects from exposure to chemicals used in plastic production,” said Jean-Baptiste Fini, a professor at the National Museum of Natural History. For instance, a 2017 French study funded by the National Agency for Food, Environmental, and Occupational Health and Safety showed that male mice chronically exposed to low doses of phthalates—commonly used as plasticizers in bottles—had disrupted sexual communication with females, leading to delayed mating. Another study found plastic accumulation in the brains of rat fetuses, impairing cognitive abilities. Is the same true for humans? That’s still unclear, but progress is being made.
A turning point in research
According to Xavier Coumoul, a professor of toxicology and biochemistry at Paris Cité University, research is at a pivotal moment. “Until now, studies have been mostly experimental: exposing mice, rats, or fish to plastic and observing physiological disruptions. But last April, for the first time, a rigorous study published in the New England Journal of Medicine linked plastic exposure to cardiovascular diseases,” he explained.
Researchers studying atherosclerosis, characterized by arterial plaque buildup, found microplastics in 73% of cases. “They also noted that higher plastic concentrations correlated with greater inflammation, consistent with earlier animal studies showing inflammatory responses,” Coumoul added. Inflammation plays a role in many conditions, including multiple sclerosis, cancer, Crohn’s disease, and Alzheimer’s.
But we don’t just ingest plastic—we breathe it in too. “We’ve only recently understood how plastic degrades, releasing ultrafine particles that can travel thousands of miles, even across continents,” explained Sonja Boland, a research engineer at Paris Cité University. These nanoparticles often come from sources like car tires or agricultural materials. Indoors, synthetic fibers in clothing and furniture are significant contributors.
Technical challenges and future risks
The health risks from inhaling plastic remain uncertain. Historical studies from the 1970s showed that workers in plastic factories developed respiratory issues and colon cancer due to high exposure. “While today’s environmental concentrations are lower, the immense quantities of plastic produced now will degrade into nanoparticles that linger in the environment for decades,” warned Boland. Current detection methods for the smallest particles are limited, presenting a major challenge for researchers.
In the meantime, experts urge reducing plastic production. “Obesity, infertility, metabolic disorders, hyperactivity, attention problems, and neurodegenerative diseases all have environmental links. Whether it’s from what we eat, drink, or breathe, we’re taking risks that could be mitigated by limiting certain plastics,” they argued.
Plastic production by the numbers
- Between 2000 and 2019, global plastic production doubled to 460 million tons annually (OECD).
- Without international action, production is expected to triple by 2060.
- Currently, only 9% of plastic is recycled, with recycling capacity projected to reach just 14% by 2040.
- Plastic production accounts for 3.4% of global greenhouse gas emissions, surpassing the aviation sector.
- An estimated 109 million tons of plastic are now in lakes and rivers, with another 30 million tons in oceans.
Reproduced with permission from La Croix International.
