Microplastics and Health

Kathryn Adel October 2, 2025 environment, Health

The industrial benefits of plastic use are widespread, and its production is estimated to quadruple by 2050. Microplastics, which are omnipresent in our environment and have the ability to persist for centuries, are raising growing concerns about their environmental impact, as well as their potential effects on human health.

What are microplastics (MP)?

Microplastics (MP) are tiny fragments of plastic found in our environment. Plastic does not decompose like food and paper, but rather fragments into increasingly smaller particles. When these particles shrink below five millimeters, they are called microplastics. MP smaller than one micrometer are called nanoplastics.

MP are found everywhere in our environment, with vehicle tires considered one of the largest sources of environmental MP. Other environmental sources include personal hygiene products containing microbeads, paint, laundry wastewater, artificial turf, plastic bags and bottles, as well as fishing tackle.

MP can enter the human body via three routes of exposure: ingestion (the main route), inhalation, and skin penetration.

The presence of MP in human feces confirms their ingestion through food. Due to the high concentration of MP in the ocean, seafood (shellfish and fish) is considered one of the main sources of MP through ingestion. Other major dietary sources of MP include bottled water, beer, salt, tea bags, canned foods, and prepared meals. MP infiltration via plastic bottles increases when the bottle is exposed to direct sunlight. Tap water contains tiny plastic particles, but bottled water contains twice as many. Metal cans and cardboard coffee cups contain a plastic lining. For decades, this lining was often made from bisphenol A (BPA), a molecule that makes plastic strong and durable. The problem is that BPA can migrate into food. BPA is recognized as an endocrine disruptor, meaning it can mimic or block the action of our natural hormones and thus disrupt the hormonal system, even at very low doses. Although more and more manufacturers now offer “BPA-free” bottles, packaging, and cans, these still contain plastic, sometimes along with other bisphenols or resins whose long-term effects remain unknown.

MP can also enter the human body through inhalation. Synthetic textiles and dust are considered the most significant sources. Clothing and fabrics made of polyester, nylon, acrylic, or elastane release microscopic plastic fibers. Every time we wear, wash, or even rub these fabrics, tiny fibers are detached and remain suspended in the indoor air. Modern interiors, filled with synthetic textiles (carpets, curtains, clothing, furniture), are therefore a continuous source of MP. Dust accumulates not only these textile fibers but also particles from hard plastics (furniture, paint, packaging, toys, vinyl flooring, etc.).

Finally, the skin can also be a gateway for MP when using certain kinds of personal hygiene and cosmetic products (ex. soap, exfoliants, creams, lotions, and makeup).

Microplastics and Health Effects

Once in the human body, MP can cross biological barriers, such as the intestinal wall, and reach various organs. Nanoplastics, which are smaller particles, can be absorbed more easily and distributed through the bloodstream. Research indicates that MP can accumulate in various organs such as the liver, kidneys, brain, reproductive organs, and even potentially reach the placenta, although the exact mechanisms and consequences of this accumulation remain unclear.

The effects of MP on human health are still largely unknown, with most studies having been conducted on animals or cell cultures. It has been suggested that exposure to MP can lead to inflammation, oxidative stress, impaired immune function, abnormal organ development and function, cellular damage, and increased cancer risks. MP can also act as vectors for other toxic substances, increasing their harmful potential. Degraded plastics can release chemical additives, such as phthalates and bisphenols, known for their endocrine-disrupting effects, thus contributing to hormonal imbalances and fertility problems.

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Author

Kathryn Adel

Kathryn holds a Bachelor Degree in Nutrition as well as a Bachelor and a Master Degree in Kinesiology, all from Laval University. She is a Registered Dietitian and active member of the Ordre professionnel des Diététistes Nutritionnistes du Québec (ODNQ) and of the American Academy of Nutrition and Dietetics. She holds the Monash University's certification for the FODMAP diet and IBS, and has considerable clinical experience in that area. She is also an accomplished athlete, having ran track and cross-country at a national level. Kathryn specializes in sports nutrition, weight loss, diabetes, as well as heart and gastrointestinal health.