Microplastics are everywhere. And a steadily growing body of evidence suggests that microplastics not only accumulate in the body but may have a range of damaging effects, including for people with rheumatic diseases.

“There’s more and more emerging science suggesting that our ingestion of microplastics is potentially very problematic in that these microplastics end up getting into our gut,” Tamiko Katsumoto, MD, a clinical associate professor of medicine and a lifestyle medicine physician in the Division of Immunology and Rheumatology at Stanford University School of Medicine, Stanford, California, told Medscape Medical News. “The whole concept of leaky gut is something that has been implicated in the pathogenesis of, for example, inflammatory arthritis…So by disturbing that gut barrier with microplastics, you may be fanning the flames of inflammatory diseases.”

There are many unknowns when it comes to the science community’s understanding of microplastics, which are defined by the United Nations as any fragment of plastic that is between 1 nm and 5 mm wide.

Primary microplastics are intentionally engineered at tiny sizes for use in skin washes and other products. Secondary microplastics are those that break down from larger plastic-containing products like containers, ultraprocessed foods, polyester clothing, tires, paint, and other sources. According to one estimate, 10-40 million tons of microplastics enter the environment each year — a number expected to double by 2040. Although a widely cited finding that the average person consumes a credit card’s worth of microplastics each week is likely overblown, it is clear that microplastics are pervasive in the modern environment.

“We can ingest them more than we realize,” Katsumoto said. “Things like plastic bottles or plastics that are used in contact with food are a problem. Believe it or not, they’ve been found and getting into our food supply, even in plants, and then they get eaten by animals and bioaccumulate in animals. And so we’re kind of getting them from all over.”

Microplastics and Rheumatic Disease: What the Evidence Says

Microplastics can enter the body through food, water, and air, and have been demonstrated to accumulate in many areas, including joints. A study published in May led by researchers at Case Western Reserve University found that geographic areas with the highest microplastic exposure had higher prevalence of stroke (prevalence ratio (PR), 1.21; 95% CI, 1.13-1.29), diabetes (PR, 1.17; 95% CI, 1.10-1.24), and hypertension (PR, 1.10; 95% CI, 1.06-1.14) compared with areas with low exposure.

“Following ingestion, inhalation, or dermal contact, sufficiently small microplastic and nanoplastic particles may cross biological barriers and enter the circulation,” said Muhammad Adil Malik, MD, a physician-surgeon and microplastics researcher in the Department of Orthopaedics at The Third Xiangya Hospital and Central South University in Changsha, China, told Medscape Medical News. “Microplastic particles have also been detected in human musculoskeletal tissues, although their precise origin, duration of retention, and clinical significance remain under investigation.”

Further elevating potential risks, plastic-associated chemicals are the thousands of synthetic substances used to make, soften, color, or protect plastics that have raised their own sets of health questions. Two of the most common types, bisphenols and phthalates, have been implicated in everything from rheumatoid arthritis (RA) to reproductive dysfunction.

A review published in July in Current Opinion in Rheumatology examined the potential role of microplastics, ultraprocessed foods, food additives, and emulsifiers in the pathogenesis of RA and other rheumatic diseases.

“These data provide preliminary mechanistic evidence linking microplastic exposure to pathways relevant to rheumatic disease pathophysiology, highlighting microplastics as emerging environmental exposures of potential rheumatologic relevance,” the study authors wrote.

According to the authors, experimental evidence indicates that microplastic exposure can induce oxidative stress, alter microbial composition and short-chain fatty acid production, and activate inflammatory pathways such as NF-κB and cGAS-STING.

A 2025 analysis of microplastics and osteoarthritis suggested that microplastics may activate inflammatory signaling pathways including TLR4/NF-κB and the NLRP3 inflammasome. At the same time, microplastics may impair mitochondrial function, promote chondrocyte apoptosis, and accelerate degradation of the cartilage extracellular matrix, the authors concluded.

“Microplastics are unlikely to contribute to osteoarthritis through a single biological pathway,” noted Malik, who was the study’s first author. “A more plausible interpretation is that they may act as an additional environmental stressor that amplifies inflammation, oxidative injury, and abnormal tissue remodeling in susceptible individuals…Taken together, these mechanisms provide biological plausibility for microplastics as a potential contributor to osteoarthritis. However, human longitudinal evidence is not yet sufficient to classify microplastics as a proven independent cause of the disease. It is more appropriate at present to regard them as a possible environmental cofactor.”

In another 2025 study, published in the Journal of Hazardous Materials, a South Korean team investigated whether polystyrene microplastics (PS-MPs) could contribute directly to RA pathogenesis. Investigators detected PS-MPs in the synovial fluid of five of 21 patients with RA from whom samples were obtained during synovectomy or total joint replacement.

Further, in two in vivo models, chronic PS-MP exposure increased arthritis-associated inflammation, while PS-MP-treated RA fibroblast-like synoviocytes (RA-FLSs) produced greater cartilage erosion and macrophage infiltration.

An in vitro study published in 2023 in International Immunopharmacology found that microplastics promoted the invasion and migration ability of RA-FLSs while promoting the secretion of inflammatory factors in RA-FLSs. Subsequent in vivo studies showed that microplastics exacerbate RA cartilage damage.

“The results show that microplastics aggravate the pathological changes of RA,” the study authors concluded. “Current research shows that microplastics aggravate RA.”

Arthritis is not the only rheumatic disease potentially affected by microplastics. A 2024 study in Science of the Total Environment found that microplastics exposure demonstrated the capacity to induce and exacerbate lupus-like symptoms in mice. This was manifested by microplastics triggering abnormal elevations of interleukin-6 and TNF-alpha.

Next Steps in Research

Even as microplastics research remains in its relative infancy, early returns are enough to get scientists thinking about what could or should come next in terms of investigations.

“The findings support three priorities,” Malik said of his team’s 2025 study results. “First is standardized methods for measuring exposure and tissue burden. Second is prospective human studies connecting exposure with long-term joint outcomes. And third is mechanistic research capable of distinguishing association from causation.”

Moving forward, the best next step is establishing sound methodologies, Sasha Bernatsky, MD, PhD, James McGill Professor of Medicine in the Division of Rheumatology and senior scientist at the Centre for Outcomes Research and Evaluation at the Research Institute of the McGill University Health Centre in Montreal, Quebec, Canada, told Medscape Medical News.

“Basic science investigators in North America need to develop robust, easily accessible, relatively inexpensive lab methods to validly detect microplastics in blood/sera (and also tissue, potentially),” she said. “Then we need to validate those methods and do a host of controlled analyses using multiple regressions controlling for age, [disease] duration, race/ethnicity, etc, including the use of longitudinal data.”

If those methods are developed, Bernatsky, a lupus researcher and epidemiologist, envisioned deeper dives into microplastics’ role in pathogenesis and outcomes.

“I would for example love to…determine if in SLE [systemic lupus erythematosus] and other autoimmune rheumatic disease populations, microplastics in blood/sera correlated with disease activity or adverse outcomes,” she said. “It would also be interesting to determine if we could trace links between habits (like using plastic tea bags, using certain dental devices, etc) and microplastics in the blood/sera of SLE patients.”

What Rheumatologists Can Do

In April, Nature Medicine published the results of a study known as the PERTH Trial.

The observational cohort study included 211 Australian participants and a 7-day pilot randomized controlled trial in 60 participants. Intervention groups received kitchenware, food, and personal-care products that were low in or free of plastics.

The group that decreased plastic exposure saw urinary levels of mono-n-butyl phthalate, monobenzyl phthalate, and bisphenol A decrease by a respective 37.5% (95% CI, -55.6 to -12.0; P = .007), 53.5% (95% CI, -72.7 to -20.6; P = .005) and 59.7% (95% CI, -82.5 to -6.87; P = .033).

“By changing dietary behaviors and consum[ing] only verified low to no plastic exposed food and drink and personal care products, people significantly reduced their exposure to bisphenols and low molecular weight phthalate chemicals,” study co-author Andrew Lucas, PhD, a senior postdoctoral fellow with the School of Biomedical Sciences at The University of Western Australia, Nedlands, Australia, told Medscape Medical News.

The findings underscore the changes that are possible with relatively simple lifestyle modifications. When discussing microplastics with patients, experts said, small adjustments can potentially pay dividends — without getting ahead of the science or causing unwarranted anxiety.

“Reasonable, low-burden measures include avoiding heating or microwaving food in plastic containers; using glass, ceramic, porcelain, or stainless-steel containers for hot foods and liquids where practical; and transferring hot takeaway food from plastic packaging to a nonplastic container,” Malik said. “Further, anyone can reduce unnecessary dependence on single-use plastic bottles, cups, utensils, and food packaging. Replacing heavily scratched, damaged, or degraded plastic food containers. Following local drinking-water safety guidance rather than making unverified assumptions about whether bottled or tap water is universally safer.”

Water filters can be an increasingly affordable way to manage microplastics.

“I encourage my patients to think about getting a water filter, carbon filter, or even better, a reverse osmosis filter, for which the prices have come down nicely,” Katsumoto said. “For around $200, you can get a reverse osmosis filter because there are microplastics and nanoplastics even in our water. And so these filters are important to filter them out.”

Katsumoto added that eating less-processed food can also help manage microplastics, in addition to being generally healthier on a number of levels.

“I think a lot of the ultraprocessed packaged food is a significant source that we need to be thinking about, which is largely why we try to recommend to people eating whole foods as much as possible, minimally processed, not packaged,” Katsumoto said.

Ultimately, efforts to reduce exposure to microplastics should complement, not replace or disrupt, established strategies.

“Precautionary measures concerning plastics should complement — not replace — established [disease] management,” Malik said. “Maintaining a healthy body weight, remaining physically active, strengthening the muscles surrounding affected joints, preventing further joint injury, and receiving appropriate evidence-based treatment remain much more firmly established components of care.”

Katsumoto, Malik, Bernatsky, and Lucas had no relevant disclosures.

Scott Harris has covered rheumatology and other healthcare topics for more than a decade. He lives near Washington, DC.