Kidney dialysis and microplastics. Should we be concerned?
- Hector Madariaga, MD
We are consistently exposed to health hazards, particularly microplastics which historically, have been linked to oxidative stress, disturbances in the immune system, endocrine disruption and reproductive issues. I recently started to be more cautious about the content of foods for my family and myself and have become increasingly aware of food preservatives as well as growing evidence regarding microplastics and nanoplastics in foods and their impact in humans and the environment.
Many individuals take multiple medications in one day, including pills, capsules, and intravenous therapies. Those capsules many of us take, are not actually plastic; rather, they are made of hardened gelatin. Traditional capsules are often derived from livestock and this can be controversial, particularly for individuals that follow strict diets, such as vegans or vegetarians or those with specific allergies; unfortunately, most drug makers are not offering vegetable-based gelatin substitutes. Another controversial chemical in the drugs is phthalate. The U.S. Food and Drug Administration and the European Medicines Agency have established clear guidelines regarding their use in pharmaceuticals. Phthalates are commonly used in foods, but also, in the pharmaceutical industry, particularly in softgel capsules. Unfortunately, many over-the-counter supplements may exceed safe phthalate levels.
Currently in the United States, there are over 35 million individuals living with kidney disease and over 500,000 have kidney failure, meaning most likely require dialysis. Dialysis is a medical therapy for individuals whose kidneys no longer function adequately to filter toxins produced in the body (Click here to learn how dialysis works). As a result, waste products accumulate, and alternative methods are needed to remove them. There are two main types of dialysis: hemodialysis and peritoneal dialysis. A third option is kidney transplantation, however the average wait time to receive a kidney transplant is approximately 3-7 years, meaning many patients remain on long-term dialysis.Dialysis procedures require the use of single use disposable products which are made out of plastics.
While reading more about this topic, I came across an observational study, one of the first large human outcome studies suggesting a direct association between plastic exposure and hard clinical outcomes, published at the New England Journal of Medicine (NEJM) in 2025. The investigators analyzed carotid endarterectomy plaques from patients with atherosclerotic disease and found that microplastics and nanoplastics present in more than half (58%) of the plaques, predominantly polyethylene and polyvinyl chloride. The study provided clinical evidence suggesting that microplastics may contribute to vascular inflammation as electron microscopy demonstrated plastic particles embedded within macrophages and plaque debris. However, causality was not established and the authors concluded that micro- and nanoplastics may represent potentially novel environmental cardiovascular risk factors.
In the nephrology field, one study published in 2025, analyzed 30 unopened dialysis fluid samples, including hemodialysis concentrates and peritoneal dialysis bags, and reported the presence of microplastics, primarily fibers, at very low concentrations. These plastics included polyethylene, PVC, ethylene-vinyl acetate and PET. The authors hypothesized that contamination may occur even before the fluid reaches dialysis machines. They also observed that patients on PD had over 50% higher exposure to plastics compared to HD patients. An important consideration was particle size. HD microplastics were larger (mean ~1.31 mm) in comparison to PD microplastics (~0.64). This is relevant because larger particles are unlikely to cross dialysis membranes, which are typically made of cellulose-based materials or synthetic polymers; however, in theory, larger particles could fragment into smaller particles or nanoplastics that in theory can cross the membranes. The authors discussed several mechanisms, but a clinical harm was not demonstrated as no biomarkers or clinical outcomes were measured. Taken together, it remains unclear whether microplastics cross dialysis membranes, reach systemic circulation or contribute to inflammation or other kidney diseased-related outcomes. At present, this is hypothesis-generating and serves as a call to action for innovation in dialysis materials as well as further research and policy development.
Furthermore, HD patients are also exposed to large volumes of treated water during dialysis, which may contain plastic particles, despite reverse-osmosis filtration. The authors of this paper, estimated that even with a 99% filtration efficiency of measurable numbers and particles, a small proportion could still reach patients. Current dialysis water standards focus mainly on microbiologic and chemical contaminants rather than plastic particles which warrants future research and improvement in filtration technologies
This paper also suggested that HD may be associated with microplastic exposure, as patients with hemodialysis demonstrated higher circulating particle levels compared with non-dialysis controls. Dialysis-related factors, such as water purification systems, plastic tubing and extracorporeal circuits, may contribute to cumulative exposure beyond environmental sources. This study has significant limitations and does not establish causality or clinical harm; however, it raises important concerns about potential inflammatory and oxidative stress implications in a population that is already vulnerable to chronic inflammation.
In conclusion, current evidence remains insufficient to establish a definitive causal relationship between microplastic exposure and adverse clinical outcomes in patients undergoing dialysis. Most recent evidence provides a compelling biologic plausibility and raises important clinical concerns, however, the available data is largely observational and hypothesis-generating. These findings should not prompt an alarm, but rather encourage a thoughtful investigation, closer monitoring and innovation in medical manufacturing and dialysis technologies. This is a call to action to the scientific community and industry partners to develop stricter standards, enhance transparency aiming at understanding and minimizing microplastic exposure in the current era of medicine.
Dr. Hector Madariaga is a transplant nephrologist and Clinical Assistant Professor at Tufts Medicine in Boston, Massachusetts.