Blood-Filtering Treatment May Also Remove Some Synthetic Chemicals And Microplastics

Therapeutic apheresis, a blood-filtering treatment used to remove excess fats from the blood of people with cardiovascular disease, may also catch far smaller passengers: certain persistent synthetic chemicals and microplastics.

Video: Untitled manual playlist

How therapeutic apheresis filters the blood

During therapeutic apheresis, a patient's blood is run through a machine that removes selected substances before returning the blood to the body.

The procedure was not created to clear environmental pollutants. Instead, it is typically reserved for severe cases in which medicines alone cannot adequately reduce cholesterol - fat-transporting particles associated with cardiovascular disease risk.

Yet German researchers found that concentrations of some synthetic chemicals dropped when they compared blood samples taken directly before and after treatment.

Preliminary results also indicate that the filters could retain particular microplastics.

PFAS reductions after therapeutic apheresis

The chemicals assessed in the Brain Health study were per- and polyfluoroalkyl substances, known as PFAS. They are used in a wide range of products, including non-stick coatings, waterproof fabrics, and certain food packaging.

Because some PFAS remain in both the environment and the human body for years, they are frequently described as "forever chemicals".

Exposure to PFAS can occur through numerous routes, from contaminated food and water to consumer goods, packaging, and even dust in the home.

"What we consider the most important finding of our study is that therapeutic apheresis, a procedure originally developed to remove lipoproteins from the blood of patients with severe cardiovascular disease, also reduced circulating levels of PFAS and microplastics," molecular endocrinologist Charlotte Steenblock of the Dresden University of Technology told ScienceAlert.

"This was unexpected, as PFAS and microplastics are chemically distinct from lipoproteins and were not the intended targets of the treatment."

Long-term exposure to some PFAS has been linked to increased total cholesterol and higher LDL (the 'bad' cholesterol), as well as immune and hormonal changes and certain cancers. However, the risk varies according to the PFAS type, the dose, and the duration of exposure.

Good HDL and bad LDL cholesterol. (University of Utah)

The team examined 14 patients receiving double-filtration plasmapheresis. First, blood cells are separated from the plasma; the plasma then flows through a second filter, which holds back larger targets including lipoproteins.

Four commonly occurring PFAS were measured in these patients before and after each of two double-filtration sessions. Directly after a single procedure, concentrations in their blood had decreased by up to 25 percent.

A separate laboratory used another method to test samples from four patients, reporting mean decreases of 43.5 to 75.8 percent for five PFAS.

However, the two findings cannot be compared directly because the samples were small and the methods differed. The larger percentages also do not show that over half of those particular PFAS molecules were removed from every patient.

Certain PFAS attach to blood proteins and may be carried with lipoproteins. They may therefore be trapped by the filters themselves or cleared alongside the treatment's intended targets.

"Our current hypothesis is that these environmental pollutants are retained directly within the apheresis filters or that they form aggregates or complexes with lipoproteins and plasma proteins, allowing them to be co-removed during the procedure," Steenblock says.

Schematic overview of how therapeutic apheresis may reduce circulating PFAS and MNPs. (Bornstein et al., *Brain Health, 2026)*

Microplastic findings remain uncertain

The results for microplastics were more variable.

Polyethylene concentrations fell in all four patients, while polyvinyl chloride declined in three. Other polymers showed no comparable pattern, however, and levels of some plastics circulating in the blood rose after treatment.

Such inconsistencies may be due to testing methods, contamination from the environment, or plastic parts within the apheresis equipment. Consequently, the study does not establish that apheresis consistently lowers microplastic levels in human blood.

According to Steenblock, the researchers repeatedly found microplastics in material rinsed from filters after their use.

"We are very confident that apheresis does not merely redistribute microplastic particles but actually removes them from the circulation, as we have repeatedly detected microplastics in the eluates recovered from the apheresis filters after treatment," she says.

Still, a particle being captured in a filter does not automatically mean the body's overall microplastic load has fallen. Blood measurements reveal only what is circulating at a particular time, while particles stored in tissues may subsequently return to the bloodstream.

This is significant because microplastics have been identified in human brain, liver, and kidney tissue, although their lasting effects on health are not yet known.

The exploratory research included small, partly distinct groups of patients, while microplastic testing is susceptible to environmental contamination. The researchers also did not establish how long any reductions continued or whether patients experienced improved health.

Larger controlled studies, standardised testing, and longer follow-up periods are therefore required before apheresis can be regarded as a treatment for exposure to environmental pollutants.

A different 2026 study in the Journal of Clinical Apheresis looked at 174 plasma-exchange procedures involving 114 patients. Microplastic concentrations declined in those whose starting levels were high, but increased in patients with low initial levels.

The authors of that study proposed that plastic tubing and fluid bags used in the procedure could have shed particles into the blood.

Related: 'Forever Chemicals' Found in 98.8% of Human Blood Samples Tested

At present, the evidence does not justify treating apheresis as a microplastic 'detox'. It remains a medical procedure for particular conditions and is carried out under specialist supervision.

Nevertheless, the results point to an interesting possibility: a filter made to capture harmful fat-carrying particles might also remove some PFAS and microplastics travelling with them.

The study was published in Brain Health.

This article was fact-checked by Rachel Garner and edited by Rebecca Dyer. While we pride ourselves on our process, we are only human. If you spot a mistake, please let us know.