Microplastics in blood bags may affect red blood cells

“This is the first study to immediately visualize microplastic particles in stored red blood cell units using microscopy and to confirm their identity through analytical chemistry,” Angelo D’Alessandro, a University of Colorado Anschutz professor and expert in red blood cell storage who was not involved in the study, says in an email. “That is an crucial technical advance.”

In experiments, a team from China found that microplastic particle concentrations increased steadily over 30 days of storage. In that time, concentrations were between 7 and 20 times those found in freshly opened blood bags; the highest concentrations measured 22.3 ng/mL. Mechanical shaking and room temperature storage, which mimic improper storage or transportation, accelerated particle discharge by growing degradation of the bags' polymer surfaces.

“The concentrations reported are not trivial and deserve careful attention, particularly to patients who receive repeated or substantial-volume transfusions, such as children with inherited anemias or individuals with chronic transfusion needs,” D'Alessandro says. “At the same time, we do not yet know what level of exposure is sufficient to create clinically meaningful impacts in humans.”

While blood is in storage, biochemical and structural changes gradually minimize the integrity and function of red blood cells; these negative impacts are known as storage lesions. The researchers observed greater storage lesion features in stored blood than in fresh blood from healthy donors.

Outside experts urge caution in interpreting these results, however, as the researchers did not establish a mechanism by which microplastic particles might be degrading blood cells.

“Storage lesions are well known to be driven by cell aging, metabolic exhaustion, and oxidative stress, so [without further evidence], it is [too soon] to conclude that particles are actively driving this harm rather than just being present,” Jordi Petriz, a group leader at the Germans Trias i Pujol Research Institute who was not involved in the study, says in an email. “Because medical-grade polymers have a long, proven security record in saving lives, calling on manufacturers to overhaul blood storage materials would be premature.”

Particle discharge also varied depending on the solution applied to preserve the blood. Ultrafiltration of the two tested preservation solutions before their incubation with whole blood and red blood cells removed 78–85% of detected microplastics and improved several measures of red blood cell integrity and function. These results suggest that microplastic particles could be damaging red blood cells, and filtering the preservation solutions before blood is added could mitigate some of the particles' impacts.

Petriz expresses doubt that plastic shedding from prolonged storage was responsible to the storage lesions. “If 80% of the particles are present in the fluid before prolonged cell storage even takes place, attributing red blood cell ‘storage lesions’ . . . strictly to in situ bag shedding over 30 days becomes a shaky premise,” Petriz says. He adds that reported microplastic concentrations should be confirmed using standardized methods that rule out environmental contamination during sample preparation.

Other practical questions remain, including whether filtration could be incorporated into routine transfusion workflows, if alternative materials could minimize particle shedding from blood storage bags, and how microplastics in stored blood might impact transfusion recipients.

“Blood transfusion has always been and remains a safe and lifesaving procedure to millions of recipients worldwide,” D'Alessandro says. “That said, there exists ample room to improvement . . . to minimize [possible] recipient exposures.”