Fish study links aged PLA microplastics to blood-cell changes

An experiment in rainbow trout found that exposure to biodegradable polylactic acid, or PLA, microplastics was associated with changes in the balance and activity of several blood-cell populations, including cells involved in immune defense. Fish exposed to particles aged under simulated sunlight showed more noticeable changes in red-blood-cell shape and distinct shifts in immune-related activity than fish exposed to newly prepared particles, according to researchers Difei Tong and Wen-Xiong Wang. The peer-reviewed findings were published in Environmental Chemistry and Ecotoxicology and indicate that the biological response to a biodegradable plastic may vary with the condition of its particles after environmental exposure.

The study examined blood as a potential indicator of responses to microplastics. Blood contains different cell populations and travels throughout the body, allowing the researchers to assess changes across immune-related cells as well as red blood cells rather than examining only one internal organ. To make tiny PLA particles visible under a microscope, Tong and Wang used fluorescent labels, then examined how the particles interacted with blood cells.

For a more detailed view of the responses of individual cell populations, the researchers used single-cell RNA sequencing to characterize gene activity in blood cells. This analysis revealed changes in the balance and activity of several types of blood cells following PLA microplastic exposure, particularly among cells associated with immune defense. The researchers also reported evidence suggesting that exposure could affect how blood cells communicate with one another.

These observations were experimental associations in rainbow trout; the release did not establish that PLA particles caused a specific disease mechanism, and the results do not show that comparable effects occur in humans or across all biodegradable plastics. Environmental aging was central to the findings. The researchers prepared aged PLA particles by exposing the material to simulated sunlight before conducting the blood-cell comparisons.

Samples from fish exposed to these aged particles showed more pronounced changes in red-blood-cell shape, together with distinct differences in immune-related activity. Because the cellular responses differed between aged and newly prepared particles, evaluating PLA only in its original condition may not fully represent its behavior after environmental alteration. The results do not establish that sunlight aging always increases the hazards of biodegradable plastics; instead, they show that the particle condition changed the cellular responses observed under the conditions tested.

Tong and Wang said the work could encourage broader use of blood-based approaches for investigating environmental pollutants. Because different blood-cell populations respond to stress, examining them may provide a wider view of an organism’s response to microplastics and help researchers identify potential hazards. The authors also said the results underline the need to consider how biodegradable materials change as they age rather than treating biodegradability alone as assurance of safety.

The evidence remains limited to the experimental species, PLA formulation, exposure conditions and analytical methods used in this study, so the findings do not provide a general measure of risk to people or a universal ranking of biodegradable plastics. The authors declared that they had no known competing financial interests or personal relationships that could have influenced the work.

Subject of Research: Experimental blood-cell responses in rainbow trout exposed to biodegradable PLA microplastics

Article Title: Scientists uncover hidden risks of biodegradable plastics through fish blood

Article References: Scientists uncover hidden risks of biodegradable plastics through fish blood. Original publication (Bibliographic details unavailable.)

Image Credits: AI Generated

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Keywords: PLA microplastics, rainbow trout, blood cells, single-cell RNA sequencing, immune response, environmental aging, microplastics, ecotoxicology, cellular stress, Scientists, uncover, hidden