Domestic researchers announced that soil contaminated with microplastics can weaken the immunity of organisms.
The National Research Foundation of Korea noted on the 22nd that a joint research team led by Professors Ahn Yoon-joo from Konkuk University and Hyeon Young-min from Yonsei University confirmed that earthworms exposed to microplastics are vulnerable to infections. The research findings were published online in the Journal of Hazardous Materials in March.
Currently, there is an increase in environmental toxicity assessment studies considering soil contamination by microplastics; however, there are nearly no studies identifying the immunotoxicity of soil-dwelling organisms, including earthworms, which play a crucial role in the soil biological food web.
The research team exposed the red wiggler earthworm, a species native to Korea, to polystyrene microplastics measuring 1 µm (micrometer, one-millionth of a meter). Observations revealed that the microplastic particles entered a type of immune cell called "amoebocyte" within 30 minutes.
In cases where the earthworms were exposed to microplastics for 24 hours, no phenomenon of immune cell death was observed. However, the phagocytic ability of immune cells that eliminate E. coli noticeably decreased starting at a microplastic concentration of 1 mg/L. E. coli is a pathogen commonly found in soil.
In another experiment where earthworms were exposed to soil contaminated with microplastics at a concentration of 0.1% for two weeks, there was no significant effect on the survival of the earthworms, but immune cell function was weakened. The phagocytic activity decreased by approximately 40% compared to the control group, while endocytosis, the process of bringing external liquid substances into the cells, decreased by about 29%.
Professor Ahn Yoon-joo stated, "This study is the first to report that the phagocytic activity of earthworm immune cells, which actively eliminate pathogens in soil contaminated with microplastics, is compromised," adding that "it holds scientific significance."
References
Journal of Hazardous Materials(2025), DOI: https://doi.org/10.1016/j.jhazmat.2025.137946