Pollution

Pollution

Assessing the Environmental Safety of Biodegradable Plastics: PLA Microplastic-Induced Stress Responses in Eisenia Fetida

Document Type : Original Research Paper

Authors
Nazima Noor
Chandan M V
M Keerthana
Srinivas V
Kaveri M
Department of Zoology, Bangalore University, Bangalore, Karnataka, India
10.22059/poll.2026.402229.3332
Abstract
Agricultural soils are among major sinks of microplastics (MPs), which have become an alarming problem in today’s environment. While polylactic acid (PLA) is widely advertised as a biodegradable and environmentally friendly material, its persistence in natural soil raises a question whether it is really safe. This study aims to examine the sublethal effects of PLA MPs on Eisenia fetida by measuring alterations in multiple biological characteristics at four different concentrations (0.5, 1.0, 1.5, and 2.0 g/kg soil) across three exposure durations (12, 24, and 36 days). All variables studied were both concentration and time dependent. SOD and CAT activities exhibited irregular changes at different concentrations and time points. At higher concentrations and longer exposure, depletion of antioxidants was observed. Also, the neurotoxicity response to AChE activity presented a complex pattern from low to high concentrations. Higher concentrations reduced the SGR, especially at mid-term exposure time. While the reproduction was greatly decreased with increased concentrations and time. The survival rate remained at 100% until day 12 but exhibited decline during the mid and long-term studies. The tissue damage assessment revealed that the harm to tissues occurred in accordance with both dose levels and duration of exposure. The results show that PLA microplastics, which can decompose in theory, present actual toxicological hazards to earthworms when found in natural soil environments. This study demonstrates that environmental risk assessments for biodegradable plastics, as alternative to conventional plastics, require more detailed and rigorous testing before their widespread commercial implementation.
Keywords
Microplastics
Polylactic acid (PLA)
Eisenia fetida
Antioxidant
Neurotoxicity and Histopathology
Subjects
Aebi, H. (1984). Catalase. Methods in Enzymology, 105, 121–126.
Angmo, D., Dutta, R., Singh, J., Chowdhary, A. B., Quadar, J., & Vig, A. P. (2023). Biochemical responses, growth and reproduction of earthworm in low density polyethylene (LDPE). Environmental Quality Management, 33(2), 223–237.
Baihetiyaer, B., Jiang, N., Li, X., He, B., Wang, J., Fan, X., Sun, H., & Yin, X. (2023). Oxidative stress and gene expression induced by biodegradable microplastics and imidacloprid in earthworms (Eisenia fetida) at environmentally relevant concentrations. Environmental Pollution, 323, 121285.
Baihetiyaer, B., Jiang, N., Li, X., Song, J., Wang, J., Fan, X., Zuo, Y., & Yin, X. (2023). Exploring the toxicity of biodegradable microplastics and imidacloprid to earthworms (Eisenia fetida) from morphological and gut microbial perspectives. Environmental Pollution, 337, 122547.
Briones, M. J. I., Ostle, N. J., McNamara, N. P., & Poskitt, J. (2009). Functional shifts of grassland soil communities in response to soil warming. Soil Biology & Biochemistry, 41(2), 315–322.
Büks, F., & Kaupenjohann, M. (2020). Global concentrations of microplastics in soils – a review. Soil, 6(2), 649–662.
Cole, M., Lindeque, P., Halsband, C., & Galloway, T. S. (2011). Microplastics as contaminants in the marine environment: A review. Marine Pollution Bulletin, 62(12), 2588–2597.
Corradini, F., Meza, P., Eguiluz, R., Casado, F., Huerta-Lwanga, E., & Geissen, V. (2019). Evidence of microplastic accumulation in agricultural soils from sewage sludge disposal. Science of the Total Environment, 671, 411–420.
de Souza Machado, A. A., Hempel, S., Rillig, M. C., Kloas, W., & Zarfl, C. (2018). Microplastics as an emerging threat to terrestrial ecosystems. Global Change Biology, 24(4), 1405–1416.
de Souza Machado, A. A., Lau, C. W., Till, J., Kloas, W., Lehmann, A., Becker, R., & Rillig, M. C. (2018). Impacts of microplastics on the soil biophysical environment. Environmental Science & Technology, 52(17), 9656–9665.
Ding, L., Luo, T., Wang, X., Ouyang, Z., Lu, G., Zhang, W., Yao, H., & Zhu, L. (2021). Effects of thresholds for plant-derived microplastics on earthworm health and sludge properties during sewage sludge treatment. Science of the Total Environment, 802, 149962.
Ding, W., Li, Z., Qi, R., Jones, D. L., Liu, Q., Liu, Q., & Yan, C. (2021). Effect thresholds for the earthworm Eisenia fetida: Toxicity comparison between conventional and biodegradable microplastics. Science of the Total Environment, 781, 146884.
Edwards, C. A., & Bohlen, P. J. (1996). Biology and ecology of earthworms (Vol. 3). Springer Science & Business Media.
Ellman, G. L., Courtney, K. D., Andres, V., & Featherstone, R. M. (1961). A new and rapid colorimetric determination of acetylcholinesterase activity. Biochemical Pharmacology, 7(2), 88–95.
Gutiérrez-Rial, D., Represas, D., Carral, E. V., & Rodríguez, T. (2025). Short- and medium-term effects of biodegradable microplastics (PLA and PHB) on earthworm development and reproduction. Ecotoxicology. Advance online publication.
Haider, T. P., Volker, C., Kramm, J., Landfester, K., & Wurm, F. R. (2019). Plastics of the future? The impact of biodegradable polymers on the environment and on society. Angewandte Chemie International Edition, 58(1), 50–62.
Han, Y., Fu, M., Wu, J., Zhou, S., Qiao, Z., Peng, C., Zhang, W., Liu, F., Ye, C., & Yang, J. (2023). Polylactic acid microplastics induce higher biotoxicity of decabromodiphenyl ethane on earthworms (Eisenia fetida) compared to polyethylene and polypropylene microplastics. Science of the Total Environment, 862, 160909.
Huerta-Lwanga, E., Mendoza-Vega, J., Ribeiro, O., Gertsen, H., Peters, P., & Geissen, V. (2021). Is the polylactic acid fiber in green compost a risk for Lumbricus terrestris and Triticum aestivum? Polymers, 13(5), Article 703.
Humason, G. L. (1979). Animal tissue techniques (4th ed.). W. H. Freeman.
Hurley, R., & Nizzetto, L. (2018). Fate and occurrence of micro(nano)plastics in soils: Knowledge gaps and possible risks. Current Opinion in Environmental Science & Health, 1, 6–11.
International Organization for Standardization. (1998). Soil quality – Effects of pollutants on earthworms – Part 2: Determination of effects on reproduction (ISO 11268-2).
Ivar do Sul, J. A., & Costa, M. F. (2014). The present and future of microplastic pollution in the marine environment. Environmental Pollution, 185, 352–364
Jeong, J., & Choi, J. (2019). Adverse outcome pathways potentially related to hazard identification of microplastics based on toxicity mechanisms. Chemosphere, 231, 249–255.
Lai, H., Li, X., Zhang, M., Liu, Y., Wang, H., & Chen, J. (2024). The comparison effect on earthworms between conventional (polyethylene) and biodegradable (polylactic acid) microplastics. Heliyon, 10(24), e41339.
Lambert, S., & Wagner, M. (2017). Microplastics are contaminants of emerging concern in freshwater environments: An overview. In M. Wagner & S. Lambert (Eds.), Freshwater microplastics (pp. 1–23). Springer.
Liang, Y., He, D., Pan, Y., Wang, Y., Zhang, T., Tao, S., & Peng, J. (2025). Reassessing whether biodegradable microplastics are environmentally friendly: Differences in earthworm physiological responses and soil carbon function impacts. Antioxidants, 14(10), 1197.
Liwarska-Bizukojc, E. (2025). Evaluation of the impact of polylactide microparticles on soil biota. Environmental Science and Pollution Research, 32, 21187–21197.
Misra, H. P., & Fridovich, I. (1972). The role of superoxide anion in the auto-oxidation of epinephrine and a simple assay for superoxide dismutase. Journal of Biological Chemistry, 247, 3170–3175.
Nizzetto, L., Futter, M., & Langaas, S. (2016). Are agricultural soils dumps for microplastics of urban origin? Environmental Science & Technology, 50(20), 10777–10779.
Organisation for Economic Co-operation and Development. (1984). Test No. 207: Earthworm, acute toxicity tests. OECD Publishing.
Organisation for Economic Co-operation and Development. (2004). Test No. 222: Earthworm reproduction test (Eisenia fetida/Eisenia andrei) (OECD Guidelines for the Testing of Chemicals, Section 2). OECD Publishing.
Parolini, M., De Felice, B., Gazzotti, S., Sugni, M., & Ortenzi, M. A. (2024). Comparison of the potential toxicity induced by microplastics made of polyethylene terephthalate (PET) and polylactic acid (PLA) on the earthworm Eisenia foetida. Environmental Pollution, 348, 123868.
Pokarzhevskii, A. D., Van Straalen, N. M., & Semenov, A. M. (2000). Agar as a medium for removing soil from earthworm guts. Soil Biology and Biochemistry, 32, 1315–1317.
Prendergast-Miller, M. T., Katsiamides, A., Abbass, M., Sturzenbaum, S. R., Thorpe, K. L., & Hodson, M. E. (2019). Polyester-derived microfibre impacts on the soil-dwelling earthworm Lumbricus terrestris. Environmental Pollution, 251, 453–459.
Qi, R., Jones, D. L., Li, Z., Liu, Q., & Yan, C. (2020). Behavior of microplastics and plastic film residues in the soil environment: A critical review. Science of the Total Environment, 703, 134722.
Sibly, R. M., & Calow, P. (1989). A life-history theory of responses to stress. Biological Journal of the Linnean Society, 37(1–2), 101–116.
Sommer, F., Dietze, V., Baum, A., Sauer, J., Gilge, S., Maschowski, C., & Gieré, R. (2018). Tire abrasion as a major source of microplastics in the environment. Aerosol and Air Quality Research, 18(8), 2014–2028.
Spurgeon, D. J., Svendsen, C., Hankard, P. K., & Weeks, J. M. (2003). Review of sublethal endpoints for earthworm ecotoxicological assessment. European Journal of Soil Biology, 39(2), 201–210.
Suleiman, H., Rorat, A., Grobelak, A., Grosser, A., Milczarek, M., Płytycz, B., Kacprzak, M., & Vandenbulcke, F. (2017). Determination of the performance of vermicomposting process applied to sewage sludge by monitoring of the compost quality and immune responses in three earthworm species. Bioresource Technology, 241, 103–112.
Teng, Y., Zhang, X., & Zhou, W. (2025). Environmental impacts of polylactic acid microplastics on soil and aquatic ecosystems: A comprehensive review. Journal of Environmental Sciences. Advance online publication.
Wang, F., Wang, Q., Adams, C. A., Sun, Y., & Zhang, S. (2021). Polylactic acid and polypropylene carbonate microplastics affect growth and reproduction in earthworm Eisenia fetida. Science of the Total Environment, 791, 148206.
Wang, H., Zhang, L., Guo, X., & Ren, J. (2022). Histopathological effects and oxidative stress induced by mixed microplastics in earthworm Eisenia fetida. Ecotoxicology and Environmental Safety, 239, 113657.
Weithmann, N., Möller, J. N., Löder, M. G. J., Piehl, S., Laforsch, C., & Freitag, R. (2018). Organic fertilizer as a vehicle for the entry of microplastic into the environment. Science Advances, 4(4), eaap8060.
Yang, Y., Liu, W., Zhang, Z., Grossart, H.-P., & Gadd, G. M. (2021). Comparative toxicity of biodegradable and conventional plastics to earthworms. Journal of Hazardous Materials, 401, 123429.
Zhang, S., Ren, S., Pei, L., Sun, Y., & Wang, F. (2023). Toxicological effects of polyethylene and polylactic acid microplastics on earthworms. Chinese Journal of Applied and Environmental Biology, 29(2), 322–327.
Zhu, D., Yang, K., Gul, Y., Song, W., Zhang, X., & Wang, W. (2014). Effect of photoperiod on growth and gonadal development of juvenile topmouth gudgeon (Pseudorasbora parva). Environmental Biology of Fishes, 97, 147–156.
Pollution
Volume 12, Issue 4
Autumn 2026
Pages 1026-1044