Multi-level ecotoxicity of biodegradable microplastic to aquatic organisms: A meta-analysis

Biodegradable plastics are increasingly used as sustainable alternatives to conventional plastics; however ecotoxicity of biodegradable microplastics (BMPs) remains poorly understood. Here, we performed a systematic meta-analysis of 717 endpoints from 28 independent studies to evaluate BMP ecotoxicity to aquatic organisms. Five endpoints-oxidative stress, behavior, growth, reproduction, and survival-were quantified using Hedges' g values under a random-effects model, with subgroup and meta-regression analyses to identify drivers of heterogeneity. BMPs significantly increased oxidative stress (Hedges' g = 0.645) and impaired behavior (Hedges' g = -2.358), reproduction (Hedges' g = -1.821), and growth (Hedges' g = -0.864), while survival effects were not significant. Behavioral disruption was the most pronounced outcome, followed by reproductive and growth inhibition. Polymer-specific risks were evident: PBS and PHB impaired growth and behavior, whereas PHB and PGA reduced reproduction and survival; PLA toxicity was strongly size-dependent but less evident at environmentally relevant concentrations. High heterogeneity across taxa, particle sizes, and exposure conditions highlighted the complexity of BMP toxicity. These findings demonstrate that BMPs pose non-negligible risks to aquatic ecosystems. As production of biodegradable plastics expands globally, BMP-specific data should be incorporated into risk assessments, regulatory frameworks, and the design of safer, truly sustainable plastics.