Impacts of real microplastic leachates on the development and behavior of developing zebrafish (Danio rerio)

Plastic pollution in aquatic environments has increased, raising concerns about the toxicity of microplastics (MPs) and their additives to developing organisms. Numerous studies have examined the physical toxicity of microplastic particles, while comparatively few have investigated the effects of their leachates, particularly on organismal neurodevelopment and behavior. Additives from the MPs can desorb into the surrounding environment, generating leachates that may impact early development. This study evaluated the effects of early developmental exposure to MP leachates on early developing zebrafish (Danio rerio), quantifying effects on larval survival, development, activity, and behavioral responses to acute stressors. MPs-acrylonitrile butadiene styrene (ABS), polyethylene terephthalate (PET), polyamide 66 (PA66), and reinforced glass fiber (MIX)-were processed into particles (<500 μm) and incubated in embryo media for 24 hours under UV-C, 35 °C, and agitation to generate leachates through accelerated weathering. Zebrafish embryos were exposed from 6 to 120 hours post-fertilization (hpf) to varying leachate dilutions (corresponding to 0.063 to 10 000 mg MPs per L). At 120 hpf, larvae were assessed for survival, prevalence of morphological defects, overall growth, baseline activity, and behavioral responses to acoustic, visual, and peripheral irritant stressors. MIX leachate significantly increased mortality, while PET leachate exposure reduced growth. No significant morphological defects were observed across treatments. ABS, PA66, and PET leachates altered larval activity and behavioral stress responses. These preliminary findings suggest that MP leachates pose varying developmental and behavioral risks to developing organisms at critical exposure concentrations. Understanding these risks is crucial for assessing the environmental impacts of MPs pollution and informing regulatory policies.