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Oxidative Stressafter Pollutant Exposure DependsStrongly on Experimental Design and Pollutant Properties in Annelids:A Meta-Analysis
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Scientists reviewed nearly 50 studies testing how tiny plastic particles and common pesticides cause "oxidative stress" (cell damage linked to disease) in worms, a standard way researchers gauge environmental health risks. They found results were highly inconsistent, often due to small study sizes and differences in how experiments were designed, meaning some past conclusions about these pollutants' harm may be shakier than assumed. This matters because it's a reminder that we need larger, more carefully designed studies before drawing firm conclusions about how microplastics and pesticides affect living things, including potentially humans.
Abstract Measurements of oxidative stress are often performed to assess a species’ general sublethal stress response to a pollutant. However, oxidative stress bioassays often produce seemingly ambiguous results, and the drivers that lead to these differences are largely unknown. To address this gap, we conducted a meta-analysis on reactive oxygen species (ROS) generation, ROS-associated damage products, enzyme activities, and gene expression levels in response to exposures to two groups of pollutants, nano- and microplastic particles (NMP) and neonicotinoid insecticides (neonics). Based on 2294 ROS-related measurements extracted from 45 studies, we show that measured effects vary substantially, with a strong overlap of measured effects with zero. As likely drivers of this variance, we identified multiple parameters of experimental design and pollutant properties. Finally, we performed data simulations and power analyses to investigate how well single experiments are able to detect oxidative stress-related effects. While most oxidative stress markers achieve sufficient power (80%) to demonstrate effects with sample sizes N < 20, conclusions derived from single studies with low sample sizes (N < 5) are at risk of being less informative than previously assumed. Our results highlight the importance of considering pollutant properties, experimental design, and sample size when measuring oxidative stress markers.
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Oxidative stress after pollutant exposure depends strongly on experimental design and pollutant properties: a meta-analysis
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This meta-analysis pools data from multiple studies to understand why measurements of oxidative stress from pollutant exposure, including microplastics, produce such varied results. It found that experimental design and pollutant properties strongly influence outcomes, which is important for accurately assessing the true health risks of microplastic exposure.
From conflicting studies to consistent signals: Microplastics increase mortality, oxidative stress and dose-related DNA damage in earthworms – A systematic review and meta-analysis
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This review combined results from 40 existing studies on earthworms exposed to microplastics. Higher microplastic exposure was linked to increased death rates past a certain level, dose-related DNA damage, and mixed effects on oxidative stress markers across the studies.
Effect of polyethylene microplastics on tebuconazole bioaccumulation, oxidative stress, and intestinal bacterial community in earthworms
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Researchers exposed earthworms to polyethylene microplastics of different sizes alongside a common fungicide and found that smaller microplastics caused the most severe oxidative stress and DNA damage. The microplastics also changed how much fungicide accumulated in the earthworms and disrupted their gut bacteria. This matters because earthworms are essential for soil health, and these effects could ripple through agricultural ecosystems that produce our food.
Genotoxic, Cytotoxic, and Physiological Effects of Nano- and Microplastics in Invertebrate Model Organisms: Mechanistic Integration, Adverse Outcome Pathways, and Multi-Omics Perspectives
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This review pulls together existing lab studies on tiny worms, water fleas, and other small creatures to map out exactly how micro- and nanoplastics damage cells—triggering stress, inflammation, and even changes to how genes are expressed. While these findings come from invertebrates rather than humans, the same cellular damage pathways (oxidative stress, mitochondrial problems, immune disruption) are relevant across species, suggesting plastics could pose similar risks to human cells. The catch: scientists still don't fully know if these effects are strong enough, or common enough in real-world exposure, to meaningfully harm human health—more stand
Microplastic pollution in annelids: A systematic review of species-specific impacts, toxicity pathways, and ecological risks
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This systematic review summarizes research on how microplastics affect annelid worms, which are important soil and sediment organisms. The findings show microplastics can cause oxidative stress, reproductive harm, and changes in behavior in these creatures. Since annelids play a key role in keeping soil healthy for agriculture, their exposure to microplastics could have ripple effects on the ecosystems that support our food supply.
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