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Effects of conventional versus biodegradable microplastic exposure on oxidative stress and gut microorganisms in earthworms: A comparison with two different soils
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Researchers compared the toxic effects of conventional polyethylene and biodegradable polylactic acid microplastics on earthworms in two different soil types. Both types of microplastic caused oxidative stress and altered gut microbiota in earthworms, with toxicity increasing at higher concentrations. The study found that microplastic concentration was more important than the type of plastic or soil in determining the level of harm, and that biodegradable plastics were not necessarily safer for soil organisms.
The ecotoxicity of microplastics (MPs) to soil animals is widely recognized; however, most studies have only focused on conventional MPs. This study compared the effects of various concentrations (0.5%, 1%, 2%, 5%, 7%, and 14%, w/w) of polyethylene (PE) and biodegradable polylactic acid (PLA) MPs on oxidative stress and gut microbes in Eisenia fetida (E. fetida) from two different soils (black and yellow soils). The results indicated that the activities of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), glutathione S-transferase (GST), and acetylcholinesterase (AchE) decreased after exposure to PE and PLA MPs for 14 days, whereas malondialdehyde (MDA) levels increased. This level of decrease or increase exhibited a "decrease-increase" trend with increasing MP exposure doses. After 28 days, the activities of SOD, CAT, POD, AchE, and GST increased, whereas MDA levels decreased, and the level of increase or decrease increased with increasing MP dose. The integrated biological response index revealed that the toxic effects of MPs were concentration-dependent, and MP concentration was more important than MP type or soil type. The toxicity of PE MPs was generally higher than that of PLA MPs on day 14, with no significant difference on day 28. Moreover, MPs did not alter the dominant gut microbiota of E. fetida, but altered the relative abundances of Actinobacteriota, Bacteroidota, Ascomycota, and Rozellomycota. Furthermore, different gut microbial phyla exhibited discrepant responses to MPs. Our results demonstrated that both conventional and biodegradable MPs induced oxidative stress in E. fetida, and biodegradable MPs showed no less toxicity compared to conventional MPs. Additionally, MP-induced toxic effects did not differ significantly between black and yellow soils, suggesting that MP-induced toxic effects were less affected by soil type.
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Response of earthworms to microplastics in soil under biogas slurry irrigation: Toxicity comparison of conventional and biodegradable microplastics
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Researchers compared the toxicity of biodegradable polylactic acid and conventional polyvinyl chloride and polyethylene microplastics to earthworms in soil irrigated with biogas slurry. They found that all microplastic types caused time-dependent toxicity, including tissue damage, oxidative stress, and disruption of antioxidant defense systems at higher concentrations. The study suggests that biodegradable microplastics may pose similar ecological risks to conventional plastics for soil organisms.
The comparison effect on earthworms between conventional and biodegradable microplastics
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Researchers compared the effects of conventional polyethylene and biodegradable polylactic acid microplastics on earthworms over an extended exposure period. They found that biodegradable microplastics caused comparable or even greater harm than conventional plastics at certain concentrations, including reduced growth and reproduction. The findings challenge the assumption that biodegradable plastics are inherently safer for soil organisms.
Toxicity comparison of multiple biodegradable and conventional microplastics on earthworms: Ingestion, tissue damage, oxidative stress, and transcriptional responses
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This study compared the toxicity of four biodegradable microplastics and conventional polyethylene microplastics on earthworms across multiple biological endpoints. Researchers found that biodegradable microplastics caused tissue damage, oxidative stress, and altered gene expression at levels comparable to or sometimes exceeding conventional plastics, challenging the assumption that biodegradable alternatives are inherently safer for soil organisms.
Soil application of PE and PLA microplastics alter earthworm (Eisenia nordenskioldi) gut bacterial community and soil microbiome-metabolome dynamics
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Researchers compared the effects of conventional polyethylene and biodegradable polylactic acid microplastics on earthworm gut bacteria and soil ecosystems over 120 days. They found that polyethylene had a more significant impact on soil microbial communities and metabolic processes than PLA at environmentally relevant concentrations. The study highlights that both types of microplastics can alter soil ecosystems, but conventional plastics may pose greater ecological risks.
Ecotoxicological effects of soil microplastic types and concentrations on earthworms
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Researchers tested the effects of conventional polyethylene and polypropylene microplastics alongside biodegradable PBAT microplastics on earthworms over 28 days. They found that PP microplastics caused significant mortality at the highest concentration, while PBAT, despite being marketed as biodegradable, induced the highest levels of DNA damage and cellular stress. The study suggests that biodegradable plastics are not necessarily less harmful to soil organisms than conventional plastics.
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