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The biodegradation of polylactic acid microplastic and their toxic effect after biofouling in activate sludge
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This study tested whether biofouling (natural coating by microorganisms) changes how toxic biodegradable PLA microplastics are to water fleas. Fresh PLA microplastics significantly reduced survival and reproduction, but after four weeks of biofouling, the coated particles were much less harmful. However, the PLA only degraded 50% over 28 days, showing that even biodegradable plastics persist in the environment long enough to cause harm before breaking down.
Biodegradable microplastics (MPs) can form biofilms through interactions with various microorganisms in aquatic system and can be exposed to organisms. This study first investigated biodegradability of polylactic acid (PLA) MPs and the characterization of PLA MPs before/after biofouling (4 weeks) and their toxic effects on the freshwater invertebrate Daphnia magna. The biodegradability rate of PLA MPs was up to 50% over 28 days, suggesting that even biodegradable MPs do not easily decompose under environmental conditions. Furthermore, biofouling of MPs led to an increase in size and, in the process, induced an additional functional peak in the PLA MPs. The exposure of biofouled MPs did not lead to a reduction in survival, reproduction, or growth during chronic exposure, nor did it cause feeding inhibition in juvenile (<4 days old) D. magna. However, pristine MPs significantly reduced survival, reproduction, and growth at concentrations of 5.0 mg L. Overall, pristine MPs caused inhibition of reproduction and growth and high mortality in D. magna, while the biofouling process did not induce these effects. Our findings highlight the complex interactions between MPs and biological components in aquatic environments, emphasizing the importance of considering biofouling dynamics when assessing the ecological impacts of biodegradable MPs.
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Multi-level toxicity assessment of polylactic acid (PLA) microplastics on the cladoceran Daphnia magna
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Researchers tested the toxicity of microplastics made from polylactic acid (PLA), a common bioplastic marketed as an eco-friendly alternative, on water fleas over 21 days. The PLA microplastics caused oxidative stress, depleted energy reserves, and reduced reproduction, though effects were generally milder than those reported for conventional plastics. This study challenges the assumption that bioplastics are harmless once they break down in the environment.
Chronic toxicity of biodegradable microplastic (Polylactic acid) to Daphnia magna: A comparison with polyethylene terephthalate
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Scientists compared the toxicity of biodegradable PLA microplastics with conventional PET microplastics on water fleas and found that PLA was actually more harmful. At higher concentrations, PLA microplastics killed nearly half the organisms, reduced reproduction, and increased birth defects more than PET particles did. This challenges the assumption that biodegradable plastics are safer for the environment, suggesting they may pose similar or even greater ecological risks than conventional plastics.
Ecotoxicity of polylactic acid microplastic fragments to Daphnia magna and the effect of ultraviolet weathering
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Scientists compared the toxicity of biodegradable PLA (polylactic acid) microplastics with conventional polyethylene microplastics on water fleas, a key species in aquatic food chains. The biodegradable PLA microplastics were actually more acutely toxic than conventional ones, partly because their higher density led to greater accumulation in the organisms. UV weathering further increased the toxicity of PLA microplastics, challenging the assumption that biodegradable plastics are automatically safer for the environment.
Toxicity comparison of polylactic acid and polyethylene microplastics co-exposed with methylmercury on Daphnia magna
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Researchers compared the toxicity of biodegradable polylactic acid microplastics with conventional polyethylene microplastics, both alone and in combination with methylmercury, on water fleas. The biodegradable microplastics caused greater harm, significantly reducing survival and reproduction while also increasing mercury accumulation in the organisms. The findings challenge the assumption that biodegradable plastics are always safer for the environment, suggesting they may actually enhance the toxicity of co-occurring pollutants.
Increased adsorption of diflubenzuron onto polylactic acid microplastics after ultraviolet weathering can increase acute toxicity in the water flea (Daphnia magna)
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Researchers found that UV-weathered biodegradable polylactic acid microplastics absorbed significantly more of the pesticide diflubenzuron than conventional PET microplastics, leading to greater toxicity in water fleas. The weathering process created more surface cracks and functional groups on the biodegradable plastic, increasing its ability to carry harmful chemicals. The study challenges the perception that biodegradable plastics are inherently safer, showing they may actually enhance pesticide toxicity in aquatic environments after environmental aging.
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When a large batch of papers lands in the Atlas, we read through it and send a short write-up of what stood out.