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A CSIC study using zebrafish cells in vitro shows that UV ageing of biodegradable bags increases their toxicity levels
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As they biodegrade, the toxicity is transferred to the compost, which may become a source of pollutants and microplastics for the soil
Photodegradation and composting increases the toxicity of plastics. | Unsplash
A study led by the Institute of Environmental Assessment and Water Research (IDAEA-CSIC) and the Institute of Agrochemistry and Food Technology (IATA-CSIC) has analysed the toxicity of compostable plastic bags, conventional plastic bags, and other recycled plastic bags in zebrafish cells. Published in the Journal of Hazardous Materials, the results show a high level of toxicity in compostable plastic bags, which increases with photodegradation: the alteration of plastic material by ultraviolet light. Although this is a preliminary study involving a small number of bags, these results are representative of degradation processes.
The experiment involved extracting compounds from the bags to analyse potential toxic substances that could be released into the environment. The toxicity of these compounds was evaluated in three different situations: directly from the bag samples; after simulated ageining with ultraviolet rays; and from the tiny fragments of the bags remaining after composting. Finally, the fertiliser resulting from the composting process of the bags was analyzed.
“We were surprised to find that cells exposed to conventional plastic bags showed no traces of toxicity. However, we did detect it in the biodegradable ones, which reduced cell viability”, explains Cinta Porte, lead author of the study and researcher at the IDAEA-CSIC.
The authors’ main hypothesis is that plastic manufacturers add chemical additives to biodegradable bags, and that these additives could be especially toxic. In addition, recycled plastic bags also showed higher levels of toxicity than conventional ones, likely because plastic additives are also introduced during the recycling process.
The researchers urge further research into the toxicity detected in biodegradable bags. They also emphasise the need for regulation of the plastic additives used in these materials.
Download the press release (in Spanish)
Wang, T., Hosseinzadeh, M., Cuccagna, A., Alakenova, R., Casademunt, P., Reyes Rovatti, A., López Rubio, A., Porte, Cinta. Comparative toxicity of conventional versus compostable plastic consumer products: An in-vitro assessment. Journal of Hazardous Materials (2023). DOI: 10.1016/j.jhazmat.2023.132123
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