Anita Jemec Kokalj

Microplastics are increasingly accumulating in agricultural soils, where they may alter microbial communities and plant–microbe interactions. Although biodegradable plastics are often considered environmentally preferable alternatives to conventional plastics, they may introduce chemically and biologically accessible components into soil. However, it remains unclear whether microplastics derived from these products alter rhizosphere soil microbiomes differently from conventional polyethylene (PE). We compared microplastics produced from a conventional PE bag and two biodegradable starch-containing poly(butylene adipate-co-terephthalate) bags intended for home (PBAT_HOME) or industrial composting (PBAT_IND). Microplastic particles were incorporated into soil at 0.5% and 1.0% (w/w dry soil), sunflower (Helianthus annuus L.) was grown for eight weeks, and bacterial and fungal communities and their annotated gene repertoires were characterized using shotgun metagenomics. Within the tested concentration range, microplastic polymer composition explained more variation in community composition than concentration. Namely, communities exposed to either PBAT type were distinct from the control and PE treatments, with fungal composition showing the clearest response. PBAT-associated indicator taxa included genera containing members linked in the literature to decomposition or anaerobic metabolism, although fungal trophic-mode ratios did not differ significantly among treatments. PBAT_IND was associated with KEGG orthologs (KOs) involved in methane metabolism and carbohydrate transport, whereas PBAT_HOME was associated with KOs related to lipid and fatty-acid metabolism. PE showed a contrasting gene repertoire associated with nitrogen acquisition and assimilation. These metagenomic patterns indicate shifts in functional potential rather than measured biogeochemical activity. Overall, starch-containing PBAT microplastics acted as biologically reactive soil inputs, selecting microbial communities and annotated gene repertoires distinct from those associated with PE. This study provides testable hypotheses about carbon and nitrogen processing induced by PBAT microplastics in planted soil.

Plastic pollution is a growing environmental concern. Bioplastics, in particular, biodegradable plastics, are increasingly promoted as sustainable alternatives to regular plastics yet their impact on the environment is currently still unresolved. Previous studies show that the general public’s understanding of these materials remains limited, particularly among younger populations. This study thus investigated the knowledge, perceptions, attitudes, and behavioral intentions of Slovenian lower and upper secondary school students regarding regular plastics, bioplastics, and biodegradable plastics. A questionnaire was administered to 697 students (12–19 years old) from schools in Ljubljana and Kamnik during the 2023/24 and 2024/25 school years. The survey assessed knowledge of bioplastics and biodegradable plastics, attitudes towards their usefulness, perceptions of their environmental impacts, evaluations of alternative packaging materials, and willingness to pay for more sustainable products as an indicator of behavioral intention. Overall knowledge scores were relatively low, indicating limited understanding of bioplastics and biodegradable plastics among students (average score: 36% of the maximum score on the five-item knowledge scale). Upper secondary students demonstrated significantly greater knowledge than lower secondary students, and female students achieved higher knowledge scores than male students. Students generally perceived bioplastics, biodegradable plastics, and paper as more environmentally beneficial than regular plastics, tin, and glass packaging. Older students and female students also expressed more favorable attitudes towards sustainable materials. Willingness to pay for environmentally friendly products was moderate and positively associated with knowledge. These findings reveal important knowledge gaps and may provide useful information for the development of educational activities addressing plastic materials and their environmental implications, as well as students’ attitudes, perceptions, and behavioral intentions towards sustainable alternatives.

Despite the widespread presence of cigarette butts in the environment, the potential toxicological effects posed by microplastics (MPs) derived from them remain poorly understood. In this study, we compared the effects of MPs from conventional cigarette butts (cellulose acetate) and heated tobacco devices (cellulose acetate and polylactic acid film), the latter being under‐investigated. We also compared their effects before and after UV‐accelerated aging. The most notable change in chemical properties of MPs following UV aging was a significant reduction in nicotine content, which fell below detection limits, while elemental composition remained largely unchanged. The surface of particles remained unchanged, but the size of heated tobacco devices cellulose acetate MPs also fragmented to smaller sizes. The effects were evaluated using Daphnia magna (48 h immobilization; 1, 10, 100 mg L ⁻¹ ), Lemna minor (168 h growth inhibition; 100 mg L ⁻¹ ), protozoan Tetrahymena thermophila (24 h, 100 mg L ⁻¹ ) and in vitro cytotoxicity test model using A549 human lung cells (24 h, 100 mg L ⁻¹ ). Toxicity tests revealed no significant effects of all types of MPs on any of used test models. UV‐aging of MPs did not change the toxicological profile. Our findings showed that cigarette butt‐derived MPs represent a complex mixture of polymers, residual nicotine, and metals. Comparing this research to previous studies suggests that MPs from different cigarette brands vary in chemical composition and toxicological potential.