Nanoplastics (NPs) are particles ranging in size between 1 and 1000 nm, and they are a form of environmental contaminant of great ecotoxicological concern. Although NPs are widespread across ecosystems, they have only recently garnered growing attention from both the scientific community and regulatory bodies. The present study reviews scientific literature related to the exposure and effects of NPs and identifies research gaps that impede the finalization of related environmental risk assessments (ERAs). Approximately 80 articles published between 2012 and 2021 were considered. Very few studies (eight articles) focused on the presence of NPs in biotic matrices, whereas the majority of the studies (62 articles) assessed the lethal and sublethal effects of NPs on aquatic and terrestrial organisms. Whilst many studies focused on nude NPs, only a few considered their association with different aggregates. Amongst NPs, the effects of polystyrene are the most extensively reported to date. Moreover, the effects of NPs on aquatic organisms are better characterized than those on terrestrial organisms. NP concentrations detected in water were close to or even higher than the sublethal levels for organisms. An ERA framework specifically tailored to NPs is proposed.

Tire particles (TPs) are one of the main emission sources of micro- and nano-plastics into the environment. Although most TPs are deposited in the soil or in the sediments of freshwater and although they have been demonstrated to accumulate in organisms, most research has focused on the toxicity of leachate, neglecting the potential effects of particles and their ecotoxicological impact on the environment. In addition, studies have focused on the impact on aquatic systems and there are many gaps in the biological and ecotoxicological information on the possible harmful effects of the particles on edaphic fauna, despite the soil ecosystem becoming a large plastic sink. The aim of the present study is to review the environmental contamination of TPs, paying particular attention to the composition and degradation of tires (I), transport and deposition in different environments, especially in soil (II), the toxicological effects on edaphic fauna (III), potential markers and detection in environmental samples for monitoring (IV), preliminary risk characterization, using Forlanini Urban Park, Milan (Italy), as an example of an urban park (V), and risk mitigation measures as possible future proposals for sustainability (VI).

A growing number of studies have reported the toxic effects of nanoplastics (NPs) on organisms. However, the focus of these studies has almost exclusively been on the use of polystyrene (PS) nanospheres. Herein, we aim to evaluate the sublethal effects on Daphnia magna juveniles of three different NP polymers: PS-NPs with an average size of 200 nm, polyethylene [PE] NPs and polyvinyl chloride [PVC] NPs with a size distribution between 50 and 350 nm and a comparable mean size. For each polymer, five environmentally relevant concentrations were tested (from 2.5 to 250 μg/L) for an exposure time of 48 h. NP effects were assessed at the biochemical level by investigating the amount of reactive oxygen species (ROS) and the activity of the antioxidant enzyme catalase (CAT) and at the behavioral level by evaluating the swimming behavior (distance moved). Our results highlight that exposure to PVC-NPs can have sublethal effects on Daphnia magna at the biochemical and behavioral levels. The potential role of particle size on the measured effects cannot be excluded as PVC and PE showed a wider size range distribution than PS, with particles displaying sizes from 50 to 350 nm. However, we infer that the chemical structure of PVC, which differs from that of PE of the same range size, concurs to explain the observed effects. Consequently, as PS seems not to be the most hazardous polymer, we suggest that the use of data on PS toxicity alone can lead to an underestimation of NP hazards.

The aim of this study was to evaluate the effects of chronic exposure (21 days) to an environmentally relevant concentration (10 μg/L) of two different nanoplastic (NP) polymers on the aquatic model organism Daphnia magna. This study examined the impact of exposure to 200 nm polystyrene nanoplastics (PS-NPs) and polyvinyl chloride nanoplastics (PVC-NPs), which had an average size similar to that of PS-NPs (ranging from 50 nm to 350 nm). The effects of polymer exposure on morphometric parameters, number of molts, swimming behaviour, and reproductive outcomes were evaluated. The findings indicate that PVC exposure induced higher body dimensions, while both polymers resulted in an increase in molting behaviour. Moreover, exposure to PVC-NPs had a negative impact on the reproduction of D. magna, as evidenced by a delay in the day of the first brood, a reduction in the total number of offspring produced, and, consequently, a slower population growth rate. It is hypothesised that the ingestion of PVC-NPs by D. magna may have resulted in an impairment of ecdysone hormone functionality and that the increased moulting events potentially representing an adaptive response to the negative effects of PVC-NP adhesion to the organism's body surfaces. These two organisms' responses could concur to explain the observed effects. This study identified the fitness impairments caused by exposure to PVC-NPs, which can lead to relevant ecological consequences. The comparative analysis of the effects induced by two types of polymers has revealed the generation of disparate hazards to D. magna. Furthermore, the chemical composition appears to be a pivotal factor in the onset of these effects. It can therefore be stated that PS is not a suitable standard for representing the toxicity of all plastics.

This study investigated the behavioural responses of the arthropods Folsomia candida (springtails) and Porcellionides pruinosus (woodlice) to leachates released from additive-free plastic polymers. Avoidance behaviour was evaluated to assess potential reductions in soil habitat function, while aggregation status was investigated to highlight possible functional impairments in the woodlice population. Leachates from pristine and artificially aged low-density polyethylene (LDPE) and polypropylene (PP) microplastics were tested at three different concentrations, ranging from environmentally relevant levels to a worst-case scenario of soil contamination. The distinct physicochemical structures of LDPE and PP led to different release compounds. The results revealed no statistically significant avoidance responses in arthropods for either treatment. Unlike PP, LDPE induced a statistically significant impairment of gregarious behaviour at the highest tested concentration (150 mg/kg d.w.). Furthermore, pristine LDPE induced more pronounced disaggregation than the aged one, suggesting that weathering may modulate behavioural responses depending on polymer type and endpoint. Therefore, it is recommended that high levels of plastic leachates can have an adverse effect on soil arthropods and that the aggregation behaviour of woodlice may be a more informative and sensitive biological endpoint than avoidance alone.