Glitter is a distinctive and largely overlooked form of primary microplastic. Unlike more commonly studied microplastics, glitter particles are typically flat, highly reflective, multi-layered, and are composed of polymers such as polyethylene terephthalate, polyvinyl chloride with metallic coatings and a wide range of additives. In response to regulatory restrictions on intentionally added microplastics and increasing consumer demand, “eco-friendly” alternatives based on modified regenerated cellulose, cellulose nanocrystals, or mica have been introduced, although their environmental safety remains insufficiently characterized. This review synthesizes current knowledge on the environmental occurrence and ecotoxicological effects of both conventional and biodegradable glitters. A systematic literature search in Scopus identified 15 peer-reviewed experimental studies meeting predefined inclusion criteria. Evidence spans a wide range of taxa, including bacteria (i.e., Aliivibrio fischeri), microalgae and cyanobacteria (i.e., Phaeodactylum tricornutum, Raphidocelis subcapitata, Microcystis aeruginosa), aquatic plants (i.e., Lemna minor, Egeria densa), marine and freshwater invertebrates as crustaceans (i.e., Daphnia magna), bivalves (i.e., Mytilus galloprovincialis), sea urchins (i.e., Paracentrotus lividus), brine shrimp (Artemia sp.) and terrestrial soil fauna (Eisenia fetida, Folsomia candida). Results indicate that glitter cannot be treated as a uniform stressor: biological responses vary markedly with particle size, shape, colour, polymer type, additive composition, and weathering time, and leachates often exert stronger effects than intact particles. Reported impacts include impaired photosynthesis and growth, oxidative stress, developmental abnormalities, altered energy metabolism, and reduced reproduction. Substantial gaps remain regarding environmental concentrations, ageing processes, mixture effects, and long-term ecological consequences, particularly for biodegradable glitters. Addressing these gaps will require realistic exposure scenarios, mesocosm and field studies, and integrated chemical–biological approaches to support robust risk assessment and safer material design.

Procambarus clarkii (red swamp crayfish) exhibits physiological plasticity that enables adaptation to variable freshwater conditions, such as those in Lake Trasimeno. This study examined whether fluctuations in hydrometric level and associated physicochemical parameters affect oxidative stress responses in the hepatopancreas and abdominal muscle of male and female individuals. Superoxide dismutase, catalase, glutathione peroxidase, and metallothionein reveal tissue, sex, and season-specific differences that indicate adaptive physiological adjustments. Temporal trends were evaluated, and multivariate analyses summarised environmental and metal gradients. Generalised Additive Models (GAMs) were used to explore relationships between oxidative responses and these gradients, with sex as a categorical factor. Associations were identified with hydrometric level, temperature, conductivity, transparency, pH, dissolved oxygen, and metals of biological relevance. These results highlight the remarkable physiological plasticity of P. clarkii, which underpins its success as an invasive species in fluctuating freshwater ecosystems.

Glitter is an intentionally manufactured microplastic widely used in consumer products and industrial applications, yet public awareness of its environmental implications remains poorly investigated. This study assessed public awareness, perceptions of environmental impact, and consumer behaviour through a 14-question online survey completed by 610 respondents. A study-specific Glitter Awareness Score (GAS; theoretical range: 0–7) combined prior awareness of glitter as a microplastic with knowledge of its applications across six industrial sectors. Overall, 59.3% of respondents recognised conventional glitter as a microplastic, and the mean GAS was 5.37 ± 1.55. Despite this awareness, 90.2% of respondents providing a classifiable response reported not checking the type of material used for glitter before purchase. Most respondents perceived glitter as having a moderate or significant environmental impact, and GAS was weakly positively associated with perceived environmental impact. Age was independently associated with GAS, with respondents aged >40 years showing lower odds of being in a higher GAS category than those aged 15–20 years. Furthermore, 89.6% reported a self-perceived informational benefit from completing the questionnaire. These findings suggest that environmental awareness does not necessarily correspond to more environmentally informed self-reported purchasing behaviour, highlighting the need for improved consumer information on glitter composition and environmental implications.

Freshwater ecosystems are increasingly threatened by microplastics (MPs), yet field evidence linking MP burden with physiological responses in freshwater bivalves remains limited. This study investigated the associations between individual MP burden and oxidative stress biomarkers in the freshwater mussel Unio elongatulus collected from the Sacchetti Ditch, northeastern Italy. Mussels were sampled bimonthly over a 10-month monitoring period. The activities of superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, glutathione S-transferase, glyoxalase I, glyoxalase II, and lactate dehydrogenase, together with metallothionein levels, were determined in the gills and digestive gland. Significant associations with MP burden were detected for glyoxalase II and lactate dehydrogenase in the digestive gland and for glutathione S-transferase in the gills. MP burden was negatively associated with glutathione S-transferase and lactate dehydrogenase activities and positively associated with glyoxalase II activity. Most biomarkers also showed significant variation among sampling periods, indicating substantial temporal variability. Although the observational design does not allow causal relationships to be established, GST, GII, and LDH were the biomarkers most consistently associated with individual MP burden. These biomarkers may therefore represent promising candidates for inclusion in integrated biomonitoring approaches aimed at assessing MP-associated sublethal stress in freshwater ecosystems.