All plastic contains additives. Once in the environment, these will start to leach out and will expose and harm aquatic biota, causing potentially lethal and sub-lethal toxic effects. Even though life cycle assessment covers the toxic impacts of several thousands of chemicals, models to assess the toxic impacts of plastic additives are only emerging. We gathered 461 data points from the literature (266 for freshwater and 195 for marine ecosystems) for 75 species belonging to 9 different phyla. The endpoints effective concentration and lethal concentration, no observed effects concentrations and lowest observed effect concentration tested in acute and chronic exposure, were harmonized into chronic values by applying extrapolation factors. The collected data points covered 75 main plastic additives. This allowed us to calculate 25 Effect factors, 19 for single chemicals and four for overarching categories (alkylphenols, benzophenones, brominated flame retardants and phosphates. In addition, we calculated an aggregated effect factor for chemicals that did not fit in any of the previous groups, as well as a Generic effect factor including 404 gathered data points. The estimated potentially affected fraction (PAF) for the single additives varied between 20.69 PAF·m³·kg^-1 for diethyl phthalate and 11081.85 PAF·m³·kg^-1 for 4-Nonylphenol. The factors can in future be combined with fate and exposure factors to derive a characterization factor for toxicity caused by additives in aquatic species. This is an important advancement for the assessment of the impacts of plastic debris on aquatic species, thus providing information for decision-makers, as well as guiding policies for the use of additives, ultimately aiming to make the plastic value chain more sustainable.

Porous stones are widely used in historical constructions and represent a major component of built cultural heritage. Their conservation commonly depends on multiple single-function products, such as consolidants, hydrophobic agents, biocides, or cleaning agents, which are often toxic and environmentally burdensome. This study performs an environmental assessment of a novel multi-function product designed for the sustainable conservation of porous stones and compares it with other conservation treatment alternatives. This product integrates green chemistry and nanotechnology through a water-based alkoxysilane modified with layered double hydroxide (LDH) particles. Laboratory and field tests on Portuguese monuments demonstrated suitable technical performance, including high substrate compatibility, effective consolidation depth, durable hydrophobicity, biocidal effect, and minimal visual alteration. To evaluate its environmental performance, a life cycle assessment (LCA) was carried out, from cradle-to-grave. The system boundaries encompassed production, application, and transportation stages, with 1 m² of treated sandstone surface as the functional unit. LCA was performed using CML-IA and ReCiPe methodologies in the SimaPro software. The results revealed the extent of environmental impacts of the novel product, addressing the multi-function strategy compared with conventional products and treatment scenarios. They identified critical life cycle stages for improvement to further enhance environmental performance across scenarios, particularly the influence of perfluorodecyltrimethoxysilane on the environmental burden of the novel product. Overall, this study demonstrates the value of LCA as a design and decision support tool for developing sustainable, multifunctional materials for cultural heritage conservation.