Plastics are polymers modified with organic and inorganic additives, constituting their formulation. Various compounds added to plastics or included in them as non-intentionally added substances can facilitate or inhibit the environmental degradation of plastics. For example, antioxidants and ultraviolet light stabilizers are added to plastics to protect them from thermal degradation during processing and photochemical degradation during outdoor use. Because plastics are typically thermally processed, most plastic products contain antioxidants, which can prolong plastic lifetimes compared to additive-free plastics. Other additives can intentionally (e.g., pro-oxidants, photocatalysts, enzymes, or microbes ) or inadvertently (e.g., pigments , catalyst residues, and unsaturated bonds 21 ) enhance degradation. Additionally, the amount of polymer used to make a product can be reduced using fillers, thereby reducing lifetimes in proportion to the amount of filler used. While additives may prove helpful for reducing environmental lifetimes, their potential harm to human health and the environment must also be appreciated. Moreover, the intrinsic toxicity of plastic will require an MI to inform design decisions. Ecocompatible plastics must be made from ecocompatible polymers and ecocompatible additives.