Exposure of wild biota to plastic additives - how much do we know and where are the current knowledge gaps?

Plastic additives are widely used in plastic production, comprising up to 70% of the polymer mass. Due to inefficient waste management, the capacity of additives to leach from polymers under environmental conditions, and their chemical persistence, they are ubiquitous across the environment. However, the exposure pathways of biota to these chemicals remain poorly characterized and insufficiently known. Certain additive groups (e.g. flame retardants and ultraviolet stabilizers) have been detected in organisms inhabiting remote places, indicating their potential for long range transportation. A review of current research reveals a predominant analytical research focus on marine organisms, while the exposure of terrestrial species to plastic additives remains underexplored. This represents a critical knowledge gap, particularly considering that many of these additives exert adverse effects on biota. Moreover, only a limited number of studies have established a link between chemical exposure and the presence of plastics in the gastrointestinal tract, underscoring the need to consider other exposure pathways such as dermal contact and respiratory uptake as routes of exposure to plastics and plastic-associated chemicals. Understanding the exposure of terrestrial organisms, especially mammals, to plastic additives is essential as an initial step towards assessing their associated risks, including for humans.