Microplastics — particles less than 5mm in size — have been found in every habitat on Earth, from ocean trenches to mountain snowfields. Their welfare impacts on wildlife are increasingly well-documented and deeply concerning.
Microplastic welfare harms operate at the cellular, individual, and population level. Inflammation, oxidative stress, and chemical toxicity from ingested microplastics cause chronic physiological harm that impairs immune function, reproduction, and neurological health. Fish larvae that ingest microplastics preferentially over natural prey face nutritional shortfall alongside toxicological insult. Seabirds feeding chicks plastic fragments cause malnutrition and gut damage in birds too young to eject boluses. The scale of microplastic distribution means essentially no wild animal in aquatic environments is unaffected. Reducing microplastic input — through wastewater treatment, tyre and brake material reduction, and synthetic textile filtration — directly reduces ongoing welfare harm at ecosystem scale.