Tiny plastic particles have crossed into the bloodstream of wild tapirs and giant anteaters living inside remote South American biomes, according to a study published in Nature.
Plastic pollution is rarely viewed as a direct threat to interior terrestrial wildlife, usually remaining associated with choked oceans and urban rivers. But researchers working across Brazil have discovered that microscopic fragments now circulate through the vascular systems of mammals residing far from direct human development.
An international research team analyzed blood samples gathered between February 2021 and November 2022 from 26 lowland tapirs and 21 giant anteaters, Agencia SINC reported. The animals roamed across three distinct Brazilian regions: the Amazon, the Cerrado, and the Pantanal.
Microplastics turned up in 43 of the 47 individual animals tested, marking a 91.5% detection rate across the sample group. The average concentration reached 73.8 particles per milliliter of blood.
The heaviest systemic loads appeared in wildlife whose home ranges sustained intense human disturbance. Animals living closer to urbanized areas and waste management facilities carried significantly higher concentrations of the synthetic material.
Yet researchers found contaminated blood samples even within populations inhabiting seemingly pristine environments. In the remote Pantanal region, scientists detected particles in every animal tested, including specimens roaming more than 65 kilometers from the nearest human infrastructure and 112 kilometers from a waste treatment plant.
“El hallazgo que más nos sorprendió fue que la relación entre el uso del hábitat por parte de los animales y la cantidad de plástico presente en su sangre no difería significativamente entre las especies,” told Marcia de Almeida Monteiro Melo Ferraz, of the University of British Columbia Okanagan, to Agencia SINC.
The targeted species possess sharply contrasting foraging habits. Lowland tapirs browse on plants, giant anteaters consume ants and termites while swallowing large amounts of soil, and giant armadillos operate as opportunistic omnivores.
“Observar un efecto constante de los cambios en el uso del suelo por parte de los seres humanos sobre la carga de microplásticos en sangre sugiere que la dieta no es el único factor que determina la ingestión de estos contaminantes,” Monteiro Melo Ferraz told Agencia SINC.
Scientists note that these fragments can travel long distances through the atmosphere, carried onward by rain, river currents, groundwater networks, and seasonal floods. Animals consequently face exposure without interacting directly with modified terrain.
“Por tanto, existen varias vías posibles para que estas partículas se dispersen por el territorio,” Monteiro Melo Ferraz told Agencia SINC. “Aunque los mecanismos todavía no están del todo claros, lo que sí podemos afirmar es que los animales no parecen necesitar interactuar directamente con paisajes modificados por el ser humano para estar expuestos a contaminantes de origen antropogénico, como los microplásticos.”
The published study did not assess the clinical health status of the captured animals, leaving direct biological consequences unmeasured. Previous laboratory experiments involving other organisms show that ultra-fine particles can breach biological membranes, pool inside tissues, and trigger toxic responses.
When testing bovine reproductive cells in vitro, the same research team observed that synthetic particles damaged sperm and oocytes.
“Los microplásticos afectan a los espermatozoides y los ovocitos y perjudican la reproducción,” Monteiro Melo Ferraz told Agencia SINC.
The team captured, examined, and released every animal safely, pairing blood extractions with GPS tracking coordinates. This methodology allowed researchers to map individual movements against surrounding land use without relying on post-mortem tissue collection.
Blood testing provides a direct measure of internal circulation, whereas fecal sampling only confirms what an animal recently swallowed. Fecal matter cannot establish whether fragments crossed the intestinal lining or simply passed through the digestive tract.
The study remains limited by its inability to track where circulating particles ultimately lodge within specific organs.
“En esta nueva fase también recogeremos muestras ambientales para comparar la contaminación presente en los organismos con la del entorno y estudiar las posibles fuentes y vías de exposición,” Monteiro Melo Ferraz told Agencia SINC.
| Species Analyzed | Sample Size | Region | Collection Window |
|---|---|---|---|
| Tapirus terrestris (Lowland Tapir) | 26 | Amazon, Cerrado, Pantanal | Feb 2021 – Nov 2022 |
| Myrmecophaga tridactyla (Giant Anteater) | 21 | Amazon, Cerrado, Pantanal | Feb 2021 – Nov 2022 |
Additional reporting from 20Minutos corroborated the nationwide scope of the sampling effort across Brazil.
