Animals, like humans, are taking up increasing amounts of tiny plastic particles. Such microplastics are demonstrably hazardous to many species under experimental conditions and it is suspected that they may also pose a threat to animals in the wild. While data about microplastic concentrations in the terrestrial environment exist, it has not yet been clear if higher exposure also translates into higher microplastics accumulation in individual animals. A new paper published in Nature (DOI: 10.1038/s41586-026-11285-x ) now confirms this link. Co-author Prof. Justin Calabrese, research team leader at the Center for Advanced Systems Understanding (CASUS) at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR), made a decisive contribution to this study with his expertise in animal movement analysis.
Microplastics are pieces of plastic smaller than 5 mm. They can travel through the atmosphere and may also be carried by rain, rivers, groundwater, and floods. Microplastics have previously been found in terrestrial wildlife but a quantitative link to microplastics sources has so far been missing.
"It is widely assumed that a higher microplastic exposure in more human-disturbed areas results in higher microplastic burdens in the animals' bodies," says Calabrese. "But to really provide evidence of that was an ambitious effort as we needed to combine in vivo microplastic measurements of free-living wild animals, with fine-scale movement data and high-resolution landscape disturbance data. Such integrated datasets simply did not exist." The scientists, led by wildlife conservation specialist Dr. Marcia de Almeida Monteiro Melo Ferraz ( University of British Columbia , Kelowna, Canada), focused on lowland tapirs (Tapirus terrestris) and giant anteaters (Myrmecophaga tridactyla) in Brazil.
"The study is highly interdisciplinary as it required very tight integration of methods used in the field, the laboratory, and by us data scientists," adds Calabrese. "The inherent difficulty in that kind of cross-discipline integration is exactly why no one else has managed to do this so far." At the end of the data acquisition the scientists had blood samples for microplastics analysis as well as movement and habitat data. More specifically, the team focused on 26 lowland tapirs and 21 giant anteaters living across the Amazon, Cerrado, and Pantanal regions of Brazil. They used GPS (Global Positioning System) tracking data on these animals to examine where the animals went and how close they were to human activity and infrastructure.
Animal movement ecology
For the Nature study, researchers used, among other tools, the open-source software package ctmm (continuous-time movement modeling), which can reliably estimate the path animals took between two recorded GPS data points. The software was also used to model the animals' home ranges. "The ctmm package uses GPS tracking data to reconstruct and analyze animal movements. In this way, it helps researchers understand how animals use their habitat—that is, where they move and how much time they spend in each area," explains Calabrese. The movement analysis framework developed by his group over the past 15 years was thus a central component of this study.
Analysis of the samples revealed that 43 of the 47 tapirs and anteaters had microplastic particles in their bodies. As expected, concentrations in the blood were significantly higher among free-ranging animals whose home ranges included more intensive human disturbance. Concentrations were also higher among those living closer to waste management facilities. "Our goal was to understand how the areas and habitats that animals move through influenced their uptake of microplastics. Animals moving in more disturbed areas, or in closer proximity to human infrastructure, do indeed tend to have higher microplastic burdens, and our paper is the first to demonstrate this linkage for terrestrial mammals," says Calabrese. The authors conclude that improved management of waste around human settlements could greatly reduce microplastic levels in wildlife. The finding is of special importance for rapidly developing countries like Brazil where waste management infrastructure lags behind rapidly expanding human settlements in frontier areas.
No humans, but microplastics in the blood nonetheless
Microplastics were also found in every animal sampled in the remote and seemingly pristine wetland region called Pantanal, including some individuals living more than 65 km from human infrastructure. The concentrations in the blood were substantially lower, though. According to the GPS data, these animals had no direct exposure to human-modified landscapes.
This result indicates that microplastics are widely dispersed even in relatively remote terrestrial environments. In areas affected by human activity, microplastic burden in animals could potentially be reduced by establishing buffer zones around nature reserves. In local conservation efforts, even small-scale measures—such as eliminating the primary sources of microplastic pollution in the immediate vicinity—can already be extremely beneficial.
