A new study has found microplastic particles in the blood of wild mammals living in Brazil, including animals in remote natural habitats located more than 40 miles (65 kilometres) from human infrastructure.
The research published in the journal Nature establishes a direct link between human activity and microplastic accumulation in terrestrial wildlife. Scientists found that animals living in areas with greater human disturbance and closer to waste management facilities generally had higher concentrations of microplastics in their blood.
The study focused on two mammal species: lowland tapirs and giant anteaters. Researchers examined 47 animals across Brazil’s Amazon, Cerrado and Pantanal regions.
Human Activity Linked to Higher Microplastic Levels
Microplastics are tiny plastic particles smaller than five millimetres. They can spread through the environment via wind, rain, rivers, groundwater and floods, eventually entering wildlife habitats.
Although microplastics had previously been detected in terrestrial animals, scientists lacked clear quantitative evidence connecting the level of environmental exposure to the amount accumulating inside individual animals.
To investigate this relationship, researchers collected blood samples from 26 lowland tapirs and 21 giant anteaters. They combined laboratory analysis with GPS tracking data to understand where the animals travelled and how frequently they encountered human settlements and infrastructure.
The findings revealed that 43 of the 47 animals had microplastic particles in their bodies.
Animals whose home ranges included more heavily disturbed landscapes had significantly higher microplastic concentrations in their blood. Levels were also elevated among animals living closer to waste management facilities.
The research team used GPS tracking and specialised movement analysis software called ctmm to reconstruct animal movements between recorded locations and estimate their home ranges.
This allowed scientists to examine how much time individual animals spent in different types of habitats and how closely their movements brought them to human activities.
According to co-author Professor Justin Calabrese of the Center for Advanced Systems Understanding (CASUS), the study combined wildlife movement data, laboratory measurements and detailed information about landscape disturbance.
Researchers said this interdisciplinary approach helped establish, for the first time, a clear connection between human land use and microplastic accumulation in terrestrial mammals.
One of the most concerning findings came from the Pantanal, a remote wetland region in Brazil.
Microplastics were detected in every animal sampled there, including individuals living more than 65 kilometres from human infrastructure. However, concentrations were substantially lower than those found in animals exposed to more heavily modified landscapes.
GPS data indicated that these animals had no direct exposure to human modified areas, suggesting that microplastics can travel considerable distances and reach seemingly undisturbed ecosystems.
The discovery highlights how plastic pollution can spread beyond cities and settlements affecting wildlife even in remote natural environments.
The researchers believe improved waste management around human settlements could significantly reduce microplastic contamination in wildlife.
They also suggest establishing buffer zones around nature reserves to limit the spread of pollution into protected habitats. Even small scale conservation measures, such as eliminating major sources of plastic waste near wildlife areas, could make a meaningful difference.
The findings are particularly relevant for rapidly developing countries such as Brazil, where waste management infrastructure has not always kept pace with expanding settlements in frontier regions.
The study led by wildlife conservation specialist Dr Marcia de Almeida Monteiro Melo Ferraz of the University of British Columbia, provides important evidence that human land use directly influences the pollution burden experienced by terrestrial mammals.
Researchers say reducing plastic waste at its source will be essential to protecting wildlife and preserving even the most remote ecosystems.