A yellow-headed caracara perches on a lowland tapir. A new study found microplastics in tapirs and giant anteaters, even in remote locations in Brazil. (Photo: Raquel Alves)
Microplastics are turning up in the blood of wild animals living tens of kilometres from the nearest town. Among the animal studies, those living closer to human development and waste facilities tended to have higher concentrations of microplastics in their blood, according to a new study co-authored by UBC Okanagan researchers.
Published in Nature , the research paired blood samples from 47 free-ranging lowland tapirs and giant anteaters with high-resolution GPS tracking data. The animals were studied in three regions of Brazil: the Amazon's Arc of Deforestation, an agricultural mosaic in the Cerrado and a relatively undisturbed ranch in the Pantanal wetland.
"This is the first study to link microplastics inside a wild animal's body to where that animal lives and travels," says Dr. Michael Noonan, assistant professor of biology and head of UBCO's Quantitative Ecology Lab . "Most terrestrial microplastics research has been about detecting particles. Although researchers are finding plastics almost everywhere they look, these studies don't help us understand why certain animals have more than others.
"We wanted to understand how individual animals' movement and habitat use shaped their microplastic burdens."
Microplastics were detected in all but four of the animals. Concentrations varied widely, averaging 73.8 particles per millilitre and ranging from zero to more than 1,200. That average falls within the range previously reported in human blood.
When the team compared those burdens with where each animal had spent its time, a pattern emerged. Animals that encountered more heavily modified landscapes had higher concentrations, as did animals that lived and travelled closer to human development and waste management facilities.
But microplastics were not restricted to human-modified landscapes. The Pantanal, the world's largest tropical wetland and home to some of the highest densities of large vertebrates in South America, offers the starkest illustration of how far the problem reaches.
Every animal sampled there carried microplastics, despite living more than 65 kilometres from the nearest development and more than 112 kilometres from the nearest waste facility.
Even where the human footprint was effectively zero, the team's model still predicted a baseline of about 10 particles per millilitre. That suggests living in a remote place isn't enough to avoid exposure. The authors say that wind and water may carry microplastics into these remote areas.
The findings are particularly relevant in Brazil, where the human footprint grew by about 42 per cent between 2001 and 2020, compared with 26 per cent globally. Waste collection and treatment haven't kept pace in many rural and interior regions of the country, allowing plastics to become mobile pollutants.
The researchers emphasize that the study measured exposure, not harm.
They also stress that the work shows an association rather than direct cause and effect, and that sampling the surrounding environment alongside the animals would strengthen the link.
"We don't yet know what these particles are doing to the animals' health, and that's what worries us," says Dr. Marcia Ferraz, the study's lead author and operations manager of the Okanagan Institute for Biodiversity, Resilience and Ecosystem Services at UBC Okanagan. "Seventy-three particles per millilitre may sound small, but these animals are also dealing with habitat loss, pesticides, climate change and wildfires.
"Plastic pollution adds to those stressors. Most health studies on microplastics use unrealistically high doses, so it's unclear how their findings translate outside of the laboratory setting. Understanding the health effects of microplastics is the next step and will tell us how seriously to treat this threat."
The study also involved researchers from the Toronto Zoo, Ludwig-Maximilians-Universität München, and two Brazilian organizations: Instituto de Conservação de Animais Silvestres and Instituto de Pesquisas Ecológicas. Additional collaborators came from institutions in Brazil, Germany, Italy, the United Kingdom and the United States.
Dr. Noonan's contribution was supported by the Natural Sciences and Engineering Research Council of Canada and the Canada Foundation for Innovation.
