Key points: Researchers detected microplastics in the stomachs of two Juruá red howler monkeys out of 47 examined in a protected area of the Brazilian Amazon—the first record of plastic ingestion in a tree-dwelling primate. Likely exposure routes include contaminated floodwaters and plastic debris snagged in trees. The finding adds to growing evidence of plastics in wildlife and human food chains and underscores the importance of reducing unnecessary plastic use and developing removal technologies.
Microplastics Found in Amazon Howler Monkeys — First Evidence of Plastic Ingestion in Tree-Dwelling Primates
Key points: Researchers detected microplastics in the stomachs of two Juruá red howler monkeys out of 47 examined in a protected area of the Brazilian Amazon—the first record of plastic ingestion in a tree-dwelling primate. Likely exposure routes include contaminated floodwaters and plastic debris snagged in trees. The finding adds to growing evidence of plastics in wildlife and human food chains and underscores the importance of reducing unnecessary plastic use and developing removal technologies.
12:34 PM, 11/15/2025Environment
Microplastics detected in Juruá red howler monkeys in protected Amazon forest
Researchers have reported the presence of microplastic particles in the stomachs of Juruá red howler monkeys living in a protected region of the Brazilian Amazon, marking the first documented case of plastic ingestion by a tree-dwelling primate.
The study examined digestive contents from 47 howler monkeys whose remains were provided over decades by subsistence hunters cooperating with local communities. Microplastics were identified in the guts of two individuals. Although the occurrence was infrequent, lead author Anamélia de Souza Jesus of the Mamirauá Institute in Tefé, Amazonas, cautioned that "still that's already a lot," underscoring concern that plastics are reaching environments previously considered protected.
"Finding microplastics in preserved environments sounds an alarm," the researcher told Mongabay.
The team suggests several likely exposure routes: these Amazonian forests are seasonally flooded for roughly half the year, so contaminated river water may introduce particles into the canopy and food sources; additionally, plastic debris such as fishing nets can become entangled in trees as floodwaters recede.
Wider context and potential impacts
This finding adds to mounting evidence that plastic pollution affects wildlife worldwide. For example, a recent study reported a green sea turtle carrying up to 26.4 grams of plastic — roughly the volume of 10 ping-pong balls. Microplastics have also been increasingly detected in human food and bodies: a 2024 study reported these particles in 90% of tested protein sources, including tofu, chicken, and beef.
Laboratory and animal studies are beginning to reveal potential health impacts. One pig study suggested microplastics may disrupt the nervous control of digestion, and research in mice has linked exposure to chronic kidney disease. However, scientists emphasize that this field is still developing and that more research is needed to determine long-term risks for wildlife and humans.
What can be done?
Experts recommend reducing unnecessary plastic use as a practical first step: choose reusable water bottles instead of single-use containers, switch to shampoo bars to avoid plastic packaging, and support better waste-management practices locally and globally. Researchers are also developing removal and remediation techniques, such as using processed agricultural waste to extract microplastics from soil and testing filtration and treatment methods to remove them from water.
The discovery of microplastics in Amazonian howler monkeys highlights how deeply plastic pollution has penetrated ecosystems once regarded as relatively untouched and reinforces the need for coordinated actions to reduce plastic inputs and improve environmental monitoring.