Dozens of contaminants are found in the feces of chimpanzees and three other primate species
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Primates living in Uganda have 97 chemical pollutants in their digestive tract, some of which are linked to hormonal changes in females and young primates.
Chemical pollutants have reached every corner of our planet, making exposure to these often harmful substances in air, food and water almost inevitable for both humans and wildlife. To find out how these affect wild primates, researchers used a minimally invasive sampling method: collecting feces.
In two months in 2017, Tessa Steiniche at Indiana University and her colleagues collected a total of 71 stool samples from chimpanzees (Pan cavemen), olive baboons (Papio anubis), red colobus (Piliocolobus tephroscele) and red-tailed monkeys (Cercopithecus ascanius) in Uganda’s Kibale National Park.
The researchers tested the poop using chemical analysis and found 97 contaminants, most of which are known to disrupt the action of hormones in mammals. Pesticides and flame retardants, both present in the samples, are examples of such contaminants.
The team also tested hormone levels. Across all species, females with higher concentrations of pesticides in their feces were more likely to have higher levels of cortisol — a stress hormone that helps regulate metabolism and the immune system. The researchers found a similar pattern in young primates, where greater concentrations of flame retardants in poop were associated with higher cortisol and lowered levels of the reproductive hormone estradiol.
“Our results showing effects in young animals are especially concerning,” says Steiniche, because early exposure to these chemicals during development can have lifelong effects. She says the team will need to monitor the primates long-term to see how these toxins affect their growth and reproduction.
This is a wake-up call to those who see national parks as places free from human influence. “I think we still have an idealized view of wild primates living in beautiful, undisturbed habitats, but the unfortunate reality is that even protected areas are not protected from the effects of pollution,” says Steiniche.
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