Chimpanzees contaminated with pesticides

Wild chimpanzees are exposed to a cocktail of harmful chemicals.

Pesticides and flame retardants are among the pollutants found in their feces, suggesting that the chemicals could have an impact on the health and development of primates.

Primate feces reveal how pollutants affect endangered species in the wild.

A new study has revealed that the feces of four primate species living in Uganda’s Kibale National Park, including chimpanzees and red mallard monkeys, contained significant amounts of pesticides and flame retardants.

Female primates and their young were the most affected, with researchers linking pollutants to higher levels of stress and reproductive hormones in these animals. This suggests that the compounds could disrupt the functioning of your body and potentially affect your growth and development.

Tessa Steiniche, PhD student and lead author of the study, says“ “Endocrine disorders in adolescents are of particular concern, as Exposure to these chemicals can have really lasting effects during critical phases of development.”

The researchers warn that the chemicals presented in this study could be just the tip of the iceberg, with probably more compounds affecting these primates.

“Unfortunately, the benefits of colonizing a “protected” area for these primates do not really include protection against chemical pollution,” adds Tessa. “Human activities around the park and even tourism and research inside can introduce potentially harmful chemicals.”

“It is likely that our study will only scratch the surface of the chemicals experienced by these primates.”

The results of the work were published in the journal Biology Letters.

The effects of chemical pollution on wildlife

Over the past century, pollution has increased worldwide without precedent. From microplastics in the Arctic and in our bodies to wastewater in our rivers and seas, the problem affects our lives to a degree that we do not yet fully understand.

Among the many types of pollution, chemical pollutants are perhaps the best understood. A large number of studies over the years have shown the impact they can have on life on different scales.

Thus, for example, the growth of algae can be affected by antibiotics in water by limiting their ability to photosynthesis.

At the other end of the scale, finisher cetacean are known to be affected by chemicals such as polychlorinated biphenyls (PCBs), a group of chemicals once used as a coolant. These can affect the animal’s immune system and reproduction if they accumulate in the orca’s fat.

But the methods behind such earlier research were problematic. In the past, these studies have used laboratory experiments that can ignore the impact of chemical mixtures on health or rely on samples from dead animals, which can have much higher than average levels of pollutants.

More recently, scientists have tried to solve these problems by turning to biomonitoring techniques that have allowed them to study wildlife in their own habitat.

In the current study, this meant taking fecal samples from four primate species living in Kibale National Park, including chimpanzees, olive baboons, red-tailed monkeys and Ugandan red mallard monkeys. This allowed the researchers to measure not only the pollutants themselves, but also the hormones that could affect them.

“Toxicology has undergone a Renaissance in recent decades to improve animal ethics, and fecal biomonitoring can provide a really valuable approach,” says Tessa. “Although fecal samples are not exactly the cleanest matrix to work with, the possibility of studying the effects of pollution on wildlife without any damage or manipulation is quite good.”

How are primates affected by chemical pollutants?

Analyzing the samples, the researchers found 97 different pollutants in the feces of the primates. These have been classified into three main groups: organochlorine pesticides (OCP), brominated flame retardants (BFR) and organophosphorus esters (OPE) used in the manufacture of plastics.

It is likely that the animals were exposed to these compounds by searching the farms around the national park for food and by met electrical and plastic waste in the woods.

Some chemicals were particularly abundant in primate feces, with BFR found in more than 70% of samples from all four species. Since experiments on mice have shown that mammals exposed to BFR at a young age are not very good at excreting the chemical, this may mean that BFR accumulates in these primates, exposing them to a greater risk of adverse health effects.

It is also believed that younger animals are at higher risk, as higher levels of BFR in juvenile primates were associated with lower levels of estradiol, a gender hormone, and higher levels of Cortisol, a stress hormone.

Although there are relatively few studies on the effects of these chemicals on mammals, they have been linked to problems such as liver damage, decreased hormone production, brain development and impaired immune system.

For endangered species such as the chimpanzee, the results of this study represent an additional burden for populations already under pressure. The researchers hope that future projects can build on this work to get a better idea of the contamination of other wild animals and their impact.

“My co-authors and I are interested in taking a closer look at the sources of chemical exposure in Kibale and understanding why different species are more or less sensitive to certain pollutants,” explains Tessa.

“It will also be important to include more social dimensions in our research so that the surrounding communities have the tools and resources they need to make informed decisions about the use and disposal of chemicals.”


Tessa Steiniche et al., Associations between fecal chemical pollutants and hormones in primates from Kibale National Park, Uganda, Biology Letters (2023). DOI: 10.1098 / rsbl.2023.0005. information about the journal: letters of biology.

This article by James Ashworth was first published by on May 24, 2023. mission statement: Chemical pollution has had the greatest impact on female and juvenile primates. Image Credit: NRRSander/ Shutterstock.

Related Posts

Leave a Reply

Your email address will not be published. Required fields are marked *