Crisis on the Planet of the Apes-Plastic, the new threat?

Chimpanzees, our closest relatives, are threatened with extinction by poaching, zoonoses, fragmentation and the destruction of their natural habitat, the tropical forests. The degradation of their habitat due to agricultural expansion and the development of road infrastructures expose them to new risks including pollution.

Kibale National Park (Uganda) covers 800km² of mid-altitude forest surrounded by agricultural areas. In the northern part of this protected area, 80% of the perimeter of the Sebitoli chimpanzees' territory is surrounded by human activities (tea, maize and banana plantations, etc.) and crossed by an asphalt road with heavy traffic. In order to study the effects of anthropization on the closest primates to our species, these chimpanzees have been habituated to humans, observed and photographed, and a non-invasive health monitoring has been carried out since 2008. Samples of soil, sediment, water, fish, exhaust gases have been tested for presence of chemicals and plastic bottles along the road were collected. Chimpanzee hair from their nests and urine were also analyzed to assess chimpanzees' exposure to different types of pollution.

Facial congenital deformities and disorders of the female sexual cycle have been observed in Sebitoli chimpanzees. Three successive campaigns showed the presence of a cocktail of chemical pollutants in the rivers that cross their territory. Biological tests of this water show endocrine disruption effects on the thyroid, estrogenic and androgenic axes. Analysis of the chimpanzees' hair showed the presence of 60 pesticide-type molecules, as well as bisphenol A and S, monomers of polycarbonate plastic compounds. Markers of oxidative stress, in particular DNA degradation, were detected in the urine of chimpanzees that frequented the border and consumed maize coated with neonicotinoids.

At the heart of tropical forests, wild chimpanzees are exposed to environmental pollution from nearby agricultural areas and the thousands of soda bottles discarded along roadside. The genotoxic oxidative stress, facial malformations and reproductive disorders detected in this community are an alarming signal not only for this species, which is already highly threatened by human activities, but also for our own species. Our research will help to clarify the etiology of these disorders in this sentinel species for our health and that of our environment, and in particular to gain a better understanding of the risks associated with plastics.