Chlordecone was widely used in banana fields from 1972 to 1993 to control the weevil, a major insect pest of these crops. In 1993, the organochlorine insecticide was banned because of its toxicity, held responsible, among other things, for the very large number of prostate cancers observed in Guadeloupe and Martinique.

Why, almost thirty years after its ban, is chlordecone still found in large quantities in the environment?

Scientists have studied two areas partially covered by banana plantations and sugar cane fields:  The Peru River basin in Guadeloupe and the Galion River basin in Martinique. They took cores of marine sediments near the mouths of the rivers and analyzed them.

The verdict is indisputable:  For more than 20 years, chlordecone has come back storming in the fine sediments of the coastal rivers of the two islands, inducing widespread environmental contamination. The researchers questioned glyphosate, a herbicide used since the late 1990s in the West Indies. By destroying plant roots, it promoted soil erosion, which released the chlordecone stored in polluted fields.

The interdisciplinary team of chemists, agronomists and geologists managed to understand the fate of chlordecone and to anticipate its long-term consequences.

In addition, since glyphosate is used worldwide, the ecotoxicological risks raised by the use of this herbicide in soils containing persistent pesticides must now be assessed.

The study was coordinated by the Université Savoie Mont-Blanc (USMB), in collaboration with the LSCE, the Center for International Cooperation in Agronomic Research for Development (CIRAD), agricultural institutions and West Indian agricultural producers.