Effects of environmental concentrations of chlordecone (insecticide), glyphosate-based herbicide and imazalil (fungicide) in mixture on reproductive rate, morphology and DNA damage in the freshwater Hydra vulgaris

International audience ; Between 1972 and 1993, 300 of tons of the organochlorine insecticide chlordecone (C10Cl10O, CLD) were dumped in the banana plantations of the French West Indies (FWI) to eradicate the black banana weevil (Cosmopolites sordidus). Today, almost all of their water and soil is contaminated and will remain so until remedial action is taken, if at all. Also, in 1999, massive water pollution in FWI was revealed as well as contamination of the majority of the population. The results of a monitoring conducted by the French Water Board showed that 130 phytosanitary products were detected: 40% herbicides, 30% insecticides and 23% fungicides. Among them, the herbicide glyphosate and the fungicide imazalil (IMAZ) were the still frequently detected (Wintz & Pak, 2021). In rivers, CLD concentrations was up to 100 µg/L due not only to erosion and runoff but also to a widely used herbicide, glyphosate. Indeed, glyphosate causes increased soil erosion and leads to the release of stable CLD stored in the soils of polluted fields (Sabatier et al., 2021). Imazalil, a possible human carcinogen according to the U.S. EPA, is a fungicide that was notably used in post-harvest treatment to control storage diseases. Banned for this use as of May 2019, it appears to be initiating a slow decline in impacted rivers (Wintz & Pak, 2021). The objective of this work was to evaluate, in the cnidarian Hydra vulgaris, Pallas, 1766, the effects of chronic exposure to mixtures of CLD, IMAZ, and a glyphosate-based herbicide (GBH) at environmental concentrations found in FWI rivers. Because multiscale studies evaluating multiple biological responses from the molecular to the population level should be emphasized in environmental toxicology, reproductive rates, morphological damage, and DNA integrity were determined after 14-day exposure. Three concentrations of CLD (0.1, 10, and 20 μg/L) were combined with a cocktail of IMAZ and GBH at two concentration levels: the lowest level (1 µg/L IMAZ and 2 µg/L active ingredient ...