Natural transformation of chlordecone into 5b-hydrochlordecone in French West Indies soils : statistical evidence for investigating long-term persistence of organic pollutants Crop protection and environmental health : legacy management and new concepts Devault, D. A. Laplanche, C. Pascaline, H. Bristeau, S. Mouvet, C. /Macarie, Hervé Kepone Curlone Pesticides Banana Martinique Hierarchical Bayesian modelling Data censoring Chlordecone (CLD) was an organochlorine insecticide whose previous use resulted in an extensive pollution of the environment with severe health effects and social consequences. A closely related compound, 5b-hydrochlordecone (5b-hydroCLD), has been searched for and often detected in environmental matrices from the geographical area where CLD was applied. The current consensus considered that its presence was not the result of a biotic or abiotic dechlorination of CLD in these matrices but rather the consequence of its presence as impurity (synthesis by-product) in the CLD released into the environment. The aim of the present study was to determine if and to what extent degradation of CLD into 5b-hydroCLD occurred in the field. To test this hypothesis, the ratios of 5b-hydroCLD and CLD concentrations in a dataset of 810 soils collected between 2006 and 2012 in Martinique were compared to the ratios measured in 3 samples of the CLD dust commercial formulations applied in the banana fields of French West Indies (FWI) and 1 sample of the technical-grade CLD corresponding to the active ingredient used in such formulations. Soil data were processed with a hierarchical Bayesian model to account for random measurement errors and data censoring. Any pathway of CLD transformation into 5b-hydroCLD occurring over the long term in FWI soils would indeed change the ratio of 5b-hydroCLD/CLD compared to what it was in the initially applied formulations. Results showed a significant increase of the 5b-hydroCLD/CLD ratio in the soils-25 times greater in soil than in commercial formulations-which suggested that natural CLD transformation into 5b-hydroCLD over the long term occurred in these soils. Results from this study may impact future decisions for the remediation of the polluted areas. Devault, D.A. (ed.) /Macarie, Hervé (ed.) Lemoine, S. (ed.) 2016 text https://www.documentation.ird.fr/hor/fdi:010066130 fdi:010066130 Devault D. A., Laplanche C., Pascaline H., Bristeau S., Mouvet C., Macarie Hervé. Natural transformation of chlordecone into 5b-hydrochlordecone in French West Indies soils : statistical evidence for investigating long-term persistence of organic pollutants. In : Devault D.A. (ed.), Macarie Hervé (ed.), Lemoine S. (ed.), . Crop protection and environmental health : legacy management and new concepts 2016, 23 (1), 81-97 Colloque Annuel du Groupement Français des Pesticides (GFP), 44., Fort-de-France (MTQ), 2014/05/26-29 EN MARTINIQUE