Natural transformation of chlordecone into 5b-hydrochlordecone in French West Indies soils: statistical evidence for investigating long-term persistence of organic pollutants

Abstract

OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible. This is an author-deposited version published in : http://oatao.univ-toulouse.fr/ Eprints ID : 15973 Abstract 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.

Natural Chlordecone Degradation Revealed by Numerous Transformation Products Characterized in Key French West Indies Environmental Compartments

“…C3-C4 TP, less chlorinated than C1-C2 TP, appeared more frequently and at a higher level, especially in one nitisol soil (above 1 mg/kg). The low concentration of 8monohydrochlordecone (< 0.01 mg/kg) agreed with previous studies [33]. While methyl polychloroindenecarboxylates were absent of all samples, many other TP were detected at low level, including di-, tri-hydrochlordecones, tetrachloroindenes (B2, B3-B4), ethyl polychloroindenecarboxylates (E1-E2) (Figure 4 and Table S7).…”

“…The only previously reported chlordecone derivatives were chlordecol and 8monohydrochlordecone, present in FWI soils at much lower levels than chlordecone (0.03-0.5 mg/kg, and 0.05-0.2 mg/kg respectively) [33,40]. Chlordecol and 8-monohydrochlordecone were actually known contaminants from commercial chlordecone, and were as such the only chlordecone derivatives included in targeted analyses until today.…”

“…Following application, chlordecone sorbs onto soil and sediments particles, especially organic rich FWI matrices. The commonly admitted paradigm of absolute chlordecone persistence for decades/centuries in the FWI based on a leaching model [31]has been recently confirmed by two studies suggesting only marginal degradation in tropical soils, if any [32,33]. Generally, POPs pollution is assessed and followed by environmental monitoring of the parent molecule, with restricted efforts dedicated to the possible TP in situ formed and their consequences as exemplified for aldrin.…”

Microbial Degradation of a Recalcitrant Pesticide: Chlordecone

“…It is also consistently associated with an increase in the risk of prostate cancer (Multigner et al, 2010, 2016; Cordier et al, 2015; Emeville et al, 2015). Chlordecone persists in the environment (Cabidoche et al, 2009; Fernández-Bayo et al, 2013; Devault et al, 2016), and since it bioaccumulates as it moves through the food chain, it was listed in the Persistent Organic Pollutants (POPs) prohibition list of the Stockholm Convention (UNEP/POPS/POPRC.1/INF/6, 2005). …”

Detection of Adsorbed Chlordecone on Microplastics in Marine Sediments in Guadeloupe: A Preliminary Study

“…Guadeloupe Island is particularly affected by an organochlorine pesticide called chlordecone. About 300 tons of this molecule were used in banana plantations in Guadeloupe and Martinique between 1972and 1993(Devault et al 2016, which causes severe damage to the terrestrial and aquatic environment (Merlin 2015). Classified as POPs (Persistent Organic Pollutants) in the Annex A of the Stockholm Convention (i.e., to be eliminated), this pesticide is highly toxic to many organisms (MacPhee and Ruelle 1969, Roberts and Bendl 1982).…”