PCB decontamination in accidentally exposed heifers

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Rychen, Guido | Fournier, Agnès | Marchand, Philippe | Dugny, François | Grunwald, Anne-Laure | Toussaint, Hervé | Delannoy, Matthieu | Le Bizec, Bruno | Feidt, Cyril

Edité par CCSD -

International audience. European Union regulation has defined maximum levels for polychlorinated dibenzop-dioxins, polychlorinated dibenzofurans (PCDD/Fs) and dioxin-like polychlorinatedbiphenyls (PCBs) in food from animal origin (Regulation N°1259/2011/EU) and in products intended for animal feed (Regulation N°277/2012/EU). Livestock exposed to contaminated forage or soil results in meat or milk unfit for human consumption. Until recently management of these crises involved euthanasia of animals. The question arising is to know if bovines contaminated by dioxin-like compounds may be decontaminated and further used for their initial purpose.The aim of this experiment was to study the decontamination process of eight young accidentally PCB contaminated heifers (“Limousine” breed) removed from their area and fed a non contaminated diet based on hay and grass silage, supplemented by corn and minerals, to allow a daily weight gain of about 1000 g/d. Every two months the animals were weighed and submitted to pericaudal biopsies. Pericaudal fat samples and experimental feed were analyzed for DL-PCBs and NDL-PCBs (ASE extraction and GC-HRMS equipped with a DB-5MS column using the SIM acquisition mode). The eight heifers (weighing 337±21 kg) showed a rather high initial PCBs concentration in fat tissue (from 25-28 pg WHO2005-TEQ/g fat). During the experimental period the kinetics of each DL-PCB and NDL-PCB congener followed an exponential decrease mainly related to the weight gain of the animals. After 120 dof depuration, the NDL-PCBs levels were found to be below the threshold value (40 ng/g fat) and after 180 d, the DL-PCBs+PCDD/Fs level was also below the threshold value (4 pg WHO2005-TEQ/g fat) for all animals. During this 6 months experiment the mean weight gain of the animals was 180 kg and at the end of this period all heifers were then considered as decontaminated. The estimated half-life is about 40 to 50 days for PCBs.This study indicates that the decontamination process mainly via dilution process during the growing is feasible. However, the length of the process also depends on the initial level of contamination and the changes in adipose tissue of animal.

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