Kaolinic clay derived PCDD/Fs in the feed chain from a sorting process for potatoes

L.A.P. Hoogenboom, M. Zeilmaker, J. van Eijkeren, K. Kan, M. Mengelers, D.M.A.M. Luykx, W.A. Traag

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At the end of 2004, during a routine monitoring project, high levels of PCDDs in milk from two farms were found. Using a bioassay and the congener patterns obtained by HRGC/HRMS, the source was traced back to the use of kaolinic clay for sorting potatoes in a production process of French fries. Rest products, especially peelings after scrubbing, were used as feed for dairy cows. Levels of PCCD/Fs in this product amounted to 44 ng WHO1998-TEQ kg(-1) (88% dw). The maximum level observed in milk was 20 pg WHO1998-TEQ g(-1) fat. A Physiologically Based PharmacoKinetic (PB-PK) model was used to model three data obtained before eliminating the source in order to estimate the starting time of the contamination of the cows, the steady-state level after prolonged contamination and the kinetics of the decrease in the levels after removal of the source. Samples of milk were continuously collected for several months showing a decrease to levels below the product limit of 3 pg WHO1998-TEQ g(-1) fat within 2 months, in excellent agreement with the decrease predicted by the PB-PK model. Different batches of clay were sampled and analysed, showing varying levels of especially PCDDs. All clays were confirmed to be kaolinic clay using X-ray analysis. Other by-products used for animal feed were also contaminated and led to precautionary measures at a few hundred farms, especially pig farms. However, levels in other animal derived products like pig meat did not exceed the product limits
Original languageEnglish
Pages (from-to)99-105
Issue number2
Publication statusPublished - 2010


  • dibenzo-p-dioxins
  • ball clay
  • united-states
  • contamination
  • pcbs
  • incident
  • pcdfs
  • milk
  • food
  • origin

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    Hoogenboom, L. A. P., Zeilmaker, M., van Eijkeren, J., Kan, K., Mengelers, M., Luykx, D. M. A. M., & Traag, W. A. (2010). Kaolinic clay derived PCDD/Fs in the feed chain from a sorting process for potatoes. Chemosphere, 78(2), 99-105. https://doi.org/10.1016/j.chemosphere.2009.10.016