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Relative bioavailability of soil-borne PCB in laying hens and dairy goats

The degree of contamination depends not only on the soil POP concentration and the amount of soil ingested, but also on the bioavailability of the compounds ingested, or in other words the capacity of the soil to retain the POP it contains in the digestive tracts of animals

chèvre et poule. © Christine Lansard, Christine Lansard
Updated on 05/24/2013
Published on 05/24/2013

Soil is a reservoir for persistent organic pollutants (POP) such as dioxins, furans or PCB (polychlorinated biphenyls).  The organic pollutants present in soil may be ingested by livestock and thus contaminate the products arising from them, such as eggs from free-range hens or milk from ruminants.  The degree of contamination depends not only on the soil POP concentration and the amount of soil ingested, but also on the bioavailability of the compounds ingested, or in other words the capacity of the soil to retain the POP it contains in the digestive tracts of animals.  These values are determined by means of relative bioavailability (RB) studies during which the response of animals to the ingestion of increasing doses of a pollutant is compared with that seen following ingestion of the same amount of pollutant contained in a reference substrate (often oil).

The aim of this study was to determine the relative bioavailability (RB) in laying hens and dairy goats of I-PCBs (indicator PCBs*) present in a polluted soil.  In August 2008, a fire affecting a store of treated timber contaminated the surrounding sandy soil.  The I-PCBs  content of this soil reached 709 ng/g dry matter.  For 14 days, 28, 24-week old laying hens placed in separate cages received feed contaminated by either 3%, 6% or 9% of this soil or by contaminated oil that would achieve the same level of contamination as that found with the added soil.  Similarly, eight Alpine dairy goats were fed for 96 days (three periods of 32 days) with feed contaminated by either increasing doses of contaminated soil (1.3%, 2.7% and 4%) or with contaminated oil that would achieve the same level of contamination as that found with the added soil.  The I-PCBs  levels in the eggs and milk from these animals were then measured.

In laying hens, the I-PCBs  content in eggs increased linearly with the quantity of I-PCBs ingested, and did not differ as a function of the type of substrate (soil or oil), with an estimated RB of 0.95.  However, in the goats, I-PCBs from the soil led to a milk PCB 1 content which was almost half that seen with the contaminated oil, with an estimated RB of 0.5.

The soil used during this study did not limit the bioavailability of I-PCBs in laying hens, but it halved that seen in dairy goats.  This considerable ability of the hens to extract these compounds from the soil could be linked to the low energy conversion ratio of birds, supported by their high level of digestive efficiency.  However, in both species, the ingestion of soil contributed significantly to the risk of contamination of animal products by I-PCBs.  It is now necessary to perform studies on other soil types and in other animal species.

 

 

* Among the different PCB congeners, seven are found particularly in contaminated products and generally account for nearly 50% of all PCBs.  Their assay is therefore used to quantify the contamination of a product by PCBs, and they are referred to as indicator PCBs.

Contact(s)
Scientific contact(s):

  • Catherine JONDREVILLE (+33(0)3 83 59 61 98) Contract-based Unit for the Animal and Functionalities of Animal Products (AFPA)
Associated Division(s):
Animal Physiology and Livestock Systems
Associated Centre(s):
Grand Est - Nancy

For further information

  • Fournier, A., Feidt, C., Travel, A., Le BIzec, B., Marchand, P., Jondreville, C., 2012, Relative bioavailability to laying hens of indicator polychlorobiphenyls present in soil,Chemosphere, 88, 300-306.
  • Feidt, C., Ounnas F., Julien-David D., Jurjanz, S., Toussaint, H., Jondreville C., Rychen G., 2012, Relative bioavailability of soil-bound Polychlorinated Biphenyls in lactating goats, submitted
  • Jondreville C., Fournier A. , Ounnas F., Julien-David D., Marchand P. , Vénisseau A., Le Bizec B., Travel A., Rychen G., Feidt C., 2011, Relative bioavailability of indicator polychlorobiphenyls present in soil to farm animals: laying hens and lactating goats.30th International Symposium on Halogenated Environmental Organic Pollutants and POPs, Brussels, Belgium, 21st-25th August 2011