Reduction of PCB bioavailability by condensation of organic matter: assessment of linearity and concentrations in tissues of orally exposed piglets.

International audience

English. Risk assessment of Polychlorobiphenyls (PCB) contaminated soils is a critical point in sanitary management all the more that few reliable information on transfer of PCBs to humans via involuntary soil ingestion is available. Indeed, young children with their hand-to-mouth activity may be concerned by an exposure to contaminated soils. In order to assess the possible impact of soil Organic Matter (OM) condensation onto bioavailability of NDL-PCBs a study completed in two parts was designed. The first study investigated the dose-response relationships in selected tissues. The second study t was subsequently completed to evaluate the incidence of organic matter condensation on NDL-PCBs levels in target tissues. In the first study, eight male piglets were orally exposed during 10 days to one of the four levels (190, 560, 940 and 1 310 ng NDL-PCBs.Kg-1 of Body Weight (BW) per day) of a corn oil spiked by Aroclor 1254. NDL-PCBs concentrations in adipose tissue, in liver and in muscles were determined for each congener by GC-MS after extraction and purification. Except for PCB 28, the analyzed levels were above the LOQs. A regression analysis showed a significant linear relationship between the administrated doses and the levels measured in the various adipose tissue, liver and muscle (R²>0.70) in a range of dose of 190 ng to 1310 ng NDL-PCBs. Kg-1 of BW.In the second study, three Artificial Soils (AS) were prepared according to OECD guideline 207,. One Standard Soil (SS), containing no organic matter, and two amended versions of this SS with Fulvic Acid (FA) or Activated Carbon (AC) were prepared to obtain 1% mass of organic. This study involved fourteen young male swine randomly distributed into 4 contaminated groups (3 replicates) and a control one (2 replicates). During 10 days, the piglets were fed AS or a corn oil spiked with 19 200 ng of Aroclor 1254 per g of dry matter (6 000 µg/g of NDL-PCBs) to achieve an exposure dose of 1.2 µg NDL-PCBs.Kg-1 of BW. Variance analyses were performed onto resulting levels of NDL-PCBs into tissues as repeated measures using MIXED procedure of SAS software. Significant treatment effect and two distinct groups of treatments were found: on one hand oil, SS and FA, on the other hand control and AC. This study highlights that condensed OM (AC) strongly reduces bioavailability whereas less condensed part (FA) doesn’t seem to have a significant effect.