| Abstract
| - The aim of this study was to determine the transfer kinetics of soil-bound polycyclic aromatichydrocarbons to milk in lactating cows. Soil (500 g/day) fortified with fluorene (104 μg/g dry soil),phenanthrene (82 μg/g), pyrene (78 μg/g), and benzo[a]pyrene (33 μg/g) was administered to threedairy cows via a rumen cannulas for 28 consecutive days. Parent compounds and their majormetabolites in milk were measured using gas chromatography−mass spectrometry. Secretion of parentcompounds in milk did not increase significantly (P> 0.05) over the control values measured beforesupply. Target monohydroxylated metabolites were not detected in control samples, but 2-hydroxyfluorene, 3-hydroxy phenanthrene, and 1-hydroxy pyrene were present in milk by the second day ofdosing. The highest concentrations of metabolites in milk (31−39 ng/mL) were for 1-hydroxy pyreneat days 7 and 14 of dosing. The observed plateaus for 3-hydroxy phenanthrene and 2-hydroxy fluorenewere lower (respectively, 0.69 and 2.79 ng/mL) but significantly increased in comparison to the controlsamples. Contrarily, 3-hydroxy benzo[a]pyrene was not detected in milk at any sampling time. Theseresults suggested a notable metabolism of the parent compounds after their extraction from soil duringthe digestive transfer. Thus, the metabolization of fluorene and pyrene can lead to higherconcentrations of metabolites than of parent compounds in milk. Despite the absence of a significanttransfer of parent PAHs to milk, the appearance of metabolites raises the questions of their impacton human health. Keywords: PAH; metabolites; soil; cow milk; mass spectrometry
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