Claire Laurent

[14C] Milk, urine and faeces excretion kinetics in lactating goats after an oral administration of [14C]polycyclic aromatic hydrocarbons

Abstract The aim of this work was to characterize phenanthrene, pyrene, benzo(a)pyrene and TCDD transfer to milk, urine and faeces in lactating goats after a single oral ingestion (2.5 10 6 Bq ) of [ 14 C ] phenanthrene , [ 14 C ] pyrene , [ 14 C ] benzo[a]pyrene or [ 14 C ] 2,3,7,8-TCDD. Seven hours after [ 14 C ] PAHs oral ingestion, a radioactivity peak was detected in plasma for all compounds studied. Regarding excretion routes, three specific types of behaviour were noticed: 2,3,7,8-TCDD was mainly excreted in milk (7.8%) and a large part of radioactivity ingested remained in the organism (71.2%). Phenanthrene and pyrene presented a similar behaviour, with a low milk transfer (1.6% and 1.9%, respectively) and a high excretion through urine (40.4% and 11.4%, respectively) suggesting their metabolization. Benzo[a]pyrene was poorly absorbed (88% of the ingested part of this compound was detected in faeces) and radioactivity due to benzo[a]pyrene was not significantly detected in milk (0.2%).

Gas chromatography-mass spectrometry study of polycyclic aromatic hydrocarbons in grass and milk from urban and rural farms

Polycyclic aromatic hydrocarbon (PAH) levels were studied in grass and milk sampled at two farms, one located in a non-contaminated, rural area, and another located in a urban area close to PAH sources such as highways, busy roads, fuel-powered trains and a steel plant. PAH concentration were measured by gas chromatography coupled to mass spectrometry (GC-MS) using internal deuterated standards. In grasses, unexpectedly, although the sum of PAH concentrations was only slightly higher at the urban farm (83.1 ± 16.1 ng g−1) than the rural farm (51.8 ± 10.6 ng g−1), this difference was not observed for all PAH members. This absence of a striking difference of PAH levels between urban and rural grasses suggests that atmospheric PAH sources, for example, vehicle exhausts and chimney fumes, could be rapidly diluted by winds. In milk, PAH concentrations were not significantly different at urban and rural farms.

Portal absorption of 14C after ingestion of spiked milk with 14C-phenanthrene, 14C-benzo[a]pyrene or 14C-TCDD in growing pigs.

Polycyclic aromatic hydrocarbons (PAHs) and dioxins are lipophilic organic pollutants occurring widely in the terrestrial environment. In order to study the PAHs and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) transfer in the food chain, pigs have been fed with milk mixed either with 14C-phenanthrene, with 14C-benzo[a]pyrene or with 14C-TCDD. The analysis of portal and arterial blood radioactivity showed that both PAHs and TCDD were absorbed with a maximum concentration at 4-6 h after milk ingestion. Then, the blood radioactivity decreased to reach background levels 24 h after milk ingestion. Furthermore, the portal and arterial blood radioactivities were higher for phenanthrene (even if the injected load was the lowest) than these of benzo[a]pyrene or these of TCDD, in agreement with their lipophilicity and water solubility difference. Main 14C absorption occurred during the 1-3 h time period after ingestion for 14C-phenanthrene and during the 3-6 h time period for 14C-benzo[a]pyrene and for 14C-TCDD. 14C portal absorption rate was high for 14C-phenanthrene (95%), it was close to 33% for 14C-benzo[a]pyrene and very low for 14C-TCDD (9%). These results indicate that the three studied molecules have a quite different behaviour during digestion and absorption. Phenanthrene is greatly absorbed and its absorption occurs via the blood system, whereas benzo[a]pyrene and TCDD are partly and weakly absorbed respectively. However these two molecules are mainly absorbed via the portal vein.