1.4.9 Kinetics and metabolism
Polycyclic Aromatic Hydrocarbons are lipophilic compounds that are readily absorbed from the lungs following inhalation, the gastrointestinal (GI) tract following ingestion and the skin following dermal exposure (ASTDR, 1995). In humans, it was reported that B(a)P measured in the lungs following inhalation of soot particles was much lower than expected. This may be due to the ability of the pulmonary epithelial cells to metabolise B(a)P thereby facilitating its absorption and clearance from the lungs (IPCS, 1998). Occupational studies have inferred that inhaled PAHs are absorbed by humans, as urinary metabolites were present in workers exposed to PAHs (ASTDR, 1998). The absorption of B(a)P following inhalation is highly dependent on the type of particles onto which it is adsorbed. Pulmonary absorption often occurs in parallel with mucociliary clearance, by which PAHs that are absorbed onto inhaled particulates are cleared out of the pulmonary tree and subsequently swallowed (IPCS, 1998; DEFRA, 2002). Few data were available regarding the absorption in humans following ingestion, but in general it is thought to be low (ASTDR, …show more content…
Similarly, rapid absorption was demonstrated in rats, monkeys and guinea pigs. No data were available regarding the distribution of PAHs in humans. In-vivo, PAHs appear to be widely distributed following both inhalation and ingestion, as levels have been detected in several organs (IPCS, 1998; ASTDR, 1995). Following oral exposure in rats B(a)P was measured in the kidney, caecum, small intestine, trachea, stomach and testes, whereas following inhalation, levels were measured in the liver, oesophagus, stomach and small intestine, and later in the large intestine and caecum (ASTDR, 1990, 1990a 1990b; DEFRA, 2002; RAIS, 1994). B(a)P
Polycyclic Aromatic Hydrocarbons are lipophilic compounds that are readily absorbed from the lungs following inhalation, the gastrointestinal (GI) tract following ingestion and the skin following dermal exposure (ASTDR, 1995). In humans, it was reported that B(a)P measured in the lungs following inhalation of soot particles was much lower than expected. This may be due to the ability of the pulmonary epithelial cells to metabolise B(a)P thereby facilitating its absorption and clearance from the lungs (IPCS, 1998). Occupational studies have inferred that inhaled PAHs are absorbed by humans, as urinary metabolites were present in workers exposed to PAHs (ASTDR, 1998). The absorption of B(a)P following inhalation is highly dependent on the type of particles onto which it is adsorbed. Pulmonary absorption often occurs in parallel with mucociliary clearance, by which PAHs that are absorbed onto inhaled particulates are cleared out of the pulmonary tree and subsequently swallowed (IPCS, 1998; DEFRA, 2002). Few data were available regarding the absorption in humans following ingestion, but in general it is thought to be low (ASTDR, …show more content…
Similarly, rapid absorption was demonstrated in rats, monkeys and guinea pigs. No data were available regarding the distribution of PAHs in humans. In-vivo, PAHs appear to be widely distributed following both inhalation and ingestion, as levels have been detected in several organs (IPCS, 1998; ASTDR, 1995). Following oral exposure in rats B(a)P was measured in the kidney, caecum, small intestine, trachea, stomach and testes, whereas following inhalation, levels were measured in the liver, oesophagus, stomach and small intestine, and later in the large intestine and caecum (ASTDR, 1990, 1990a 1990b; DEFRA, 2002; RAIS, 1994). B(a)P