Distribution, retention, and elimination of pyrene in rats after inhalation.

Pyrene was measured in tissues of Fischer 344 rats are various times after inhalation of pyrene aerosols (500 microgram/l; mass median diameter, 0.3-0., micrometer) for 1 h. Significant quantities of pyrene were found in nasal turbinates, trachea, lungs, kidney, and liver immediately after exposure. Clearance from the respiratory tract was rapid; concentrations in the trachea and lungs 48 h after exposure were 20 and 5% of the concentrations present 1/2 h after exposure. Pyrene also cleared from liver and kidney at a relatively rapid rate; concentrations in these tissues 48 h after exposure were approximately 10% of those 1/2 h after exposure. Concentrations in the gastrointestinal tract 24 h after exposure were 4 times those found 1/2 h after exposure. Pyrene cleared from the gastrointestinal tract approximately 4 d after exposure. Thus, inhaled pyrene is rapidly cleared from the respiratory tract by mucocilliary action from the trachea and bronchi and by translocation from the respiratory tract to the liver and kidney; it is eliminated primarily through the gastrointestinal tract.