Gastrointestinal tract particulate

Ingestible materials get into the mouth through hand-to-mouth contact, and through coughing when inhaled particulate material is removed from the lungs to the throat and then swallowed. Since there are acids, alkalies and enzymes in the gastrointestinal tract, the toxic nature of a compound may be enhanced or diminished. 

The respiratory system may be damaged directly by particulate matter that enters the blood systems or lymph system through the lungs. In addition, the particulate material or soluble components of it, heavy metals, for instance, may be transported to organs. Particles cleared from the respiratory tract are to a large extent swallowed into the gastrointestinal tract. 

Ponchel, G., and Irache, J.M., Specific and non-specific bioadhesive particulate systems for oral delivery to the gastrointestinal tract, Adv. Drug Del Rev., 34 191-219 (1998). 

Hennessy, D.R., Ali, D.N. Tremain, S.A. (1995) The partition and fate of soluble and digesta particulate associated oxfendazole and its metabolites in the gastrointestinal tract of sheep. International Journal for Parasitology, 24, 327-333. 

People exposed to PAHs in conjunction with particulates from tobacco smoke, fossil-fuel combustion, coal fly ash, and asbestos fibers are at increased risk of developing toxic effects, primarily cancer. Even people not susceptible to the toxic effects of PAHs may become affected when exposure occurs in conjunction with exposure to particulates (NRC 1983). This enhanced effect results from the adsorption of PAHs onto the particulates. They are vacuolized into cells, and distributed differently in tissues depending on the size and type of particulate matter. This increased PAH uptake may result in more efficient induction of AHH activity at low PAH concentrations. This activity also increases the dose to the gastrointestinal tract as a result of mucocilliary clearance (NRC 1983). This synergistic action between PAHs and particulate matter in air pollution has been associated with the occurrence of stomach cancer in humans (Fraumeni 1975). 

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