Ultrafine Particles

Absorption and Distribution

Many of the effects observed from ultrafine particulates are logical considering the primary route of exposure. Absorption of ultrafine particulate is thought to occur primarily through the lung, however particulate can be observed systemically. The initial interaction with the pulmonary epithelium causes a variety of adverse effects, and is responsible for much of the cardiopulmonary pathology observed. Due to the small size of ultrafine particulates, however, individual particles are able to cross the pulmonary epithelium and enter the blood. From there, transportation carries the particles to the liver, bone marrow, and heart, leading to systemic contamination. Studies in canines have supported these findings. Studies in rats have demonstrated significant transport of inhaled ultrafine particles to the liver.

It is hypothesized that asthmatics may be at highest risk for the adverse effects of ultrafine particulate due to deposition of particulates in the lungs central airways. The reason for this is not entirely clear. Elderly patients, and patients with underlying cardiopulmonary disease, are also at increased risk for adverse health effects from exposure to ultrafine particulates, primarily due to exacerbation of underlying conditions.