Sunday, April 03, 2005

Particles Absorbed Through the Lung Cause Blood Clotting

Now that it's been established that increases in particulate air pollution are associated with [BrooklynDodger vacillated on whether to say "causes" or to back off to epidemiologese, and decided for today to go with the fuzzier scientific diction] increases in cardiovascular morbidity and mortality at the community level, laboratory studies are attempting to explain this observation.

The notable finding is that fine and ultrafine particles penetrate the lung into systemic circulation. This causes a profound shift in local concentration. Consider 70 micrograms of a substance dissolved into a 70 kg human body: concentration at the cellular level is 1 picogram per liter of body. [BrooklynDodger invites fact checking on this math; the Dodger picked 70 to avoid finding a calculator] As particles, the concentration at the particle surface approaches 1 kilogram per liter in contact with the biological material. That's a major change in physiology, especially for cascading effects like cancer, where a single cell can start a clone which grows to any size, or immunological effects.

This abstract, in paraphrase, notes:

Recently, we have demonstrated that ultrafine particles are able to translocate from the lung into the systemic circulation in hamsters and humans. We evaluated the acute effect (1 h) of diesel exhaust particles (DEP) in a hamster model of peripheral clotting induced by injury to blood vessel membranes. Intratracheal doses of 5-500 microg of DEP per animal induced inflammation with elevation of immune cells, total proteins and histamine in lung washing. DEP enhanced experimental arterial and venous platelet rich-thrombus formation in vivo. Blood samples taken from hamsters 30 and 60 min after instillation of DEP caused platelet activation. The direct addition of DEP to untreated hamster blood also caused platelet aggregation [pre clotting; the Dodger has to look at concentration]. These effects persisted up to 24 h after instillation.


Toxicol Lett. 2004 Apr 1;149(1-3):243-53.

Possible mechanisms of the cardiovascular effects of inhaled particles: systemic translocation and prothrombotic effects.

Nemmar A, Hoylaerts MF, Hoet PH, Nemery B.Laboratory of Pneumology, Unit of Lung Toxicology, K.U. Leuven, Herestraat, 49, Leuven 3000, Belgium.

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