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ACCUMULATION AND TISSUE DISPOSITION OF PARTICLE ASSOCIATED ELEMENTS IN THE RAT AFTER REPEATED INTRATRACHAEL ADMINISTRATION OF SOURCE PARTICLES
Citation:
McGee, J K., J. A. Sullivan, A. G. Ross, M. Schladweiler, D. C. Christiani, D L. Costa, AND U P. Kodavanti. ACCUMULATION AND TISSUE DISPOSITION OF PARTICLE ASSOCIATED ELEMENTS IN THE RAT AFTER REPEATED INTRATRACHAEL ADMINISTRATION OF SOURCE PARTICLES. Presented at American Toracic Society, San Diego, CA, May 20-25, 2005.
Description:
The goal of this study was to determine the fate of source particle tracer elements following repeated intratracheal instillation (IT) to rats. PM samples comprised Mt. St. Helens ash (MSH) with no water-soluble metals, and oil flyash emission PM (EPM) with water-leachable soluble metals. Study results were used to correlate with observed toxicological endpoints, assess accumulation, uptake, and clearance of PM-metals, and their tissue interbalance. We estimated the bioavailability range of MSH and bulk EPM by extracting with both ultrapure water and 1M HCl, then analyzing the extracts for elemental content (EPA Method 200.7 ver4.4). Male Wistar Kyoto rats (n=8) were exposed weekly for 16 weeks with IT MSH or EPM. Each weekly dose was the equivalent amount of PM the animals would receive by inhalation exposure of a 10 or 20 mg/m3 atmosphere for 6 hours/day, 1 day/week. Animals were sacrificed two days after the final IT.. Samples of lung, heart, kidney, liver, blood, and plasma were digested prior to elemental analysis (EPA Method 200.11). Crustal elements aluminum, silicon, titanium, manganese, iron, strontium, and barium were elevated in MSH-exposed rat lungs. Oil fly ash tracer elements vanadium, manganese, iron, nickel, cadmium, and lead were elevated in EPM lung samples. Not all the tracers behaved as expected, based on their water and acid solubilities. Vanadium was not thought to be very bioavailable in EPM as it was insoluble in water. However, levels in tissues, blood, and plasma indicated significant uptake at extrapulmonary sites over time. MSH-associated metals such as aluminum, cobalt, chromium, silicon, and EPM-associated metals such as lead and manganese were not detected in the plasma indicating that no release occurred over time from the lung. Repeated exposure to either PM and their extracts did not significantly affect levels of clinical elements magnesium, potassium, calcium, copper, zinc, or selenium in tissue and plasma samples of any of the treatment groups. However, the study showed that PM associated vanadium may have a systemic disposition beyond that expected by basic water bioavailablity. (Abstract does not reflect USEPA policy)