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Engineering system for simultaneous inhalation exposures of rodents to fine and ultrafine concentrated ambient particulate matter from a common air source
Citation:
WALSH, L. C., M. I. GILMOUR, D. W. DAVIES, E. Lapp, D. TERRELL, J. W. HIGHFILL, AND K. L. DREHER. Engineering system for simultaneous inhalation exposures of rodents to fine and ultrafine concentrated ambient particulate matter from a common air source. Presented at American Association for Aerosol Research 2010 International Conference, San Diego, CA, March 22 - 26, 2010.
Impact/Purpose:
The US EPA, National Health and Environmental Effects Laboratory established a novel multipollutant capability for small animal inhalation exposures within its research facility at Research Triangle Park, NC. Systems in the exposure laboratory utilized technologies developed at the Harvard School of Public Health to effectively concentrate ambient particles of different size fractions. Ultrafine mode ambient PM (UCAPs) were concentrated using a Harvard Ultrafine Concentrated Air Particles System
Description:
Exposure to elevated levels of ambient particulate matter (PM) smaller than 2.5 11m (PM2.5) has been associated with adverse health effects in both humans and animals. Specific properties of either fine (0.1-2.5 11m), or ultrafine « 0.1 11m) PM responsible for exposure related health effects remain an active area of investigation to determine the roles of various size fractions. The US EPA, National Health and Environmental Effects Laboratory established a novel multipollutant capability for small animal inhalation exposures within its research facility at Research Triangle Park, NC. Systems in the exposure laboratory utilized technologies developed at the Harvard School of Public Health to effectively concentrate ambient particles of different size fractions. Ultrafine mode ambient PM (UCAPs) were concentrated using a Harvard Ultrafine Concentrated Air Particles System. Fine mode ambient PM (CAPs) were concentrated using multiple stage slit virtual impactor technology. Air containing the various concentrated PM fractions was then delivered to individual chambers. Systems were engineered to allow introduction of additional pollutants as desired. Control exposures used filtered ambient air. Together, these systems provide a unique capability to conduct acute and sub-chronic exposures of rodents to atmospheres ofUCAPs and CAPs simultaneously from a common ambient air source therefore allowing investigators to assess PM size specific health effects. Systems have been operated for summer and winter, 13 week protocols, with exposures 6 hours daily, M-F. Extensive engineering controls and detailed QNQC practices employed insured exposure atmospheres were effectively monitored, and characterized. State of the art computer aided monitoring and control methodologies incorporated physical and electronic measurement of PM concentrations and size. Engineering parameters such as chamber temperatures, relative humidities, static pressures, flow rates, as well as numerous concentrating equipment operational variables were continuously monitored, recorded, and displayed. Operators optimized ambient PM concentrating effects and chamber conditions in real-time. Redundant monitoring methodologies allowed operators to cross check exposure conditions as well as covering any data gaps occurring during more than 6 months ofdaily operations. Study average PM concentrations from filter data for summer exposures were: UCAPs -173 ug/nr', CAPs 309 ug/rrr', Controls 6.2 ug/rrr', and Ambient PM2.516.9 ug/nr'. Concentrations for winter exposures were: UCAPs -378 ug/rrr', CAPs 221 ug/rrr', Controls 8.8 ug/rrr', and Ambient PM25 8.7 ug/rrr'. During the subchronic tests, exposure operations were completed for 2222 chamber hours of 2226 (99.8%) scheduled with 4 hours missed due to system mechanical problems. Results to date have shown that both fine and ultrafine particles impact a number of health effects in mice. (This abstract does not necessarily reflect EPA policy)