Airborne Particles of the California Central Valley Alter the Lungs of Healthy Adult Rats

• Published in: Environmental health perspectives 2003-06, Vol.111 (7), p.902-908
• Main Authors: Smith, Kevin R., Kim, Seongheon, Recendez, Julian J., Teague, Stephen V., Ménache, Margaret G., Grubbs, David E., Sioutas, Constantinos, Pinkerton, Kent E.
• Format: Article
• Language: English
• Subjects: Aerosols; Air Pollutants - analysis; Animals; Average linear density; Bronchoalveolar Lavage Fluid; California; Chemical hazards; Composite particles; Environmental Exposure; Lung - chemistry; Lungs; Macrophages; Male; Particle mass; Particulate matter; Rats; Rats, Sprague-Dawley; Winter
• ISSN: 0091-6765; 1552-9924
• DOI: 10.1289/ehp.5964

Epidemiologic studies have shown that airborne particulate matter (PM) with a mass median aerodynamic diameter < 10 μm ( PM10) is associated with an increase in respiratory-related disease. However, there is a growing consensus that particles < 2.5 μm ( PM2.5), including many in the ultrafine (< 0.1 μm) size range, may elicit greater adverse effects. PM is a complex mixture of organic and inorganic compounds; however, those components or properties responsible for biologic effects on the respiratory system have yet to be determined. During the fall and winter of 2000-2001, healthy adult Sprague-Dawley rats were exposed in six separate experiments to filtered air or combined fine ( PM2.5) and ultrafine portions of ambient PM in Fresno, California, enhanced approximately 20-fold above outdoor levels. The intent of these studies was to determine if concentrated fine/ultrafine fractions of PM are cytotoxic and/or proinflammatory in the lungs of healthy adult rats. Exposures were for 4 hr/day for 3 consecutive days. The mean mass concentration of particles ranged from 190 to 847 μ g/ m3. PM was enriched primarily with ammonium nitrate, organic and elemental carbon, and metals. Viability of cells recovered by bronchoalveolar lavage (BAL) from rats exposed to concentrated PM was significantly decreased during 4 of 6 weeks, compared with rats exposed to filtered air (p < 0.05). Total numbers of BAL cells were increased during 1 week, and neutrophil numbers were increased during 2 weeks. These observations strongly suggest exposure to enhanced concentrations of ambient fine/ultrafine particles in Fresno is associated with mild, but significant, cellular effects in the lungs of healthy adult rats.