We tested the hypothesis that particulate air pollutants are associated with metals that have a capacity to transport electrons and that biologic activity of the particulates can correlate with the concentrations of these metals. The metals studied were titanium, vanadium, chromium, manganese, iron, cobalt, nickel, and copper. Measurements included ( 1 ) oxidized products of deoxyribose catalyzed by particulates, (2) induction of a neutrophilic alveolitis after particdate instillation, (3) increments in airway reactivity after particulate instillation, and (4) mortality after exposures to both dusts and a microbial agent. Employing 10 different dusts of either natural or anthropogenic origin, in vitro generation of oxi- ~ dized products of deoxyribose increased with ionizable concentrations of all metals, except for titanium, associated with the particles. After tracheal instillation of dust into rats, both the neutrophil influx and lavage protein increased with ionizable concentrations of these same metals. Changes in airway reactivity following instillation of dusts in rats alsoappeared to be associated with the ionizable concentrations of these metals. Similarly, mortality after injection of particles in mice with subsequent exposure to aerosolized Streptococcus zooepidemicus reflected metal concentrations. We conclude that particulate air pollutants are associated with metals which have a capacity to catalyze electron transfer. An in vitro measure of oxidant production increased with ionizable concentrations of the metals. Indices of in vivo lung injury also corresponded to concentrations of these same metals.

Epidemiologic reports by C.A. Pope III et. al. demonstrated that in the Utah Valley, closure of an open-hearth steel mill over the winter of 1987 was associated with reductions in respiratory disease and related hospital admissions in valley residents. To better examine the relationship between plant-associated changes in ambient particulate matter (PM) and respiratory health effects, we obtained total suspended particulate filters originally collected near the steel mill during the winter of 1986 (before closure), 1987 (during closure), and 1988 (after plant reopening). PM subcomponents were water-extracted from these filters and Sprague-Dawley rats were intratracheally instilled with equivalent masses of extract. Data indicated that 24 hr later, rats exposed to 1986 or 1988 extracts developed significant pulmonary injury and neutrophilic inflammation. Additionally, 50% of rats exposed to 1986 or 1988 extracts had increased airway responsiveness to acetylcholine, compared to 17 and 25% of rats exposed to saline or the 1987 extract, respectively. By 96 hr, these effects were largely resolved except for increases in lung lavage fluid neutrophils and lymphocytes in 1986 extract-exposed rats. Analogous effects were observed with lung histologic assessment. Extract analysis using inductively coupled plasma-mass spectroscopy demonstrated in all three extracts nearly 70% of the mass appeared to be sodium-based salts derived from the glass filter matrix. Interestingly, relative to the 1987 extract, the 1986/1988 extracts contained more sulfate, cationic salts (i.e., calcium, potassium, magnesium), and certain metals (i.e., copper, zinc, iron, lead, strontium, arsenic, manganese, nickel). Although total metal content was (3/4) 1% of the extracts by mass, the greater quantity detected in the 1986 and 1988 extracts suggests metals may be important determinants of the pulmonary toxicity observed. In conclusion, the pulmonary effects induced by exposure of rats to water-based extracts of local ambient PM filters were in good accord with the cross-sectional epidemiologic reports of adverse respiratory health effects in Utah Valley residents.

Acute ozone (O3) exposure in humans produces changes in pulmonary function that attenuate with repeated exposure. This phenomenon, termed adaptation, has been produced in unanesthetized rats. Rats exposed to O3 (0, 0.35, 0.5, or 1.0 ppm) for 2.25 h for 5 consecutive days showed an increased frequency of breathing and a decreased tidal volume on Days 1 and 2 of exposure at all O3 concentrations. However, by Day 5 these breathing responses to O3 were diminished in rats exposed to 0.35 and 0.5 ppm, but not in rats exposed to 1.0 ppm. In addition, a flow limitation in smaller airways was observed after the second day of exposure to 0.5 ppm O3 that initially attenuated and then disappeared by the fifth day of exposure. In contrast to these findings, a light microscopic examination of fixed lung tissue sections from rats exposed to 0.5 ppm indicated a 5-day progressive pattern of epithelial damage and inflammation in the terminal bronchiolar region. A sustained 37% increase in lavageable protein was also observed over the course of the 5-day exposure regimen to 0.5 ppm. Lung glutathione increased initially, but it was within the control range on Days 4 and 5. Lung ascorbate was significantly elevated above control levels on Days 3 and 5. These data suggest that attenuation of the pulmonary function response to O3 occurs in laboratory rats with repeated exposure while biochemical and morphologic aspects of the tissue response continue to progress.

Controversy persists regarding the validity of intratracheal instillation (IT) of particulate matter (PM) as a surrogate for inhalation exposure (IH) in rodents. Concerns center on dose, dose-rate, and distribution of material within the lung. Acute toxicity of a residual oil fly ash (ROFA) administered by IH was compared to those effects of a single IT bolus at an IH-equivalent dose. Male Sprague Dawley rats (60 days old) were exposed by nose-only IH to approximately 12 mg/m3 for 6 h. Inter-lobar dose distribution of ROFA, dissected immediately post exposure, was assayed by neutron activation. Vanadium and nickel were used as ROFA markers. IT administration of the IH-equivalent dose (110 microg) showed similar (<15%) interlobular distribution, with the exception of the inferior lobe dose (IT>IH approximately 25%). Evaluation of airway hyperreactivity (AHR), bronchoalveolar lavage fluid (BALF) constituents, and histopathology was conducted at 24, 48, and 96 h post exposure. AHR in the IH group was minimally (p > 0.05) affected by treatment, but was significantly increased ( approximately 40%) at both 24 and 48 h post IT. Inflammation in both groups, as measured by alterations in BALF protein, lactate dehydrogenase and neutrophils, was virtually identical at all time points. Alveolitis and bronchial inflammation/epithelial hypertrophy were prominent 24 h following IT, but not apparent after IH. Conversely, alveolar hemorrhage, congestion, and airway exudate were pronounced at 48 h post-IH but not remarkable in the IT group. Thus, IT-ROFA mimicked IH in terms of lobar distribution and injury biomarkers over 96 h, while morphological alterations and AHR appeared to be more dependent on the method of administration.

Particulate matter air pollution (PM) has been associated with morbidity and mortality from ischemic heart disease and stroke in humans. It has been hypothesized that alveolar inflammation, resulting from exposure to PM, may induce a state of blood hypercoagulability, triggering cardiovascular events in susceptible individuals. Previous studies in our laboratory have demonstrated acute lung injury with alveolar inflammation in rats following exposure to residual oil fly ash (ROFA), an emission source particulate. In addition, increased mortality has been documented following exposure to ROFA in rats with preexistent cardiopulmonary disease. ROFA's toxicity derives from its soluble metal content, which appears also to drive the toxicity of ambient PM. The present study was conducted to test the hypothesis that exposure of rats to a toxic PM, like ROFA, would adversely alter hemostatic parameters and cardiovascular risk factors thought to be involved in human epidemiologic findings. Sixty-day-old male Sprague-Dawley rats were exposed by intratracheal instillation (IT) to varying doses (0.3, 1. 7, or 8.3 mg/kg) of ROFA, 8.3 mg/kg Mt. Saint Helen's volcanic ash (MSH, control particle), or 0.3 ml saline (SAL, control). At 24 h post-IT, activated partial thromboplastin time (APTT), prothrombin time (PT), plasma fibrinogen (PF), plasma viscosity (PV), and complete blood count (CBC) were performed on venous blood samples. No differences from control were detected in APTT and PT in ROFA-exposed rats; however, ROFA exposure did result in elevated PF, at 8.3 mg/kg only. In addition, PV values were elevated in both ROFA and MSH-exposed rats relative to SAL-control rats, but not significantly. Although no changes were detected in APTT and PT, alteration of important hematologic parameters (notably fibrinogen) through PM induction of an inflammatory response may serve as biomarkers of cardiovascular risk in susceptible individuals.

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Alpha-1-antitrypsin (A1AT) defi ciency is characterized by increased neutrophil elastase (NE) activity and oxidative stress in the lung. We hypothesized that NE exposure generates reactive oxygen species by increasing lung nonheme iron. To test this hypothesis, we measured bronchoalveolar lavage (BAL) iron and ferritin levels, using inductively coupled plasma (ICP) optical emission spectroscopy and an ELISA, respectively, in A1AT-defi cient patients and healthy subjects. To confi rm the role of NE in regulating lung iron homeostasis, we administered intratracheally NE or control buffer to rats and measured BAL and lung iron and ferritin. Our results demonstrated that A1AT-defi cient patients and rats postelastase exposure have elevated levels of iron and ferritin in the BAL. To investigate the mechanism of NE-induced increased iron levels, we exposed normal human airway epithelial cells to either NE or control vehicle in the presence or absence of ferritin, and quantifi ed intracellular iron uptake using calcein fl uorescence and ICP mass spectroscopy. We also tested whether NE degraded ferritin in vitro using ELISA and western analysis. We demonstrated in vitro that NE increased intracellular nonheme iron levels and degraded ferritin. Our results suggest that NE digests ferritin increasing the extracellular iron pool available for cellular uptake.