Judith A. Graham

Inhalable particles and pulmonary host defense: In vivo and in vitro effects of ambient air and combustion particles

The ability of particulate air pollutants (and possible constituents) to alter pulmonary host defenses was examined using an in vitro alveolar macrophage cytotoxicity assay and an in vivo bacterial infectivity screening test which employed intratracheal injection of the particles. A wide range of response between particles was seen at the 1.0-mg/ml level in vitro and the 0.1-mg/mouse level in vivo. A sample of fluidized-bed coal fly ash, bentonite, asbestos, some ambient air particles, and heavy metal oxides greatly increased susceptibility to pulmonary bacterial infection. Most coal fly ash samples and some air particles caused moderate increases in infectivity, while diesel particulates, volcanic ash, and crystalline silica caused only small increases. Cytotoxic effects on macrophages in vitro were observed with most of the particles. The in vivo and in vitro assays produced a similar ranking of toxicity; however, not all particles that were highly cytotoxic were potent in increasing bacterial infectivity. Increased toxicity measurable by either assay often appeared to be associated with small size or with the presence of metal in the particles.

Size Considerations for Establishing a Standard for Inhalable Particles

The U. S. Environmental Protection Agency (EPA) is required, under the amended Clean Air Act of 1977, to review the scientific basis for the total suspended par-ticulate (TSP) ambient air quality standard and determine whether a revised particulate standard can be promulgated by December, 1980. It is recommended that research to develop information for a size-specific standard should focus on inhalable particulate (IP) matter defined as airborne particles ≤15 jum aerodynamic equivalent diameter. This particle size range relates to that fraction of particulate matter which can primarily deposit in the conducting airways and the gas-exchange areas of the human respiratory system during mouth breathing. It is also recommended that a second particle size cut-point of ≤2.5 yum diameter be incorporated in the air sampling devices, based upon considerations of the chemical composition and the size distribution of airborne particles, and on the predominant penetration of particles ≤2.5 /im diameter into the gas-e...

Protein accumulation in lung lavage fluid following ozone exposure

Abstract Accumulation of protein in lung lavage fluid was used as an indicator of pulmonary damage following exposure of guinea pigs to O 3 . Exposure of animals to 510, 1000, or 1960 μg/m 3 (0.26, 0.51, or 1.0 ppm) of O 3 for 72 hr resulted in significantly elevated levels of lavage fluid protein when compared to that of air controls. This effect was not observed in animals exposed to 196 μg O 3 /m 3 (0.10 ppm). When exposure time was reduced to 3 hr, the O 3 -induced protein accumulation in lavage fluids was undetectable unless the time of lavage was delayed 10–15 hr following the exposure. Under these conditions, elevated protein content was seen in lung lavage fluids obtained from animals exposed to O 3 ranging from 510 to 1470 μg O 3 /m 3 (0.26-0.75 ppm) and a dose relationship between the amount of protein accumulation in the lung and the concentration of O 3 to which the animals were exposed was observed. Vitamin C deficiency did not enhance this O 3 -induced lesion in guinea pigs. The dose relationship has also been confirmed by polyacrylamide gel electrophoresis of the lavage fluids. Lung lavage fluid protein content in animals exposed to 353 μg O 3 /m 3 (0.18 ppm) for 8 hr/day for 5 or 10 consecutive days was not different from that of air controls.

Influence of cadmium, nickel, and chromium on primary immunity in mice☆

The effects of metals on the primary humoral immune system of mice were investigated using a hemolytic plaque technique to determine the number of specific antibody-producing spleen cells. Inhalation of NiCl/sub 2/ for 2 hr resulted in a significant negative linear dose response, the lowest effective concentration tested being 250 ..mu..g of Ni/m/sup 3/. Following a 2 hr aerosol exposure to NiCl/sub 2/, the lung cleared Ni on a first-order kinetics basis. A significant reduction in the number of plaques per 10/sup 6/ cells also was observed with exposure to 190 ..mu..g of Cd/m/sup 3/. Analyses of the data from intramuscularly exposed mice indicated that concentrations greater than or equal to 3.90 ..mu..g of Ni/g body weight (as NiSO/sub 4/) and greater than or equal to 9.25 ..mu..g of Ni/g body weight (as NiCl/sub 2/) resulted in significant immunosuppression. Intramuscular treatments with NiO, CdCl/sub 2/, and CrCl/sub 3/ had no effect at the concentrations tested.

Species comparison of acute inhalation toxicity of ozone and phosgene

A comparison of the concentration-response effects of inhaled ozone (O3) and phosgene (COCl2) in different species of laboratory animals was made in order to better understand the influence of the choice of species in inhalation toxicity studies. The effect of 4-h exposures to ozone at concentrations of 0.2, 0.5, 1.0, and 2.0 ppm, and to COCl2 and 0.1, 0.2, 0.5, and 1.0 ppm was determined in rabbits, guinea pigs, rats, hamsters, and mice. Lavage fluid protein (LFP) accumulation 18-20 h after exposure was used as the indicator of O3- and COCl2-induced pulmonary edema. All species had similar basal levels of LFP (250-350 mg/ml) when a volume of saline that approximated the total lung capacity was used to lavage the collapsed lungs. Ozone effects were most marked in guinea pigs, which showed significant effects at 0.2 ppm and above. Mice, hamsters, and rats showed effects at 1.0 ppm O3 and above, while rabbits responded only at 2.0 ppm O3. Phosgene similarly affected mice, hamsters, and rats at 0.2 ppm and above, while guinea pigs and rabbits were affected at 0.5 ppm and above. Percent recovery of lavage fluid varied significantly between species, guinea pigs having lower recovery than other species with both gases. Lavage fluid recovery was lower following exposure to higher levels of O3 but not COCl2. Results of this study indicate that significant species differences are seen in the response to low levels of O3 and COCl2. These differences do not appear to be related in a simple manner to body weight.

Epithelial injury and interstitial fibrosis in the proximal alveolar regions of rats chronically exposed to a simulated pattern of urban ambient ozone

Abstract Electron microcopic morphometry was used to study the development of lung injury during and after chronic (78 weeks) exposure to a pattern of ozone (O3) designed to simulate high urban ambient concentrations that occur in some environments. The daily exposure regimen consisted of a 13-hr background of 0.06 ppm, an exposure peak that rose from 0.06 to 0.25 ppm, and returned to the background level over a 9-hr period, and 2-hr downtime for maintenance. Rats were exposed for 1, 3, 13, and 78 weeks. Additional groups of rats exposed for 13 or 78 weeks were allowed to recover in filtered clean air for 6 or 17 weeks, respectively. Rats exposed to filtered air for the same lengths of time were used as controls. Samples from proximal alveolar regions and terminal bronchioles were obtained by microdissection. Analysis of the proximal alveolar region revealed a biphasic response. Acute tissue reactions after 1 week of exposure included epithelial inflammation, interstitial edema, interstitial cell hypertrophy, and influx of macrophages. These responses subsided after 3 weeks of exposure. Progressive epithelial and interstitial tissue responses developed with prolonged exposure and included epithelial hyperplasia, fibroblast proliferation, and interstitial matrix accumulation. The epithelial responses involved both type I and type II epithelial cells. Alveolar type I cells increased in number, became thicker, and covered a smaller average surface area. These changes persisted throughout the entire exposure and did not change during the recovery pefiod, indicating the sensitivity of these cells to injury. The main response of type II epithelial cells was cell proliferation. The accumulation of interstitial matrix after chronic exposure consisted of deposition of both increased amounts of basement membrane and collagen fibers. Interstitial matrix accumulation underwent partial recovery during follow-up periods in air; however, the thickening of the basement membrane did not resolve. Analysis of terminal bronchioles showed that short-term exposure to O3 caused a loss of ciliated cells and differentiation of preciliated and Clara cells. The bronchiolar cell population stabilized on continued exposure; however, chronic exposure resulted in structural changes, suggesting injury to both ciliated and Clara cells. We conclude that chronic exposure to low levels of O3 causes epithelial inflammation and interstitial fibrosis in the proximal alveolar region and bronchiolar epithelial cell injury.

Effects of subchronic exposure to a mixture of O3, SO2, and (NH4)2SO4 on host defenses of mice

Mice exposed 5 h/d, 5 d/wk up to 103 d, to 0.2 mg O3/m3 or to a mixture of O3, 13.2 mg SO2/m3, and 1.04 mg (NH4)2SO4 aerosol/m3 showed significantly greater susceptibility to group C streptococcal aerosol infection relative to filtered air controls. Pulmonary bactericidal activity by alveolar macrophages was significantly enhanced in the lungs of mice exposed to the mixture relative to those inhaling filtered air or O3 alone. The total number and distribution of the free cells lavaged from the lungs, as well as cellular ATP levels, did not change due to the pollutant exposures. In vitro cytostasis in tumor target cells cocultured with peritoneal macrophages from the exposed mice was significantly enhanced in the O3-exposed and in the mixture-exposed treatment groups relative to controls and also in the mixture-exposed relative to the O3-exposed group when a target-to-effector-cell ratio of 1:10 was used; no such effects were observed when this ratio was 1:20. Splenic T-lymphocyte function, as measured by blastogenesis to mitogens and alloantigens, was affected by exposure to O3 and/or the mixture, although the patterns of effects were qualitatively different. Splenic B-cell function and macrophage antigen processing, as measured by the generation of antibody plaque-forming cells, was unaffected by exposure.

The Effects of Inhalation of Organic Chemical Air Contaminants on Murine Lung Host Defenses

The potential health hazards of exposure to threshold limit value (TLV) concentrations of acetaldehyde, acrolein, propylene oxide, chloroform, methyl chloroform, carbon tetrachloride, allyl chloride, methylene chloride, ethylene trichloride, perchloroethylene, benzene, phenol, monochlorobenzene, and benzyl chloride, compounds which may be present in the ambient or work room atmosphere were investigated. The effects of single and multiple 3-hr inhalation exposures were evaluated in mice by monitoring changes in their susceptibility to experimentally induced streptococcus aerosol infection and pulmonary bactericidal activity to inhaled Klebsiella pneumoniae. When significant changes in these parameters were found, further exposures were performed at reduced vapor concentrations until the no-measurable-effect level was reached. Multiple exposures on 5 consecutive days were then performed at this concentration. Significant increases in susceptibility to respiratory streptococcus infection were observed after single 3-hr exposure to TLV concentrations of methylene chloride, perchloroethylene, and ethylene trichloride. For methylene chloride and perchloroethylene, these exposure conditions also resulted in significantly decreased pulmonary bactericidal activity.

Effects of arsenic trioxide inhalation exposure on pulmonary antibacterial defenses in mice

The effects of single and multiple (5 and 20) 3-h inhalation exposures to aerosols of arsenic trioxide on the pulmonary defense system of mice were investigated. Arsenic trioxide mist was generated from an aqueous solution and dried to produce particulate aerosols of 0.4 micron mass median aerodynamic diameter. Aerosol mass concentration ranged from 125 to 1000 micrograms As/m3. Effects of the exposures were evaluated by determination of changes in susceptibility to experimentally induced streptococcal aerosol infection and in pulmonary bactericidal activity to 35S-labeled Klebsiella pneumoniae. Significant increases in mortality due to the infectious challenge and decreases in bactericidal activity were seen after single 3-h exposures to 270, 500, and 940 micrograms As/m3. Similarly, 5 or 20 multiple 3-h exposures to 500 micrograms As/m3 produced consistently significant increases in mortality and decreases in pulmonary bactericidal activity. At 125 or 250 micrograms As/m3, a decrease in bactericidal activity was seen only after 20 exposures to 250 micrograms/m3. Results from earlier studies with an arsenic-containing copper smelter dust were compared to these data. The possibility of the development of adaptation during multiple exposures to arsenic trioxide is also considered.

A comparison of biochemical effects of nitrogen dioxide, ozone, and their combination in mouse lung.

Swiss Webster mice were exposed to either 4.8 ppm (9024 microgram/m3) nitrogen dioxide (NO2), 0.45 ppm (882 microgram/m3) ozone (O3), or their combination intermittently (8 hr daily) for 7 days, and the effects were studied in the lung by a series of physical and biochemical parameters, including lung weight, DNA and protein contents, oxygen consumption, sulfhydryl metabolism, and activities of NADPH generating enzymes. The results show that exposure to NO2 caused relatively smaller changes than O3, and that the effect of each gas alone under the conditions of exposure was not significant for most of the parameters tested. However, when the two gases were combined, the exposure caused changes that were greater and significant. Statistical analysis of the data shows that the effects of combined exposure were more than additive, i.e., they might be synergistic. The observations suggest that intermittent exposure to NO2 or O3 alone at the concentration used may not cause significant alterations in lung metabolism, but when the two gases are combined the alterations may become significant.