Suppression of pulmonary host defenses and enhanced susceptibility to respiratory bacterial infection in mice following inhalation exposure to trichloroethylene and chloroform

Figures & data

Figure 1.  Cumulative mortality following exposure to the test atmospheres. Cumulative mortality following exposure to (A) trichloroethylene (TCE) or (B) chloroform. Mice were exposed for 3 h to the indicated concentrations of TCE or chloroform and then challenged by aerosol with S. zooepidemicus. Data represent a composite of three TCE experiments and two chloroform experiments with a minimum of 38 mice per exposure group. **Value significantly different from air at P ≤ 0.01.

Figure 2.  Bacterial clearance from the lung. Results shown are measures of bacterial clearance from the lung following (A) trichloroethylene (TCE) and (B) chloroform exposure. Mice were exposed for 3 h to indicated concentrations of TCE or chloroform and then challenged by aerosol with S. zooepidemicus. Mice were then sacrificed and colony-forming units (CFU) determined as described in Methods. Each data represents the mean (±SE) for five TCE-exposed and 10 chloroform-exposed mice. For mice that had no detectable bacteria, one colony less than the limit of detection (LOD) was used to determine the mean. LODs ranged from 5 to 25 CFU. **Value significantly different from air at P ≤ 0.01; *significantly different from air at P ≤ 0.05.

Figure 3.  Percent of mice infected at various timepoints post-infection. (A) At 72-h (trichloroethylene [TCE]) or (B) at 48-h (chloroform) post-infection. Data represent 100 × (the number of mice from which one or more colony-forming units (CFU) were detected in lung lavage (TCE) or lung extract (chloroform)/ total number tested) for (A) TCE (n = 5) and (B) chloroform (n = 10). *significantly different from air p<= 0.05; **significantly different from air p<=0.01.

Figure 4.  Effect of (A) trichloroethylene (TCE) and (B) chloroform on alveolar macrophage phagocytosis. Data represent the mean (±SE) for five (TCE) or six (chloroform) mice. *significantly different from air p<= 0.05; **significantly different from air p<=0.01.

Table 1.  Comparison of no observable effect levels (NOEL) across different endpoints.

Endpoint	Trichloroethylene	Chloroform
Mortality at 20 days	25 ppm	500 ppm
Bacterial clearance 24 h	<50 ppm	100 ppm
48 h	ND^a	100 ppm
72 h	50 ppm	ND
% Infected mice 24 h	<50 ppm	100 ppm
48 h	ND	500 ppm
72 h	100 ppm	ND
Phagocytic index	100 ppm	<100 ppm

^aND = not done.