Health Assessment Document for Diesel Emissions - NSCEP | US ...

1 control]). Heinrich et al. (1986a,b; see also StOber, 1986) found a significant increase in wet and
2 dry weights of the lungs of rats and mice exposed at 4.24 mg/m 3 particulate matter for 1 year in
3 comparison with controls. After 2 years, the difference was a factor of2 (mice) or 3 (rats). After
4 the same exposure periods, the hamsters showed increases of 50 to 75%, respectively. Exposure
5 to equivalent filtered diesel exhaust caused no significant effects in any of the species. Vinegar
6 et al. (1980, 1981a,b) exposed hamsters to two levels of diesel exhaust with resultant
7 concentrations of about 6 and 12 mg/m 3 .particulate matter for 8 h/day, 7 days/week for 6 mo.
8 Both exposttres significantly increased lung weight and lung weight to. body weight ratios. The
9 difference between lung weights of exposed and control hamsters exposed to 12 mg/m 3
1 0 particulate matter was approximately twice that of those exposed to 6 mg/m 3 •
11 · Heinrich et al. (1995) reported that rats exposed to 2.5 and 7 mg/m 3 for 18 h/day, 5
12 · days/week for 24 mo showed significantly lower body weights than control starting at day 200 in
13 the high-concentration group and at day 440 in the low-concentration group. Body weight in the
14 low-concentration group was unaffected, as was mortality in any group. Lung weight was
15 increased in the 7 mg/m 3 group starting at 3 mo and persisting throughout the study while the 2.5
16 mg/m 3 group showed increased lung weight only at 22 and 24 mo of exposure. Mice (NMRI ·
17 strain) exposed to 7 mg/m 3 in this study for 13.5 mo had no increase in mortality and minimal,
18 insignificant decreases in body weight. Lung weights were dramatically affected, with increases
19 progressing throughout the study from 1.5-fold at 3 mo to 3-fold at 12 mo. Mice (NMRI and
20 C57BL/6N strains) were also exposed to 4.5 mg/m 3 for 23 mo. In NMRI mice, the body weights
21 were reported to be significantly lower than controls, but the magnitude of the change is not
22 reported so biological significance cannot be assessed. Mortality was slightly increased, but
23 statistical significance is not reported. The C57BL/6N mice showed minimal effects on body
24 weight and mortality, which were not reported to be statistically significant. Lung weights were
25 dramatically affected in both strains.
26 Nikula· et al. ( 1995) exposed male and female F344 rats to diesel particle concentrations ·.
27 of2.4 and 6.3 mg/m 3 for 16 h/day, 5 days/week, for 23 mo in a study designed to compare the
28 effects of diesel with those of carbon black. Significantly reduced survival was observed in
29 males exposed to 6.3 mg/m 3 but not in females or at the lower concentration. Body weights were
30 decreased by exposure to 6.3 mg/m 3 diesel exhaust in both male and female rats throughout the
31 exposure period. Significant increases in lung weight were first seen at 6 mo in the high-
32 exposure group and at 12 to 18 mo in the low-exposure group.
33 No evidence was found in the published literature that chronic exposure to diesel exhaust
34 affected the weight of body organs other than the lung and heart (e.g., liver, kidney, spleen, or
35 testes) (Table 5-4). Morphometric analysis of hearts from rats and guinea pigs exposed to 0.25,
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