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

1 Heinrich et al. ( 1986a; see also StOber, 1986) performed histopathologic examinations of
2 the respiratory tract of hamsters, mice, and rats exposed to diesel exhaust that had 4 mg/m 3
3 particulate matter. Exposures were for 19 h/day, 5 days/week; the maximum exposure period
4 was 120 weeks for hamsters and mice and 140 weeks for rats. Histological examination revealed
5 different levels ofresponse·among the three species. In hamsters, the exhaust produced
6 thickened alveolar septa, bronchioloalveolar hyperplasia, and what were termed emphysematous
7 lesions (diagnostic methodology not described). In mice, bronchioloalveolar hyperplasia
8 occurred in 64% of the mice exposed to the exhaust and in 5% of the controls. Multifocal
9 alveolar lipoproteinosis occurred in 71% and multifocal interstitial fibrosis occurred in 43% of
1 0 the mice exposed to exhaust but in only 4% of the controls. In exposed rats, there were severe
11 inflammatory changes in the lungs, as well as thickened septa, foci of macrophages, and
12 hyperplastic and metaplastic lesions.
13 Nikula et al. (1995) reported in detail the nonneoplastic effects in male and female F344
14 rats exposed to 2.4 or 6.3 mg/m 3 of diesel exhaust particles. At 3 mo in the low-concentration
15 group, enlarged particle-containing· macrophages were found with minimal aggregation. With
16 higher concentration and longer duration of exposure, the number and size of macrophages and
17 aggregates increased. Alveolar epithelial hyperplasia was found starting at 3 mo and in all rats at
18 6 mo. These lesions progressed to chronic active inflammation, alveolar proteinosis, and septal
1@ fibrosis at 12 mo. Other lesions observed late in the study included bronchiolar-alveolar
20 metaplasia, squamous metaplasia, and squamous cysts. This study reports in detail the
21 progression of lesions in diesel exhaust exposure and finds relatively little difference between the
22 lesions caused by diesel exhaust exposure and exposure to similar levels of carbon black
23 particles.
24 The effects of diesel exhaust on the lungs of 18-week-old rats exposed to 8.3 ± 2.0 mg/m 3
25 particulate matter were investigated. by Karagianes et al. (1981). Exposures were for 6 h/day, 5
26 days/week, for 4, 8, 16, or 20 mo. Histological examinations of lung tissue noted focal
27 aggregation of particle-laden AMs, alveolar histiocytosis, interstitial fibrosis, and alveolar
28 emphysema (diagnostic methodology not described). Lesion severity was related to length of
29 exposure. No significant differences were noted in lesion severity among the diesel eXhaust, the
30 diesel exhaust plus coal dust (5.8 ± 3.5 mg/m 3 ), or the high-concentration (14.9 ± 6.2 mg/m 3 )
31 coal dust exposure groups following 20. mo of exposure.
32 Histological changes in the lungs of guinea pigs exposed to diluted diesel exhaust
33 containing either 0.25, 0;75, l.S, or 6.0 mg/m 3 particulate matter were reported by Barnhart et al.
34 · (1981, 1982). Exposures at 0.75 and 1.5 mg/m 3 for 2 weeks to 6 mo resulted in an uptake of
35 exhaust particles by three alveolar cell types (AMs, Type I cells, and interstitial macrophages)
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