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

1 Mauderly et al. (1987b) evaluated the relative susceptibility of developing and adult rat
2 .lungs to damage by exposure to diesel exhaust. Rats ( 48 per test group) were exposed to diesel
3 exhaust containing 3.5 mg/m 3 DPM and about 0.8 ppm N0 2 • Exposures were for 7 hlday,
4 5 days/week through gestation to the age of 6 mo, or from the age of 6 to 12 mo. Comparative
· 5 studies were conducted on respiratory function, immune response, lung clearance, airway fluid
6 enzymes, protein and cytology, lung tissue collagen, and proteinases in both age groups. After
7 the 6-month exposure, adult rats, compared with controls, exhibited (1) more focal aggregates of
8 particle-containing AMs in the alveolar ducts near the terminal bronchioles, (2) a sixfold increase
9 ·in the neutrophils (as a percentage of total leukocytes) in the airway fluids, (3) a significantly
10 higher number oftotallymphoidcelis in the pulmonary lymph nodes, (4) delayed clearance of
11 diesel particles and radiolabeled particles (t 112 = 90 days versus 47 days for controls), and (5)
12 increased lung weights. These effects were not seen in the young rats. On a weight for weight
13 (milligrams ofDPM per gram of lung) basis, DPM accumulation in the lungs was similar in
14 young and adult rats immediately after the exposure. During the 6-month postexposure period,
15 DPM clearance was much more rapid in the neonatal rats, approximately 2.5-fold; During
16 postexposure, diesel particle-laden macrophages became aggregated in the neonatal rats, but
17 these aggregations were located primarily in a subpleural position. The authors concluded that
18 exposure to diesel exhaust, using pulmonary function, structural (qualitative or quantitative)
19 biochemistry as the indices, did not affect the developing rat lung more severely than the adult rat
20 lung.
r
21 · As a result of the increasing trend of using diesel-powered equipment in coal mining
22 operations and the concern for adverse health effects in coal miners exposed to both coal dust or
23 coal mine dust and diesel exhaust, Lewis et al. (1989) and Karagianes et al. (1981) investigated
24 the interaction of coal dust and diesel exhaust. Lewis et al. (1989) exposed rats, mice, and
25 cynomolgus monkeys to (1) filtered ambient air, (2) 2 mg/m 3 DPM, (3) 2 mg/m 3 respirable coal
26 . dust, and (4) 1 mg/m 3 ofboth DPM·and respirable coal dust.· Gaseous and vapor concentrations
27 were identical in both diesel exhaust exposures. Exposures were for 7 h/day, 5 days/week for up
28 to 24 mo. Synergistic effects between diesel exhaust and coal dust were not demonstrated;
29 additive toxic effects were the predominant effects ·noted.
30 Karagianes et al. ( 1981) exposed rats (24 per group) to diesel exhaust containing
31 8.3 mg/m 3 ofDPM alone or in combination with about 6 mg/m 3 of coal dust. No synergistic
32 effects were found between diesel exhaust and coal dust; additive effects in terms of visual dust
33 burdens in necropsied lungs were related to dose (i.e., length of exposure and airborne particulate
34 concentrations).
35 The health effects of airborne contaminants from sources other than diesel engines may
36 be altered in the r,resence ofDPM by their adsorption onto the diesel particles. When adsorbed
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