Health Assessment Document for Diesel Emissions - NSCEP | US ...
Health Assessment Document for Diesel Emissions - NSCEP | US ...
Health Assessment Document for Diesel Emissions - NSCEP | US ...
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1 thoracic area at subsequent times. The biological half-life of the iron oxide deposited in the rats'<br />
2 lungs was nearly twice that of controls.<br />
3 Heinrich also used labeled iron oxide aerosols to study clearance in rats exposed to 0.8,<br />
4 2.5, or 7 mg/m 3 diesel DPM <strong>for</strong> 24mo (Heinrich et al., 1995). Clearance measurements were<br />
5 carried out at 3, 12, and 18 mo of exposure. Half-times of clearance were increased in a<br />
6 concentration- and duration-related way in all exposed groups, with a range of a 50% increase in<br />
7 the 0.8 mg/m 3 group at 3 mo to an 11-fold increase in the? mg/m 3 group at 19 mo. The<br />
8 differential cell counts in these animals were stated to have shown clea.r effects in the 2.5 and 7<br />
9 mg/m 3 groups, but specific in<strong>for</strong>mation about the changes is not reported.<br />
10 Wolff et al. (1987) investigated alterations in DPM clearance from the lungs of rats<br />
11 chronically exposed to diesel exhaust at 0, 0.35, 3.5, or 7.0 mg/m 3 DPM <strong>for</strong> 7 hlday, 5 days/week<br />
12 <strong>for</strong> up to 24 mo. Progressive increases in lung burdens were observed over time in the 3.5 and<br />
13 7.0 mg/m 3 exposure groups. Levels of DPM in terms of milligrams per lung were 0.60, 11.5, and<br />
14 20.5 after 24 mo of exposure at the 0.35, 3.5, or 7.0 mg/m 3 exposure levels, respectively. There<br />
15 were significant increases in 16-day clearance half-times of inhaled radio labeled particles of<br />
16 · 67 Ga 20 3 (0.1 IJ.m MMD) as early as 6 moat the 7.0 mg/m 3 level and 18 moat the 3.5 mg/m 3<br />
17 level; no significant changes were seen at the 0.35 mg/m 3 level. Rats inhaled fused<br />
18 aluminosilicate particles (2 1-1m MMAD) labeled with 134 Cs after 24 mo of diesel exhaust<br />
19 exposure; long-term clearance half-times were 79, 81,264, and 240 days <strong>for</strong> the 0, 0.35, 3.5, and.<br />
20 7.0 mg/m 3 groups, respectively. Differences were significant between the control and the 3.5 and<br />
21 7.0 mg/m 3 groups (p < 0.01).<br />
22 Mauderly et al. ( 1987b) compared the effects of diesel exhaust in the developing lung to<br />
23 the adult lung by exposing groups of male F344 rats to3.5 mg/m 3 <strong>for</strong> 7 hlday, 5 days/week <strong>for</strong> 6<br />
24 mo. One group (adult) was exposed between 6 and 12 mo of age, and the other was exposed<br />
25 beginning in utero and until 6 mo of age. Clearance of an inhaled monodisperse 2 IJ.m<br />
26 aluminosilicate particle was measured after exposure <strong>for</strong> 6 mo. The clearance half-time of the<br />
27 slow phase was found to be doubled in adult rats compared with age-matched controls and was<br />
28 · not significantly affected in developing rat lungs.<br />
29 Mauderly et al. compared the effects of diesel exhaust in normal lungs with rats in which<br />
30 emphysema had been induced experimentally by instillation of elastase 6 weeks be<strong>for</strong>e diesel<br />
31 exhaust exposures. The rats were exposed to 3.5 mg/m 3 DPM <strong>for</strong> 7 h/day, 5 days/week <strong>for</strong> 24<br />
32 mo. Measurements included histopathology, clearance, pulmonary function, lung lavage, and<br />
33 immune response. In the rats that were not pretreated with elastase, there was a significant<br />
34 · reduction in the number of macro phages recovered by pulmonary lavage in contrast to the<br />
35 increases in macrophages reported by Strom (1984) and Henderson et al. (1988). The half-time<br />
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