Jhe. Arts et al., Short-term inhalation exposure of healthy and compromised rats and mice tofine and ultrafine carbon particles, INHAL TOXIC, 12, 2000, pp. 261-266
Epidemiological studies have consistently shown associations between acute
pulmonary effects and relatively low levels of ambient particulate matter (
PM). The present study was carried out to examine the pulmonary toxicity of
inhaled fine (FCB) and ultrafine carbon (UFC) particles as model compounds
for carbonaceous (primary) PM, and to identify whether particle sizer part
icle number, and/or mass could be critical in inducing the deleterious effe
cts. Healthy and compromised rats and mice were exposed for 4 h/day during
3 consecutive days to 10(4) or 10(5) fine carbon black (similar to 300-500
nm), or 10(5) or 10(6) ultrafine carbon (similar to 30-60 nm) particles/cm(
3), covering a mass range of about 10 to 10,000 mu g/m(3). Separate groups
of rats were also exposed to a combination of FCB and fine ammonium nitrate
at similar number and mass concentrations. Animals were sacrificed the day
after the last exposure to determine their pulmonary responses using bronc
hoalveolar lavage fluid (BALF) analysis and lung histopathology. Exposure t
o FCB resulted in early signs of lung injury. Effects were not enhanced in
compromised animals when compared to healthy animals. Exposure to UFC parti
cles at similar and higher number concentrations did not induce any biologi
cally relevant changes. These data may indicate that at number concentratio
ns occurring in ambient air, the size of the particles (in air) is more imp
ortant than their number.