Sh. Gavett et al., METAL AND SULFATE COMPOSITION OF RESIDUAL OIL FLY-ASH DETERMINES AIRWAY HYPERREACTIVITY AND LUNG INJURY IN RATS, Environmental research, 72(2), 1997, pp. 162-172
The biological effects of particulate matter (PM) deposition in the ai
rways may depend on aqueous-leachable chemical constituents of the par
ticles. The effects of two residual oil fly ash (ROFA) PM samples of e
quivalent diameters but different metal and sulfate contents on pulmon
ary responses in Sprague-Dawley rats were investigated. ROFA sample 1
(R1) had approximately twice as much saline-leachable sulfate, nickel,
and vanadium, and 40 times as much iron as ROFA sample 2 (R2), while
R2 had a 31-fold higher zinc content. Four groups of rats were intratr
acheally instilled with a suspension of 2.5 mg R2 in 0.3 ml saline (R2
), the supernatant of R2 (R2s), the supernatant of 2.5 mg R1 (R1s), or
saline only. By 4 days after instillation, 4 of 24 rats treated with
R2s or R2 had died, compared with none treated with R1s or saline, and
pathological indices were greater in both R2 groups compared with the
R1s group. In surviving rats, baseline pulmonary function parameters
and airway hyperreactivity to acetylcholine challenge were significant
ly worse in R2 and R2s groups than in the R1s group. Numbers of bronch
oalveolar lavage neutrophils, but not other inflammatory cells or bioc
hemical parameters of lung injury, were greater in both R2 groups comp
ared with the R1s group. These results reinforce the hypothesis that t
he composition of soluble metals and sulfate leached from ROFA, an emi
ssion source particle, is critical in the development of airway hyperr
eactivity and lung injury.