Induction of pulmonary and hepatic cytochrome P-450 species by coal fly ash inhalation in rats

Subacute inhalation toxicity assessment of fly ash from industrial waste incinerators

Fly ash from industrial waste incinerators has been a significant concern because of their constituent toxic heavy metals and organic compounds. The objective of this study was to identify the subacute inhalation toxicity of fly ash from industrial waste incinerators, using whole body inhalation exposure chambers. Male and female groups of Sprague-Dawley rats were exposed to fly ash by inhalation of concentrations of 0, 50, 100, 200 mg/m(3), for 6 h/day, 5 days/week for 4 weeks. There was no significant difference in body weight, and relative organ weight to body weight, between the exposure groups and the control group. Hematological examinations revealed a significant increase of monocyte counts in fly ash exposed rats and brown pigment laden macrophage was found in the lungs of rats exposed to high concentration of fly ash. A decrease of blood glucose levels and an increase in glutamate oxaloacetate transaminase activity were observed in fly ash treated rats. There was also a significant increase of lactate dehydrogenase levels in rat blood exposed fly ash. A significant dose-dependent increase of DNA damage was found in lymphocytes, spleen, bronchoalveolar lavage, liver, lung, and thymus of rats exposed to fly ash. In addition, the level of lipid peroxidation was increased in the plasma of rats exposed to a high concentration of fly ash. These results suggest that inhalation of fly ash from industrial waste incinerators can induce histopathologic, hematological, and serum biochemical changes and oxidative damage.

Elevation of rat pulmonary, hepatic and lung surfactant lipids by fly ash inhalation

Fly ash contains many polycyclic aromatic hydrocarbons and genotoxic trace elements. In rats, fly ash exposure profoundly affects lung and liver histology. In the present study, the effect of fly ash inhalation on lung and liver lipids of rats was examined. Male Wistar strain rats were exposed daily to fly ash (0.27 +/- 0.01 mg/L air) in an inhalation chamber, 6 hr daily over a period of 15 days, and were killed on various days, i.e. 16, 30, 60, and 120. Fly ash inhalation significantly (P less than 0.05) increased total phospholipids (PL), phosphatidylcholine (PC) and phosphatidylethanolamine (PE) in lungs. PC and dipalmitoylphosphatidylcholine (DPPC) contents in microsomes and lung surfactant also were significantly (P less than 0.05) higher in rats exposed to fly ash compared to control group animals. Radiolabeled precursor incorporation studies indicated that fly ash induced the synthesis of PC and DPPC by both CDP-choline pathway and N-methylation of PE in lung microsomes and enhanced their secretion into lung surfactant. In liver, PC and PE contents were elevated significantly (P less than 0.05) by fly ash exposure on days 16 and 30 respectively. A similar elevation of PC was observed in hepatic microsomes; this increase was due to its increased synthesis. However, the increased synthesis of PC in liver occurred to a greater extent by the N-methylation pathway than by the CDP-choline pathway.