HEALTH RISK ASSESSMENT OF ENVIRONMENTAL NANO PARTICLES USING MOLECULAR BIOLOGICAL METHODS

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We evaluated the usefulness of molecular biological methods in the health risk assessment of environmental nanoparticles. (1) Lung and heart tissues were collected from aged rats (aged 22-24 months) that had been exposed to diesel particles for 7 months or concentrated air particles (CAPs) for 3 days. The results of DNA profile analysis showed increases in DNA gene expression in complements, macrophage activated cytokine, chemokine, CINC-2, hemoxidase, and angiotensin II receptor in the lung exposed to diesel emission, in complements, inflammation-related components and blood coagulation-related items in the lung exposed to CAPs, and in complements in the heart exposed to CAPs. The increases in DNA expression level did not necessarily correspond with mRNA expression or protein concentration. Physiological and pathological findings and changes in DNA and mRNA expression showed only slight correlations in aged rats exposed to diesel particles or CAPs. On the other hand, the expression of inflammation-related cytokine mRNA was higher in the lungs of rats treated with diesel particles washed with organic solvent (E-DEP) than in those of rats treated with unwashed particles (DEP). E-DEP had a larger particle area per weight than DEP. These findings support the hypothesis that nanoparticles have greater toxicity in the lung than fine particles. The results of our study suggested that DNA profile analysis are useful for the selection of disease-related biomarkers in the first step of the health risk assessment of nanoparticles. Following this, the levels of mRNA expression and protein concentration are confirmed for the selected biomarkers. The final health risk assessment of nanoparticle toxicity should be based on an overall evaluation of molecular biological, biochemical, hematological, pathological and physiological data.