Toxicity of wide-range polarity fractions from wood smoke and diesel exhaust particulate obtained using hot pressurized water

Epidemiological and toxicological studies correlate the adverse health effects of particulate matter (PM) with the available information regarding their chemical characterization, which has focused on nonpolar organics (e.g., polycyclic aromatic hydrocarbons [PAHs]), which are limited to 15 to 50% of total organic carbon. To study both polar and nonpolar species, we have employed hot pressurized (liquid) water for the fractionation of diesel exhaust and wood smoke PM. In agreement with the results of previous studies, nonpolar fractions from both PM samples showed strong cytotoxicity (cell viability decreased to 50-60%) corresponding to the presence of PAHs. Surprisingly, similar decreases in cell viability were also found in polar fractions (50degreesC) from both diesel exhaust and wood smoke PM. The midpolarity fractions (100-150degreesC) from wood smoke PM also displayed high cytotoxicity corresponding to methoxyphenols and oxy-PAHs. Although the midpolarity fractions from diesel exhaust PM showed no cytotoxicity, genotoxicity was found in the 150degreesC fraction, possibly corresponding to nitroaromatics. The present study demonstrates the suitability of hot pressurized water (as a single, nontoxic solvent) for the fractionation and toxicological characterization of wide-range polarity constituents of PM and, possibly, other environmental matrices.