Mutagenicity from ozonation of humic substances.

Eight structural components of humic substances were ozonated. Mutagenic activity was found using TA100 with and without S9 mix for all ozonated components. p-Hydroxybenzaldehyde was chosen as an important component and ozonation products were determined by gas chromatography-mass spectrometry (GC-MS). Aldehydes, ketones and carboxylic acids were identified as the ozonation products. Among these products, acetaldehyde, formaldehyde, glyoxal, methylglyoxal and glyoxylic acid were recognized to be mutagenic. Furthermore, p-hydroxybenzaldehyde was first ozonated and then chlorinated. A great variety of chlorinated organic compounds, many of which are known mutagens, have been identified by GC-MS in the ether extract. The same compounds have previously been reported as chlorination products of humic substances. Aldehydic products by ozonation were identified from ozonation followed by chlorination of humic substances and p-hydroxybenzaldehyde.