Atmospheric nitration makes toxic aromatics
The nitroaromatic compounds – many of which are known to be toxic and mutagenic – found in cloud and rain water, are formed by nitration reactions from phenols and cresols. These two substances are the main sources of all the nitroaromatic compounds found in the atmosphere. They are taken up by water droplets in the atmosphere where they undergo a number of reactions. Laboratory studies have identified the various nitration reactions – with nitrate radicals, nitronium ions and nitrogen dioxide, as well as nitration initiated by hydroxyl radicals – and have shown that they can occur to significant extents. Field studies have confirmed that the majority of dinitroaromatic compounds observed in the air of towns and cities are formed as a result of these reactions taking place in the atmosphere.
