Ames test residues

Freeze-drying. For a 7000-fold concentration, 70 L of drinking water was lyophilized in a Virtus Unitrap II. The dried residue was then divided into equal weights and packed into two columns (25 X 1.5 cm) with a sintered glass filter. The organic material was eluted consecutively with acetone, ether, and DMSO. The ether in the ether eluate was removed by rotary evaporation, and the dried residue was dissolved in DMSO. The DMSO concentrates were sterilized by filtration over a 0.2-/xm Teflon filter (Millipore). The acetone and DMSO concentrates were tested in the Ames test. 

We worry with some justification about chemical carcinogens in the workplace - blue asbestos and chromium salts being prime examples - but there is a high degree of over-reaction to things like pesticide residues and artificial flavours and colours in our diet. As the American biochemist Bruce Ames (inventor of the so-called Ames test for mutagenicity) has pointed out ... 

Several Amadori products, notably those containing aromatic amino acid residues, have been found to behave as direct-acting mutagens in Salmonella typhimurium his strains [52] (i.e., in the Ames test), and some (e.g., nitrosated fructose-tryptophan and fructose-serotonin compounds) are known to induce DNA repair synthesis in cells of the human HeLa S3 cell line [53]. 

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