Basis and consequences of primary and secondary prevention of gastrointestinal tumors

DNA damage and DNA-protein cross-linking induced in rat intestine by the water disinfection by-product potassium bromate

The genotoxic effects of potassium bromate (KBrO3), a food additive and water disinfection by-product, on the small intestine of rats are reported here. Adult male rats were given a single oral dose of KBrO3 (100 mg kg(-1) body weight) and sacrificed 12, 24, 48, 96 and 168 h after this treatment while control animals were not given KBrO3. Administration of KBrO3 caused a significant increase in DNA damage when analyzed by the comet assay which suggests the induction of DNA strand breaks. This was also shown by colorimetric assay of nucleotides formed upon DNA degradation. KBrO3 treatment also resulted in increased formation of DNA-protein cross-links in the intestine. The maximum changes in these parameters were 48 h after administration of KBrO3 after which recovery took place. Thus, a single oral dose of KBrO3 exerts genotoxic effects in the intestine of rats, possibly through the mechanism of oxidative DNA damage.

The comet assay with 8 mouse organs: results with 39 currently used food additives

We determined the genotoxicity of 39 chemicals currently in use as food additives. They fell into six categories-dyes, color fixatives and preservatives, preservatives, antioxidants, fungicides, and sweeteners. We tested groups of four male ddY mice once orally with each additive at up to 0.5xLD(50) or the limit dose (2000mg/kg) and performed the comet assay on the glandular stomach, colon, liver, kidney, urinary bladder, lung, brain, and bone marrow 3 and 24h after treatment. Of all the additives, dyes were the most genotoxic. Amaranth, Allura Red, New Coccine, Tartrazine, Erythrosine, Phloxine, and Rose Bengal induced dose-related DNA damage in the glandular stomach, colon, and/or urinary bladder. All seven dyes induced DNA damage in the gastrointestinal organs at a low dose (10 or 100mg/kg). Among them, Amaranth, Allura Red, New Coccine, and Tartrazine induced DNA damage in the colon at close to the acceptable daily intakes (ADIs). Two antioxidants (butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT)), three fungicides (biphenyl, sodium o-phenylphenol, and thiabendazole), and four sweeteners (sodium cyclamate, saccharin, sodium saccharin, and sucralose) also induced DNA damage in gastrointestinal organs. Based on these results, we believe that more extensive assessment of food additives in current use is warranted.