Genotoxicity of brown-colored polymerization products formed in smoke flavors.

Smoke aroma essences, which are prepared from smokehouse smoke by condensation and purification, are used for flavoring raw food products. The essences spontaneous decompose and produce brown-colored polymerization products, which may react with protein and be liberated within the acidic environment of the human stomach. The potential of these products to cause DNA damage was studied in two microbial and two in vivo assay systems. The polymerization products induced his+ reversion in Salmonella typhimurium TA 100 after metabolic activation by liver enzymes. There was no significant activity in a differential killing assay with repair-deficient strains of Escherichia coli WP2. In vivo tests demonstrated significant increases in the rate of sister chromatid exchanges in bone marrow cells of Chinese hamsters, but no increase in micronuclei was detectable. Thus, genotoxic components may be present in the brown-colored fractions of smoke aroma essences, but further study is needed.