Sister chromatid exchange induced by several types of coffees in Chinese hamster ovary cells

Different brands of commercial caffeinated and decaffeinated coffees (roast ed, high roast, blend ground, and instant coffees) were studied. These coff ees were tested for their ability to induce sister chromatid exchanges (SCE ) in CHO-K1 cells. Tests were performed in the presence and in the absence of a metabolic activation system (S-9 mix). Results were compared to the ro asting procedure because genotoxic products could be formed from these proc esses. Our results indicate that caffeinated instant coffees showed higher genotoxic activity than decaffeinated coffees. Non-significant genotoxic ac tivity was detected with the green coffee (unroasted). The highest increase of the frequency of SCE occurred when the caffeinated instant coffee was t ested in the absence of metabolic activation system. The repeatability of t he test was checked through three assays with the same sample. (C) 2001 Wil ey-Liss, Inc.