||P.483 Sidebar 12.4 1st paragraph: "Oxidation products in urine provide an estimate of the rate of ongoing damage to the cellular genome. By recent estimates, the genomes of some human cells suffer as many as 10^3 oxidative hits a day, about 10-fold less than the rate at which depurination of bases occurs. The resulting oxidized bases are largely but not totally removed and replaced with the appropriate normal bases. Rats cells suffer about 10-fold more oxidative hits per cell per day in their genomes than do human cells because they have about a 7-fold greater metabolic rate (Figure 12.13). Any unrepaired oxidative lesions will accumulate with time, especially in the genomes of cells that are not mitotically active."