Naturally-occurring comparative carcinogenicity

A detailed examination of HERP-index did not provide the possibility to conclude that the risk of exposure to industrial carcinogens and pesticides outside the workplace are trivial compared with those of naturally occurring carcinogens found mostly in the diet... 

A qualitative outline of chromium kinetic behavior emerges from these studies. Chromium(VI) is absorbed, distributed, and excreted substantially more readily than Cr(III). At the same time, reduction of Cr(VI) to Cr(III) occurs so rapidly in the lung, the gastrointestinal tract, and the body that to a large extent the kinetics of Cr(VI) have been thought of as the kinetics of Cr(III). This is not precisely correct. The rapidity with which Cr(VI) is reduced, compared to the rapidity of its absorption and excretion processes, controls a sensitive balance that determines overall absorption, distribution, and excretion of chromium as well as the amounts absorbed, distributed, and excreted as Cr(VI). In addition, the nature and rate of the reduction process itself appear to be linked with Cr(VI) pulmonary carcinogenicity. 

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