Effect of Cr(VI) exposure on sperm quality.

Received 30 October 2001I have a number of difficulties with Li et al. (2001),starting with its title ‘Effect of Cr(VI) exposure…’.The chemical species Cr(VI) does not exist as a freeentity under normal conditions. Normally it is foundin the form of the anion chromate associated with acation. Hence, ‘Effect of chromate exposure…’ mighthave been a more accurate statement with regard toboth the workers in the electroplating factory and therats (but see below). Even then, the cation(s) presentshould have been stipulated as they may well deter-mine how the body reacts to chromate, particularly athigh exposures.However, I can see no evidence that the workersstudied were actually exposed to any form of chro-mate. It may be so, but no data are presented forexposure or exposure conditions. The presence of theelement chromium in the blood does not establishexposure to chromate since the analytical methodsused on the blood and semen samples do not permitdetermination of this chemical species, or indeed ofany chemical speciation (Ebdon et al. , 2001). Sinceno measurements of exposure are reported, there isno possibility of considering the effects of othersubstances to which these workers may have beenexposed. Not even their smoking habits are reported.Nor is there any consideration of nutritional expo-sures or, indeed, of the nutritional status of theworkers in the study. Both sperm quality and uptakeof chromate (or other forms of chromium) must bedependent on the nutrition of those at risk. This isparticularly important in animal experiments whererats are exposed by oral feeding.The relevance of oral feeding of CrO