Acceptable level of chromium in food

I thank Professor Abul Hossain for replying to my letter on chromium scare. I have nothing much to say about the acceptable limit of chromium except the fact that different values for the same parameter are not uncommon in the field of Environmental Science. For instance, in an EPA-sponsored Toxicological Review of Trivalent Chromium, the National Research Council has identified an Estimated Safe and Adequate Daily Dietary Intake (ESADDI) for trivalent chromium at 50-200 microgram per day, while the Food and Drug Administration has selected a Reference Daily Intake of 120 microgram per day. These numbers represent the amounts that are adequate to meet the essential body requirements and do not necessarily indicate that any amount in excess of these would be harmful to health. Based on an experiment, the authors of the same review article have chosen a value of, what they termed, No-Observed-Adverse-Effect Level (NOAFL) of trivalent chromium at 1.5 milligram per kg body weight per day. That means a 60-kg person can tolerate 90 milligram of trivalent chromium per day without any adverse effect. Thus even if a person eats daily 1 kg of chicken brain which, according to the article, contains the highest amount of chromium (4.56 milligram per kg), s/he is within safe limits, provided that all the chromium is in the trivalent state.

Now about the question whether it is necessary to measure hexavalent chromium. My answer is yes. As far as I know, there is no evidence that trivalent chromium is carcinogenic. In contrast, hexavalent chromium is widely known for its carcinogenic properties. But can't some trivalent chromium become oxidized into hexavalent chromium during the process to make poultry feed? In presence of reducing agents present in chicken and eggs, hexavalent chromium may rather be converted back into trivalent chromium. Only direct measurement of hexavalent chromium can provide an unequivocal answer.

Professor M Lutfor Rahman
Department of Environmental Science
Independent University, Bangladesh