Is chromium scare scientific?

I would like to make some comments on the report, “Chickens, eggs made risky,” carried by the July 5 issue of TDS. My comments would be limited to chromium part only, as I have no expertise in antibiotics, the other part.

The part on chromium toxicity has been prepared based on the research work carried out by Professor Abul Hossain of the University of Dhaka. Firstly, they analysed tanned skin-cut wastes (SCW) and leather shaving dust (LSD) and also deshi bone meat (DBM) and found substantial amounts of chromium. This is not surprising as a large amount of chromium is used in the tanning process. Interestingly, they found no chromium in the poultry feed obtained from the market. They mixed this poultry feed with SCW, LSD and DMB and chicks were fed on those for one or two months and then different body parts of these chickens were analysed for their chromium content. The question that naturally comes to one's mind is whether poultry farms use the same method of feeding. If the answer to this question is negative, such large amounts of chromium as have been found in their experiments are not likely to be present in the farmed chicken.

Secondly, Graphite Furnace Atomic Absorption Spectrophotometry has been used as an analytical technique that measures total chromium rather than any particular oxidation state of chromium. The chemistry of chromium tells us that of the different oxidation states in which chromium exists, trivalent and hexavalent forms are the most stable. The effects of these two states on human body are vastly different. According to WHO, the trivalent form is an essential nutrient for humans, the required amount being 50 – 200 microgram per day. Hexavalent chromium is far more toxic than trivalent chromium. It is the hexavalent form that is held responsible for causing mutation, cancer and cell damage. Thus the toxicity of chromium depends on how much of the total chromium is hexavalent chromium. It would be extremely difficult to assess the toxicity of chicken and eggs without measuring the amount of hexavalent chromium present in them. To my mind, this hue and cry about chromium toxicity and the panic created in the public mind about eating chicken and eggs are not founded on solid scientific evidence.

Professor M Lutfor Rahman
Department of Environmental Science
Independent University