If you study the periodic system of elements, you will notice that both are in the same group IId. Thus, they have similar chemical characteristics and will not surprisingly end up in the same materials. The origin of the zinc ore and the manufacturing process of the supplement, will determine how much cadmium will be present in the different supplements

Dear Mr. Tang,

the zinc ore from which the chemical compound has derived plays an important part. Sphalerite and smithsonite both have sulfidic (greenockite) and carbonate (otavite) analogues. Particularly in low-temperature mineralization the Cd content significantly increases with part of it also transferred during subsequent processing into chemical compounds as those mentioned by you. Sometimes it may also closely related with another trace element indium in natural zinc sulfide.

Best regards

H.G.Dill

I agree with Dr Dill and Dr Kan about the similarities of zinc and cadmium which are very difficult to separate (I'll submit very soon a theoretical and experimental study about this difficult case of separation).

I do think that the supplementation preparations based on zinc should be purified to a high degree (although difficult) to reduce cadmium content to a trace level before marketing authorization because cadmium is highly toxic and causes harmful neurological disorders and even cancers.

Since zinc is also toxic (even less than cadmium), in my opinion, these drugs should be administered with extreme caution, except for extreme cases, and not be considered as 'harmless' pharmaceutical products.

Please read the following useful items:

http://www.veganhealth.org/articles/cadmium

Int J Food Sci Nutr. 2001 Jul;52(4):379-82.

Cadmium in zinc-containing mineral supplements.

http://www.veganhealth.org/articles/cadmium