 In a non @-@ smoking population , food is the greatest source of exposure . High quantities of cadmium can be found in crustaceans , <unk> , <unk> , and algae products . However , grains , vegetables , and <unk> roots and <unk> are consumed in much greater quantity in the US , and are the source of the greatest dietary exposure . Most plants bio @-@ accumulate metal toxins like Cd , and when <unk> to form organic fertilizers yield a product which can often contain high amounts ( e.g. , over 0 @.@ 5 mg ) of metal toxins for every <unk> of <unk> . <unk> made from animal dung ( e.g. , cow dung ) or urban waste can contain similar amounts of Cd . The Cd added to the soil from fertilizers ( rock <unk> or organic fertilizers ) become bio @-@ available and toxic only if the soil <unk> is low ( i.e. , acidic soils ) . Zinc is chemically similar to cadmium and some evidence indicates the presence of <unk> ions reduces cadmium toxicity . 
