# Potential Metal Contamination in Foods of Animal Origin--Food Safety Aspects
## 2 Major Toxic Metals in Food
### Cadmium (Cd)
The bioavailability of cadmium in animal tissues (e.g., mammalian liver, hepatopancreas of crustaceans) is generally lower than that of highly soluble cadmium chloride [44; 45; 48; 49]. Cadmium levels are highest in shellfish, oysters, salmon, and of course, in liver- and kidney-containing products, while they are lower in dairy products, meat, and poultry. During chronic exposure, cadmium accumulates most in the kidney, followed by the liver, testis, pancreas, and spleen [49; 50]. It accumulates to a lesser extent in muscle and bone [51; 52]. Cadmium was not detectable in the muscle or fat tissue (<0.3 mg/kg) of pigs fed phosphate supplementation (and thus a cadmium content of 1.2 mg/kg in feed) until they reached a slaughter weight of 90 kg; however, it was present in the liver at 0.35 mg/kg and in the kidney at 1.68 mg/kg [53]. In fish (e.g., rainbow trout), cadmium is primarily concentrated in the gills and kidneys, with lower levels measured in the liver [43]. Cadmium concentration was lower in marine and freshwater fish (sardine: 0.07 \(\pm\) 0.02 mg/kg, tuna: 0.03 \(\pm\) 0.01 mg/kg, rainbow trout: 0.03 \(\pm\) 0.02 mg/kg), but it was 5-10 times higher in shellfish species (0.26 \(\pm\) 0.12 mg/kg, oysters (0.28 \(\pm\) 0.08 mg/kg), and squids (0.30 \(\pm\) 0.16 mg/kg) [26; 27; 28; 29; 54]. Cadmium levels in the kidneys of 6-7-week-old broiler chickens raised for human consumption were 0.05 mg/kg, and in muscle, they were <0.005 mg/kg w.w. [55]. Even in cases of very high cadmium intake in laying hens (100 mg/kg in wet liver), cadmium could not be detected in the egg white, and the yolk contained only about 0.1 mg/kg [56; 57]. A similar trend was observed in dairy cows. Long-term intake does not significantly increase the cadmium content of milk [52; 58; 59]. In a study using radioactive cadmium, it was found that cadmium is primarily bound to casein, to a lesser extent to albumin and lactose, and is undetectable in milk fat [60]. Data suggest that cadmium levels in meat, milk, and eggs of food-producing animals are lower than in feed, although cadmium concentrations in the liver and kidney may be higher [61]. However, in wild animals, the Cd content in the muscle, liver, kidney, and fat of roe deer (Carpelous capreolus) ranged from 0.24 to 1.46 mg/kg w.w. [62]. The most important sources of Cd exposure to humans are several types of meat and meat products and different plants (e.g., cereals and cereal products, vegetables, nuts and pulses, starchy roots or potatoes) primarily due to their high consumption. Compared to the world average, the consumption of cocoa products among children in the EU is higher, which also contributes to the higher intake. Vegetarians, due to the consumption of highly contaminated vegetables, may have higher dietary exposure. The average exposure by consumption of different foods ranges from 1.9 to 3.0 ug/kg b.w./week in adult humans of EU Member States and is between 2.5 and 3.9 ug/kg b.w./week in high consumers. Exposure in infants and children may be higher than in adults, primarily due to the consumption of larger amounts of food relative to body weight [63].