Which foods are prone to heavy metal cadmium? From detection to prevention and control suggestions

The detection of heavy metal cadmium in food is closely related to industrial pollution, agricultural production and environmental migration. The following are the main food categories and typical cases: 1. High-risk agricultural products Rice and grain Rice is the "hardest hit area" of cadmium pollution, especially in the acidic soil areas of the south. Studies show that the cadmium content of rice sold in our country exceeds the standard by about 10%, and the cadmium content of rice in some polluted areas such as Hunan and Guangdong can reach 0.348mg/kg (nearly 2 times exceeding the standard). The absorption capacity of rice for cadmium is 2-3 times that of corn and soybean. Super rice has a higher risk of cadmium enrichment due to its developed root system. In addition, if wheat, corn and other grains are planted in cadmium-contaminated soil, cadmium may also remain in the grains. Leafy vegetables and root vegetables Leafy vegetables (such as spinach, lettuce) and rhizomes (such as radish, potato) have high cadmium content due to direct contact with soil or strong absorption capacity. The cadmium content of leafy vegetables in the polluted area around a smelter reached 1.148mg/kg, and that of root vegetables reached 1.742mg/kg, which exceeded the national standard (0.05mg/kg) by 23 times and 35 times, respectively. This is related to the biological availability of cadmium in soil and the metabolic characteristics of plants. Tea trees have strong enrichment capacity for cadmium, especially in tea gardens grown in mining areas or around industries for a long time. Studies have shown that the cadmium content of some tea leaves can reach 0.5-1 mg/kg, exceeding the cadmium limit of tea leaves in GB 2762-2022 "National Food Safety Standard" (0.5mg/kg). Second, aquatic products crustaceans and shellfish sea crabs, shrimp crabs, scallops, etc. are typical representatives of cadmium enrichment. The 2020 State Regulation for Market Regulation sampling showed that 87.6% of the batches of crabs failed to meet the cadmium standard, and some swimming crabs had cadmium content exceeding the standard by 7 times. The cadmium content in the internal organs and gills of shellfish such as scallops was significantly higher than that in muscle tissue, and cadmium in aqueous phase was the main source of pollution. If fish and frogs freshwater fish (such as crucian carp, catfish) and farmed frogs (such as bullfrogs) live in cadmium-contaminated water bodies, cadmium may be detected in the muscles and internal organs. For example, shrimp male and swimming crab sampled in Nantong in 2017 failed to meet the cadmium standard. III. Animal-derived food Meat and offal Livers and kidneys of pigs, cattle and sheep are the main accumulating organs of cadmium. A dietary survey of residents around a smelter showed that meat contributed about 10% to cadmium exposure, and the cadmium content in internal organs was significantly higher than that in muscles. In addition, if cadmium-contaminated grains or forage are used in animal feed, meat residues can also be caused. Preserved eggs and dairy products may become a source of cadmium pollution due to the illegal use of industrial copper sulfate (containing cadmium) in the processing process. In the "poisoned preserved eggs" incident exposed by CCTV in 2023, the cadmium content of some products exceeded the standard several times. In terms of dairy products, if dairy cows drink cadmium to pollute water sources, trace cadmium may be detected in milk. IV. Processed Foods and Special Scenarios Soy Sauce and Seasoning Soybeans, the raw materials of soy sauce, if planted in cadmium-contaminated soil, may lead to cadmium residues in the finished product. Tests in 2025 showed that cadmium (0.00572-0.110mg/kg) was detected in 12 of the 13 zero-added soy sauces, although not exceeding the standard, but reflecting the prevalence of raw material contamination. Leftovers and vomit If leftovers are stored in cadmium-contaminated containers (such as substandard stainless steel tableware), it may increase the risk of cadmium dissolution. In medical tests, vomit and gastric dissolution can be used to evaluate acute cadmium poisoning, but this is a clinical category. Groundwater and river water contaminated by industrial wastewater or mining in drinking water may contain cadmium. The cadmium content in drinking water of residents around a smelter reached 0.006mg/L. Although it was lower than the national standard (0.005mg/L), long-term drinking still requires vigilance. 5. Pollution Mechanism and Regulations Bioconcentration and Food Chain Amplification Cadmium has a half-life of 10-35 years in organisms, and is gradually concentrated through the food chain of "plankton shellfish fish humans". For example, the "pain disease" incident in Japan was caused by long-term consumption of cadmium-contaminated rice. According to the regulations and standards of our country GB 2762-2022, the cadmium limit of rice is 0.2mg/kg, 0.05mg/kg for leafy vegetables, and 1.0mg/kg for crustaceans (sea crab, mantis shrimp) muscle tissue. The European Union only sets restrictions on crustacean muscle tissue, excluding parts such as crab roe, which also leads to differences in the detection of imported aquatic products.