The sources of food poisoning can be classified into four categories: natural toxins, environmental pollution, processing, and anthropogenic additives. Natural toxins exist in certain animals and plants, such as solanine found in sprouted potatoes and colchicine found in fresh yellow flowers. These alkaloids and glycosides may cause acute poisoning upon ingestion. Some foods can also produce toxins when stored improperly, such as aflatoxin from moldy peanuts, which is a strong carcinogen far more toxic than cyanide. Environmental pollution is another important source, as heavy metals from industrial emissions enter the food chain through soil and water bodies. Harmful substances such as lead and mercury often exceed the standard in contaminated agricultural products. Excessive use of pesticides and fertilizers in agricultural production can form residues on the surface of fruits and vegetables, and organophosphate pesticides can damage the function of the human nervous system.

The food processing process may generate new toxic substances. Acrylamide generated from high-temperature fried foods has neurotoxicity, and nitrosamines formed by the combination of nitrite and amine in pickled foods are clear carcinogens. Improper use of food additives also poses a hidden danger. Excessive use of certain preservatives and bleaching agents can damage liver metabolic function, while synthetic pigments may cause abnormal behavior in children. Microbial contamination is common in biological hazards, with pathogenic bacteria such as Salmonella and Staphylococcus aureus rapidly reproducing at suitable temperatures, producing enterotoxins that can lead to collective food poisoning. Plasticizers and other chemicals in packaging materials may also migrate to food, especially in oily foods where these harmful ingredients are more easily dissolved.

The toxicity caused by human factors is particularly worthy of vigilance, including the illegal use of industrial raw materials to replace food additives, and malicious behaviors such as processing and selling dead livestock and poultry meat. The water injected meat caused by private slaughter and excessive slaughter not only reduces its nutritional value, but also triggers allergic reactions due to histamine substances produced by spoilage bacteria. In addition, the illegal use of plant growth regulators in off-season planting may interfere with the normal function of the human endocrine system. These diverse pollution pathways constitute the entire risk chain from farmland to dining tables, and require systematic prevention and control measures to address them.