Lard residue is refined from pork, a by-product of boiling lard, and its production process includes high-temperature frying, which is prone to the formation of carcinogenic substances, and long-term or excessive consumption may increase the chances of cancer. When lard is boiled for a long time and the oil temperature is high, the decomposition of carbonaceous organic substances by heat will produce polycyclic aromatic hydrocarbons, one of which is benzo(a)pyrene, which is currently recognized as one of the three major carcinogens. When the oil temperature is above 200℃, in addition to benzopyrene, a large amount of peroxide and other carcinogenic substances will be produced. And boiled and burnt oil residue will produce tar, dimethyl nitrosamines and other carcinogenic substances. Long-term or excessive consumption of lard dregs can easily cause indigestion and prolonged retention of food in the stomach, prompting the secretion of large amounts of gastric acid, which will cause certain stimulation to the gastric mucosa, and over time, it will easily lead to gastric mucosal erosion and ulceration, plus the stimulation of carcinogenic substances to the digestive tract mucosa, which will increase the chance of esophageal cancer and gastric cancer. Lard residue contains a large amount of animal fat, which is a saturated fatty acid, and in addition to increasing the risk of cancer, it also tends to cause obesity, and can also raise cholesterol, leading to atherosclerosis, hypertension and cardiovascular and cerebrovascular diseases. In summary, excessive consumption of lard dregs should be avoided. In addition, extra attention should be paid to other foods prepared at high temperatures to prevent the adverse effects of excessive intake of carcinogens.