Nitrite poisoning

作者：admin  点击次数：112  发布时间：2025-05-16

(I) Etiology
1. Causes of poisoning
Nitrite food poisoning has occurred from time to time in recent years. In summary, there are several main reasons: (1) Nitrite looks and tastes similar to salt, and is easily mistaken for salt and added to food, leading to poisoning. This type of poisoning often occurs at construction sites.
(2) Nitrite poisoning is caused by eating a large amount of unfresh vegetables (especially leafy vegetables). Many vegetables (such as spinach, Chinese cabbage, beet leaves, radish leaves, leeks, etc.) contain a lot of nitrates, especially when nitrogen fertilizers and herbicides are applied in large quantities or when molybdenum fertilizers are lacking in the soil, the nitrate content in vegetables is even higher. If the vegetable is stored at a high temperature for a long time, especially when it rots, the nitrate in the vegetable can be converted into nitrite by nitrate-reducing bacteria (such as Escherichia coli, Salmonella, Clostridium perfringens, Bacillus subtilis, etc.), which can cause poisoning if eaten in large quantities.
(3) Cooked vegetables placed in unclean containers at high temperatures and stored for too long will also increase the nitrite content in them.
(4) Vegetables that have been pickled for a short time contain a large amount of nitrite (especially when the salt concentration is less than 15%), which can easily cause food poisoning after eating. Generally, the nitrite content of vegetables increases after 2-4 days of pickling, and the highest level is 7-8 days; the nitrite content in spoiled vegetables is even higher, such as spoiled pickled radish leaves, which can be as high as 2296mg/100g. (5) Well water in some areas contains more nitrates and nitrites, which is generally called bitter well water. If this water is used to cook food and stored for too long under unsanitary conditions, the nitrate will be converted into nitrite due to the action of bacteria, resulting in an increase in the nitrite content in the food and causing poisoning; if porridge is cooked with warm water from an overnight pot, it can also cause poisoning. (6) Nitrates and nitrites are often used as colorants in meat processing, and excessive use can also cause poisoning.
(7) Under certain disease conditions, such as gastrointestinal dysfunction, malnutrition in children, anemia, intestinal parasitic diseases and reduced gastric acid concentration, nitrate-reducing bacteria in the gastrointestinal tract can multiply in large numbers. At this time, if a large amount of vegetables with high nitrate content are consumed, a large amount of nitrite can be formed in the body, causing nitrite poisoning, which is called enteric cyanosis.
2. Mechanism of poisoning
Nitrite is a strong oxidant. After being absorbed into the blood through the digestive tract, it can oxidize the low-iron hemoglobin in the blood into high-iron hemoglobin, thereby losing the function of carrying oxygen, causing tissue hypoxia and producing a series of corresponding poisoning symptoms. The poisoning dose of nitrite is 0.3~0.5g, and the lethal dose is 1~3g.
(II) Symptoms of poisoning
The length of the incubation period of nitrite poisoning is related to the amount of nitrite ingested and the cause of poisoning. Poisoning caused by ingestion of pure nitrite usually occurs about 10 minutes after ingestion, while poisoning caused by ingestion of large amounts of vegetables containing nitrite or other reasons usually occurs 1 to 3 hours after ingestion, and the incubation period can be as long as 20 hours. The main symptoms of poisoning are: cyanosis caused by tissue deficiency, such as blue lips, tongue tip, fingernails and skin, and headache, fatigue, increased heart rate, nausea, vomiting, abdominal pain, diarrhea, etc. In severe cases, coma, convulsions, incontinence, and often death from respiratory failure.
(III) Preventive measures (1) Strengthen management and properly store nitrite. The containers for packaging or storing nitrite should be marked with eye-catching signs to prevent accidental ingestion. Nitrite should be kept by a dedicated person and stored in a dedicated container, and the registration procedures for receiving and issuing should be sound. (2) Do not eat spoiled vegetables. Vegetables should be eaten fresh. If they need to be stored, pay attention to the storage conditions and avoid storage for too long and rotting. Leftover vegetables should not be stored at high temperatures for a long time before being eaten. Salted vegetables should be pickled thoroughly before being eaten (at least pickled for more than 20 days). Fresh vegetables should be used for cooking. (3) Improve water quality and pay attention to drinking water safety. Water quality treatment should be carried out in areas with high nitrate content in drinking water. If bitter well water must be used, do not use it to cook porridge. Cooked food should not be stored at room temperature overnight as much as possible. Do not drink repeatedly boiled water.
(4) Strictly manage the hygiene of food additives. Control the scope of use, dosage and residual amount of nitrite as a food additive in food.
(5) Improve the soil environment. For example, the reasonable application of molybdenum fertilizer can reduce the nitrate content in vegetables and grains. (6) Use reasonable processing and cooking methods to reduce the nitrate content in vegetables. For example, blanching vegetables before cooking and discarding the soup before stir-frying can greatly reduce the nitrate content. Soaking vegetables in 1% salt water or vitamin C solution for a day and night can reduce the nitrate content by 90%.