Editor's Note
Recently, a 5-year-old girl in Zhuji, Zhejiang Province, after eating her own pickled kimchi, developed symptoms of poisoning, was diagnosed with nitrite poisoning, appeared purple lips, had obvious symptoms of hypoxia, and was treated out of danger of life. So, what is nitrite? How does food poisoning occur? What are the relevant standards and regulations?
Nitrites are a class of nitrogen-containing inorganic compounds that are common in nature and can be applied as food additives to meat products. In the process of nitrate formation, due to the action of microorganisms, it is often accompanied by the production of nitrite. Common nitrites mainly include sodium nitrite and potassium nitrite, which are similar in appearance to table salt, white to yellowish, powder or granular, odorless, slightly salty, easy to deliquesce and soluble in water.
Excessive intake can lead to intoxication
Under normal diet, the nitrites in the human body are mainly converted from the nitrates in food and drinking water under the action of bacteria in the mouth and stomach. Studies have shown that nitrite can be reduced to nitric oxide through certain pathways.
However, if a large amount of nitrite is ingested orally (mistakenly ingested or over-ingested) in a short period of time, it is easy to cause acute poisoning, so that the low ferritoglobin with normal oxygen carrying capacity in the blood is oxidized into methemoglobin, losing the ability to carry oxygen, resulting in tissue hypoxia, called methemoglobinemia. When the intake reaches 0.2g to 0.5g, it can lead to poisoning, and when the intake exceeds 3g, it can cause death. Poisoning is characterized by cyanosis, and the symptoms and signs include headache, dizziness, fatigue, chest tightness, shortness of breath, palpitations, nausea, vomiting, abdominal pain, diarrhea, lips, nails, and cyanosis of the whole body, mucous membranes. In severe cases, they are confused, irritable, comatose, and respiratory failure until death.
The occurrence of food poisoning caused by nitrites has nothing to do with gender and age, and there is no obvious seasonal and geographical distribution, so the poisoning field is mostly a collective canteen and a catering unit.
There are four common causes of food poisoning caused by nitrite, one is that because nitrite is similar in appearance to table salt, nitrite is mistakenly used or eaten as table salt, which is the main cause of poisoning. Second, because many areas of China have the habit of homemade processed meat products, if you eat meat products containing excessive nitrites, it will also cause food poisoning. Third, the content of nitrite in vegetables that have been stored for too long, rotted or cooked for too long and have just been pickled will increase, and it is easy to cause poisoning when eaten in this case. Fourth, the well water in individual areas contains more nitrate (called "bitter well water"), and if the rice cooked with this water is stored for too long, the nitrate can be reduced to nitrite under the action of bacteria and lead to poisoning.
It is worth mentioning that the nitrite content in pickled vegetables is only abundant on the second to tenth day of pickling, and during the "peak" period of nitrite, the content can reach more than 100mg/kg or even higher, which may reach the level of pathogenic content. In short, pickles eaten within two days after pickling or half a month to a month later often contain nitrite content that does not affect the human body.
The national food safety standards make strict provisions on the use of nitrites
The Food and Agriculture Organization of the United Nations and the Joint Expert Committee on Food Additives (JECFA) stipulate that the allowable daily intake of nitrite is 0 to 0.2 mg/kg·bw. Countries around the world also stipulate the limits of the use of nitrite in food.
China's national food safety standards have strict requirements for the use and safety management of nitrites, and it is safe to use nitrites in accordance with the standards. The National Standard for Food Safety and the Standard for the Use of Food Additives (GB 2760-2014) stipulates that sodium nitrite and potassium nitrite can be used as color protectors and preservatives in cured bacon products, sauce and marinated meat products and smoked, roasted, grilled meat and other processing, and stipulates the maximum use and maximum residue. The Limit of Contaminants in Food (GB 2762-2012) stipulates the corresponding limits on the amount of nitrite residues in raw milk, packaged drinking water, pickled vegetables and other products. The former Ministry of Health and the former State Food and Drug Administration "Announcement on Prohibiting the Procurement, Storage and Use of Food Additive Nitrite by Catering Service Units" (Ministry of Health Announcement [2012] No. 10) prohibited catering service units from purchasing, storing and using food additive nitrite.
Multi-party cooperation to prevent risks
Food production and trading enterprises shall strictly comply with relevant laws and regulations. When food production and processing enterprises use nitrite, they should set up special places for safekeeping, strict labeling and use management. Under the premise of complying with relevant standards, through effective measures such as raw material control and production practices, the content of nitrite in food is reduced.
Catering service units shall strictly comply with relevant regulations. Strictly implement the relevant regulations prohibiting the procurement, storage and use of nitrites, especially strictly monitor the production process and storage environment conditions of cooked meat products.
Regulators should strengthen the management of the production and use of nitrites. It is strictly forbidden for catering service units to purchase and store nitrites, and it is strictly forbidden to use industrial salt.
Consumers should increase their awareness of self-protection. Table salt sold through formal channels should be purchased. Pay attention to eating fresh vegetables, do not eat vegetables that have been stored for too long or spoiled; leftover cooked vegetables should not be stored for too long at high temperatures, and meals are best eaten freshly. Try not to use "bitter well water" to cook rice, and when you have to use it, you should avoid storing it for a long time.
□ Zhao Yunfeng Ma Guansheng Chen Fang Cao Yanping Ruan Guangfeng
Source: China Industry and Commerce Daily