Each of us at least once in our lives faced with the unpleasant consequences of eating foods with nitrates. For some, such a meeting continued with a slight intestinal disorder, and someone managed to get to the hospital and for a long time looked with caution at any fruits and vegetables bought on the market. A near-scientific approach and lack of awareness make s altpeter a monster that can even kill, but it’s worth getting to know these concepts better.
Nitrates and nitrites
Nitrites are s alts of nitric acid in the form of crystals. They dissolve well in water, especially in hot water. On an industrial scale, they are obtained by absorbing nitrous gas. Used to obtain dyes, as an oxidizing agent in the textile and metalworking industries, as a preservative.
Nitrates are s alts of nitric acid, formerly called s altpeter. They are obtained after exposure to nitric acid on metals, and in themselves they are very strong oxidizing agents. Well soluble in water. The decomposition of nitrates occurs at temperatures above three hundred degrees Celsius. The main use of nitrates is agriculture, but some compounds are used in pyrotechnics as explosives and as components of rocket fuel.
The role of nitrates in plant life
One of the four basic elements that make up a living organism is nitrogen. It is necessary for the synthesis of protein molecules. Nitrates are s alt molecules that contain the amount of nitrogen the plant needs. Absorbed by the cell, s alts are reduced to nitrites. The latter, in turn, through the chain of chemical transformations reach ammonia. And it, in turn, is necessary for the formation of chlorophyll.
Natural sources of nitrates
The main source of nitrates in nature is the soil itself. When the organic substances that it contains are mineralized, nitrates are formed. The speed of this process depends on the nature of land use, weather and soil type. The earth does not contain much nitrogen, so environmentalists do not worry about the formation of a significant amount of nitrate. Moreover, agricultural work (harrowing, disking, constant use of mineral fertilizers) reduces the amount of organic nitrogen.
Therefore, natural sources cannot be considered a factor in groundwater pollution and nitrate accumulation in plants.
Anthropogenic sources
Conditionally anthropogenic sources can be divided into agricultural, industrial and municipal. To the first categoryinclude fertilizers and animal waste, the second - industrial wastewater and industrial waste. Their impact on environmental pollution varies and depends on the specifics of each particular region.
Determination of nitrates in organic materials gave the following results:
- more than 50 percent is the result of the harvesting campaign;
- about 20 percent is manure;
- urban municipal waste is approaching 18 percent;- everything else is this is industrial waste.
The most serious damage is caused by nitrogen fertilizers, which are applied to the soil to increase yields. The decomposition of nitrates in soil and plants produces enough nitrites for food poisoning. The intensification of agriculture only exacerbates this problem. Nitrate levels are highest in main drains that collect water after irrigation.
Effect on the human body
Nitrates and nitrites first compromised themselves in the mid-seventies. Then in Central Asia, doctors recorded an outbreak of watermelon poisoning. During the investigation, it was found that the fruit was treated with ammonium nitrate and, apparently, a little overdone. After this incident, chemists and biologists came to grips with the study of the interaction of nitrates with living organisms, in particular humans.
- In the blood, nitrates interact with hemoglobin and oxidize its iron. This forms methemoglobin, which cannot carry oxygen. This leads to disruption of cellular respiration and oxidation of the internal environment.organism.
- By disturbing homeostasis, nitrates promote the growth of harmful microflora in the intestines.
- In plants, nitrates reduce vitamin content.
- An overdose of nitrates can lead to miscarriage or sexual dysfunction.
- In chronic nitrate poisoning, there is a decrease in the amount of iodine and a compensatory increase in the thyroid gland.
- Nitrate is a trigger factor for the development of tumors of the digestive system.
- A large dose of nitrates can simultaneously lead to collapse due to a sharp expansion of small vessels.
Nitrate metabolism in the body
Nitrates are derivatives of ammonia, which, getting into a living organism, are built into the metabolism and change it. In small quantities they are not a cause for concern. With food and water, nitrates are absorbed in the intestines, pass through the bloodstream through the liver and are excreted from the body by the kidneys. In addition, nitrates pass into breast milk in breastfeeding mothers.
In the process of metabolism, nitrates turn into nitrites, oxidize the iron molecules in hemoglobin and disrupt the respiratory chain. In order to form twenty grams of methemoglobin, just one milligram of sodium nitrite is enough. Normally, the concentration of methemoglobin in blood plasma should not exceed a couple of percent. If this figure rises above thirty, poisoning is observed, if above fifty, it is almost always fatal.
To control the level of methemoglobin in the body ismethemoglobin reductase. It is a liver enzyme that is produced in the body from the age of three months.
Nitrate limits
Of course, the ideal option for a person is to avoid getting nitrates and nitrites into the body, but in real life this does not happen. Therefore, the doctors of the sanitary and epidemiological station have established the norms of these substances that cannot harm the body.
For an adult weighing more than seventy kilograms, a dose of 5 milligrams per kilogram of body weight is considered acceptable. Without serious he alth consequences, an adult can ingest up to half a gram of nitrates. In children, this figure is more average - 50 milligrams, regardless of weight and age. At the same time, a fifth of this dose will be enough for a baby to be poisoned.
Infiltration routes
You can get nitrate poisoning in the alimentary way, that is, through food, water and even medicines (if they contain nitrate s alts). More than half of the daily dose of nitrates enters a person with fresh vegetables and canned food. The remaining dose comes from baked goods, dairy products and water. In addition, an insignificant part of nitrates are metabolic products and are formed endogenously.
Nitrates in water - this is a reason for a separate discussion. It is a universal solvent, therefore, it contains not only useful minerals and trace elements necessary for normal human life, but also toxins, poisons, bacteria,helminths, which are pathogens of dangerous diseases. According to the World He alth Organization, about two billion people fall ill every year due to poor-quality water, and more than three million die from them.
Chemical fertilizers containing ammonium s alts seep through the soil and into underground lakes. This leads to the accumulation of nitrates, and sometimes their amount reaches two hundred milligrams per liter. Artesian water is cleaner, as it is extracted from deeper layers, but toxins can also get into it. Residents of rural areas, along with well water, receive eighty milligrams of nitrates daily from every liter of water they drink.
In addition, the nitrate content of tobacco is high enough to cause chronic poisoning in long-term smokers. This is another argument in favor of fighting a bad habit.
Nitrates in foods
During the culinary processing of products, the amount of nitrates in them is significantly reduced, but at the same time, violation of the storage rules can lead to the opposite effect. Nitrites, the most toxic substances for humans, are formed at temperatures from ten to thirty-five degrees, especially if the food storage place is poorly ventilated, and the vegetables are damaged or have begun to rot. Nitrites are formed in thawed vegetables, on the other hand, deep freezing prevents the formation of nitrites and nitrates.
Under optimal storage conditions, you can reduce the amount of s altpeter in products up to fifty percent.
Nitrate poisoning
Signs of nitrate poisoning:
- blue lips, face, nails;
- nausea and vomiting, there may be pain in the abdomen;
- yellowness of the whites of the eyes, bloody stools;
- headache pain and drowsiness;- noticeable shortness of breath, palpitations and even loss of consciousness.
Sensitivity to this poison is more pronounced in hypoxic conditions, such as high in the mountains, or when carbon monoxide poisoning or strong alcohol intoxication. Nitrates enter the intestines, where the natural microflora metabolizes them to nitrites. Nitrites are absorbed into the systemic circulation and affect hemoglobin. The first signs of poisoning can be replaced after an hour with a large initial dose or after six hours if the amount of nitrates was low.
It should be remembered that acute nitrate poisoning is similar in its manifestations to alcohol intoxication.
It is impossible to separate our lives from nitrates, because it will affect all areas of human life: from nutrition to production. However, you can try to protect yourself from excessive consumption of them by following simple rules:
- wash vegetables and fruits before eating;
- store food in refrigerators or in specially equipped rooms;- drink purified water.
