Nitrate poisoning is a symptom complex that develops with the alimentary intake of nitrogenous substances into the body in concentrations exceeding the maximum permissible. Signs of nitrate intoxication are dyspeptic disorders, acrocyanosis, tachycardia, heart pain. Severe poisoning is accompanied by convulsions, cardiopulmonary insufficiency, coma. To confirm the diagnosis and assess the current status, blood methemoglobin, ECG, EchoCG are determined. First aid includes gastric lavage, intake of enterosorbents, after hospitalization, antidote, infusion therapy, and oxygen therapy are connected.
ICD 10
X44 X49
General information
Nitrate poisoning is an acute or chronic intoxication caused by salts of nitric (nitrates) and nitrous acids (nitrites). Acute poisoning develops with the use of 1-4 g of nitrates, usually they are accidental. Such intoxications cause methemoglobinemia of varying severity and can lead to death. Chronic poisoning is associated with an increased risk of stomach cancer, cardiovascular and neurological disorders. Children of the first year of life are particularly sensitive to the excessive content of nitrates in water and food.
Causes
Nitrates are widely used in agriculture (as a fertilizer), the food industry (for canning and salting), medicine (they are part of medicines). The largest amount of nitrates (70%) enters the body when eating plant foods, 20% − with water, 10% ‒ with meat products and only 0.1% − through the respiratory tract. According to the frequency and degree of significance , the causes of nitrate poisoning are arranged in the following sequence:
- The use of agricultural crops. Nitrogen fertilizers are added to the soil when growing most vegetables and fruits. The maximum amount of nitrates accumulates in root crops (potatoes, beets, carrots, radishes), melons (watermelons, melons), leafy vegetables (spinach, lettuce), cruciferous (cabbage), pumpkin (cucumbers, zucchini). A lot of nitrates are contained in freshly prepared juices, as well as “off-season” agricultural products, for the cultivation of which large doses of agrochemicals are used.
- Drinking water consumption. Drinking chemically contaminated water from wells and boreholes leads to the development of water-nitrate intoxication. In infants, poisoning is possible when preparing adapted mixtures and even when breastfeeding, if the mother drank water contaminated with nitrates.
- Taking toxic doses of pharmacopreparations. Poisoning with nitrates (nitroglycerin, nitrosorbide) can occur in patients with angina pectoris with simultaneous administration of large doses of antianginal drugs. Drugs can be injected into the body orally, sublingually, transdermally. Less often, the intake of nitrates (in particular, silver nitrate) is carried out not for therapeutic, but for suicidal purposes.
- The use of canned and smoked foods. In food production, nitrites are used for smoking sausages, cooking canned meat and fish, enhancing flavor and taste. Prolonged consumption of a large number of animal products causes chronic alimentary nitrate-nitrite intoxication.
- Inhalation of toxic fumes. Relatively rare etiofactors that cause nitrate poisoning are inhalation of deodorizing aerosols, paint vapors, solvents, combustion products in case of fire, and the use of pyrotechnic devices.Gorenje
- Erroneous use of nitrates. There are cases of poisoning caused by the erroneous use of nitrogen fertilizers instead of table salt and baking soda for home preservation or cooking.
Pathogenesis
Nitrates and nitrites are toxic substances of methemoglobin-forming action. Getting into the digestive tract, they are partially absorbed, partially excreted from the body. Part of the nitrates with the participation of conditionally pathogenic intestinal microflora and its enzymes is transformed into nitrites. Nitric acid salts, interacting with blood hemoglobin (Hb), form the compound methemoglobin (MetHb), which cannot transport oxygen. This leads to a decrease in the oxygen capacity of the blood and the development of tissue hypoxia.
The level of methemoglobin is regulated in the blood with the participation of the enzyme methemoglobin reductase, which is able to restore MetHb to Hb. However, this enzyme begins to be produced in children only after 3 months of age, so infants are particularly vulnerable to nitrates and easily get poisoned if a nursing mother uses high-nitrate products.
The maximum safe daily dose of nitrates for adults is 300-325 mg, for children – 10-50 mg. The lethal dose of nitrates is 8-14 grams. With a concentration of MetHb in the blood < 30%, signs of acute poisoning develop, with a content of 50% methemoglobin, death occurs.
Symptoms
Signs of acute nitrate intoxication occur 1-6 hours after consuming contaminated products or water. The rate of symptoms and severity of poisoning depends on the concentration of nitrates, body weight, age, and the initial state of human health. Early manifestations of the problem are gastrointestinal disorders: epigastric pain, vomiting, diarrhea. However, unlike conventional food poisoning, when intoxicated with nitrates, the liver increases, soreness in the hypochondrium, jaundice of the sclera occurs.
The clinical picture is complemented by arterial hypotension, palpitations, shortness of breath, pain in the back of the head. Limbs become cold, bluish. With the development of severe methemoglobinemia, drowsiness appears, facial muscle cramps occur, coordination disorders. In extremely severe cases of acute poisoning, lethargy, impaired consciousness, coma develops.
Chronic nitrate intoxication is relatively milder. Digestive disorders are poorly expressed, the clinical picture of chronic hypoxia comes to the fore. Patients are concerned about rapid fatigue, persistent weakness, arrhythmias, shortness of breath.
Complications
Acute nitrate poisoning can cause damage to internal organs: catarrhal hemorrhagic gastroenteritis, toxic myocarditis and hepatitis. In the long-term period after recovery, cardiac dysfunction and encephalopathy persist. In severe cases, the cause of death is pulmonary heart failure. In long-term observations, there was a connection between chronic nitrate poisoning and atrophic gastritis, stomach cancer, increased mortality from oncological diseases of the gastrointestinal tract, lymphoid and hematopoietic systems.
Diagnostics
As a rule, nitrate poisoning is indicated by a food, water or medicinal history: the use of fresh vegetables, canned meat, drinking well water, taking nitrate-containing drugs, as well as clinical features. The final verification of the diagnosis remains with the toxicologists who carry out the curation of patients. After the patient is delivered to the hospital ,:
- Determination of the level of blood methemoglobin. When taking the analysis, the color of venous blood draws attention – with methemoglobinemia, it becomes “chocolate”, dark brown. Normally, the level of MetHb does not exceed 2%, elevated indicators confirm nitrate poisoning.
- Biochemical research. Electrolytes, liver samples, and cardiospecific markers are examined to assess the degree of damage to internal organs. The blood braid is determined.
- Assessment of cardiac activity. tachyarrhythmia, a violation of the contractile ability of the heart, is recorded on the ECG. Myocardial dysfunction is also detected by echocardiography.
Differential diagnosis is performed with PE, impaired cerebral circulation, myocardial infarction. To exclude these conditions, a chest CT scan and brain, an ECG in dynamics is performed. Other poisoning with methemoglobin-forming poisons, food toxicoinfections are also rejected. In order to determine the source of nitrates, a laboratory study of water and food products used by the patient is performed.
Treatment
Emergency care
In the prehospital period, the primary measure is copious gastric lavage. After receiving clean washing waters, any enterosorbents should be taken, in the absence of diarrhea, a saline laxative. To prevent dehydration, it is necessary to strengthen the drinking regime, to give the victim pharmacy solutions for rehydration.
If the fact of nitrate poisoning is not in doubt, it is recommended to take several tablets of ascorbic acid – it does not allow nitrates to recover to toxic nitrosoamines. At any severity of symptoms, it is necessary to call an ambulance.
Intensive care
Patients with suspected nitrate poisoning are hospitalized in toxicology departments. In a hospital setting, after confirming the diagnosis, intravenous infusions of antidote solutions are made: methylene blue and ascorbic acid, which reduce the level of methemoglobin in the blood.
Infusion rehydration with glucose-salt solutions is being adjusted, forced diuresis is being carried out, symptomatic therapy (cardiotonics, antihypoxants, etc.). The method of respiratory support (oxygen therapy through a mask, ventilator) depends on the degree of respiratory insufficiency and the objective condition of the patient.
Forecast
Despite the fact that most cases of nitrate poisoning occur in mild to moderate form and end well, they can present adverse long-term health consequences. These include toxic lesions of the heart, brain, pancreas, liver. In severe acute intoxication, a fatal outcome is possible.
Prevention
In order to prevent nitrate poisoning, it is recommended:
- refuse to buy “out-of-season” fruits, berries and vegetables;
- before eating, vegetable products should be thoroughly washed, soaked, boiled;
- peel the root crops, cut off the stalk, remove the stalk from the cabbage, because these parts of the plants accumulate the largest amount of nitrates;
- in melons and watermelons, leave a small amount of pulp near the crust, do not eat it until the end;
- together with vegetables, include a sufficient amount of vitamin C in the diet;
- if the greens are grown in your own garden, when applying nitrogen-containing fertilizers to the soil, you must carefully read and follow the manufacturer’s instructions.
For your own peace of mind and family safety, you can purchase a nitrate meter or test strips to measure the nitrate content in food and water. This will significantly reduce the risk of nitrate poisoning.