Exposure to nitrogen oxides (nitrous gases)
Nitrogen oxides are an inconstant mixture comprising nitric oxide (NO), nitrogen dioxide (N₂O₄), and nitrogen sesquioxide (N₂O₃). Contact with these compounds is characteristic of metallurgy, blasting operations, the combustion of fossil fuels, as well as the manufacturing of synthetic fertilizers and nitric acid.
The clinical presentation of intoxication directly depends on which specific oxides predominate in the inhaled mixture:
- Acute poisoning: Nitric oxide (NO) provokes a picture of anoxemia. Nitrogen dioxide exerts a pronounced caustic effect, as it transforms into nitric and nitrous acids within the body. The initial symptoms of acute injury include asphyxia, cough, dyspnea, which may be accompanied by cardiac weakness and headache.
- Chronic poisoning: Prolonged contact leads to the development of chronic bronchitis and respiratory catarrh. In addition, neurological disorders, a drop in blood pressure, muscular and cardiac weakness, as well as metabolic disturbances are observed. A specific sign is dental damage: a greenish coating appears on the teeth, and the incisors are destroyed first.
Effects of inorganic acids
Workers in contact with hydrochloric, sulfuric, and nitric acids are susceptible to a specific occupational pathology. According to R.Ya. Pekker's classification, they develop mass lesions of the oral cavity and teeth.
The pathogenesis mechanism lies in the fact that acids cause decalcification of the tooth enamel. This inevitably leads to the development of acid necrosis. The process localizes predominantly on the lower and upper anterior teeth. Within just a few months of work in hazardous manufacturing, early signs of damage appear:
- Loss of the natural luster of the enamel.
- Change in its normal color.
- Appearance of marked roughness on the tooth surface.
Prevention of lead poisoning
To prevent lead intoxication in the workplace, a set of sanitary-hygienic and medical measures is implemented. Air quality monitoring is mandatory (the MAC must not exceed 0.05 mg/m³), along with regular medical examinations and strict adherence to personal hygiene: washing hands before meals and taking a shower after the shift.
Preventive nutrition: Workers are assigned a specialized diet No. 3. The provision of free breakfasts is organized, enriched with vitamins, proteins, and specific nutritional substances that increase the body's overall resistance to the effects of poisons.
Medical restrictions: Adolescents and women are strictly prohibited from working with lead. In addition, there is a strict list of diseases for which employment or continuation of work is impossible:
- Diseases of the blood system, liver, and kidneys.
- Hypertension and peptic ulcer disease.
- Endarteritis.
- Endocrinopathies.
- Mental illnesses and organic lesions of the nervous system.
Briefly: answers to topical questions
What are the main symptoms and stages of chronic lead poisoning in addition to blood and nervous system damage?
In addition to blood and nervous system damage, chronic lead poisoning affects the digestive, cardiovascular systems, and kidneys.
The following stages and symptoms are distinguished:
- Early signs — pale gray facial complexion and a lead line (Burton's line) in the form of a purplish stripe along the gingival margin.
- Stage of overt intoxication — lead colic (sharp paroxysmal abdominal pain).
Additional manifestations include:
- Hypersalivation — excessive salivation accompanied by a specific foul odor from the mouth and a sweetish metallic taste.
- Nephropathy — kidney damage.
- Hemosiderosis — pathological accumulation of iron in the tissues of various organs.
Constipation is also noted on the part of the gastrointestinal tract.
What pathological changes occur in internal organs during severe nitrogen oxide poisoning?
Nitrogen oxide poisoning results in pathological changes in the respiratory, cardiovascular systems, and blood.
Depending on the nature of the exposure, the following disorders are distinguished:
- Acute poisoning — nitrogen dioxide has a caustic effect (converts into nitrous and nitric acids), while nitric oxide causes a picture of anoxemia. It is accompanied by asphyxia, dyspnea, and cardiac weakness.
- Chronic poisoning — provokes respiratory catarrh, development of bronchitis, and anemia.
Additionally, metabolic disorders, a decrease in blood pressure, muscle weakness, and worsening of pre-existing cardiovascular diseases are observed in internal organs and systems.
To memorize the symptoms of acute nitrous gas poisoning, use the mnemonic COHDH: Cough, Asphyxia (UduShʹe), Headache, Dyspnea, Heart weakness.
Class and exam questions
What mechanism underlies the damage to teeth by inorganic acids?
The main mechanism is the decalcification of tooth enamel under the action of acids, ultimately leading to the development of acid necrosis.
What components make up nitrous gases?
This inconstant mixture includes nitric oxide (NO), nitrogen dioxide (N₂O₄), and nitrogen sesquioxide (N₂O₃).
Who is strictly contraindicated from working under conditions of lead exposure?
Women, adolescents, and individuals with diseases of the blood, liver, kidneys, peptic ulcer disease, hypertension, and a number of other chronic pathologies are not allowed to work with lead.
What else to study on this topic
- Pathogenesis of anoxemia development in nitric oxide (NO) poisoning
- Caustic action of nitrogen dioxide and the mechanism of its conversion into acids
- Features of the therapeutic and preventive diet No. 3
- Classification of dental lesions according to R.Ya. Pekker
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