Sulfur Dioxide

SULFUR DIOXIDE, sulfur anhydride, SO₂, a colorless gas with a sharp irritating odor, specific weight 2.23. It is used in industry for bleaching various products: wool, silk, paper pulp, feathers, straw, wax, bristles, horsehair, food products, for disinfecting fruits and preserves, etc. As a by-product, sulfur dioxide is formed and released into the air of work premises in a number of industries: sulfuric acid production, cellulose production, when roasting ores containing sulfur metals, in pickling shops at metal plants, in the production of glass, ultramarine, etc. It is often found in the air of boiler rooms and ash rooms, where it is formed by burning sulfur-containing coals. Quite a lot of data has been collected regarding the content of SO₂ in the air of work premises; its amounts vary widely - from 0.01 to 0.3 mg per 1 liter of air. In boiler rooms of the Moscow region, amounts from 0.001 to 0.04 mg were found, in forges - from 0.014 to 0.05-0.1 mg; in cold vulcanization, much larger amounts were found - 0.4-0.5 mg. Poisoning by sulfur dioxide in industrial conditions usually takes the form of mild cases, severe poisonings are rare. In the USSR for the years 1924-29, 82,472 cases were registered, both with and without loss of working capacity; it should be taken into account that in 1924/25 a completely accidental poisoning unrelated to production occurred in 296 people; in the remaining years the number of cases was 35, 50, 75, 9. The main causes of poisoning are accidents or poor condition of equipment. The essence of the action of sulfur dioxide is reduced to the action of sulfuric acid, since SO₂ when in contact with moist tissues turns into sulfurous, and then into sulfuric acid. Due to its high solubility in water, SO₂ is absorbed and therefore has its main effect on the upper respiratory tract. Experimental research conducted at the Ukrainian Institute of Pathology and Industrial Hygiene showed that in acute poisoning in animals, severe changes occur throughout the respiratory tract, and they are especially sharply expressed in the trachea and bronchi. In chronic poisoning (0.5 mg/l), a slight catarrhal bronchitis and bronchiolitis develops. In people unaccustomed to it, concentrations of sulfur dioxide of 0.06 mg/l air irritate the respiratory tract so much that staying for more than 1/2 hour becomes impossible. For those working constantly in an atmosphere of sulfur dioxide, habituation occurs and they tolerate concentrations of 0.1-0.2 mg per 1 liter of air for many hours. As the maximum permissible concentration of SO₂ in the air of work premises, the People's Commissariat of Health of the USSR established 0.02 mg/l, in exceptional cases with short-term stay in the atmosphere of sulfur dioxide - 0.04 mg/l. The symptoms of exposure to sulfur dioxide are expressed in sneezing, coughing, spasm of the vocal cords, which forces workers to leave the room, and this prevents the general action of the gas, which is limited mainly to the upper respiratory tract. In rare severe cases, bronchitis and even pulmonary edema may develop. Similarly, the vapors of fuming sulfuric acid act, which contain sulfuric anhydride SO₃ along with SO₂. When inhaling these vapors in significant concentrations, more severe phenomena than those described above may develop, namely - deep bronchitis, edema of the larynx, bronchopneumonia, in very severe cases pulmonary edema. Lung complications usually do not develop immediately, but 1-2 days after inhaling the vapors. Prolonged inhalation of fuming sulfuric acid vapors can lead to the development of chronic bronchitis and conjunctivitis. In the prevention of sulfur dioxide poisoning, the main importance is complete sealing of equipment and monitoring its proper condition; if it is not possible to prevent the release of sulfur dioxide into the air, exhaust installations are necessary directly above the place of gas release (e.g., pickling shops) or the installation of general ventilation, which makes it possible to reduce the gas concentration in the air to the established values. Great importance is given to the rationalization of the production process: in pickling shops, for example, the addition to the sulfuric acid solution of so-called additives (various substances that accelerate the production process and at the same time reduce the release into the air of droplets and vapors of pickling liquids) sharply reduces the release of SO₂ into the air. Bleaching processes, often still carried out in a primitive way by 'smoking', must be rationalized. - Treatment for acute poisonings, as in poisoning by other irritating gases, is immediate removal from the poisoned atmosphere, inhalation of oxygen, exciting agents, etc.

N. Rozenbaum. Discovery in forensic cases and determination in professional poisonings. When examining internal organs, smoked meat, preserves, etc., they are placed in a flask plugged with a cork with two tubes. One of them is connected to a Kipp apparatus for the release of carbon dioxide, the other with receivers for absorbing sulfur dioxide. The latter contain a solution of iodine in the presence of potassium iodide. After displacing sulfur dioxide with carbon dioxide, the liquid from the receivers is boiled to remove iodine, and sulfuric acid is detected and determined quantitatively in the solution. In another variation of the method, sulfur dioxide is displaced into a solution of potassium chlorate (Berthollet's salt) and the amount of ion obtained by the reduction of chloric acid ions is determined. For the detection and quantitative determination of sulfur dioxide in the air, a certain volume of it is passed through absorbers (see Poisons, isolation) with a solution of Berthollet's salt and the amount of chlorine ion is determined by titration with silver nitrate or nephelometrically, by converting it to silver chloride.