Formalin
(syn.
formol
) - an aqueous 37-40% solution of formaldehyde containing up to 15% methanol (to prevent polymerization). Formalin is used for fixing histological, anatomical and microbiological preparations, in the manufacture of vaccines and serums, as a disinfectant for washing hands, medical instruments, dishes, premises, clothing, as well as in the manufacture of various deodorants, means for washing the skin during excessive sweating, in production plastics, chemicals fibers, for dressing seeds, tanning leather, etc. Formalin has a strong irritant, cauterizing and sensitizing effect, and is a hepato- and nephrotoxic poison (see Poisoning). There is evidence that formaldehyde (see Formic aldehyde) and Formalin exhibit embryotropic properties and mutagenic and oncogenic activity. Formalin in industries associated with its production and use can cause acute and chronic poisoning.
Formalin is characterized by a relative density at 18° 1.101 -1.076 and a refractive index at 18° 1.3766 -1.3776, it is a colorless transparent liquid with a pungent odor, the pH value ranges from 2.8 to 4.0. Sometimes in Formaldehyde the appearance of a white precipitate of paraformaldehyde, a dimer of formaldehyde, is noted; the precipitate dissolves when water is added. Formalin is determined using its ability, characteristic of all aldehydes (q.v.), to reduce silver salts (q.v.), i.e., to give the so-called. silver mirror reaction, and color the fuchsinsulfur solution red (Schiff reaction).
Formalin is part of lysoform (Lysoformium), a soap solution of formaldehyde (formalin 40 parts, potassium soap 40 parts, 95% ethyl alcohol 20 parts), used for douching in gynecology. practice (1-4% aqueous solutions), for disinfection of hands and premises (1-3% solutions). To wipe the skin with excessive sweating, use formidron (Formidronum) - a liquid containing 10 parts of formaldehyde, 50 parts of water, 39.5 parts of 95% ethyl alcohol, 0.5 parts of cologne, or formalin ointment (Unguentum Forma-lini ), composed of boric acid (5 g), salicylic acid (2 g), formalin (15 g), glycerin (14 g), polyethylene oxide (62.5 g), fragrance (1.5 g). The ointment has a white color and a faint odor of F. and fragrance.
In industry, Formalin is used as a source of formaldehyde, convenient for transportation and storage.
Application of formaldehyde in histological technique and anatomy
Formalin in its pure form, as well as with the addition of a number of salts, is a universal fixative. In addition, F. is part of many complex fixing liquids: Zenker-formol, alcohol-formol, liquids of Orta, Rego, Ramon y Cajal, etc. It is believed that the fixing properties of F. are based primarily on its ability to combine with proteins and denature them. F. solutions are usually prepared with tap water, which partially neutralizes the usual acidic reaction of F. For most methods of tissue staining, F.'s acidity is not harmful, and for certain methods of studying nervous tissue it is even desirable. However, F. is less suitable for gistol. detection of iron, glycogen, to study the fine structures of the cell nucleus, as well as when using stains with azure-eosin. When using formalin with a pH below 6.0, a brown “formalin pigment”—acidic formalin hematin—appears in tissues, especially those rich in blood. This pigment can be removed by treating the material with 1% ammonia or caustic potassium in 70% alcohol or 3% hydrogen peroxide. To improve the perception of color by tissues, as well as to prevent the appearance of “formalin pigment,” F. solutions are neutralized. To do this, pour a 2-3 cm thick layer of chalk or magnesia onto the bottom of the bottle with F. and shake the liquid periodically. After a day, the pH value rises to 6.3-6.5. F.'s neutralization is controlled using indicators - litmus papers or by adding 0.1% neutral red solution to the solution (the appearance of an orange-yellow color indicates the achievement of neutral pH values). Complete fixation of pieces of tissue up to 2 cm thick in a 10% F solution at room temperature occurs in 1-2 days, in a 2% F solution at a temperature of 55° - within 3 hours. The more concentrated the F solution, the more significant the compaction of the fixed tissues. Very concentrated solutions delay fixation, causing a sharp compaction of the surface layers of the pieces of tissue being fixed. When fully fixed, a piece of tissue on the cut has a uniform gray-brown color due to the restoration of oxyhemoglobin in the blood into metahemoglobin. Material in F. can be stored for years. F. in its pure form, as well as in complex mixtures, is used for fixation and storage of organs and tissues intended for the manufacture of anatomical preparations (see Anatomical preparations) and for embalming corpses (see).
Using formaldehyde solution
Formalin is used as a convenient source of formaldehyde used in the production of polyvinyl formalin. It is also indispensable as an antiseptic for disinfecting premises, tools, clothing, and tanning leather raw materials. It is used for embalming organic substances (organisms and organs). Formalin, the use of which for the preservation of anatomical preparations does not surprise anyone, is also used as a fungicide. Many plant growers treat seeds, tubers, and root crops with this solution before planting and sowing.
Formalin, the quality of which is controlled by GOST 1625-89, is used in the manufacture of synthetic resins, surfactants, rubber, polyhydric alcohols and some other methylene derivatives. Formaldehyde solution is also used in the textile industry. It is used to improve the consumer properties of fabric in terms of resistance to shrinkage and creasing. In the paper industry, formaldehyde improves paper quality and strength.
Formaldehyde as an occupational hazard
The main toxic active principle of Formaldehyde is formaldehyde - a gas with a pungent suffocating odor. Formaldehyde, when produced and used, is released into the air of industrial premises, is present in the exhaust gases of cars and emissions from power plants during incomplete combustion of organic fuel. Formaldehyde can be released from various building materials, fabrics and other products, in the production of which polymers containing formaldehyde were used (see Polymer materials, Synthetic resins).
Formaldehyde is a strong irritating poison that affects c. n. With. and causing dystrophic changes in parenchymal organs. In the body, formaldehyde is oxidized to form formic acid (see) and methyl alcohol (see). The threshold for the irritant effect of formaldehyde for humans is 2.4 mg/m3.
With chronic poisoning with formaldehyde in low concentrations, dyspeptic disorders, sweating disorders appear, rhinitis, pharyngitis, pulmonary emphysema, hron. bronchitis (often with an asthmatic component), hyperesthesia and hyperalgesia, damage to c. n. With. (mental agitation, headache, sleep disturbance, visual disturbance, ataxia). In severe cases, diffuse toxic pneumosclerosis, liver damage (jaundice) and kidneys (oliguria), the appearance of urticaria, rhinopathy, asthmatic bronchitis, allergic gastritis, Quincke's edema, dermatitis and eczema of an allergic nature, and the development of pulmonary heart failure are often noted. Nails are often affected (softening and brittleness are noted).
Treatment chronic. Formaldehyde intoxication is symptomatic with unconditional cessation of contact with the irritating agent and temporary transfer to another job.
In acute inhalation formaldehyde poisoning, the phenomena of damage to the conjunctiva (lacrimation, pain in the eyes) and the mucous membrane of the upper respiratory tract (sore throat, runny nose, sneezing and coughing, shortness of breath, suffocation) predominate, including pulmonary edema, toxic hepato- and nephropathy, general weakness , sweating, headaches, unsteady gait, facial skin is hyperemic, sometimes dizziness, a feeling of fear, and convulsions occur. After poisoning, an increase in sensitivity to F is noted.
When the poison enters inside - a wedge, a chemical picture. burns of the digestive tract, vomiting blood, thirst, toxic shock.
When formaldehyde solutions (even diluted to 0.015%) come into contact with the skin, hyperemia and infiltration of the skin can develop, sometimes with the formation of hard nodular thickenings and cracking of hardened surfaces.
Chemical composition of formalin
How is formaldehyde obtained? The formula of this substance is CH2O. Formaldehyde (formic acid aldehyde), which is a colorless gas with a suffocating odor, turns into a clear liquid when cooled to -21 ° C. Its melting point is -92° C. Upon oxidation, it turns into formic acid. Formaldehyde is produced by exposing methyl alcohol to methyl alcohol in the form of vapor in the presence of catalysts. Of these, silver has proven to be particularly productive, although the industry uses copper, which is more readily available. The resulting distillation accumulates water, resulting in formaldehyde. It may contain impurities of acetone, acetic or formic acid. When formaldehyde is evaporated, the residue is a dense mass of polymers that are insoluble in cold water.
First aid and emergency therapy
In case of eye irritation in case of F. poisoning, urgent rinsing with warm water, 2% sodium bicarbonate solution or isotonic sodium chloride solution, instillation of 2-3 drops of 1% novocaine solution or 0.5% solution is indicated Dicaina. If formaldehyde gets on your skin, you should immediately wash the affected area with 5% ammonia solution or water.
In case of inhalation poisoning with formaldehyde, it is necessary to immediately remove the victim to fresh air and provide inhalation of water vapor (a few drops of ammonia are added to hot water); in severe cases - alkaline or oil inhalations. For coughing attacks, take codeine or dionine orally. In case of spasm of the glottis, 0.5-1.0 ml of 0.5% atropine solution is injected subcutaneously; in severe cases, intubation (see) or tracheostomy (see), measures to combat pulmonary edema (see). In case of acute heart failure, it is necessary to warm the body, subcutaneously administer camphor, caffeine, corazol or cordiamine (1-2 ml). To stimulate breathing, it is recommended to administer cititone or lobeline. If poison gets inside, it is necessary to immediately and abundantly lavage the stomach with 2-3% sodium bicarbonate solution, drink a mixture consisting of 2% ammonium salt solution with 10-20% urea, enveloping agents (raw eggs, mucous decoctions). Further treatment is symptomatic.
Formaldehyde effect on the human body, fetus Wikipedia: therapy for poisoning
The first step in case of formaldehyde poisoning is gastric lavage. Next, an antidote is prescribed in the form of a 3% solution of ammonium chloride or carbonate. A special feature is the need to administer the drug enterally. Therefore, if a person is unconscious, this medicine is administered using a tube. When providing first aid to a person, it is also necessary to provide him with access to oxygen.
Depending on how serious the damage to the body was, symptomatic therapy is then carried out, that is, treatment aimed at restoring the affected organs.
People who work with formalin need to use personal protective equipment, take breaks from work, and ventilate the room.
Prevention measures
For those working in contact with formaldehyde or phosphorus, the use of personal protective equipment is mandatory - filtering industrial gas masks of grade A, insulating hose gas masks (see), protective clothing (see Special clothing). Preventive measures include sealing equipment, improving equipment and technology. processes, introduction of remote control in production, installation of effective ventilation (see). Preliminary and periodic medical examinations (once every 12 months) are required for all workers in contact with formaldehyde (see Medical examination).
The maximum permissible concentration of formaldehyde in the air of the working area is 0.5 mg/m3.
Formalin in forensic medicine
Poisoning when F. is ingested is mainly accidental. During autopsies of people who died from F. poisoning, chemicals are discovered in the first hours after ingestion of large quantities of poison. burn of the mucous membrane of the mouth, esophagus and stomach (due to the fixing effect of F. on red blood cells, staining of necrotic tissues with blood pigment does not occur, and they have a white or pink-gray color), compaction, wrinkling of the stomach wall, and with a longer course of poisoning - also pronounced dystrophic changes in the kidneys, liver, myocardium. Histologically, necrosis of the mucous membrane, and sometimes the muscular layer of the esophagus and stomach, edema and infiltration of the submucosal and muscular layers, and in some cases - phlegmonous inflammation of the entire wall of these organs are detected; necronephrosis, degenerative changes in neurons of the cerebral cortex, severe vascular congestion and perivascular hemorrhages in brain tissue.
At court-chem. identification Formalin is isolated from biol. material by steam distillation. Qualitative detection of F. in distillate is based on reactions with concentrated sulfuric acid (when codeine or morphine is added, a red or blue-violet color is formed) or with concentrated sulfuric acid and a solution of fuchsinsulfuric acid (blue or blue appears - violet color; the color that develops in no more than 30 minutes is taken into account). Quantitative determination of F. is carried out by volumetric iodometric titration or colorimetric method (see Colorimetry), based on the interaction of Formalin with fuchsinsulfur.
Bibliography:
Harmful substances in industry, ed. N.V. Lazarev and E.N. Levina, vol. 1, p. 505, L., 1976; Kiseli D. Practical microtechnology and histochemistry, trans. from Hungarian, p. 54, Budapest, 1962; Lilly R. Pathohistological techniques and practical histochemistry, trans. from English, p. 36 and others, M., 1969; Merkulov G. A. Course of pathological techniques, p. 13 and others, L., 1969; Emergency care for acute poisoning, ed. S. N. Golikova, p. 284, M., 1977; Roberts J. and Caserio M. Fundamentals of Organic Chemistry, trans. from English, vol. 1-2, M., 1978; Guide to forensic medical examination of poisonings, ed. R.V. Berezhny et al., p. 78, M., 1980; Handbook of Occupational Pathology, ed. L. N. Gratsianskaya and V. E. Kovshilo, p. 4, L., 1981; Shvaikova M. D. Toxicological chemistry, p. 83, M., 1975; Schreiner R. et al. Identification of organic compounds, trans. from English, M., 1983; Blum F. Der Formaldehyd ais antisepticum, Munch. med. Wschr., S. 601, 1893.
N. G. Ivanov (gist.), P. F. Kaliteevsky (hist.), N. V. 11ro-kazova (biochemist), A. F. Rubtsov (judge).
