CADMIUM (Cadmium, Cd) — chemical element of the second group of a periodic system of D. I. Mendeleyev. Specific fiziol, value is not established, but its influence on exchange of zinc, copper and iron and toxic action on a human body is known. To. it is applied in the industry to a surface protection of steel products from corrosion in the conditions of their contact with sea water or other aggressive environment. Alloys K. with other metals easily are exposed to machining therefore they are widely used in the equipment. Some connections K. are very poisonous and represent considerable professional harm.
Sequence number To. 48, atomic weight 112,41. 8 stable isotopes are known To. with mass numbers 106, 108, 110, 111, 112, IZ, 114, 116 and several radioisotopes. To. it was open as impurity to zinc oxide it is mute. the chemist F. Strohmeyer in 1817. In the nature kadmiysoderzhashchy minerals greenockite (CdS) and a carbonate are known To., being in zinc ores.
To. has the expressed alkaline properties, it is dissolved in nitric, is weaker — in sulfuric and salt to-takh, forming the corresponding salts (colourless crystal substances) which are easily forming complex connections.
To. — silvery white metal, malleable and viscous, ud. weight is 8,65 g/cm 3 (at t ° 20 °), t ° pl 320,9 °, t ° kip 767 °, specific conductivity 13,2•10 4 ohm - 1 • cm - 1 . On chemical properties K. it is similar to zinc. In connections dvukhvalenten; at the increased humidity on air becomes covered by a film of oxide. During the heating in an air flow To. paints a flame in red color, burns with formation of a brown oxide To. (CdO), water-insoluble, but dissolved in to-takh. Volcanic breeds contain 0,2 mg To. on 1 kg, sedimentary breeds — clays of 0,3 mg/kg, sandstones — 0,03 mg/kg, limestones — 0,035 laid down To. on 1 kg. The soils which are formed on crystal breeds are usually richer To. On average soils contain 0,06 mg To. on 1 kg. Contains in sweet waters apprx. 0,08 mg To. on 1 l, in sea — 0,00011 mg on 1 l. Also find in air To., especially there is a lot of it in air of the cities — to 0,062 mg/m3. Geophytes are richer To., than sea — 0,6 mg/kg in comparison with 0,4 mg/kg; mushrooms (concentrators K.) contain to 4 K. on 1 kg. Land animal organisms are more homogeneous according to contents To. (on average apprx. 0,5 mg/kg), than sea (0,15 — 3 mg/kg). Ability to concentrate To. mollusks — oysters, sometimes fishes possess.
An important link in biogenic cycles of chemical elements in the biosphere are the stern and foodstuff which define receipt To. in an organism of animals and the person (tab. 1).
Contains in a human body weighing 70 kg apprx. 0,03 g To. Distribution To. on bodies and tissues of the person it is shown in table 2.
Average content To. in urine of the person makes apprx. 13 mkg on 1 l. According to many authors, keeping To. in bodies and tissues of the person and animals changes depending on many conditions (receipts To. with food, season, a sex, age, etc.).
Absorption To. happens in thin department of intestines (especially in a duodenal and ileal gut); it is easily adsorbed by lungs. To. it is deposited in a liver and kidneys. At the person To. it is allocated with urine 20% of the accepted quantity at normal loading and with a stake — apprx. 80%.
At introduction to an organism of excess amounts of cadmium exchange of phosphorus, calcium, iron, copper is broken, synthesis of hemoglobin (hypochromia microcytic anemia) is oppressed, reserves of copper in a liver and other bodies sharply decrease. The increased consumption To. at a lack of a diet of copper leads to death of animals. Introduction to an organism To. in deadlines for pregnancy can become the reason of toxicosis of pregnancy. To. influences reproductive function, causing a degeneration of seed plants and infertility of males. Introduction To. to a diet of laying hens stops egg production. Copper and zinc level or detain toxic action To. Between To. and zinc in many cases observes antagonism.
The metalenzymes containing To., are not known, but the possibility of formation of in vitro of complexes K is established. with nek-ry enzymes (e.g., with carboxypeptidase).
Inhibiting effect To. on activity of a number of enzymes is explained by its linkng with active centers of enzymes, it is probable with their sulphhydryl (SH-) groups.
To. considerably strengthens and extends hyper glycemic effect of adrenaline.
For determination of content To. in fabric or biol, liquids (blood, urine, a hinge plate of any fabric) burn test in a refractory flask with sulfuric or nitric to - that. For qualitative and quantitative test To. the cation, alkaline solution to-rogo in the presence use a reactant To. it is painted in orange-red color; for this purpose use also dithizon and difenilkarbazid. Quantity To. determine by the size of absorption in an ultraviolet light.
problems of toxicology have Great practical value To. Their value is defined by growth of its industrial receiving and use. To. and its connections can come to air of production rooms by production of alkaline accumulators, phosphors, electrocontacts; during the use To. and its connections as paint for glass, porcelain and plastic, stabilizers for polyvinylchloride, during the drawing anticorrosion and decorative coatings, during the welding of the metals supporting K. Osobenno thermal processes during the receiving are adverse from the point of view of professional harm To. and its alloys at which the oxide gets to air To., and also drying, crushing and packaging of finished goods.
All connections K. are toxic. Are especially highly toxic an oxide To. (CdO) and salts K. (sulfate, chloride, nitrate); are moderately toxic — metal To. in the form of an aerosol, organic compounds K. (stearate, caprylate, laurate, salicylate); low solubility connections K. — sulphurous To. and sulfoselenide K. malotoksichna. To. has the expressed cumulative properties, collecting generally in a liver and kidneys. He is slowly brought from an organism, deficit of calcium in an organism increases K. Zatravk's delay an aerosol of an oxide To. experimental animals in concentration of 1,8 — 2 mg/m 3 during 1 — 2 hour a day in a month leads to disturbances in exchange of protein, lipids, vitamins (With and B 1 ), to disturbance of conditioned reflexes. Salts K. possess the cauterizing action on skin and mucous membranes.
Maximum allowable concentrations: oxides To. and stearate K. 0,1 mg/m 3 (on To.).
Definition of cadmium in air is made by a polyarografichesky, photometric method with dithizon, a turbidimetrichesky method with trifeniltetrazoliykhloridy, a colorimetric method with brombenztiazoniyevy dye.
At poisonings To. or its connections at autopsy observe sharp gastric flatulence and intestines, a plethora and hemorrhages in internals, dystrophic changes in a liver and kidneys, necrotic changes in testicles, desquamation of an epithelium of a stomach.
Clinical picture of acute intoxication cadmium it is characterized by disturbances from outside went. - kish. a path (abdominal pains, a hematemesis and a diarrhea) and a respiratory organs (tracheitis, bronchitis, a bronchiolitis with attacks of painful convulsive cough with a phlegm), sharp weakness, a headache appears. In hard cases bronchial pneumonia and a fluid lungs develops. The main symptoms hron, intoxications To. and its connections are a yellow border on teeth, the anosmia, Qatar of upper respiratory tracts, the hypochromia anemia accelerated by ROE, disturbances of exchange of calcium, a proteinuria, disturbance of appetite, weight loss. At the expressed forms of intoxication the liver and kidneys are surprised, changes in structure of a bone tissue, a pneumosclerosis, a neurotic syndrome are observed.
First aid and treatment
At acute poisoning with connections K. the victim needs to be transferred immediately to fresh air and to provide it the maximum rest. It is necessary to prevent overcooling. At irritation of respiratory tracts — heatwet inhalations of 2% solution of baking soda, drink of warm milk with soda or alkaline mineral water. At persistent cough — codeine, dionine, mustard plasters on a thorax; for prevention of pneumonia — streptocides, antibiotics. At the beginning fluid lungs — oxygen therapy, intravenous administration of calcium chloride (on 10 — 20 ml of 10% of solution), 40% of solution of glucose (20 ml) with ascorbic to - that (500 mg), an electrolyte-deficient diet, cardiacs. Specific treatment of poisonings To. — use of the kompleksonobrazuyushchy drugs connecting To. (EDTA, etc.).
For protection against dust K. use respirators or the filtering industrial gas masks with additional filters during the work with aerosols (smokes) To., rubber gloves and aprons.
Measures of the prevention
Improvement of working conditions in those productions where are used and is formed in technological process of connection K., it can be reached by improvement of technological process, use of modern tight designs, the equipment, effective ventilation, hydrodedusting, use of individual protection equipment. It is necessary to accept vitamin D preventively.
Cadmium in the medicolegal relation
At poisoning with connections K. the following wedges, symptoms have expert value: sharp pains in a stomach, nausea, vomiting, sometimes bloody, a diarrhea, emergence of erythrocytes and protein in urine, increase in a liver.
At necropsy the following changes are noted: fatty dystrophy of a liver and kidneys, hypostasis and plethora of lungs. Hemorrhages in lungs (a partial atelectasis) can be found. At a serious poisoning connections K. fatty infiltration of a pancreas, a plethora of a spleen are described.
Court. - chemical definition To. it is made in various bodies and bones of a corpse of the person by a fractional method after oxidation of organic substrate in mix concentrated sulfuric and nitric to - t or in chloric to - those in presence sulfuric and nitric to - t. A certain volume of the mineralizat exempted from oxidizers is extracted in the presence of diethyldithiocarbamate of sodium chloroform, then reekstragirut 1 N solution salt to - you.
At court. - chemical definitions To. previously connect the copper almost always accompanying To. For this purpose add excess of the potassium cyanide transferring copper to complex connection to the studied liquid, and saturate solution with hydrogen sulfide or process sodium sulfide. In the presence To. the yellow deposit — CdS is formed.
Detection To. it is made by means of macro - and micromethods.
The macromethod allows to find To. at its content of 4 mg in 100 g of body.
With saturated solution of brucine in the presence of potassium bromide in the solution containing To., the colourless prismatic crystals collected in spheroids are formed. At effect of potassium bromide in the presence of pyridine crystals in the form of spheroids are formed.
Quantitative definition To. it is made by means of a complexon of III in the presence of a chromogen of black ET-00 or eriochrom blue.
In a liver and kidneys To. it can be defined in number from 0,64 to 6,68 mg and from 1,32 to 8,48 mg in 100 g of fabric respectively. Naturally contained quantity To. in a human body it has to be considered at court. - medical assessment of results of definition To. in human organs.
Table 1. CONTENT of CADMIUM IN SOME FOOD &PRODUKTAKHNBSP; (across Gennigu, 1976)
Table 2 CONTENT of CADMIUM IN BODIES AND TISSUES of the PERSON (&vnbsp; &mkgnbsp; on 1 g of weight of fabric)
Bibliography Vorobyov R. S. and Shabalin L. P. Pilot study of toxic properties of various compounds of cadmium, Gigabyte. and dignity., No. 2, page 102, 1975; Radiation protection, the lane with English, under the editorship of M. A. Smirnov, page 171, M., 1961; Tarasenko N. Yu. and Vorobyova R. S. Hygienic problems during the use of cadmium, Vestn. USSR Academy of Medical Sciences, No. 10, page 37, 1973; Tarasenko N. Yu., etc. Cadmium in external environment and its influence on exchange of calcium, the Gigabyte. and dignity., No. 9, page 22, 1975, bibliogr.; Toxicology of rare metals, under the editorship of 3. I. Israelson, page 135, M., 1963; X e N of N and And. Mineral substances, vitamins, biostimulators in feeding of farm animals, the lane with it., page 197, M., 1976; Shvaykova M. D. Toxicological chemistry, page 337, M., 1975; AnkeM. and. the lake of Cadmium and its influence on plants, animals and man, in book: Trace substances in environm, health, ed. by D. D. Hemphill, v. 10, p. 105, Univ. Missouri, Columb., 1976; F r i-b e rgL. o. Cadmium in the environment, Cleveland, 1974; Malcolm D. Potential carcinogenic effect of cadmium in animals and men, Ann. Occup. Hyg., v. 15, p. 33, 1972, bibliogr.; Nordberg G. F. Cadmium metabolism and toxicity, Stockholm, 1972, bibliogr.; U n d e r w o o d E. J. Trace elements in human and animal nutrition, p. 243, N. Y., 1977.
V. V. Kovalsky; P. S. Vorobyova (gigabyte.), A. F. Rubtsov (court.).