Industrial Poisons

INDUSTRIAL POISONS (more correctly production or occupational poisons), substances that a worker encounters in the process of their occupational activity and which, under unfavorable conditions of production and labor organization and when appropriate precautionary measures are not taken, can cause pathological consequences. The number of occupational poisons is extremely large, exceeding several hundred different names: in connection with the progress of technology and the constant change of various production processes, all the time new and new poisons appear. While some disappear from the field of view of occupational hygiene and the poisonings caused by them accordingly vanish, they are constantly replaced by new ones both as a consequence of the use of ever new substances in industry and as a consequence of the technological use of old and new complex mixtures. In bourgeois countries, poisons are very often introduced into production under various names, sometimes the most fantastic ones that conceal the true composition of the substance, and patenting and industrial secrecy make it possible to conceal from workers and even from the technical personnel of industry the true action and real danger of various substances. This problem is acquiring a very topical significance in the West now, and the most active workers in the field of occupational toxicology (such as e.g. Prof. Zangger in Zurich) speak out in the special and general press (of course completely without result) against a system that makes it possible to poison workers with impunity to please the inviolability of the principle of industrial property and industrial secret. It is especially characteristic that in Germany and other countries new toxic substances are frequently released under the old familiar label and under a name that has won popularity for itself. Sometimes special masking substances are added to change the color and especially the odor. Finally, firms frequently release their toxic products with inscriptions on the packaging that the given substance is completely non-toxic, that in contrast to analogous products of competing firms, in this case special measures have already been adopted in the production itself to neutralize them, or their danger or toxicity is sometimes indicated in a highly veiled form. As a result, heightened carelessness is created in their application. It goes without saying that under Soviet conditions all this is absolutely unthinkable. With us, not only is there no industrial secret from the bodies of sanitary and industrial supervision, but the clearly criminal actions of enterprises producing toxic substances described above are also completely unthinkable. But this is not all: industry itself, actively interested in creating the most healthy conditions of labor, together with public health bodies, trade unions, and research institutes of all departments, works untiringly on the possibility of eliminating the most toxic substances from production and replacing them with less toxic or completely non-toxic substances; at the same time, all measures are taken to create maximally safe conditions of labor in those cases when avoiding the use of toxic substances is impossible. Industrial poisons can not only cause occupational poisonings, but can also exert the so-called "metatoxic action," i.e., cause successive diseases arising as a result of a preceding but already essentially completed poisoning after the complete elimination of the poison or the product of its chemical decomposition from the organism and the cessation of the pathological processes directly caused by them. Furthermore, occupational poisons can lower the resistance of the organism to diverse harmful influences and in particular to infections (including chronic tuberculosis, syphilis, etc.). Poisons can in a definite way change the picture of general pathology of individual occupational groups, lowering, intensifying, or accelerating the spread of those or other general as well as occupational diseases apart from poisonings. Finally, the action of poisons can also manifest itself in a decrease in working capacity and a drop in labor productivity. Occupational poisons are sometimes divided into those acting locally and resorptively. Such a grouping is somewhat artificial, since for the most part one and the same substance can act in both directions (locally and resorptively); still, it is expedient, and it is especially important to isolate such substances that act directly at the site of contact with the surface of the organism, causing definite changes in it that often prevent the penetration of the poison into the organism. These substances (alkalis, acids, salts of certain metals, and finally certain organic substances that are derivatives of petroleum, coal, and wood distillation) act on the skin, mucous membranes of the eye, and upper respiratory tract, causing changes in cell proteins, local blood vessels, etc., at the site of contact with them. As a result, there may occur either burns (alkalis and acids), or various kinds of inflammatory phenomena (alkalis, salts of heavy metals, etc.), or eczemas, dermatitis (calcium cyanamide, chromates, basic slag, etc.), or finally ulcers, keratinization, precancerous growths up to malignant tumors (products of petroleum and the distillation of stone and wood coal). The characteristic local action of a number of gaseous substances (e.g., chlorine, ammonia, nitrogen oxides, sulfur dioxide, acrolein, bromine, hydrogen fluoride, hydrogen sulfide, etc.) leads to these poisons even being called irritating gases. They cause significant irritation mainly of the mucous membranes, and in some cases, at a sufficiently high concentration, also of the skin. Their action manifests itself in lacrimation, salivation, sneezing, increased blinking reflexes up to the closure of the eyelids, etc. At more significant concentrations, they make staying in the working environment completely impossible. At weak concentrations, the irritation caused does not have any serious effect on health. At stronger concentrations, these industrial poisons cause inflammatory processes of varying intensity in different parts of the respiratory tract. At the same time, the more easily a gas dissolves in water, the greater the quantity in which it is retained on the moist surface of the upper respiratory tract and the smaller the quantity in which it reaches the lungs; a poorly soluble gas, on the contrary, easily penetrates into the lower respiratory tract and lungs and here mainly concentrates its action. At the same time, there is a definite parallelism between the solubility and absorbability of gases. Therefore, the easier and faster a given gas is absorbed in the upper respiratory tract, the less of it falls to the share of the lower respiratory tract, and, conversely, a poorly absorbable gas penetrates in greater quantity into the lower sections of the respiratory tract and especially into the pulmonary alveoli. The greatest danger is presented by the least soluble irritating gases, which upon penetration into the alveoli cause irritation of the pulmonary tissue with possible pulmonary edema, which in severe cases always ends fatally (as for example nitrogen oxides). However, in some cases gases irritating the upper respiratory tract may also present a danger, insofar as they can reflexively cause spasm of the vocal cords, laryngeal edema, or even lowering of the epiglottis with closure of the glottis, naturally leading to asphyxia (for example ammonia). Occupational poisons can be encountered in the form of solid, liquid, gaseous, and vaporous substances. The significance of the latter two groups is especially great, since the state of the toxic substance determines to a significant degree the routes of penetration into the organism. Occupational poisons can penetrate into the organism by various routes. They most rarely penetrate inward by absorption through undamaged skin; this can take place only in those cases when the poison dissolves the surface skin fat, which is an excellent defense against the introduction of various foreign substances into the bloodstream. Such substances include gasoline, benzene, and all its derivatives. Aside from substances soluble in lipoids, mercury is also absorbed through the skin. Other poisons can also penetrate into the organism through the skin, but this happens only when there are abrasions, scratches, small wounds, and the like. Besides that, a part of the toxic dust as well as gases penetrates into the stomach with saliva, but most often industrial poisons penetrate into the organism through the respiratory organs in the form of dust, fumes, vapors, or small droplets suspended in the air. The ability of toxic substances to penetrate through one or another entry gate is determined not only by their physico-chemical and biological properties, but also by their physical state. Solid bodies, if they do not dust, can cause poisoning only in the case of constant and frequent contacts with them of a significant surface of the skin (if they penetrate through the undamaged stratum corneum). Solid bodies producing large-sized dust can penetrate into the organism only through the digestive organs. Solid bodies producing fine dust can penetrate through all three routes (including the lungs). Liquid substances can penetrate into the organism through the skin (e.g., aniline, lead-containing glaze, etc.). The possibility of the penetration of poisons through the respiratory organs is determined to a significant degree by their volatility.

Furthermore, they can also penetrate the respiratory tract in the form of the smallest droplets raised into air as a result of any violent gas-forming processes (chemical processes with the release of gases, such as during pickling in the etching of metals, etc.). Poisonous vapors and gases can naturally penetrate through all portals of entry with the predominance of the role of the respiratory tract. Industrial poisons can be encountered in production under the most diverse conditions. Workers may encounter them as: a) raw materials (e.g., mercury, benzene, and other substances as initial products of further processing in chemical and pharmaceutical industries); b) an intermediate product going then into further processing (e.g., sulfur dioxide obtained during the roasting of iron pyrite in the production of sulfuric acid); c) an accidental impurity (e.g., arsenic in various kinds of metals and acids); d) a substance serving as a means of production used in the processing process (various solvents, acids used for nitration); e) a finished product even in cases where the raw material or intermediate product does not possess toxic properties (e.g., various products of the distillation of petroleum, coal, and wood, sulfur dioxide obtained by the oxidation of non-toxic sulfur, white or yellow phosphorus obtained from bones, etc.); f) a byproduct, mostly completely unutilized or, more correctly, production waste (the majority of poisonous vapors and gases released during the production process, such as nitrogen oxides, carbon monoxide in metallurgy, aromatic hydrocarbons in various chemical industries, etc.); g) a substance present in the working atmosphere as a result of natural physical-chemical or biological processes not related to production (e.g., hydrogen sulfide or carbon dioxide in sewers, pits, irrigation fields, etc.); h) a constituent part of the working atmosphere associated with previous production processes or preliminary contents of workplaces (products of putrefaction and fermentation in various types of vats in the leather industry, remnants of toxic vapors in tanks, cisterns, etc., during their cleaning or painting, etc.); i) an object of transportation, loading, unloading, transshipment, etc. (e.g., during the transport of acids, unloading of pitch, etc.). Industrial situations causing exposure of the organism to industrial poisons are very diverse. - I. The overwhelming majority of poisoning is caused by the penetration of industrial poisons into the organism in a dispersed state. Most occupational poisonings depend on the entry of toxic dusts, vapors, and gases into the air of the workplace and are therefore directly related to the sanitary-technical condition of the enterprise's production process (more precisely, its equipment). These include: 1. Leaks in individual apparatuses, gas pipelines, conveyors, etc. 2. Conducting processes associated with the generation of toxic gases at normal atmospheric pressure or failure to use, for various technical reasons, the vacuum established for these processes (e.g., in the production of nitric acid by the Valentiner method). 3. The absence of rational devices for dispensing liquid substances, unloading and packaging powdery substances, etc. 4. Irrational devices for loading various furnaces, boilers, etc., as a result of which toxic substances can penetrate into the air at the moment of loading itself from the specified apparatuses. 5. The absence of installations for removing gases, vapors, and dust from the place of their generation, as well as devices for their further capture and utilization. 6. The absence of special safety measures during individual hazardous production operations (discharge from a furnace or other vessel, dispensing, pouring, packaging, etc.). - II. Reasons associated with labor organization, training of workers, and the conduct of the technological process itself. This group of causes of occupational poisonings includes: 1. An incorrect regime of the production process. For example, there are a number of productions (chemical ones) closely interconnected so that the disruption of the work of one of them immediately affects the others. 2. Substandard or unusual composition of raw materials. In a number of cases, this has led to very severe and unexpected poisonings due to the fact that technical personnel and the workers themselves did not suspect the possibility of toxicity of the product with which they were usually accustomed to working. Thus, a number of severe poisonings arose (e.g., with arsine). 3. Poor maintenance and insufficiently attentive supervision of equipment, gas pipelines, etc., as a result of which easily fixable leaks become a source of poisonous gases entering the workplace. 4. Lack of personal responsibility in the maintenance and repair of hazardous installations and aggregates. 5. Insufficient technical literacy of workers, their lack of training in correct work methods, often leading to elementary violations of safety requirements and causing severe poisonings both to the worker violating safety rules himself and to his coworker. - III. An unexpectedly arisen circumstance that entailed a violent inflow of gas into the air of the workplace (explosions and other accidents associated with sudden damage to the integrity of tanks, boilers, gas pipelines, etc.). - IV. Work in narrow confined spaces lacking sufficient communication with the surrounding normal atmosphere, with the threat of the presence of various toxic vapors in the air. These include: a) work in sewer manholes, in deep trenches during construction work, in gas and other wells; here one can always expect a large accumulation of carbon dioxide and sometimes various products of putrefaction and fermentation (hydrogen sulfide, ammonia, methane, etc.); b) work on cleaning sewer systems; c) work on cleaning and changing liquids, etc., in fermentation, tanning, and other vats of leather and other industries; d) work in silos and ship holds, especially during the transport of toxic substances capable of releasing arsenic and other vapors, such as ferrosilicon; e) work on cleaning slag, sludge, and all kinds of masses in gas and other similar industries; f) work on cleaning, installation, and repair of various gas installations, gas pipelines, gas chambers, etc., in the metallurgical and chemical industries; g) disinfection and disinsection in various warehouses using new methods, in particular vapors of chlorinated hydrocarbons, cyanide, etc.; h) cleaning of various tanks, reservoirs, boilers, cisterns, etc., in which volatile toxic substances were located or transported; the latter are often adsorbed in fairly significant quantities on the metal, wooden, and other walls of these vessels and are then slowly released into the air during work; the amount of adsorbed vapors is especially great in various seams, joints, flanges, channels, rust, etc.; work associated with the use of acetylene or electric welding is exceptionally dangerous in this case due to a significant increase in temperature; i) internal painting and enameling of the aforementioned reservoirs, covering them with a layer of waterproof and anticorrosive substances (which is usually accompanied by the release of a large amount of volatile solvents into the air). - V. Unexpected deteriorations of general hygienic conditions in the workshop (unexpected heating, suspension of ventilation, cessation of vacuum in equipment, etc.). - VI. Suction of toxic gases and vapors from neighboring rooms due to the irrational arrangement of the room and especially due to the irrational design of general ventilation (frequently observed significant excess of exhaust over intake). In general, it is necessary to take into account the significance for the danger of poisoning of the intensity and direction of air currents associated with both convection heat and production processes.

Even insignificant air currents can contribute to the emergence of poisoning hazards (or, conversely, can be used for prevention) in certain workplaces. Cases of poisoning by aniline, as well as by carbon monoxide, have been observed in textile factories, in shops where the emission of these poisons did not take place at all. - VIII. Finally, sometimes poisoning can be caused by the gradual release of a gas previously present in the room, which persisted despite even intensive ventilation, having been adsorbed on wooden objects, on fabrics, on various materials, and the like; a case of this sort caused, for example, carbon monoxide poisoning some time after a fire that had occurred in the workshop. The degree of danger of occupational poisons depends both on the physicochemical and biological characteristics of the toxic substances themselves, and on the entire sanitary-technical production environment, and finally on the individual characteristics of the workers themselves (see above). The action of industrial poisons can be combined with the action of a number of other occupational hazards (fatigue, dust, high temperature, and the like). The diverse combinations of these various influences can intensify and somewhat modify the picture of the action of individual industrial poisons. In the production environment, one extremely often has to deal with the toxic action of combinations of various industrial poisons. For measures to combat the effects of industrial poisons, see Occupational Poisoning. Above is given a table of maximum permissible concentrations of industrial poison vapors in the air (in mg/l), which is of great practical importance, comparing the data of our institutes and legislation with the characterization of their toxicity according to Lehmann and Henderson-Haggard. It is necessary, however, to emphasize with all force the merely orientational significance of these norms.

S. Kaplun.