Medico-tactical characteristics of accidents.

THE PLAN OF LECTURE

1. Introduction.

2. Medico-tactical characteristic of accidents on chemically dangerous enterprises.

3. Medico-tactical characteristic of failures on radiation dangerous objects.

4. Failures on fire-explosive enterprises and rendering the medical aid.

1. Introduction.

Last two decades are characterised by rough development of synthesis of new chemical connections which now, to the present time, in the world more than 7 millions names are registered. They actively take part into manufacture and agriculture. By the information of the World organisation of public health services the man uses about one million chemical substances, and annually their number increased by 200-1000 new substances (Yoder L., 1985). More than 53 thousand from them are recognized as toxical and are potentially dangerous for man.

The enterprises making various chemical production, petroleum, pharmaceutical preparations, and also enterprise, having freezants, large aqueduct and clearing structures, railway stations with the ways of storing the structures with the poisoning chemicals, warehouses, storehouses, transport pipelines etc. concern to chemically dangerous objects of a national economy.

The greatest danger is represented by the chemical connections, meeting in economic activity having highly toxic activity and capable during long time to poison the environment, Capable during Long-time Poisoning Substances (CLPS). The quantity of their names exceeds two hundreds, and manufacture and manufacture exceeds them in the world on soul of the population 1 thousand tons per one year (WHO. 1987). Only for the countries of the Western Europe amount made annually most widespread toxic of chemical products phosgene, ammoniac and hydrocyanic acid - reach 100 billion dozes, fatal to the man, and chlorine in 100 times more (Legasov V.A. 1988).

At extreme situations of natural, industrial, transport character the escape of the chemical substances in an environment is possible: in an atmosphere or on a surface of ground open reservoirs - stores and other objective with subsequent. By distribution of fog aerosols on territory of the occupied items. There are items of information on that (Shigovcev G.G., Predthechenski M.B., 1993), that at ignition of low-toxic poisoning, chems and mineral fertilizers there are consequences noticed at influence highly lexical of connections – of so-called dangerous substances (explosive, liquid gases, tire-dangerous, gases under pressure etc.).

It puts before a medical service extremly complex both technical, and organisational problems at rendering the medical help by an injured in specific conditions of chemical failures and accidents. Let's try to determine the basic questions describing the extreme situations, created by the chemical infection both principles and tasks of a medical servises on rendering the medical help struck.

2. Medico-tactical characteristic of accidents on chemically - dangerous enterprises.

The enterprises making various chemical production, petroleum, pharmaceutical preparations, and also enterprises having cooling agents, large water towers and purifying structures, railway stations with ways of rolling-stock settings with pest-killers, warehouses, storehouses, transport pipelines etc are considered chemically dangerous objects of a national economy. In the territory of Ukraine there are 1728 chemically dangerous objects of a national economy. 877 chemically dangerous objects are making or use the HATA as raw material in technological processes, which annual production in 1992 made 287000 tons. On Ukraine 794 oil bases are functioning with a general stock of petroleum more than 6000000 м³. On the territory of Ukraine passes 2350 km of an oil pipeline, in which each kilometer holds more than 250 м³ of petroleum, which is under pressure up to 90 atmospheres.

In the beginning of the 90-s the stocks of various HATA totaled: in Severodonetsk 293000 tons, in Uman 150000 tons H2SO4, in Verhnedneprovsk 150000 tons of chlorine, in Chuguev 108000 tons of chlorine, in Gorlovka 22000 tons of ammonia, in Shostka 25000 tons of ammonia, in Cherkassy 12500 tons of ammonia and 26000 tons of chlorine. In zones of possible HATA pollution on Ukraine there are 135 cities with an aggregate number of the population about 22 mln people, including Kiev, Odessa, Vinnitsa, Cherkassy, Krivoi Rog, Nikolaev, Herson, Zaporozhye, Dnepropetrovsk, Mariupol, Rovno, Simferopol, Sumy, Shebelinka, Severodonetsk, Shostka, Gorlovka with an aggregate number of the population more than 13 millions people. They are ecologically dangerous for living.

The greatest danger is represented by chemical substances, used in economic activity and having high toxicity and capable of infecting an environment for a long time, they are called highly active poisonous substances (HATA). At extreme situations of natural, industrial, transport character the outflow of various chemical substances to an environment is possible: in an atmosphere or on a surface of ground open reservoirs - stores and other objects with the subsequent distribution of steams, aerosols on territory of the settlements. There is information that at ignition of lightly-toxic pest-killers and mineral fertilizers there are consequences noticed as influence of highly toxic substances - of so-called dangerous substances (self-igniting, fire-dangerous, explosive, liquefied gases, gases under pressure etc.)

The world experience of the analysis of chemical accidents testifies that destruction of the enterprises of a chemical industry, warehouses and other objects and the emission of various poisons in an environment can result in serious consequences. The similar situations can develop as due to acts of nature (earthquakes, fires, floods), and to industrial failures.

The possible categories of failures on chemically dangerous objects:

I – only the territory of object is chemically infected

II – the territory of object with an environment is infected chemically

III - regional accidents

IV - accidents of state scale

V - accidents with international consequences

Various inorganic, organic and elementary organic substances of industrial importance, and also pest-killers, used in agriculture (pesticides etc.) belong to HATA.

From the point of view of their danger to the man it was offered to allocate the four classes of danger of substances. 1 and 2 groups are the most dangerous poisons:

• Some connections of metals (organic and inorganic arsenic derivatives, mercury, lead, cadmium, thallium, zinc etc.);

• Substances containing cyanogen group (HCN and its salt), bensaldegyd, hydren, nitrils, organic isocyanats (methylcyanogen B-Khopal);

• phosphorus compounds (Phos, phosphorus chloride, phosphorus oxychloride, phosphine, phosphydin);

• Fluorine-organic compounds (fluorine-acetic acid, its ethers, fluorine ethanol etc.);

• chlorhydrins (ethylene chlorhydrine, epychlorhydrine);

• halogens (chlorine, bromide);

• Other compounds (ethylenoxide, celylic alcohol, methylbromide phosphen, toxic phosphorus).

• The moderately dangerous poisons (group 3) are the following:

• Mineral and organic acids (sulfuric, nitric, phosphoric, acetic etc.);

• Alkalis (ammonia, soda lime, caustic potash etc.);

• compounds of sulfur (dimethylsulphate, soluble sulphides, carbon bisulphide, soluble tiocyans, sulfur chlorides, sulfur ftorides);

• The chlorine and bromine-replaced hydrocarbon derivatives (chloride methyl, bromide methyl);

• Some spirits and acids aldehydes;

• Organic and inorganic nitro- and aminocompounds (hydroxylamine, hydrasine, aniline, tholuidine, amylnitrid, nitrobensol, nitrotoluol, denitrophenol);

• Phenols, cresols, and their derivatives;

• Heterocyclic compounds.

The special group of substances are the pesticides - the preparations intended for fighting with agricultural pests, weeds etc. Many from these compounds are rather toxic for the man. By a chemical structure the pesticides can be divided into the following groups:

• Phos (paratinol, dimetoxidichlorvenilphospate, carbophos, chlorophos);

• carbomates (serin, carbotion etc.);

• chlorine-organic compounds(methylomercury, acetatemethoxyl of mercury etc.);

• phenoxyacetic acid derivatives (2,4-dechlorphenoxyacetic acid-2,4-Д, 2,4,5-threechlorphenoxyacetic acid-2,4,5 Р);

• piperidine derivatives (parakvat, dekvat);

• Organic nitrocompounds (denitroortocresol, denitrophenol);

• Others.

Basically, any of the listed chemical substances can become the reason of a heavy poisoning of the man. However, the formation of mass sanitary losses as a result of destruction of industrial objects, dwellings, warehouses can arise only at a combination of the following conditions: wide HATA usage in an industry and economic activity and as a consequence, their accumulation in many manufactures and warehouses, and action of the HATA through skin and respiration organs. Not all from the above listed substances answer these requirements, nevertheless the list of potentially dangerous poisons is rather great.

The most probable HATA, capable to cause mass poisonings, nowadays are considered: chlorine, the ammonia, nitric acid, bromide methyl, nitrogen oxides, carbon monoxide, sulphureous anhydride, carbon bisulphide, hydrocianic acid, three-chlorine phosphorus, tiophos, acetic acid, fluoride and chloride hydrogen, cyan hydrogen, phosgen, methylisocyanat, asymmetrical dimethylhydrasine, nitril of acrylic acid, some pest-killers and number of other compounds.

The essential moment in extreme toxicology is the concept of levels of influence of chemical substances from which depends the character of their damaging action. On the WHO classification they are subdivided on low, dangerous, threatening and extremely high.

Low level of influences is understood as such conditions of man’s contact with toxicant, at which there are convertible changes in state of health or condition of health not limiting the activity (for example, symptoms of irritating action - cough, lacrimation); expiring after the termination of contact with the chemical agent and not causing the subsequent changes in a condition of health.

Dangerous are such levels of chemical pollutants, at which the convertible changes in a condition of health demanding restrictions of human activity (for example, expressed blepharospasm, others reflective reactions, weak chemical burns) are expressed.

Threatening are levels of influence with possible irreversible changes in a health condition requiring immediate termination of human activity.

Extremely high are levels of influences with occurrence of irreversible changes in human organism resulting in fatal outcome. Such influences frequently are called catastrophes. At any chemical failure the key question is the definition of the chemical substance which has got in an environment. It is very difficult to foresee substance, which can lead to trouble, however experience shows, that most widespread are toxic steams and gases: chlorine, ammonia, phosgen, benzol, carbon oxide, four-chloride carbon, metal carbonils, nitrogen oxides, emissions of protein-vitamin compounds. The emergencies in the latter case arise, as a rule, under adverse meteorological conditions and result in rather slow increase of injured people. The listed above chemical connections should be by a basis for drawing up of the programs on preparation of the personnel for rendering the medical help, at which planning it is expedient also to provide acquaintance with the most dangerous groups of chemical substances. In view of their chemical properties the following classification is expedient:

• Combustible (acetone, acetylene, akrilonitril, petrol, kerosene, liquefied gases, alkaline metals etc.);

• Corrosive (acid, alkali etc.);

• Oxidizers (ammunition, explosive smoke boxes, means for fireworks etc.).

The characteristic of the HATA affect centers and technique of an estimation of chemical conditions at failures and accidents at the chemical enterprises.

The HATA are capable to cause damage not only for people, but also animals, plants, they can infect territory on long time, resulting to serious ecological consequences. They can penetrate in the organism through respiratory ways, skin, eyes and alimentary tract mucous membranes, acting with food or water. Practically all HATA in steam and aerosol condition, penetrate into an organism by an aerosol way. Therefore, the greatest danger is represented by gas, highly volatile, liquid (with high relative density via air) and substances, easily dispergible into solemn compounds in the air. Some chemical compounds relating to HATA (chlorine, phosgen, hydrocianic acid, methylisocyanat etc.), in the past were applied or were planned to application as battle (military) poisoning substances. And it means, that subdivision of many considered chemical compounds for battle tactico-chemical substances) and HATA in the certain measure is conditional and lot of parameters used for an estimation of the affecting factors of battle poisoning substances, can be applied also for the characteristic of highly active poisonous substances. So, for example, HATA at failures on chemically dangerous objects, as well as BTCS at their battle application have:

а) vast action, that means, the territory not only in area of failure, but also air space are contaminated too;

b) By ability of many compounds to penetrate in organism through the intact skin covers, that causes necessity to use the means of skin protection;

c) By property to cause damage during certain, sometimes rather long time (days, months).

In the medico-tactical attitude HATA are characterized:

• By suddenness, speed and mass character of an arising injury;

• With ability to pollute the environment;

• By presence of the combined defeats (HATA intoxication + burn, HATA intoxication + mechanical trauma etc.).

The centers of chemical pollution created by HATA, have a number of differences from the centers created by BTCS, including features of formation of zones (sizes, density of pollution). The stability of substances on the area, degree of their influence on the people are dangerous by contamination of large groups of the population.

At failure on chemically dangerous object the single-moment air contamination by two and more toxic agents is not excluded, it’s formed as a result of secondary chemical reactions, caused by failure. And it can become the reason of the combined action on organism of several rows. Thus the toxic effect can be amplified (synergism) or weakened (antagonism). The HATA affecting action depends not only from the toxicity, but also from their physic-chemical properties, which determine the behavior of substances on area and in an atmosphere; opportunities of their penetration, distribution and transformation of them inside the organism, mechanism of toxic action and substantiation of methods of antidote influence, choice of effective means of neutralization (degasation). The major characteristic of HATA danger is relative density of their steams (gases). If steam density of any substance is less than one unit, it means, that it is easier than air and will be quickly dissipated. Large danger is represented by HATA, relative density of which steams is more than one unit, they are kept on a surface of ground (longer chlorine, etc.), collected in various deepenings of district, their influence on the people will be more long.

The HATA are kept in the closed capacities under pressure of own gases (steams). After destruction of capacity the pressure above liquid substances falls up to atmospheric, HATA boil away (boiling temperature is below 2 C), and they are discharged in an atmosphere as gas or steam. The cloud of HATA gas (steam), formed at the moment of destruction of capacity, is named the initial cloud of contaminated air. It is distributed to large distances. The remained part of a liquid (especially at boiling temperature of 20 С) spreads and also evaporates, and steams (gases) act in an atmosphere, forming a secondary cloud of contaminated air. This cloud is distributed to smaller distance. Thus, the territory which has suffered the HATA influence, includes a place of its direct flood, i.e. centre of a chemical affect and zone of chemical contamination formed as a result of steam distribution.

The zone of chemical infection is divided into two parts: a zone of extremely dangerous infection and zone of dangerous infection.

An estimation of chemical conditions means definition of scale and character of RS and HATA infection, analysis of their influence on activity of objects and population.

The basic initial data at an estimation of chemical conditions: - RS or HATA type, area,

• Time and amount of the poured out poisonous substances,

• Meteorological and topographical conditions of an area,

• Degree of security of the people, engineering, property.

The meteorological data can be received from posts of the chemical control, which inform about the speed and direction of the ground wind, degree of vertical stability of air.

The degree of vertical stability of air is characterized by the following condition of an atmosphere in the ground air layer:

The inversion - at it the bottom layers of air is more cold than top, arises at clear weather, small (up to 4 м/sec) speeds of a wind, approximately one hour prior to sunrise and ends within one hour the ambassador sunrise;

Convection - the bottom layer of air is heated up stronger than top and there is a hashing of it on a vertical, arises at clear weather, small (up to 4 м/sec) speeds of a wind, approximately through 2 hours the ambassador sunrise and ends approximately for 2-2,5 hours before call of the sun;

Isothermia - temperature of air within the limits of 20-30 m from the ground is almost identical, is usually observed in cloudy weather and at a snow cover.

The estimation of chemical conditions can be made by a method of forecasting and on the data of chemical investigation.

Major parameters determining the sizes and character of the center of a defeat, are toxicity (concentration of toxic substance in ground layer in territory of distribution of a cloud) and duration of influence of this substance on human organism. The center of an affect (area of direct HATA emission) at presence of storehouse crash is equal to the area of crumbling territory. At the absence of falling it is possible to make approximate account that the spread liquid has covered ground with a layer no more than 0,05 m. The product of the overflowing area to thickness of a liquids’ layer gives an approximate volume of the overflow part.

The depth of DS distribution depends on HATA concentration and speed of a wind. The substantial growth of speed of a wind (6-7 m/sec and more) promotes fast distribution of a cloud. The increase of ground and air temperature accelerates HATA evaporation, and, hence, increases it concentration in the polluted territory. The depth of HATA distribution and size of its concentration largely is influenced by vertical flows of air, their direction described by a degree of vertical stability of an atmosphere. The important characteristic of the center of a chemical affect (CCA) is the stability of pollution. It determines the time of self-degasation, and probability of HATA existence. The stability of CCA, which has arisen in territory, is influenced by a number of the special factors. The buildings and structures of city are heated up by solar beams faster, than located in village district. Therefore, in the city the intensive movement of air is connected, usually, with its flow from periphery to the centre on main streets. It promotes the HATA penetration in court yard, impasses, basement premises (rooms) and creates the increased danger of an affect of the population. As a whole it is possible to consider, that the stability of HATA is higher in city, than in open district.

Width of a secondary HATA cloud at a steady wind (fluctuation from the basic direction no more 6о) is accepted equal to 1/5 of appropriate depth (pic.3), at a unstable wind (fluctuation of a wind more 6о) - 4/5 depths. The zone of direct action at destruction of sources of the storage is rather small and reaches 1-1,5 km on extent. Height of rise of a gases cloud changes in limits from 25 up to 50 m, that is in a few times less, than at BTCS.

The depth of distribution of polluted air is determined in distance from windward side of HATA flow up to border of distribution of polluted air with dangerous concentration. It depends on meteorological conditions, relief of an area, presence of woods and density of buildings of the settlements.

In the open district in conditions of convection the depth of distribution of polluted air cloud decreases approximately in 2 times, in conditions of inversion will be increased approximately in 1,5-2 times. In the settlements with continuous building and woods the depth of distribution of polluted air considerably decreases (in 3-3,5 times).

The sources of chemical danger in the majority are of prolonged action (flood of tanks, storehouses). Fallout of drops on account of their diameter increase occurs near to sources. The zone of solemn particles fallout does not exceed - 1-3 km, liquid - 5-10 km, gas-aerosol - 10-35 km.

In the medico-tactical characteristic of the chemical centers of a defeat at failures it is accepted to allocate 6 types (Marshall V., 1989); thus two last types are characteristic only for HATA. Their medico-tactical characteristic is enough full given in a military toxicology course and isn’t regarded in the given manual.

We only conduct classification of the chemical centers formed by HATA.

1. Unstable with quick action: ammonia, petrol, bensol, hydrasin, dechlorethane, methaphos, hydrogen sulfide, carbon bisulfate, chlorine, hydrochloric acid, cyanic acid, methylisocyanate, akrilonitril

2. Unstable with the slow action: phosgene, hexochlorine, brommethyl, ТЭС, granoson

3. Stable with quick action: phosphorus poisonous compounds (PPC), aniline

4. Stable with the slow action: a sulfuric acid, intrita, ethyl-lead

5. Semi-stable with quick action: formic acid, acetic acid, furphurol, chlorpikrine

6. Semi-stable with the slow action: a nitric acid, oxides of nitrogen

Organization and contents of the medical help to victims in the focus of chemical infection with HATA.

The organization of the medical help to victims at technological failures at the chemical enterprises has certain features. The plenty of the chemical enterprises having various work cycles and making various chemical substances, results in uniqueness of almost each emergency. First of all, it is necessary to emphasize, that chemical accident by virtue of suddenness, extremely high toxicity and highly dangerous substances, absence of time reserve for realization of rescue measures and rendering of the medical aid (first minutes - maximum hours, when the toxic agent acts in an environment intensively), creates most difficult conditions for of a medical services’ activity. As a result of secondary chemical reactions, frequently unpredictable, the additional HATA allocation in an atmosphere is possible. This factor together with other features of chemical accidents (destruction, fires, explosions etc.) causes high probability of development of combined injuries (poisoning - burn, poisoning - trauma), and complex (various HATA)ones, creates serious difficulties of search and collecting of victims.

The decisive importance in surviving of the people has the time of rendering the first medical aid. So, if it is carried out within three hours after a poisoning, up to 60 % of victims die, over six hours - up to 90% dies. The numerous experience testifies that the victims ratio with different degree of complicity in conditions of industrial failures remains rather constant: 1-4 % - critical, 5-10 %, - average degree of severity, 85-90 % - light. The lethality makes about 1- 2%. The experience of liquidation of chemical accidents consequences testifies, that the quota critically wounded contingent is formed among the persons who are in immediate proximity from epicenter of failure, where there are extremely high concentration of toxic substances. Only immediate (during first minutes) help can rescue their life. In other zones of an affect people with light and average degree of severity of a poisoning prevails. In some hours after failure, at the expense of the further intoxication development, the density of critically wounded grows. In these conditions the specialized help should be supplied within the first 1-2 hours. The absence of opportunity of realization of the urgent specialized help to victims before evacuation and the incorrect forecast of development of syndrome displays of an affect makes the evacuation prognostically dangerous. The greatest difficulties in diagnostics are made with poorly expressed forms of affects, initial stages of light poisonings and cases, not developed in a detailed injury picture. The rational sorting in the similar situation which is taking into account stated features of organization of the help to victims, can be done only by experienced physicians and toxicologists.

In the first period (duration up to 30 minutes) - after direct contact of the people with toxicant the evacuation of victims from a zone of pollution, decontamination and urgent symptomatic treatment directed on elimination of vital functions’ disorders is required. In conditions of chemical accident the effort of a medical service in the first minutes and hours should be concentrated on stopping and preventive maintenance of life-menacing intoxication syndromes taking into consideration their structure and dynamics of development. Thus the realization of urgent measures of therapeutic help must be based on general principles of treatment of sharp poisonings.

In the second period (hours) – the rendering of the specialized medical help is necessary, taking into account the character of toxicants’ action, possible antidote therapy; at presence of a latent period, probably, the application of precautionary treatment.

In the third period (days, week) the rehabilitation will be carried out, taking into account the character of toxicants’ action.

The clinic of HATA affects is of multi-syndrome character, complicating syndromological diagnostics and choice of antidote therapy. Nevertheless, syndromological principle of diagnostics of poisonings in a combination with the data of the preliminary forecast and medical investigation, even at absence of poison indication, is the main in organization of the medical aid at mass receipt of victims. In this connection, we can allocate three groups of HATA, with common symptomocomplex: first with irritating and cauterizing action; second - with mainly resorbtional action; third – with mixed action.

The primary measures are to stop local toxin action and its resorbtion by means of individual protection, to leave the contamination zone and to take victims out, realization of sanitary processing. Especially it is important to remove quickly from skin and mucous membranes the substances having strong cauterizing action, that is achieved by long (10-15 min) washing of the affected sites with water.