Chemically hazardous substances, ecotoxicology

At present more than 6 million chemical compounds are known (more than 90% of them are organic). Practically all substances are dangerous in one way or another and in various conditions, and only a few dozen belong to the category of chemically dangerous.

Classification of chemically hazardous substances according to the degree of danger of impact on people:

I - extremely dangerous (compounds of mercury, lead, cadmium, zinc, metal carbonyls, substances containing cyanide ions (hydrocyanic acid and its salts), halogens (Cl2, Br2), halocarbons (HF, HCl, HBr), chlorohydrins, organofluorine compounds, phosphorus compounds, etc.);

II - highly dangerous (mineral and organic acids (sulfuric, nitric, hydrochloric, acetic), alkalis (sodium hydroxide), ammonia, sulfur compounds (sulfides, thioacids, carbon disulfide), halogenated hydrocarbons (methyl chloride, methyl bromide), some alcohols and aldehydes (methanol, formaldehyde));

III, IV - moderately and low-risk (all other chemical compounds).

Classification of chemically hazardous substances by the nature of impact on people:

1. Substances with predominantly suffocating action:

1.1 with concentrated cauterizing action (chlorine, etc.);

1.2 with weak cauterizing action (phosgene, etc.).

2. Substances of general toxic effect (cyanide, hydrogen cyanide (hydrocyanic acid and its salts).

3. Substances possessing suffocating and generally toxic effect:

3.1 with concentrated cauterizing action (nitrile acrylic acid, etc.);

3.2 with weak cauterizing action (sulfurous anhydride, hydrogen sulphide, nitrogen oxides, etc.).

4. Neurotropic poisons acting on generation, carrying out and transmission of nerve impulses (carbon disulfide, etc.).

5. Substances of asphyxiating and neurotropic action (ammonia, etc.).

6. Metabolic poisons, which poison the body as a result of not direct action, but intracellular metabolism and their biochemical conversion into hazardous compounds (methylene chloride, ethylene oxide, etc.).

7. Carcinogenic substances.

Carcinogenic substances are responsible for emergence and development of cancer diseases (tab. 4).

Carcinogenic compounds and target organs

Table 4

The group of heavy metals includes lead, copper, zinc, nickel, cadmium, cobalt, antimony, bismuth, mercury, tin, vanadium with the exception of noble and rare metals, which have density more than 8,000 kg/m³. Such separation looks rather conditional and usually the group of heavy metals also includes chromium, silver, gold, platinum, iron, manganese, and also semimetal arsenic.

Clinical syndromes of lead poisoning:

1. Changes in the nervous system include: a) asthenic syndrome - functional disorders of the central nervous system (headaches, fatigue, memory impairment, etc.); b) encephalopathy (from headaches and epileptic seizures to "leaden meningitis" and violations of speech and auditory functions); c) motor disorders - paresis and paralysis, polyneuritis with a predominant lesion of the extensor muscles; d) visual analyzers damage.

2. Changes in the blood system - from reticulocytosis, anisocytosis and microcytosis to lead anemia, more often oligochromic.

3. Endocrine and metabolic disorders (enzymatic disorders, impaired metabolism of porphyrins, menstrual and genital functions).

4. Changes from the gastrointestinal tract (from nausea, heartburn to lead colic).

5. Changes in the cardiovascular system (arrhythmia, sinus bradycardia or tachycardia, vasoneurosis).

6. Impaired renal function.

Rules of safe behavior and actions of the population in case of accidents with the release of CHS.

The main methods of protection from ACHS (accidentally chemically hazardous substances) are:

1. Refuge in shelters and sealed rooms.

2. Use of personal protective equipment, taking into account which CHS is the source of infection.

3. Restriction of time of stay in the open area.

4. Removal of CHS from skin, mucous membranes and from the body; neutralization of CHS or products of its decay.

When receiving the warning on the threat of chemical contamination, it is recommended for people to take the following actions immediately:

1. Wear personal protective equipment (PPE) - respiratory equipment and leave the area of infection.

2. If you can not get out of the contamination zone, stay indoors, put on personal respiratory protective equipment, seal the room (use various tapes, adhesive plaster, paper to fill up the cracks in the windows and doors, close chimneys and ventilators).

3. In case of impossibility of further staying in the room, it is necessary to disconnect heating and household electrical appliances, gas, dress children and elderly people, take warm clothes and non-perishable products for 3 days, and, going out, move perpendicular to the direction of the wind, following such rules:

> move fast, but do not run and make dust;

> use means of protection;

> do not lean against buildings and do not touch surrounding objects;

> avoid passage through tunnels, ravines and other open reclining places;

> when leaving the contaminated area, remove the outer clothing and leave it on the street, rinse the eyes and open areas of the body with water, take a warm drink, if necessary, seek medical help.

4. If possible, provide the necessary assistance to victims.

Basic principles of first aid:

1. Stop CHS intake into the body (remove the affected person from the contamination zone, remove CHS from the skin or from mucous membranes, remove contaminated clothing);

2. Restoration of impaired body functions and maintenance of life (artificial respiration, cardiac massage);

3. Removal of CHS from the body (gastric lavage, emetics, adsorbents);

4. Use of appropriate antidotes and medications that enhance the protective properties of the body.