Harm of toxic chemicals on human body

With the development of society, the application of chemicals is becoming more and more extensive, and the production and usage are also increasing. Therefore, humans living in modern society are likely to be exposed to various chemical substances to varying degrees through different channels, especially Workers in chemical workplaces will have more exposure to chemicals. The impact of chemicals on health ranges from mild rashes to some acute and chronic injuries and even cancers, and the more serious harm is some dramatic chemical disasters. For example: on December 3, 1984, the methyl isocyanate leakage accident at the Joint Carbonization Plant in Bhopal Town, India, killed 200,000 people and killed 2,500 people; Up to 150 people died and 41 people died. Chemical hazards cause extremely serious losses to the national economy and people ’s lives and property. Therefore, understanding the basic knowledge of the hazards of chemical substances to human bodies is very necessary to strengthen chemical management and prevent the occurrence of poisoning accidents.

1.1 The way of poison entering the human body

Poisons can enter the body through the respiratory tract, digestive tract and skin. In industrial production, poisons mainly enter the body through the respiratory tract and skin, but also enter the body through the digestive tract, but are more secondary.

1.1.1 Respiratory tract

It is the most important way for industrial production of poisons to enter the body. All poisons in the form of gas, vapor, mist, smoke, and dust can invade the body through the respiratory tract. The human lung is composed of hundreds of millions of alveoli. The walls of the alveoli are very thin and there are abundant capillaries. Once the poison enters the lungs, it will soon be transported to the whole body through the alveolar wall into the blood circulation. The most important factor affecting absorption through the respiratory tract is its concentration in the air. The higher the concentration, the faster the absorption.

1.1.2 Skin

In industrial production, poisoning caused by absorption of poison through the skin is also relatively common. After the fat-soluble poison is absorbed through the epidermis, it still needs to be water-soluble in order to be further diffused and absorbed, so substances that are both water and fat-soluble (such as aniline) are easily absorbed by the skin.

1.1.3 Digestive tract

In industrial production, the absorption of poisons through the digestive tract is mostly due to poor personal hygiene habits. The poisons contaminated by the hands enter the digestive tract along with eating, drinking or smoking. After the insoluble poison entering the respiratory tract is cleared, it can be swallowed through the pharynx and enter the digestive tract.

1.2 The process of poison in the body

1.2.1 Distribution

After being absorbed, the poison is distributed throughout the body with blood circulation (partly with lymph). When a certain concentration is reached at the point of action, poisoning can occur. Poisons are unevenly distributed in various parts of the body, and the distribution of the same poison in different tissues and organs is more or less. Some poisons are relatively concentrated in a certain tissue or organ, we call this organ the target organ. For example, lead and fluoride are mainly concentrated in bone, and benzene is mostly distributed in bone marrow and lipids.

1.2.2 Biotransformation

After the poison is absorbed, it is affected by the biochemical process in the body, and its chemical structure undergoes a certain change, which is called the biological transformation of the poison. As a result, the toxicity can be reduced (detoxification) or increased (poisoning). The biotransformation of poison can be attributed to oxidation, reduction, hydrolysis and combination. The toxic metabolites formed by the conversion are excreted from the body.

1.2.3 Discharge

Poisons can be excreted in the body after transformation or without transformation. Toxic substances can be excreted through the kidneys, respiratory tract and digestive tract, among which excretion through the kidneys with urine is the most important way. The concentration of urinary poisons is closely related to the concentration in the blood. Urinary poisons and their metabolites are often measured to monitor and diagnose poison absorption and poisoning.

1.2.4 Accumulation

When the total amount of poison entering the body exceeds the total amount of transformation and excretion, the poison in the body will gradually increase. This phenomenon is called the accumulation of poison. At this time, most of the poisons are relatively concentrated in certain parts, and the poisons can have a toxic effect on these accumulated parts. The accumulation of poisons in the body is the basis of chronic poisoning.

1.3 Harm to human body

The harm of toxic substances to human body is mainly caused by poisoning. The toxic effects of chemicals can be divided into the following clinical types:

Cause irritation, allergies, hypoxia, coma and anesthesia, systemic poisoning, carcinogenesis, teratogenicity, mutagenicity, pneumoconiosis

1.3.1 Stimulation

Irritation means that the body has been in contact with chemicals quite severely. Generally, the irritated parts are skin, eyes and respiratory system.

1.3.1.1 Skin

When certain chemicals come into contact with the skin, the chemicals can cause the skin protective layer to peel off, causing dry, rough, and painful skin. This condition is called dermatitis, and many chemicals can cause dermatitis.

1.3.1.2 Eye

Injuries caused by contact with chemicals and eyes range from mild to temporary discomfort to severe permanent disability. The severity of the injury depends on the dose of poisoning and the speed of first aid measures.

1.3.1.3 Respiratory system

Fog, gas, vapor chemical irritants and the upper respiratory system (nose and throat) will cause a hot feeling, which is generally caused by soluble substances, such as ammonia, formaldehyde, sulfur dioxide, acids, and alkalis. Absorbed by the wet surface of the nasopharynx. These chemicals must be handled with care, such as when spraying drugs, to prevent inhalation of these vapors.

Some irritation to the trachea can cause tracheitis, and even seriously damage the trachea and lung tissue, such as sulfur dioxide, chlorine, coal dust. Some chemicals will penetrate into the alveolar area, causing strong irritation. It is generally not easy to detect these chemicals in the workplace, but they can seriously endanger workers' health. Pulmonary edema is caused by the reaction of chemicals and lung tissues immediately or a few hours later. This symptom starts with a strong irritation, and then coughing, difficulty breathing (shortness of breath), hypoxia, and excessive sputum. For example, the following substances can cause the above reactions: nitrogen dioxide, ozone, and phosgene.

1.3.2 Allergies

Exposure to certain chemicals can cause allergies. Allergic symptoms may not appear at the beginning of exposure, however, prolonged exposure can cause body reactions. Even exposure to low concentrations of chemicals can cause allergic reactions, and the skin and respiratory system may be affected by allergic reactions.

1.3.2.1 Skin

Skin irritation is a symptom that looks like dermatitis (rash or blisters). This symptom does not necessarily appear in the area of ​​contact, but may appear in other parts of the body. The chemicals that cause this symptom are: epoxy resin, amine Hardeners, azo dyes, coal tar derivatives and chromic acid.

1.3.2.2 Respiratory system

Allergic reactions of the respiratory system to chemicals cause occupational asthma. This symptom response often includes coughing, especially at night, and difficulty breathing, such as wheezing and shortness of breath. The chemicals that cause this reaction are toluene, polyurethane, and fu Formalin.

1.3.3 Hypoxia (asphyxia)

Asphyxia involves interference with the oxidation of body tissues. This symptom is divided into three types: simple asphyxia, blood asphyxia, and intracellular asphyxia.

1.3.3.1 Simple asphyxia

This situation is because the surrounding oxygen is replaced by an inert gas, such as nitrogen, carbon dioxide, ethane, hydrogen, or helium, so that the amount of oxygen is insufficient to sustain life. In general, the air contains 21% oxygen. If the oxygen concentration in the air drops below 17%, the body's tissues are not supplied with enough oxygen, which can cause dizziness, nausea, and regulatory disorders. This situation generally occurs in workplaces with limited space. When severe hypoxia causes coma and even death.

1.3.3.2 Blood suffocation

This situation is due to the fact that the chemical substance directly affects the body's ability to transmit oxygen. The typical blood suffocating substance is carbon monoxide. When the content of carbon monoxide in the air reaches 0.05%, it will cause a serious drop in the oxygen carrying capacity of the blood.

1.3.3.3 Intracellular asphyxia

This is because chemicals directly affect the body's ability to bind oxygen, such as hydrogen cyanide and hydrogen sulfide, which affect the ability of cells to bind oxygen, even though the blood contains sufficient oxygen.

1.3.4 Coma and anesthesia

Exposure to high concentrations of certain chemicals, such as ethanol, propanol, acetone, butanone, acetylene, hydrocarbons, ether, and isopropyl ether, can cause central nervous system depression. These chemicals have a similar effect to drunkenness, and a large amount of exposure can cause coma and even death. But it can also cause some people to indulge in this kind of narcotics.

1.3.5 Systemic poisoning

The human body is made up of many systems. Systemic poisoning refers to the phenomenon that chemicals cause harmful effects on one or more systems and extend to the whole body. This effect is not limited to a certain point or a certain area of ​​the body.

The role of the liver is to purify toxic substances in the blood and convert them into harmless and water-soluble substances before excretion. However, there are some substances that are harmful to the liver. Depending on the dose and frequency of exposure, repeated damage to liver tissue may cause damage and cause disease (cirrhosis) and reduce liver function, such as solvent alcohol, carbon tetrachloride, trichloroethylene, chloroform , May also be mistaken for viral hepatitis, because the symptoms of liver damage (yellow skin, yellow eyes) caused by these chemicals are similar to viral hepatitis.

The kidney is a part of the urinary system. Its role is to eliminate waste generated by the body, maintain water and salt balance, and control and maintain the acidity in the blood. Various parts of the urinary system may be damaged by toxic substances. For example, chronic beryllium poisoning is often accompanied by urinary tract stones. Insectamidine poisoning may cause hemorrhagic cystitis. However, kidney damage is common. Many productive poisons are toxic to the kidney, especially heavy metals and halogenated hydrocarbons. Such as mercury, lead, thallium, cadmium, carbon tetrachloride, chloroform, hexafluoropropylene, dichloroethane, methyl bromide, ethyl bromide, ethyl iodide, etc.

The nervous system controls the body's active functions. It can also be damaged by certain chemicals. Long-term exposure to some organic solvents can cause fatigue, insomnia, headache, nausea, and more severely will cause motor nerve disorders, paralysis, and sensory nerve disorders; nerve endings do not work and are related to exposure to hexane, manganese, and lead, leading to carpal droop; Exposure to organophosphate compounds such as parathion may cause the nervous system to lose function; in addition, exposure to carbon disulfide may cause mental disorders (psychosis). Exposure to certain chemicals may have an effect on the reproductive system, leading to male infertility and abortion of pregnant women. Chemicals such as ethylene dibromide, benzene, chloroprene, lead, organic solvents and carbon disulfide are related to male worker infertility. Abortion is related to exposure to chemicals such as narcotic gases, glutaraldehyde, chloroprene, lead, organic solvents, carbon disulfide, and vinyl chloride.

1.3.1 Carcinogenic

Long-term exposure to certain chemicals may cause uncontrolled growth of cells and form cancerous tumors. These tumors may appear many years after the first exposure to these substances. This period is called the incubation period, which is generally 4-40 years. The location of occupational tumors is varied and not necessarily limited to the contact area, such as arsenic, asbestos, chromium, nickel and other substances may cause lung cancer; nasal cancer and sinus cancer are caused by chromium, nickel, wood, leather dust, etc .; bladder Cancer is related to exposure to benzidine, naphthylamine, leather dust, etc .; skin cancer is related to exposure to arsenic, coal tar, and petroleum products; exposure to vinyl chloride monomer can cause liver cancer; exposure to benzene can cause aplastic anemia.

1.3.7 Teratogenic

Exposure to chemicals may cause harm to the unborn baby and interfere with the normal development of the fetus. During the first three months of pregnancy, important organs such as the brain, heart, arms, and legs are developing. Some studies have shown that chemicals may interfere with the normal cell division process , Such as narcotic gases, mercury and organic solvents, which can cause fetal malformations.

1.3.8 Mutagenicity

The influence of certain chemicals on the worker's genetic genes may cause abnormalities in the offspring. The experimental results show that 80% -85% of the carcinogenic chemicals have an effect on the offspring.

1.3.9 Pneumoconiosis

Pneumoconiosis is due to the deposition of small dust particles in the ventilation area of ​​the lung and the reaction of lung tissue to these deposits. It is difficult to detect changes in the lungs early. When the X-ray examination finds these changes, the condition is already serious. Pneumoconiosis patients have decreased lung ventilation and shortness of breath symptoms during stressful activities. This effect is irreversible. Substances that can cause pneumoconiosis include quartz crystals, asbestos, talc, coal powder, and beryllium.

Poisoning caused by chemical poisons is often damage to multiple organs and systems. Such as the common poison lead can cause nervous system, digestive system, hematopoietic system and kidney damage; trinitrotoluene poisoning can occur cataracts, toxic liver disease, anemia, methemoglobinemia and so on. The organs and performance of acute and chronic poisoning caused by the same poison can also be very different. For example, acute benzene poisoning mainly manifests as an anesthetic effect on the central nervous system, while chronic poisoning mainly involves damage to the hematopoietic system. This is a very common phenomenon in the harmful effects of toxic chemicals on the body. In addition, the harm of toxic chemicals to the body depends on a series of factors and conditions, such as the characteristics of the poison itself (chemical structure, physical and chemical properties), the dose, concentration and duration of the poison, the combined effect of the poison, the individual's sensitivity Wait. In short, the interaction between the body and toxic chemicals is a complex process, and the performance after poisoning is ever-changing.

The above are the hazards of toxic chemicals sorted out by the editors to the human body. Relevant staff should do protective work when they come into contact with the chemicals.

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