How chemical poisons enter the human body

The way in which poisons invade the human body

Toxic chemicals are harmful to the human body through the respiratory tract (inhalation), digestive tract (oral intake), skin (absorption), and other special ways such as subcutaneous, muscle, intravenous injection, and mucous membranes. The fastest poison absorption rate is intravenous injection, followed by respiratory, oral, and skin absorption. In industrial production, the most harmful route of toxic chemicals is the respiratory tract, followed by the skin, and other routes through the digestive tract, mucous membranes and other rare.

1, enter through the respiratory tract

This is the most important, most common and dangerous way. In the production process, poisons that exist in the production environment in different forms such as gas, vapor mist, smoke, and dust can be inhaled into the respiratory tract at any time.

Whether the poison can enter the alveoli with the inhaled air and is absorbed by the alveoli, has a great relationship with the particle size and water solubility of the poison: When the poison is in the form of gas, vapor, smoke, etc., due to the small particles, it is generally 3 microns. Below, it is easy to reach the alveoli. However, most of the mists and dusts larger than 5 microns are mostly blocked by the nasal cavity and upper respiratory tract when entering the respiratory tract, and when passing through the respiratory tract, they are easily dissolved by the mucus in the upper respiratory tract and do not reach the alveoli; however, the concentrations are high. In special circumstances, there are still some areas that reach the alveoli. When the poison reaches the alveoli, the water-soluble poisons are absorbed more rapidly by the alveoli; similarly, small particles of the poison are more easily dissolved and absorbed by the alveoli.

After the poison is absorbed by the alveoli, it directly enters the blood circulation without being detoxified by the liver, and is distributed throughout the body, resulting in a toxic effect. Therefore, it is more dangerous.

2, enter through the skin

The skin absorbs poison mainly through two ways, namely through the epidermis barrier and through the hair follicle. In some cases, it can also enter through the sweat gland duct.

Because the epidermis cell membrane under the epidermis is rich in phospholipids, it has a barrier effect on non-fat-soluble substances, and the basement membrane at the junction of epidermis and dermis has a similar effect. Although fat-soluble substances can pass through this barrier, unless they have a certain degree of water solubility, they are not easily absorbed by the blood.

The second route of entry of poisons into the body through the skin is to bypass the epidermal barrier, which is absorbed by the blood through the hair follicles directly through the sebaceous gland cells and the hair follicle wall into the dermal papilla capillaries.

Some poisons can enter the skin through the epidermis and hair follicles at the same time.

The amount and rate of absorption of toxic substances through the skin, in addition to its fat-soluble, water-soluble, concentration, and skin contact area, are also related to external conditions such as temperature and humidity.

The toxic substances that are invaded by the skin, after absorption, are not detoxified by the liver but are distributed directly along the blood circulation.

3, enter the digestive tract
In the production environment, it is rare for poisons to be absorbed from the digestive tract alone. Many eating habits caused by bad health habits, such as eating or drinking water in the production environment can lead to ingestion; or poisons invade the human body from the respiratory tract, and some of them are attached to the secretions in the nasopharynx and are not intended to be swallowed. After entering the digestive tract, poisons are mostly excreted in the faeces. Some of them are absorbed in the small intestine and are detoxified by the liver and discharged. Only a small part enters the blood circulation system.

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