Mechanism of a chemical burn
The specificity of chemical burns is the partial or complete destruction of the molecules, the cells or the structure of the skin or the eye induced by either an irritant or a corrosive chemical product. The burn degree is determined by the subsequent modification of the tissues.
Development of chemical burns
Which chemicals induce chemical burns?
Corrosive and irritant agents are the two categories of hazardous chemicals which can induce chemical burns after a single contact with the eye or the skin.
Some of them represent a double hazard because they combine a generalized toxic action with a primary corrosive attack (see hydrofluoric acid).
Mechanism of chemical burn injuries
Corrosive and irritant chemicals can create an exchange with the constituents of the eye or the skin, which results in chemical burns.
The six kinds of aggressive chemical reactions supporting this exchange are: acid, basic, oxidation, reduction, chelation of magnesium or calcium and solvatation.
The different steps of a chemical burn
The mechanism of burns breaks down in three stages:
- the contact which is the origin of the burn
- the penetration
- the reaction which constitutes the burn
Depending on the nature of the chemical involved, there is a gap lasting from a few seconds to a few minutes only between the time of contact and the time of reaction, in which an efficient intervention is possible.
Some factors affect the severity of burns
- the nature of the chemical
- its concentration
- the duration of contact
- the temperature of the aggressive product
How does HF present a specific hazard?
Hydrofluoric acid has a dual action:
- a corrosive action due to the acid ions H+, which can damage the superficial tissues (such as corneal epithelium or epidermis)
- a toxic action due to the F– ions, which can deeply penetrate thanks to the acid destruction of the superficial layers of the skin or the eye, and can chelate calcium and thus disturb the biological balances, which leads to more or less deep physiological disorders
By definition, fluorides in acidic medium (such as boron trifluoride, for instance) carry the same kind of hazard.
Advantages of an active rinsing with the HF Burns solution
Because of this specific hazard and in addition to its sweeping effect, an efficient rinsing must quickly and simultaneously:
- stop the further spread of the aggressive agent that has yet penetrated into the tissues
- remove the chemical thanks to the flow of osmotic pressures
- absorb all the aggressive potential of the chemical product (H+ et F– )
These three properties define the concept of active rinsing.
For decontamination to be optimal, the three above criteria must be gathered.
The following diagram gathers all the elements mentioned above
The consequences induced by a chemical splash depend on the precocity and quality of its management.