Chemical Injuries

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Many chemicals present a serious hazard.    

At home, products such as Drain cleaners, Oven cleaners, Brick cleaners and Rust removers, have the potential to cause a chemical injury if they come into contact with the skin or the eye.

At work the risks increase significantly because the volume, concentration and variety of chemicals increases.

Associated problems are:

  • Being able to identify the chemical.
  • The lack of knowledge regarding the chemical’s mechanism.
  • The lack of synergy between the chemical and the Emergency Management Protocol.

The consequences following a splash with an aggressive chemical can result in a chemical injury (lesion) or

 What is a chemical Injury (lesion)?

A chemical lesion is the local result of the reaction (*) that corrosive or irritant chemical products have with

biological tissue.

(*)  The chemical lesion is characterised by partial or total destruction of the biological tissue.

The severity of the lesion is proportional to the amount of tissue destruction:  the severity of the chemical lesion is basically related to the type of product, the nature of the tissue involved and the area affected.

The skin, eye and digestive or respiratory tract are in direct contact with the outside of the body and are therefore the primary targets of chemical products.   Chemical lesions are injuries inflicted by contact between chemical products and these specific tissues.

The chemical lesion may also be accompanied by other systemic symptoms.   When the chemical product causing the chemical lesion is toxic or harmful and passes into the body, reaching the organs or the bloodstream, it may interact with other biological targets.

Hydrochloric Acid

Sodium Hydroxide

Which chemical products cause a chemical Injury (lesion)?

The chemical products that may cause a chemical lesion are categorised according to the seriousness of the lesions that they may induce:  they are Corrosive or Irritant.

 

Irritant

Corrosive

 

 

 

A chemical product is classified among corrosive or irritant agents when it is capable of reacting with biochemical components of the cells and the tissues of the skin, the eye and the respiratory or digestive tracts. The CLP/GHS regulations of the European Chemicals Agency provide the following definitions of corrosive or irritant products (CLP page L 353/87):

Skin corrosion means the production of irreversible damage to the skin, namely, visible necrosis

through the epidermis and into the dermis, following the application of a test substance for up to 4 hours.

The reversibility of the skin lesions is to be considered in assessing the irritant nature of a substance.

It is Corrosive when it causes a severe lesion.   Corrosive products cause destruction of the

tissues with which they come into contact.

it will be considered Irritant if it only causes irritation, redness or inflammation.

The same chemical product may be Corrosive or only Irritant depending on the circumstances:

  • If present in a mixture or on its own
  • Depending on its concentration
  • Depending on the environment in which it is present

Some chemicals have the additional potential to cause other problems to human health such as those classified as

Toxic
Harmful

The hazard that a chemical product represents is indicated on its label by the manufacturer according to the    regulatory obligations of the European Chemicals Agency.

Why talk about a chemical Injury (lesion) rather than a burn?

Chemical lesion or chemical burn?   Lesions on the human body caused by chemical products are very different from thermal burns.   The mechanisms of development of these injuries are different:  mere heat transfer is involved in the case of a thermal burn – a chemical reaction in the other case.  The cicatrisation periods of both these types of injuries are variable.   The semantic distinction is therefore also necessary.

What is the mechanism of a chemical Injury (lesion)?

It all begins with a chemical reaction between two molecules. On a microscopic level, the chemical lesion results from a chemical reaction between an aggressive chemical product and a biological constituent.

This reaction destroys the biological constituent and hence the tissue, this forms the chemical lesion.

The mechanism involved in development of the lesion depends on many parameters, the most significant of which is the nature of the reaction initiated.

Depending on its type, each chemical product will react with a different component of the biological tissue by means of one of following actions:

  • Acid-base reaction:  H+ proton exchange reaction between an acid and an alkali.
  • Redox reaction:  electron exchange reaction between an oxidising agent and a reducing agent.
  • Chelation:  or formation of a complex from two molecules.
  • Solvation:  dissolution of a chemical species in a solvent.

Examples:

Acid-Base reaction between the OH ions of caustic soda and the ester bonds of fats.

Solvation of the lipids of the cell membranes by hydrophobic solvents (diesel oil, toluene).

Chelation of the Ca2+ calcium ions contained in the cells by F fluoride ions (originating for example from Hydrofluoric acid HF).

There are as many reactions that may cause chemical lesions as pairs of aggressive chemical product/biological target.

Stages of development of a chemical Injury (lesion):

The mechanism of development of the lesion may be divided into three phases:

  • Contact between the chemical product and the tissue.
  • Penetration of the chemical product into the tissue.
  • Reaction between the product and the biological component of the tissue.

Skin or eye contact occurs when the chemical product is splashed on the skin or in the eye.   Contact with the digestive tract (mouth, oesophagus, stomach…) occurs when the chemical product is swallowed. In the case of the airways, it takes place when vapours of the chemical product are inhaled.

Once the product is in contact with the tissue, it may penetrate the tissue, in spite of the biological barriers. The characteristics of the chemical product define its penetration potential and penetration rate into tissue.

Examples:

  • A solid chemical product cannot readily penetrate through the skin.
  • A small chemical molecule generally penetrates more quickly than a large molecule.
  • A molecule penetrates more readily if it is lipophilic.

The chemical product will penetrate into tissue until it encounters a biological constituent with which it can react. The penetration depth of the chemical product into the tissue before it reacts therefore depends on its type.

The chemical product is subsequently able to react with its biological target.

Once the chemical product has reached the biological constituent of the target tissue, the chemical reaction takes place.   The biological equilibrium is changed, the tissue is locally destroyed and the lesion forms.

The lesion therefore only develops during the chemical reaction, once the chemical product has reached its target.   Each splash of chemical product contains a very large number of molecules capable of reacting with a target molecule or with a target cell of the human body.

The lesion progresses in this manner for as long as any chemical product still remains in contact with the tissue and has not yet reacted.

Rapid intervention following contact makes it possible to restrict the extent of the lesion:

Emergency Decontamination is Paramount

Factors that worsen the Injury (lesion).

The type, depth and severity of the lesion depend on many factors:

  • The nature of the aggressive chemical product.
  • Its concentration.
  • The contact time between the tissue and the chemical product.
  • The temperature of the chemical product and the pressure.

Emergency treatment and caring for a chemical Injury (lesion):

After receiving a chemical splash, any contaminated clothing and contact lenses must be, carefully, removed from the casualty, if safe to do so and the affected tissues must be washed as quickly as possible.

Note:   Contaminated clothing and contact lenses must not be allow to be put back on.

Washing with Water

Rinsing with water was the first protocol used for chemical decontamination and this dogma persists on the basis of arguments which are more practical than scientific, because of its general-purpose and non-toxic character, and of its availability.   It allows the chemical agent to be diluted and removed from the surface of the affected tissue and to be carried away by a mechanical washing effect.

However, there are limits to washing with water:

  • It does not act on the potentially Corrosive or Irritant nature of the chemical agent.
  • There is not a rapid return to a physiological state (the effect of carrying the chemical agent away is limited to the surface tissue and has no in-depth effect.
  • Water favours the chemical agent’s penetration of the tissue (see publication: Prof, Schrage, Klin Monastbl Augenheilkd, 2004.
  • In order to obtain optimal results it is necessary to intervene ‘immediately’ according the European Standard EN15154 (10 seconds according to ANSI Standard) after the splash. However, there is sometimes only partial effectiveness, in particular on concentrated, corrosive chemicals.
  •  Significant side effects such as secondary care and surgical intervention, often resulting in permanent disability or disfigurement and even fatalities, are regularly reported in the scientific literature.
  • Recent comparative studies have shown the possibility of improving on rinsing with water.

Increasing the Chances of Reducing Injury

Improving on rinsing with water consists of finding other solutions without these limitations in order to increase the chances of the casualty being saved and experiencing minimum injury.

In order to accomplish this, Diphoterine® Solution, an aqueous solution that contains an amphoteric and chelating molecule was introduced.   The aim of the resulting solution is to prevent chemical burns or to  significantly lessen their seriousness.

Washing with Diphoterine® Solution 

Diphoterine ® Solution has been classified as a Medical Device according the 93/42 CEE Directive.   It claims to act on the chemical agent in order to stop, or minimise, the development of chemical burns. It is classified IIa because it can be used on injured skin. (see publication: Dr Cavallini – Cavallini, Annals of Burns and Fire disasters 2004, vol XVII-2, 84-87 and Cavallini, European Journal of Anasesthesiology 2004, 21, 389-392)

The Benefits of Washing with Diphoterine® Solution: 

  • It stops the Corrosive and Irritant agent’s actions on the eye and skin, thanks to its amphoteric and chelating properties.
  • It stops the chemical agent’s penetration of the tissue and carries the chemical away from the interior to the exterior of the tissue, thanks to its hypertonicity.
  • It achieves a rapid return to a pH level between 5.5 and 9, reducing the risk of a chemical injury.
  • It has a prolonged intervention time compared to water (in the first minute following the chemical splash) with improved washing effectiveness: the absence of after-effects, little or no need for secondary care and little or no loss of work.

Secondary treatment and caring for a chemical Injury (lesion):

Once decontamination as part of first aid is completed and has been effective, the chemical lesion no longer progresses, it is then possible to treat any damaged tissue in order to facilitate cicatrisation.

If the chemical product is toxic, this hazard can now be dealt with.

Chemical lesions may require secondary treatment and management by a physician.

  • The secondary treatment must be appropriate:
  • It must be specific to the chemical product involved.
  • It must be scaled depending on the lesion that has developed.

Chemical lesions are conventionally managed in hospital burn treatment centres.  The treatment is often similar to that required in case of thermal burns, with a few differences:

  • Cicatrisation takes longer.
  • Skin grafts take less easily on chemical burns than on thermal burns.

For more detailed information please see section;  Diphoterine® Solution Information