Hazardous Chemicals That Damage The Eyes And How To Know Them

As it will be explained in our next post; causes of chemical eye injuries, there are six main groups of chemicals that damage the eyes and they include: organic solvents, surfactants, irritants and allergens, aerosols, acids and alkali.

Organic solvents

Numerous substances of this type are used in various industries but they rarely cause permanent damage. Exposure to their vapour causes irritation and a more intense reaction occurs if they are splashed into the eye as a liquid. They cause superficial punctate keratitis of the cornea and conjunctiva. Some of the compounds are caustic and may enter the stroma, denature the protein and produce scarring. The subjective syptoms are pain, photophobia, lacrimation and stinging. Such complaints are reported by those working with lacquers when solvents such as alcohol, acetone, comphor, ether, toluene, benzol and acetates are used. 

Examples of organic solvents and their uses in industries include the following;

1. Hydrocarbons (aliphatic and aromatic): used in dyeing, leather, rubber, linoleum, paints, varnish and lacquer industries; motor fuels.
2. Halogenated hydrocarbons: solvents for fats, waxes, gums, resins, oils. Used in rubber and in paints, lacquers and varnishes; insecticides; antiseptics.
3. Alcohols: solvents used in lacquers and polishes.
4. Ketones: solvent in plastics, rubber, dyes and paint industries.
5. Aldehyde: solvent for oils, resins, cellulose and are used in plastics and rubber industries.
6. Ether: solvent in plastics manufacture.
7. Ester: solvent in many industries; it is the least toxic organic solvent.

It is also important to note that, when absorbed, these solvents have toxic effects that suppress the central nervous system.

Surfactants

These compounds have a fat-soluble group at one end of the molecule and water-soluble group at the other end. This structure allows the compound to lower the surface tension of water and to make fat-soluble materials miscible. They are used as industrial detergents and as emulsifying agents and cause contact dermatitis and mucosal irritation. Surfactants are divided into three main groups: cationic, anionic and non-ionic.

Recommended: Acid and Alkali Chemical Eye Injury

The cationic group of surfactants causes damage to the cornea and conjunctiva by precipitating the protein and if severe enough, will lead to opacification of the corneal stroma, with subsequent vascularization; quaternary ammonium compounds, such as benzylkonium chloride, belong to this group. Anionic surfactants, such as soap, cause slow saponification of intracellular lipoid substances and lysis of the cells. Healing occurs quite quickly, leaving no permanent damage. The non-ionic surfactants are usually esters of fatty acids with polyoxyethylene or sorbitol. These do not cause any permanent damage as any corneal erosion produced heal with no scarring

Irritants and allergens

Numerous substances may irritate the eyes without causing permanent damage. A true allergy requires sensitization of cells by prior exposure to an allergen. Subsequent exposure to the allergen will then result in a typical allergic reaction. Common allergens are organic substances of animal or vegetable origin, e.g. wool, pool and dairy products. They produce the characteristic redness and swelling of tissues of the lids and conjunctiva.

As new processes are introduced into industry, the numbers of substances causing dermatitis and conjunctivitis increase and many have not yet been isolated. Unfortunately the appearance of the skin and conjunctiva often give no clue to the actual agent involved.

It is possible to desensitize people who are liable to attacks. In certain industries, allergic skin reactions are well known and are recognized as industrial diseases. Special trades may have easily identifiable irritants but there is no explanation as yet for the fact that large numbers of people work for years with common irritants, such as soap, without any ill effects.

Industries with a high percentage of workers reporting dermatitis include baking, chemical manufacturing, engineering, metal working, painting, preserving and textile manufacturing. Adequate ventilation and protective goggles should be provided where necessary to prevent dust and fumes contacting the eyes, as these may cause serious secondary effects, such as purulent conjunctivitis and corneal erosions.

Aerosols

Aerosols are commonly used in households as well as industry. Their fine spray can cause a superficial corneal inflammation, known as superficial punctate keratitis. After staining with fluorescein these show up quite clearly as small punctate dots when seen under ultraviolet (UV) light; these are temporary.

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