Eczema sufferers - with their telltale angry-looking, scaly skin - are a familiar sight these days although, just a few decades ago, they would have been a small minority. Now, in most countries, about one in five children and one in 12 adults are living with some degree of this condition.
What has pushed eczema up the ranks to become one of the most common skin disorders of modern life? One short answer is the increasingly toxic environment in which we now live. We unwittingly expose ourselves to hundreds of chemical irritants and allergens - day in, day out. The sources of these toxins are often innocuous and ubiquitous to our current lifestyle - that bottle of washing-up liquid in the kitchen, that tube of toothpaste in your bathroom, that box of laundry detergent.
For atopic eczema sufferers who have an inherited allergic susceptibility, exposure to these chemicals aggravates their symptoms and perpetuates painful flare-ups. For those who weren’t born with particular allergic tendencies, constant contact with toxic substances enables substantial amounts of chemicals to enter your system (the skin can absorb up to 60 per cent of whatever substances with which it comes into contact). These chemicals build up to the point where they push the immune system into toxic overload, triggering an eczema reaction. This type of eczema is called ‘allergic contact eczema’.
Causal substances (or allergens) are not necessarily harsh or irritating, and don’t provoke a reaction in everyone - only in those who have become sensitised to them.
The type of eczema that’s not linked to an allergic reaction is known as ‘irritant contact eczema’. Causal substances (or irritants) are often abrasive, and can cause inflammation in almost everyone if there is long- or strong-enough or frequent-enough contact.
Many eczema triggers have both allergenic and irritant properties. To find these toxic triggers, you need look no further than your own home. So, let’s take a quick tour around your house and finger the usual chemical suspects.
Our first stop is the kitchen. Look under the sink and you’ll find a veritable Pandora’s box of chemicals among the cornucopia of household-cleaning products. Our obsession with removing dirt and making our homes germ-free regularly exposes us to a laundry list of skin irritants. One of these is sodium lauryl sulphate (SLS), frequently found in washing-up powders/liquids. It’s a powerful foaming agent known for its effective degreasing ability - which is why it’s also used in car washes and in garages to degrease car engines.
SLS concentrations as low as 0.5 per cent are already capable of causing irritation; higher concentrations of 10-30 per cent can cause skin corrosion, severe irritation and are even deemed dangerous (J Am Coll Toxicol, 1983; 2: 183-235). The powerful cleansing effect of this chemical dissolves and dries out the natural protective oils of your skin. It can also alter the quality of skin proteins (denaturation), which not only leads to skin irritation, but also makes the protective epidermal layer more permeable, thereby allowing easier access to other toxins to penetrate into the lower, more sensitive layers of the skin as well as to attack the immune system (Acta Dermatol Venereol, 1957; 37: 269-75).
Other common household-cleaner ingredients that are particularly corrosive to the skin and may trigger allergic reactions include:
* bacteria-killing disinfectants such as ammonia, chlorine and pine oil
* grease-cutting petrochemicals such as mineral spirits and phenol (or carbolic acid)
* stain-removing alkalis such as sodium or potassium hydroxide.