Read the Label: Penetration Enhancers
Modern bodycare products are designed to go deep into the skin. Every day we absorb any number of harmful chemicals in the name of beauty. Pat Thomas reports
Your skin absorbs up to 60 per cent of the chemicals that come into contact with it and sends them directly into the bloodstream. Research suggests it can take as little as 26 seconds for some of these substances to go from the skin to every major organ of the body.
How quickly a bodycare product penetrates the skin and how deeply it is absorbed depends on a number of factors – made yet more complicated by the fact that certain chemicals can speed up the penetration and absorption of others. These chemicals, known as penetration enhancers, are found in all kinds of bodycare products, but are particularly prevalent in body lotions and face creams. The concern is not so much that they are toxic – many of them are safe used on their own – but that they alter the superficial structure of the skin, thus allowing greater absorption of other harmful chemicals in the product.
How do they work?
Penetration enhancers fall into three main categories: emollients, detergents and solvents. Emollient (i.e. moisturising) ingredients can include any oil or fatty acid. They may also include microscopic liposomes and nanosomes, which are nanoscale emollients designed to drive ingredients deeper into the skin. As they are absorbed into the skin, they can carry fat-soluble toxins with them. Solvents – such as polyethylene glycol (PEG) compounds and perfumes – and detergents (used in shampoos and shower gels) alter the structure of the skin by dissolving its protective oily barrier.
allows other chemicals in the product to penetrate deeper. Because the skin is laced with tiny blood vessels, these chemicals eventually find their way into your bloodstream and your internal organs. Penetration enhancers also usually have more than one function. Major active ingredients such as emollients, detergents and solvents are often added to products because their penetrationenhancing effects can offer visible but temporary ‘quick fix’ results.
What are the dangers?
It’s difficult to say for sure. A child’s skin absorbs more than an adult’s. How much you absorb from a particular product will also depend on the condition of your skin, which can be influenced by the number and types of products you use every day. For instance, a body wash based on harsh detergents may strip the skin of protective oils. If you then apply a moisturiser containing penetration enhancers to your denuded skin, the ingredients will penetrate much deeper than if you had bathed with a gentler organic soap and used a simpler natural moisturiser. Because of their ability to get past the protective oily layer of the skin, penetration enhancers are also significant sources of skin irritation. Using several products laced with these types of ingredients is likely to lead to allergic reactions to active ingredients – such as fragrances, surfactants and preservatives – in people with susceptible skins.
Sidebar
The list of ingredients that can act as penetration enhancers is incredibly long but commonly includes:
- Detergents and surfactants such as sodium lauryl sulphate, sodium carboxylate, sodium hyaluronate and sodium ascorbate.
- Solvents such as acetone, ethanol, limonene, polyethylene glycol (PEG) compounds, propylene glycol (PPG) compounds, xylene, acetamide and trichloroethanol.
- Emollients such as butyl acetate, diethyl succinate, ethyl acetate and some isopropyl, methyl and sorbitan, capric acid, lactic acid, oleaic acid and palmitic acid, lipsomes and nanosomes.
Sidebar: Read the Letters
For the last few months The Ecologist’s Read the Label campaign has been encouraging readers to write to the manufacturers of their favourite bodycare products and ask why they continue to use potentially toxic ingredients, when safer and equally effective alternatives exist… and then send us the replies Ecologist reader Peter Brenton wrote to Green People with his concerns about the company’s use of nano-sized titanium dioxide in their suncream.
Green People’s Information and Technology Officer, Ian Taylor, responded: “We do use micronised or nano-sized titanium dioxide because it is the only form that offers effective protection against UVA rays… The reason that the titanium dioxide particles have to be so small has to do with the way they scatter invisible UV light. For titanium dioxide to be effective against UVA radiation, the particles must be between 20 and 80 nanometers in diameter… Instead of offering UV protection, lotions containing titanium dioxide particles of much greater than 100 nanometers form a visible white layer on the skin, rather like a layer of paint. “The concerns over titanium dioxide nanoparticles are two-fold – that they have an increased ability to react with other molecules, particularly oxygen; and that they may enter the body through the skin and thereby reach internal organs where they may cause damage due to their reactivity. “To counter these two potential problems, the manufacturers of titanium dioxide for use in cosmetics treat the mineral by coating each particle with a very fine layer of silicates – basically they coat it in glass. This … renders the mineral absolutely inert. Secondly, when the titanium dioxide is incorporated into a cream or lotion it clumps together, forming aggregations… too large to cross through the skin-blood barrier. Instead, they remain on the surface of the skin where they reflect and scatter UV light.”
Pat Thomas replies: There is no evidence that nano-sized titanium dioxide is the only form that offers effective UV protection. The problem is purely one of aesthetics, since at normal scale titanium dioxide leaves a white film on the skin. New evidence suggests that when nanoparticles of titanium dioxide come into contact with living tissue they may cause oxidative damage. Earlier this year, researchers at the US Environmental Protection Agency examined the effect of nanoparticles of titania (titanium oxide, similar to titanium dioxide) on cultures of mice brain cells and found that they triggered the release of chemicals that cause oxidative damage to brain cells. This is the same sort of damage that is thought to be the underlying cause of some neurodegenerative diseases such as Parkinson’s and Alzheimer’s. Previously research has suggested that nano-sized titanium dioxide is toxic to other types of cell, such as skin, bone and liver cells. No one knows whether nanoparticles applied on the skin, inhaled or ingested can find their way to the brain, or at what concentrations. But it is wrong to assume that a substance that is inert at normal scale is still inert at the nano scale since nano-sized particles behave in unpredictable ways. Indeed, at the nano scale a substance must be considered an entirely new chemical substance and must be studied and regulated accordingly. Where nanoparticles in cosmetics are concerned the precautionary principle should apply. Unfortunately, the commercial lure of nano-technology has meant that manufacturers and the government have been reluctant to put this principle into action.
This article first appeared in the October 2006 edition of the Ecologist.
