Luscious metallic lip colour, age renewal creams that can reverse time, shampoos that enliven every strand - we're undoubtedly in an age of supercosmetics. This beauty revolution has been fuelled by a science called nanotechnology - however, not many know that the silky hair and satin skin could be accompanied by something that's far less desirable.

There are already concerns about the toxicity of chemical-based cosmetics;nanotechnology, in some cases, can intensify the toxicity to dangerous levels. And use of the latter in cosmetics without proper safety tests can have repercussions as serious as DNA damage.

Recent studies carried out by the Council of Scientific and Industrial Research (CSIR) reveal that certain nanoparticles used in some cosmetic products can be potentially dangerous. These nanoparticles are so tiny that they easily permeate the skin and enter the body - thus, in a chemical-based cosmetic, the chances of the incredibly teeny-weeny chemical particles entering human organs is very high.

A recent study by the Nanomaterial Toxicology Group (NTG) at the Indian Institute of Toxicology Research, CSIR, published in the journal Apoptosis, shows that exposing human liver cells to zinc oxide nanoparticles can damage the DNA. Zinc oxide is used in a variety of cosmetics and personal care products such as make-up, nail polish, lotions, soaps and sunscreens.

"Our study shows that zinc oxide nanoparticles can cause DNA damage and apoptosis or cell death in human liver cells. The exposure of human cells to titanium dioxide nanoparticles has shown similar results. These nanoparticles have been found to be carcinogenic (having the potential to cause cancer) in both in vitro (outside the organism, eg in a test tube) and in vivo (processes taking place in a living organism) studies. Most international and domestic cosmetic brands make use of nanotechnology, but there is barely any proper toxicological evaluation, " says Alok Dhawan, member of the NTG and director of the Institute of Life Sciences, Ahmedabad University.

Nanotechnology is a favourite with cosmetic brands because of its immediate results on skin. For instance, zinc oxide in sunscreens may form a white layer, but if it is in the form of nanoparticles, it permeates the skin and dissolves in it, giving a more natural appearance. The same is true for anti-aging and whitening creams, which widely use nanoparticles. Some of the common types of nanomaterials employed in cosmetics include nanosomes, liposomes, fullerenes, solid lipid nanoparticles and others.

"Nanoparticles penetrate the skin very easily. It stands to reason that the cosmetic products making use of these will have a stronger effect and may improve the skin instantly. It's very difficult to say what kind of toxic effects they may have later, " says Ravi Agarwal, founder-director of Toxics Link, an environmental NGO.

At present, there is no regulation in India requiring labels on cosmetic products that affirm the use of nanomaterials, which are merely mentioned as 'penetration enhancers' by many big brands. Some of the latter do mention nanoparticles in their advertisements but as a plus point, one which makes their products more effective.

"Since cosmetics are not regulated properly, many of them make use of heavy metals which are endocrine disruptors. Some whitening creams use mercury because it can block melanin production, which is responsible for pigmentation in hair and skin, " adds Agarwal.

Not just cosmetics, the Nanomaterial Toxicology Group has also found that nanomaterials being released into water or air can be so potent that they can enter inside bacteria and alter their life cycle. "It is quite dangerous as we do not have a system to evaluate the effects of nanoparticles on our ecology. And, nanoparticles can find their way into the environment. For example, a shampoo containing nanoparticles can end up in water bodies after it is washed off. A proper study is therefore needed, " says Dhawan.

In November 2008, Which, a European consumer organisation which generates information on consumer products, did a review of cosmetics that use nanotechnology. Most of the companies they surveyed, including some leading brands also sold in India, acknowledged that they were using nanoparticles. A majority of the brands confirmed that they used titanium dioxide and zinc oxide at nanolevels in their sunscreen. Their main reason behind using nanomaterials for these compounds was that "they are both transparent and absorb UV radiation much more efficiently".

According to Friends of Earth, a federation of environmental organisations, none of the governments currently have made any regulations governing the use of nanotechnology. But the European Union has at least begun to take action to understand the risks posed by nanomaterials in cosmetics and personal care products - the EU's Scientific Committee on Consumer Products advised in 2008 that a review of the safety of nanotechnology was necessary and current approaches were inadequate.
Beauty may be only skin-deep, but toxic chemicals are surely permeating deeper with nano cosmetics.