Earlier this year an advertisement for skin-whitening pills with the slogan "white makes you win" went viral. Thai model Cris Horwang was seen with gradually darkening skin, as she says: "If I stop taking care of myself, everything I have worked for, the whiteness I have invested in, may be lost." The 50-second ad was soon removed but the message lingered loud and clear: lighter skin equals success.

Though skin-bleaching products are illegal in several countries around the world,the prevalence of skin-lightener usage is on the increase globally. Governments in Kenya, Nigeria, South Africa, Zimbabwe and most recently, Ivory Coast, have banned the import and sale of skin lightening products, particularly those containing mercury and hydroquinone (HQ). Unfortunately, the same rigour and policies are not evident in Asian countries such as India, Japan and China. The industry is thought to be worth more than $1bn worldwide.

Ophelia Dadzie, a consultant dermatologist at The Hillingdon Hospitals NHS Foundation Trust and Founder and Director of London Ethnic Skin Limited, warns in the British Medical Journal this week that skin bleaching with the use of glutathione is on the rise in the UK.

The phenomenon of skin bleaching is not new. Skin-lightening agents have been used for centuries, but their increased use for cosmetic reasons in the last decade has raised new concerns about detrimental effects. Though physicians can treat pigmentary disorders with skin-lightening products, this should be distinguished from cosmetic lightening.

There are many brands familiar to a western audience that offer 'whitening' ranges, such as Lancome and L'Oreal, and Nivea offer a deodorant that will whiten your armpits. There are even creams available that can lighten your vagina. Big brands tend to be secretive about formulations, but even if they include low levels of lightening agents, or none at all, the marketing message is still overt.

American rapper Azealia Banks recently compared skin bleaching to having a nose job or wearing a weave. So what's the difference? Firstly, there's the physical risk. Skin-bleaching creams can cause skin sensitivity and patchiness. Moreover, chronic application over time changes the underlying structures in the skin as the "toxic" compounds accumulate. Without intervention, this could lead to a clinical condition know as ochronosis, which leaves skin irreversibly damaged – only repaired with skin grafts. Intravenous glutathione for skin whitening can cause headaches, conditions such as Stevens-Johnson syndrome or long-term health risks like the potential transmission of infections.

Then, there's the cultural significance.

In the US skin lightening became popular among people of African descent because during the era of chattel slavery (1620-1865), people with lighter skin (and European ancestry) enjoyed social advantages. Legally enforced segregation of "Negroes" and "Whites" heightened awareness of skin tone, and led to increased stigmatisation of the dark-skinned. This in turn added impetus to people of African ancestry to "pass" as white.

The highest reported prevalence of skin lighteners is in Africa, but their use continues to increase in East and South Asia, the Middle East and the Caribbean. With more than two thirds of the world's darker-skinned population, it is little wonder that Africa reports the highest prevalence of skin-lightener use in the world.

A skin lightener prevalence in women of 25-67% on the African continent reflects the obsession that predominantly women over men have with changing the colour of their skins. According to reports, 75% of the population in Nigeria, 52–67% of the Senegalese population, 59% Togo, 25% Mali and 35% of South African women use skin-lightening products.

With rising incomes, consumer-based advertising, TV and movies featuring glamorous models with fairer complexions, Asians are purchasing these products in ever greater quantities.

Modern cultural meanings vary but the basic beliefs hold: in Japan, a light complexion is associated with purity, wealth and a good education. In China, a light-skinned woman will be "happier" or, for a man, finding a woman with a light skin is the secret to happiness. In Thailand, people with lighter skins are deemed to have higher social status and wealth.

A regional survey in 2004 found that skin-whitening products were used by at least 58% percent of Thai women; 50% Filipino women; 45% of Hong Kong women; and 41% of Malaysian women. On average, these women spent approximately 10% of their monthly income on skin lightening products.

Approximately 61% ($250m out of $410m) of the Indian skin care and cosmetic market is dedicated to skin lightening. Traditionally a female-associated practice, it is becoming increasingly popular among males in India and this practice is fast spreading to other parts of the world.

Although good prevalence data on skin-lightener use are missing for the Caribbean region, the practice of skin lightening/bleaching – and especially the use of illegal formulations in Jamaica – appears to be widespread. The ultimate reasons for this practice, it would seem, are rooted in colonial histories of slavery and oppression, but the proximate reasons are low self-esteem and hopes for social and economic advancement through lighter skin.

In Europe, darkly pigmented women, mainly of African, Afro-Caribbean, or South Asian descent, tend to use skin lighteners in an overall topical application to produce a more global lightening effect. Although hydroquinone has now been banned throughout Europe, numerous products remain easily obtainable through illicit means.

A diverse range of compounds are currently used in skin-lightening preparations globally, but a large majority continue to include hydroquinone (HQ) and its derivatives (monobenzyl ether and monomethyl ether), mercury-containing compounds, potent corticosteroids and retinoids. Hydroquinone (HQ) is an effective skin lightener through preventing the production of the skin pigment, melanin, by blocking the activity of tyrosinase – the enzyme needed to produce the pigment melanin in human skin cells called melanocytes.

Although banned by the European Union (EU) and Japan in 2001, HQ continues to be available in the US in dermatologically-based preparations and its use for treating pigmentary conditions such as pregnancy-induced skin darkening. Products containing 1.5-2.0% hydroquinone are legally available over-the-counter in the US, and more concentrated preparations are available by prescription.

Mercury and its derivatives are predominantly used in photographic solutions. Despite being banned by the FDA in 1973 and by the EU in 1976 from being used in cosmetic formulations due to their toxicity, these mercurials continue to be produced and exported to countries in Africa and the Caribbean. Most often used in combination with HQ and/or mercury, high levels of corticosteroids and retinoids are included due to their function of enhancing skin penetration. Unfortunately, these compounds lead to severe consequences such as skin thinning and fragility.

Overall, the desire for lighter skin as a form of social capital has driven demand for continued use of skin-lightening preparations in many countries, with increasing availability and advertising of commercial products appearing to be driving the demand for illegal formulations among the impoverished.

Examples of subliminal advertising include massive poster boards littered throughout Africa (Senegal, Ivory Coast and Nigeria) with images of sad dark-skinned women who magically transform after skin-lightener application to smiling, lighter skinned individuals. In 2010, Vaseline promoted a Facebook page reflecting a split-face image of an Indian male reflecting with a profound difference in skin colour after the use of their products. Today, with the increased advent of advertisements on all the social media platforms, the exposure of the pandemic which is skin lightening, is inevitably going to increase substantially.

Interestingly, the extremely low level of skin lightener usage in Brazil for example, a country sometimes described as a "multi-coloured democracy," supports the hypothesis that one of the primary personal motivations for skin lightener use is because lightness is viewed as a passport to upward social mobility.

So, what can be done to stop this? Earlier this year a BBC undercover investigation revealed illegal skin-whitening creams are being sold by UK high street cosmetics shops despite a number of prosecutions. UK based magazine gal-dem, written by women of colour, sent writer Charlie Brinkhurst-Cuff to visit shops in south London, where she found a plethora of illegal products available. "Wherever women of colour frequent for their beauty buys, skin-lightening products seem to follow", she wrote. "What we tried to highlight throughout the skin lightening series was that skin lightening is more than an equivalent to 'fake tan'... In many cases educating people about skin lightening and its dangers seems to have worked... Speak loud enough and things can change. Lancôme appear to have removed their Blanc Expert products from their UK website."

As part of the series, Naomi Mabita also wrote how leading European beauty companies offer skin-lightening products that they only promote in black and Asian markets: "They're marketing 'pearl perfect whiteness' to all except white women, and everyone consuming the brand is complicit." She believes we should boycott brands to get these products removed from the shelves. "The more positive images of dark-skinned women we put out there for the world to see, the less room there will be in our lives for manufactured shame," she writes.

Dr Dadzie suggests two ways of beginning to tackle the problem of skin lightening in the UK. As well as addressing our underlying attitudes to beauty, so that all skin colours are embraced within our collective definition of beauty, we should also consider skin bleaching as a public health issue.

The use of illegal ingredients in skin-lightening products continues to prevail globally. A strong argument exists over the safety of creams containing any hydroquinone to justify a temporary ban (in all countries) on over-the-counter use pending long term trials of their safety. Many countries in Africa have banned the products, while others have promoted public health education to dissuade people from using bleaching creams. Ultimately, the onus should be on manufacturers rather than consumers to establish safety.

There needs to be a collective urgency to continue research into the motivations for skin lightening. Given the inability of government bans to effectively prevent skin lightening, current studies should investigate other strategies aimed at improving industry compliance such as random testing and penalties.

Lester Davids is an Associate Professor of Medical Cell Biology in University of Cape Town's Department of Human Biology. He runs a scientific research lab specialising in skin cancer and wound healing. His other lab focus is the study of the global biological and psychosocial effect of skin lightener use with special interest in Africa.

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