Among all the siren songs of the beauty industry - less cellulite, fewer wrinkles, plumper lips - one of the most treacherous, and least-discussed, is the promise of paler skin. There are good reasons for this, as many skin-whiteners are illegal, and are mostly bought by people who are not white and who, for a whole poisonous stew of cultural reasons, are embarrassed to admit to using them.

The subject is in the news again because a south London couple, Yinka and Michael Oluyemi, have just been fined nearly £100,000 and given suspended nine-month prison sentences for selling £1m-worth of skin-whiteners.

Unlike legal products, which can cost £30-90, illegal creams contain powerful steroids, hydroquinone, and often mercury; they can cause kidney damage, permanent scarring, and skin cancer. (Interestingly, it is not illegal to make them in Britain and ship them abroad to less fussy climes; they are then smuggled back in; both routes are lucrative.)

Cue much chin-stroking about self-hatred in black women, but in Britain at least, it is not that simple, says Sherry Dixon, editor-at-large for Pride magazine. Whiteners were "first prescribed to even out the skin tone" of black and Asian people suffering from hyperpigmented facial scarring. "And then some people realised that it worked to lighten the skin, and a minute amount of people have chosen to use it that way. For years black people have stereotyped each other, and the lighter-skinned person, they feel, is a prettier or more acceptable person and gets better jobs."

In the Caribbean and parts of Africa and South America, light-skinned women are particularly prized by men, so it is a case of competition. In India it is a caste issue. "They feel that the darker people are the people who work in the sun - which is similar to slavery," says Dixon. Skin-shade and genocide are unfortunately linked: Tutsis tend to have more European features than Hutus. The important thing to remember is that people "don't want to be white: they want to be lighter".

In Britain all it would take, Dixon believes, is education. "Some of those women don't know they're going to get kidney failure or cancer of the skin. If they were targeted the same way as white people are about sunbathing and sunbeds, they would stop using it."