THE Korogocho slum is one of the poorest in Nairobi, Kenya's teeming capital. Its 120,000 residents occupy a stinking square kilometre by the city rubbish dump. Nearly three-quarters are under 30 years old. Many are alcoholics.

The equivalent of $1 is enough to buy four glasses of illegally brewed chang'aa—and oblivion. Some drink the local special, jet-five, so called because the fermentation of maize and sorghum is sped up with pilfered jet fuel. It can damage the brain. Elsewhere in Nairobi, chang'aa is spiked with embalming fluid from mortuaries.

The name, meaning literally “kill me quick”, is well chosen. This and other methanol-based kickers are sometimes fatal: 10ml of methanol can burn the optic nerve; 30ml can kill. Even without the kicker the brew is impure. The water is filthy with fecal matter. When police recently made some raids, decomposing rats and women's underwear were found in servings of chang'aa. But the price and the potency are more tempting than the heavily taxed bottles of beer that are the staple of richer Kenyans.

Kenya is not alone. The UN's World Health Organisation reckons that half of all alcohol drunk in Africa is illegal. Neighbouring Uganda may consume more alcohol per person than any country in the world. Much of this is waragi, a banana gin. Some 100 Ugandans died from toxic waragi in April alone. Botswana, arguably sub-Saharan Africa's most successful country, serves up laela mmago, meaning “goodbye mum”.

East African Breweries is one of Kenya's biggest companies and taxpayers. It wants to see illicit chang'aa replaced with a safer commercial version. Yet bringing the price of alcohol down to that of water risks increasing alcoholism and forcing the very poorest into even dodgier booze dens. In any case, it could add other costs: crime, violence to women and children, unsafe sex and bad health. Catholic priests in Korogocho host an Alcoholics Anonymous meeting, but in Kenya, as elsewhere in Africa, state help for recovering alcoholics is rare.

What is clear is that urbanisation is changing the way alcohol is drunk. Illicit brews smooth dealmaking and reconciliation in the countryside. But in the sprawling city slums, where most of Nairobi's people live, they are more often a cheap way of blotting out a sense of abandonment.