Children picking through rubbish, their pets meandering in sewage - the perfect breeding ground for countless diseases but a common site in the sprawling poverty belts that surround São Paulo, South America's largest city. According to a study last year by the ministry of health, 50 people die every day in Brazil as a result of inadequate basic sanitation. Many of them are children.

Many of these problems are linked to poverty and more importantly to a lack of basic waste management and water treatment infrastructure. Yet others are due simply to a lack of basic sanitary practices, particularly among young children.

With the local and federal governments directing much of their spending towards primary school education, public child care centres are often under-funded with inadequate installations and poorly motivated staff.

For the past five years, Schering-Plough, the pharmaceuticals company, and hundreds of volunteer employees have worked to bring basic health concepts to children in kindergartens in the poorest neighbourhoods in southern São Paulo city in a project called Criança é Vida (Children are Life).

At Arrastão nursery in Campo Limpo, one of the city's most impoverished and violent neighbourhoods, toddlers are laughing and splashing around a bowl of water, with a toothbrush in one hand and a set of Dracula teeth in another. Volunteers from Schering-Plough are teaching them to brush their teeth.

Some children routinely have to a share a toothbrush with the entire family, increasing the risk of spreading diseases. Other routines that involve song and games deal with a host of basic hygiene issues from washing hands to disinfecting fruits and vegetables.

The incidence of diarrhoea and skin diseases, such as scabies, has fallen considerably. "The children weigh more and are not sick as much as they used to be - they are generally much healthier," says Jurema Freitas, the kindergarten's nurse.

"You cannot put a price on that project," says Selma Dau Bertagnoli, operations manager at the kindergarten. She says the eagerness and goodwill of the volunteers spark the interest of the children and parents alike. "Their workshops regularly have higher attendance among parents than our own," says Ms Bertagnoli.

Two years into the project, volunteers began educating parents and kindergarten instructors as well, on issues ranging from sterilising drinking water to banning animals from their sleeping quarters. More than two-thirds of the parents did not know how to read a thermometer, recalls Regina Stella, who has been co-ordinating the project from the start.

Schering-Plough financed and developed educational material specifically designed to meet the socio-economic environment of the children and parents they were targeting. Ministry of health guidelines which recommend nursing a baby until the age of two, for instance, are unrealistic in Campo Limpo, where 70 per cent of mothers are single and return to work within two to three months of giving birth. "You have to listen to the community or else you are wasting your time," says Ms Stella.

In response to requests, Criança é Vida in 1998 began training volunteers of other institutions, including two city hospitals, and providing them with their educational material. Through these partnerships, the project now reaches 39,000 children in 17,300 impoverished families.

The programme has won several awards, including one from the American Chamber of Commerce, which for nearly two decades has been evaluating and prizing companies’ socially and environmentally responsible projects in Brazil according to well-established criteria.

In part, Criança é Vida has earned its laurels because of its simplicity and its measurable results. Gian Enrico Mantegazza, head of Schering-Plough in Brazil and the intellectual author of the project, insists: "It is not that hard to do. You need determination and commitment but not a lot of money. It is very cost-efficient."

Though Mr Mantegazza believes consumers in Brazil will eventually also prefer socially responsible companies, he maintains "this is not an investment to generate business". In fact, Schering-Plough will continue to finance Criança é Vida, even though it is becoming an independent institute open to other corporate sponsors.

Whatever the motivation for a company to be socially responsible, the bigger the return it gets, the more sustainable it is, argues Valdemar de Oliveira Neto of Ethos, a non-government organisation dedicated to promoting social responsibility. "I don't care if they act out of self-interest or philanthropy, given Brazil's dramatic situation, what counts is the result."