The 'Gap kids' you won't see in the adverts

Eight-year-old Motselisi is a different kind of "Gap kid". She is one of the children that scavenges for offcuts from garment factories that dominate the mountain Kingdom of Lesotho. The Thetsane rubbish dump where she was photographed belongs to the dark side of the denim trade.

A portrait of her dressed in rags in front of burning piles of scraps from a factory that supplies Levi Strauss and Gap was among an award-winning series taken by the photographer Robin Hammond. The nearby factory was accused of illegally dumping chemical waste, including caustic soda, at municipal sites. Witnesses described rivers that ran an unnatural blue as clothing dyes and other effluents were allowed to run into waterways that local people rely on for washing and cooking.

It was also alleged that the Taiwanese firm running the factory that supplies the US retail giants was dumping needles, razors and harmful chemicals at two landfills where children like Motselisi scavenge for anything they can sell.

The remote highlands of Lesotho are an island of intense poverty surrounded by the comparatively affluent South Africa. The former British protectorate is crippled by some of the world's highest HIV-Aids infection rates and is now contemplating ending its bid to become part of South Africa to help it develop.

The "Toxic Jeans" series highlighted the unintended consequences of efforts to stimulate trade with Africa. The firm in the spotlight, Nien Hsing, is the largest denim fabric and jeans producer in Africa and employs 9,000 workers in Lesotho. The $120m facility at the heart of the scandal was hailed in Washington as the biggest success in the decade since the African Growth and Opportunity Act was signed to create incentives for business to invest in some of the continent's poorest countries.

The act saw clothing imports from Africa nearly triple and created an estimated 300,000 jobs, supporting about 3 million people in 12 countries. It helped make the denim mills and garment factories Lesotho's largest employer.

After the original publication of these images last year Gap and Levi Strauss ordered investigations into their suppliers' practices and promised a clean-up. Gap said it had put the factory on notice to improve, while Levi Strauss said it was "disturbed" by the findings.

Toxic Jeans by Robin Hammond is at the Human Rights Action Centre, New Inn Yard, London EC2 3EA, 16-30 November