An international environmental institute has named the Riachuelo river in Argentina as one of the ten most polluted sites in the world. And it is the only one in Latin America. Critics blame Argentine politicians for breaking promises to clean up the Riachuelo. But those working to clean up the waters have reacted angrily, saying progress is being made and that the findings are based on out-of-date information. Al Jazeera's Daniel Schweimler reports from Buenos Aires.