Talks began yesterday in Geneva on a global treaty to control or ban 12 toxic chemicals known as “the dirty dozen,” including DDT, dioxin, and PCBs. Enviros are pressing negotiators to move quickly to ban the persistent organic pollutants (POPs), which break down extremely slowly, are absorbed into the food chain, and have been linked to cancer, birth defects, and other grave health problems. This week’s talks are the third in a planned series of five, and Klaus Toepfer, head of the U.N. Environment Program said he is confident that negotiators will produce a legally binding agreement on POPs by the end of next year. A key issue is financial and technological aid that developing countries need to help them phase out the toxic chemicals. Controversy is expected over DDT, which the World Health Organization says is still needed to control malaria-carrying mosquitoes.