Centuries ago, Indian princes would bathe in the cool Kazhipally lake in Medak. Now, even the poorest villagers here in India's baking south point to the barren banks and frothy water and say they avoid going anywhere near it. A short drive from the bustling tech hub of Hyderabad, Medak is the heart of India's antibiotics manufacturing business: A district of about 2.5 million that has become one of the world's largest suppliers of cheap drugs to most markets, including the US. But community activists, researchers and some drug company employees say the presence of more than 300 ...