In what can be called potential health threat, scientists from Jawaharlal Nehru University (JNU), have found Polychlorinated Benzene (PCB), a well known cancer causing agent, in the Yamuna, which is the main source of drinking water in Delhi. The threat is maximum near the Nazafgarh area of West Delhi where PCB concentration rises as high as 782 parts per billion (PPB) during monsoon, A. K. Bhattacharyya, a professor at the School of Environmental Science in JNU.