 Environmental activist Vandana Shiva has written extensively about the social, political and economic impacts of the Green Revolution in Punjab.According to Shiva, the Green Revolution's reliance on heavy use of chemical inputs and monocultures has resulted in water scarcity, vulnerability to pests, and incidents of violent conflict and social marginalization.A Greenpeace Research Laboratories investigation of 50 villages in Muktsar, Bathinda and Ludhiana districts revealed that twenty percent of the sampled wells had nitrate levels above WHO limits for drinking water.