The state of California has adopted regulations to curb greenhouse-gas emissions from transportation fuels, codifying evidence that biofuels are significantly dirtier than they were once thought to be.
Links:
[1] http://admin.indiaenvironmentportal.org.in/feature-article/california-clean-fuel-drive
[2] http://admin.indiaenvironmentportal.org.in/category/author/jeff-tollefson
[3] http://admin.indiaenvironmentportal.org.in/category/journal/nature
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/vehicular-pollution
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/land-use
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/food-crops
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/food-prices
[8] http://admin.indiaenvironmentportal.org.in/category/thesaurus/ethanol
[9] http://admin.indiaenvironmentportal.org.in/category/thesaurus/fuel-standards
[10] http://admin.indiaenvironmentportal.org.in/category/thesaurus/climate-change
[11] http://admin.indiaenvironmentportal.org.in/category/thesaurus/green-house-gases
[12] http://admin.indiaenvironmentportal.org.in/category/thesaurus/biofuel
[13] http://admin.indiaenvironmentportal.org.in/category/thesaurus/california