In September, the California Environmental Protection Agency’s Office of Environmental Health Hazard Assessment (OEHHA) released a notice of intent to list the herbicide glyphosate and the insecticides tetrachlorvinphos, parathion, and malathion as known to the state to cause cancer under the Safe Drinking Water and Toxic Enforcement Act of 1986, or Proposition 65. OEHHA’s determination is based on conclusions of the International Agency for Research on Cancer (IARC), which recently classified glyphosate and malathion as “probably carcinogenic to humans” and tetrachlorvinphos and parathion as “possibly carcinogenic to humans.” Under California law, certain substances classified by IARC are required to be listed as known to cause cancer under Proposition 65. Glyphosate has agricultural and non-agricultural uses throughout the world. Tetrachlorvinphos, parathion, and malathion are organophosphate insecticides. IARC notes that tetrachlorvinphos is banned in the European Union, and all authorized uses of parathion were cancelled in the EU and U.S. by 2003. According to the agency, malathion continues to be produced in “substantial volumes” throughout the world, and is used in agriculture, public health, and residential insect control. OEHHA’s notice of intent is available on the agency's website. OEHHA also provides a “plain language” explanation of Proposition 65.