California to List Glyphosate, Three Insecticides under Proposition 65

Published September 16, 2015

The California Environmental Protection Agency’s Office of Environmental Health Hazard Assessment (OEHHA) released a notice of intent to list glyphosate, an herbicide, and three insecticides as known to the state to cause cancer under the Safe Drinking Water and Toxic Enforcement Act of 1986, or Proposition 65. Tetrachlorvinphos, parathion, and malathion are the insecticides that OEHHA has determined meet the criteria to be listed under Proposition 65.

OEHHA’s determination is based on conclusions of the International Agency for Research on Cancer (IARC), the specialized cancer agency of the World Health Organization, which has classified glyphosate and malathion as “probably carcinogenic to humans” and tetrachlorvinphos and parathion as “possibly carcinogenic to humans.” Under California law, certain substances identified by IARC are required to be listed as known to cause cancer under Proposition 65. IARC has concluded that there is sufficient evidence of carcinogenicity in experimental animals for all four of the chemicals named in OEHHA’s notice of intent.

IARC describes glyphosate as a “broad-spectrum, post-emergent, non-selective, systemic herbicide, which effectively kills or suppresses all plant types,” and a plant-growth regulator and desiccant when applied at lower rates. According to the agency, 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 is requesting comments about whether these four chemicals meet the criteria to be listed under Proposition 65 regulations. The comment period is open until Oct. 5. View the notice of intent and learn more about submitting comments on OEHHA’s website.

OEHHA’s website provides a “plain language” explanation of Proposition 65 for further information.