Effective July 7, California’s Office of Environmental Health Hazard Assessment will add glyphosate, the active ingredient in a number of weed killers, to the list of chemicals known to the state to cause cancer for purposes of the Safe Drinking Water and Toxic Enforcement Act of 1986 (Proposition 65). Since this list was first published in 1987 it has grown to include approximately 900 chemicals.
Prop 65 does not ban or restrict the use of listed chemicals. Instead, beginning one year after a chemical is added to the Prop 65 list businesses are required to provide a “clear and reasonable” warning before knowingly and intentionally exposing anyone to that chemical unless they can show that the anticipated exposure level will not pose a significant risk of cancer or is significantly below levels observed to cause birth defects or other reproductive harm. This warning can be given in several ways; e.g., labeling a consumer product.
No such warning is required if exposure to a chemical occurs at or below any established safe harbor level. OEHHA had proposed a regulatory safe harbor level for glyphosate of 1100 micrograms per day, but its announcement adding glyphosate to the Prop 65 list offered no further details. If this safe harbor level is approved no warning would be required for exposures to glyphosate below this level, but businesses with 10 or more employees who cause exposures above this level might need to provide warnings.