Following a failed legal challenge by Syngenta Crop Protection, California’s Office of Environmental Health Hazard (OEHHA) announced today that it has added a group of broadleaf herbicides to the list of chemicals under Proposition 65 known to cause reproductive harm.

The listing of atrazine, propazine, simazine, and their chlorometabolites des-ethyl atrazine (DEA), des-isopropyl atrazine (DIA) and 2,4-diamino-6-chloro-s-triazine (DACT) will take effect on July 15, 2016, and the warning requirement will take effect one year later.

Listing of the herbicides was initially to be effective in August 2015, but was delayed several times by Syngenta’s legal challenge of the authoritative basis for listing the chemicals. Syngenta lost that case in April of this year and appealed. Since the appellate court has not granted a stay, OEHHA has gone ahead with the listing.

Atrazine is widely used in growing corn and sugarcane, and on turf such as golf courses and residential laws. Propazine is used for sorghum crops, and simazine is widely used in growing grapes, apples, citrus, corn and wheat.

Sedaxane and Styrene Listed as Carcinogens

Other chemicals recently added to the Prop. 65 list include sedaxane and styrene. Sedaxane is a seed treatment fungicide. It was listed under Prop. 65 as a carcinogen on July 1, and the warning requirement takes effect one year later, on July 1, 2017.  

Styrene is used to make a wide variety of plastic consumer products, including polystyrene foodservice packaging such as drinking cups, egg cartons, meat packaging, plates and bowls, and take-out containers. The warning requirement takes effect on April 22, 2017. OEHHA has proposed a safe harbor exposure level for styrene of no more than 27 micrograms per day. Exposure below this level would not require a warning. 

A complete list of Prop. 65 chemicals is available at

Prop. 65 prohibits businesses from knowingly and intentionally exposing California consumers to a chemical known to the state to cause cancer or reproductive harm without first providing a warning. Violations are subject to potential penalties of up to $2,500 per day for each violation, and each sale can constitute a violation. Prevailing plaintiffs can also recover their attorneys’ fees.

Please click here to learn more about Bryan Cave’s California Proposition 65 Practice.