Sacramento, CA—Polystyrene, a plastic utilized in everything from yogurt containers to foam packaging, may soon be found on the list of known carcinogens maintained by California under Proposition 65.

The state has filed a notice of intent to list styrene, the organic compound used to create polystyrene, following failed attempts to do so in the past.

The Safe Drinking Water and Toxic Enforcement Act of 1986, better known as Prop 65, dictates that California businesses must disclose the use of any chemical on a list that now numbers around 800. Each of these chemicals has been determined to increase the risk of cancer, birth defects or other reproductive harm in humans.

The California Office of Environmental Health Hazard Assessment (OEHHA)’s past attempts to list styrene were blocked. In 2009, a California judge ruled that there was insufficient evidence to class styrene as a carcinogen, and a later attempt to list the chemical was withdrawn. Then, a federal judge decided in 2013 to allow the U.S. Department of Health and Human Services to list styrene in its 12th Report on Carcinogens as a “reasonably anticipated human carcinogen.” Now, perhaps with new momentum, OEHHA is trying again.

Many chemicals listed under Prop 65 have a specific “safe harbor” number, which is an exposure level below which businesses are not required to disclose the presence of the chemical to the public. If styrene is listed and no safe harbor level is established for it, products that expose individuals to styrene would be required to provide a Prop 65 warning, unless they can show that the exposure level in the product does not pose a significant health risk.

The impact of listing styrene could be dramatic in California. It is widely used in food packaging, and styrene plastics are used in the transport of fruits like strawberries and blueberries, which are key portions of California’s lucrative agriculture industry.

Many sources are quick to argue the point that polystyrene plastic as used in food service does not pose any health risks. Nevertheless, if styrene is listed, a large number of Prop 65 complaints and enforcement actions are to be expected. Retailers might want to look out for a shakeup in the way products are shipped and packaged in California if this comes to fruition.

Published in WholeFoods Magazine, July 2015, (online 6/11/2015)