What is California’s Prop 65?


Proposition 65 (Prop 65) is a California law proposed initially as the Safe Water and Toxic Enforcement Act and approved by voters in 1986. The law was intended to address public concerns in the 1980s when residents started learning more about chemicals and compounds in the environment. This law became commonly known as Prop 65. 

What is Prop 65 intended to do?

Prop 65 is intended to provide California residents with information about compounds in the environment around them that might be harmful (i.e. have been linked to cancer, reproductive harm, or developmental defects). Prop 65 dictates that California businesses with more than 10 employees that sell products in the state are required to provide “clear and reasonable warnings” about a chemical’s ability to cause cancer, reproductive harm, or birth defects on packaging or labels.

What’s included in the Prop 65 list?

The 800 chemicals and compounds included presently in Prop 65 range from naturally occurring compounds to synthetic and manmade chemicals that are present in our everyday lives. Here is a brief overview of what is included:

  • Additives or ingredients in pesticides
  • Common household products
  • Drugs, food, or dyes
  • Solvents
  • Chemicals in manufacturing or construction
  • Byproducts of chemical processes.

Each listing is categorized as carcinogenic, reproductive or developmental.

Has the list of chemicals included on Prop 65 evolved over time?

The list of compounds is updated once a year and currently includes about 800 naturally occurring or manmade chemicals found in an individual’s everyday environment. The Office of Environmental Health Hazard Assessment (OEHHA) is the lead office that’s responsible for the Prop 65 program and is part of the California Environmental Protection Agency.  These two state agencies get input from various independent sources, assess and evaluate the safety of current chemicals, and propose new listings each year. 

How does a compound get listed in Prop 65?

Listings typically begin with a submission or rationale sent from one of OEHHA’s independent committees, delegated authoritative bodies, federal and/or state government, or the identification of a chemical or compound in the California Labor Code.  

Submission within a committee is reviewed by OEHHA’s independent scientific committee(s): Carcinogen Identification Committee (CIC) and/or the Developmental and Reproductive Toxicant Identification Committee (DARTIC), which are made up of experts.

With public input, the committees can approve or decline a chemical’s listing based on the review and evaluation of current scientific evidence. Other pathways for listing a chemical include identification of a chemical in federal guidelines such as the CA Labor Code or Federal/State labeling requirements. Further, if any of the authoritative bodies listed below deem a chemical to cause cancer, reproductive harm, or birth defects then it will be listed:

  • U.S. Food and Drug Administration (FDA)
  • Environmental Protection Agency (EPA)
  • National Toxicology Program (NTP) of NIEHS
  • National Institute for Occupational Safety and Health (NIOSH)
  • International Agency for Research on Cancer (IARC)

What does Prop 65 mean for me?

Prop 65 is a right-to-know law that provides information on products to help consumers make more informed decisions in the form of pervasive labeling.  However, the Prop 65 labels do not mention or identify the level of risk, specific to the compound. Because of this, Prop 65 may be confusing to consumers who are encountering it in their day-to-day lives.  

Moreover, it is important to understand how the threshold levels for Prop 65 inclusion are determined. The OEHHA has set “Safe Harbor” levels of exposure for many of the chemicals listed under Prop 65. If the amounts found in a certain product are less than the Safe Harbor level, the product does not require a warning label. It should  be noted that Safe Harbor levels are frequently around 1,000 times lower than levels set by regulatory agencies such as the FDA, EPA and World Health Organization.

This leads to common and natural byproducts like 4-MEI being included on the Prop 65 list. In reality, it is almost impossible for a human to be exposed to an amount of 4-MEI that would cause negative health effects. The U.S. Food and Drug Administration has even stated that “based on the available information, FDA has no reason to believe that there is any immediate or short-term danger presented by 4-MEI at the levels expected in food”.

While Prop 65 labeling will give you more information, it’s important to keep in mind the broader perspective. These labels do not identify the actual compound or where the compound is located in the product, nor do these labels assess risk levels. Instead, keep in mind that for overall health it’s important to choose a dietary pattern that is rich in lean protein, healthy fats, whole grains, fruits, and vegetables.

This blog post was written by Danielle Corrado, food science/policy intern from the University of Massachusetts, Amherst.