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Environmental Health

California Proposition 65: Toxics Law You Need to Know

Proposition 65, the Safe Drinking Water and Toxic Enforcement Act of 1986, was enacted as a ballot initiative in November 1986. The Proposition was intended by its authors to protect California citizens and the State's drinking water sources from chemicals known to cause cancer, birth defects or other reproductive harm, and to inform citizens about exposures to such chemicals.

It requires businesses to post signs warning customers about the presence and/or use of harmful chemicals listed under this regulation. Proposition 65 requires the Governor to publish, at least annually, a list of chemicals known to the state to cause cancer or reproductive toxicity.

The decision to provide a Proposition 65 warning is made by the respective business based upon its knowledge of the types of chemical exposures it is responsible for causing to individuals. To receive information about the chemicals of concern and the levels of exposure related to a particular product's use, one should review the materials safety data sheet (MSDS) or contact the manufacturer of the product.

Businesses with less than 10 employees, governmental agencies, and public water systems are exempt from the warning requirement and discharge prohibition of Proposition 65.

For more information and food establishment-specific details, see CA Proposition 65 page.

Questions about Proposition 65? Visit Office of Environmental Health Hazards Assessment, check the Frequently asked Questions page, contact Cynthia Oshita or Susan Luong in the Proposition 65 office: (916) 445-6900, email Ms. Oshita at or email Ms.Luong at

Common Proposition 65 Chemicals

The following are common Prop 65 chemicals found in automotive cleaners and degreasers. Included are common synonyms and Chemical Abstract Service (CAS) numbers, which are unique to each chemical. Note: most products contain more than one solvent.

  • 1-Bromopropane (1-BP or n-propyl bromide)           CAS 106-94-5
  • Toluene (methyl benzene)                                            CAS 108-88-3
  • Ethylbenzene  (phenylethane)                                      CAS 100-41-4 
  • N-Methyl pyrrolidone                                                       CAS 872-50-4
  • Benzene                                                                            CAS 79-06-1
  • P-Dichlorobenzene                                                         CAS 106-46-7
  • Methylene chloride (dichloromethane)                       CAS 75-09-2
  • Tetrachloroethylene (perchloroethylene)                    CAS 127-18-4
  • Trichloroethylene                                                             CAS 79-016   

View the complete list of Prop 65 chemicals