California Proposition 65

Intrinsik’s scientific experts can offer advice for Proposition 65 (Prop 65).  Prop 65 is a California initiative intended to protect consumers and inform them about exposure to toxic chemicals.

The State of California publishes a list of chemicals known to cause cancer or birth defects or other reproductive harm.  This continually evolving list includes more than 900 chemicals.  Proposition 65 requires businesses to warn Californians about significant amounts of Prop 65-listed chemicals in the products they purchase.  Businesses are exempt from the warning requirement if the exposures they cause are so low as to create no significant risk of cancer or birth defects or other reproductive harm.

To assist businesses, the Office of Environmental Health Hazard Assessment (OEHHA) develops numerical guidance levels, known as Safe Harbor Levels for determining whether a warning is necessary or whether discharges of a chemical into drinking water sources are prohibited.  Safe Harbor Levels include No Significant Risk Levels (NSRL) for chemicals listed as causing cancer and Maximum Allowable Dose Levels (MADL) for chemicals listed as causing birth defects or other reproductive harm.  If a Safe Harbor Level has not been established for a listed chemical, businesses that expose individuals to that chemical are required to provide a Proposition 65 warning, unless the business can show that the anticipated exposure level will not pose a significant risk of cancer or reproductive harm.  A business has “safe harbor” from Proposition 65 warning requirements if exposure to a chemical occurs at or below the Safe Harbor Levels.


  • Review product formulations for the presence of Proposition 65-listed chemicals
  • Inform labelling decisions by conducting exposure-based risk assessments specific to your product following the Safe Use Determination process established by OEHHA
  • Development of No Significant Risk Levels (NSRLs) and Maximum Allowable Dose Levels (MADLs) for chemicals with no OEHHA-derived Safe Harbor Level
  • Assist with responses to plaintiff issued 60-day notices
  • Provide expert advice in legal proceedings and in discussions and negotiations with plaintiffs, OEHHA and the Attorney General

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