California’s “Proposition 65” warning requirements (Health & Safety Code Sections 25249.6 et seq.) have long been a major concern for businesses that want their products offered for sale in the State’s large marketplace. Businesses whose products contain even a detectable amount of any one of more than 900 chemicals often face enforcement lawsuits brought by for-profit plaintiffs unless their products contain a “clear and reasonable” Proposition 65 warning. Short of eliminating the chemical entirely, the only way for businesses to immunize themselves from such “bounty hunter” claims has been for companies to label or display their products with a generic “safe harbor” warning—language set forth in the original Proposition 65 regulations. It states: “This product contains chemicals known to the State of California to cause cancer and birth defects or other reproductive harm.”

For companies that believe no such warning is appropriate for their products, the State also has adopted safe harbor warning thresholds for a few ubiquitous chemicals. While these safe harbor numbers are frequently set at levels that many scientists consider unjustifiably low, they have the benefit of providing a floor on the warning threshold and thereby facilitating compliance programs. Relying on the safe harbor can also eliminate one of the most expensive and uncertain elements of litigation in enforcement actions: determining the warning threshold.