At its simplest, California's Proposition 65 requires businesses to provide "clear and reasonable" warnings prior to exposing individuals to one or more of the 900+ Prop 65 listed chemicals. And that is where the "simplicity" ends and the complexity begins.

A plaintiff who can demonstrate that a business failed to provide warnings in compliance with the statute may seek civil penalties and payment of significant attorneys' fees and costs, as well as injunctive relief through a civil lawsuit. It is a common misconception that all "exposures" to Prop 65 listed chemicals require a warning, when in fact it is only those exposures that exceed the regulatory level specified for the chemical that actually necessitate a warning. This is known as the "safe harbor" affirmative defense, and once an enforcement action is brought, the burden shifts to the defendant to prove that it applies.

Health and Safety Code § 25249.10 details the defense and establishes that warnings are not required if the defendant company can demonstrate that: (i) for listed carcinogens, the exposure is below the no significant risk level (NSRL), i.e., does not pose a significant risk of cancer assuming that the individual is exposed to the chemical over a 70-year lifetime; and (ii) for reproductive toxicants, the exposure is below the maximum acceptable dose level (MADL), which is 1/1000th of the no observable effect level for the chemical. The Office of Environmental Health Hazard Assessment (OEHHA), the agency tasked with overseeing Prop 65, has provided safe harbor levels for many of the listed chemicals. For chemicals without established safe harbor levels, it is left to the defendant company to prove up a safe level of exposure under the regulations.

So, how does a company show that the exposure at issue is within the "safe harbor" level? It is necessary to carry out an exposure assessment to demonstrate how often and to what extent an average user will be exposed to the subject product. Under the statute, the implementing regulations, and applicable case law, the courts should consider the "average user" of the product, versus high-end users. Existing precedent also supports that it is appropriate to average exposure to the product over time, versus a single day exposure. In Environmental Law Foundation v. Beech-Nut Nutrition Corp. (2015), one of the few Prop 65 cases to make it to the appellate level, the court affirmed that calculating exposure to lead in foods should be based on average consumption over time and average lead levels detected across product lots over time.

Establishing the average exposure and whether or not it exceeds the "safe harbor" value is a costly and complex scientific undertaking that requires employing experts and conducting testing. And the challenges do not end there, because plaintiffs will dispute every single aspect of a defendant's exposure assessment, creating "issues of fact" under the law. This turns the case into a battle of the experts that requires the parties to litigate, experts to testify, and the courts to adjudicate. In the end, the "safe harbor" defense presents a challenging and expensive threshold for defendants to meet, and the costly burden of proof leads many companies to settle even when they have a strong defense and know that an exposure does not exceed the regulatory levels.

The reality is that the cost of litigating the issues arising under Prop 65 is typically exponentially higher than the cost of settlement, and Prop 65 enforcers are known to exploit this fact. Determining if using the "safe harbor" defense is the best option for your company is an important evaluation for every business facing a Proposition 65 enforcement action, and our team is experienced in walking clients through these steps, from start to finish.

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.