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As this space has discussed on several occasions, there are many issues with California's Prop 65 (check out some of my prior posts about unintended consequences here and here). In full disclosure, most of the issues I discuss here are presented from the viewpoint of businesses that find themselves at odds with citizen enforcers or their counsel, the language of the Proposition, and/or the California courts’ interpretation of that language.

However, Prop 65, otherwise known as California’s toxic substance warning law, appears to be the subject of equal opportunity complaining.

Mateel Environmental Justice Foundation (Mateel) recently argued before a California appellate court that California’s Office of Environmental Health Hazard Assessment (OEHHA) did not use the statutory required testing when it determined the safe harbor exemption for lead. OEHHA's safe harbor number, Mateel argued, even if multiplied by 1000, would still have “no observable effect" and therefore was not sufficiently protective of human health.


Lead was listed as a chemical that caused reproductive toxicity and therefore subject to Prop 65 warnings on February 27, 1987. The Maximum Allowable Dose Limit (MADL) of 0.5 micrograms per day was enacted on July 10, 1989.  In January 2015, Mateel filed a petition against OEHHA seeking to invalidate those MADL regulations relating to the safe harbor for lead.  After some procedural wrangling and a court ordered stay, in April 2016, the trial court denied Mateel’s petition.

An appeal ensued.

Appellate Arguments

In May 2018, Mateel argued that OEHHA, in adopting the U.S. Occupational Safety & Health Administration's (OSHA) federal maximum for lead in the workplace, had violated Prop 65 because OSHA’s “permissible exposure level” is not a rigorous as California’s “no observable effect” standard.

As the lead safe harbor limits were set in 1989, the appeals court panel questioned why the challenge to OEHHA's agency action was being brought 29 years later. Mateel responded that a 2015 court decision, Environmental Law Foundation v. Beech-Nut Nutrition Corporation, had raised the threshold for the safe harbor exemption based on a calculation of the average exposure using a product over a two-week period, rather than the average daily use. Thus, the allowable dose level of 0.5 micrograms per day could be multiplied by 14 and still be within the safe harbor.

As a consequence, Mateel asked the court to eliminate the safe harbor number completely, requiring “lead free” or zero lead” in products or affixing Prop 65 warnings to all products containing any amount of lead.

Ironically, Counsel for defendants California Chamber of Commerce and California Farm Bureau Federation found himself defending a safe harbor number that the defendants had long disagreed with. He explained that the State had already divided the OSHA number by 1000 (as required by Prop 65) and that the OSHA number accounted for lead existing in levels in the blood, which is not required under Prop 65.

Counsel for OEHHA argued that OEHHA’s decisions should be granted deference and there was no evidence of abuse of discretion by the agency during the rulemaking process.


The appellate court in the Mateel case is faced with the long history of California courts in fact giving OEHHA deference (see, for example, the Glysophate listing saga here, here, and here) when faced with balancing often-challenging science and Prop 65’s stated public policy considerations of providing warnings.

Past is not prologue, so it will be interesting to see where this lead issue leads.

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Daniel J. Herling

Member / Co-chair, Product Liability Practice

Daniel J. Herling is a highly regarded product liability defense attorney at Mintz. He handles litigation and class actions involving consumer products, leveraging his deep knowledge of California's consumer protection regulations and laws.