The Personal Care Products Council (PCPC) has asked a federal court to permanently block California from requiring Proposition 65 cancer warnings for diethanolamine (DEA), arguing that the state is compelling businesses to make claims that are "undisputedly controversial and, ultimately, false".
Filed on 27 April in the US District Court for the Eastern District of California, the motion for summary judgment says California’s warning requirement for DEA violates companies' First Amendment protection against government-compelled speech that is not purely factual or uncontroversial.
If successful, the legal effort would mark the fourth time an industry body has successfully challenged the constitutionality of a Prop 65 warning in scenarios where the scientific evidence about a substance’s toxicity is not sufficiently robust.
The same court previously blocked Prop 65 warning requirements for glyphosate, acrylamide and respirable titanium dioxide, the latter of which was also sought by PCPC.
Across all cases, business groups argued that government-mandated commercial disclosures are permissible only if they are purely factual, uncontroversial and not unduly burdensome.
For DEA, the cancer warning requirement fails all three prongs, PCPC said. The science does not support a finding that DEA is a known human carcinogen, regulatory bodies worldwide dispute its carcinogenicity, and the burden on companies facing costly litigation over alleged Prop 65 violations is unjustified, according to the trade group.
Scientific uncertainty
According to PCPC’s motion, California's Office of Environmental Health Hazard Assessment (OEHHA) listed DEA as a Prop 65 carcinogen in 2012 without making an independent scientific determination, instead relying on a classification by the International Agency for Research on Cancer (IARC).
IARC classified DEA as possibly carcinogenic to humans (group 2B) in 2011, based on a single 1999 mouse study by the US National Toxicology Program (NTP), the PCPC said.
However, that "defective" study cannot support the Prop 65 warning requirement, the trade group argued.
The mice used in the study often develop liver tumours spontaneously at high rates, according to the motion. Furthermore, the biological mechanism of concern has no established relevance to humans, and the tumours appeared in the test mice only after "chronic exposure at extreme doses", PCPC said.
In addition, several major regulatory bodies that reviewed the same NTP study declined to classify DEA as a human carcinogen, including the NTP itself, along with the US EPA, the US Food and Drug Administration (FDA), ECHA, and Australia's Industrial Chemicals Introduction Scheme (AICIS), the trade group said.
Additionally, OEHHA's own scientists reached a similar conclusion in 2003, declining to list DEA under the agency's independent review process before reversing course after IARC's 2011 reclassification, PCPC said.
The trade group told the district court it should "follow the clear weight of the scientific evidence and First Amendment precedent as applied to Proposition 65 and hold that the compelled DEA cancer warnings are unconstitutional", as they relate to cosmetics and personal care products.
The California attorney general's office has until 20 June to respond. A hearing on the summary judgment motion is currently scheduled for 27 August before District Judge Daniel Calabretta.
The case is The Personal Care Products Council v Bonta.