Environmental Law & Toxic Tort Alert: California Ruling Limits Chemicals That May Be Classified As Carcinogens Under California’s Proposition 65

The California Court of Appeal affirmed a lower court’s ruling that styrene and vinyl acetate should not be listed under Proposition 65, a law that requires warnings for products that contain substances known to cause cancer, birth defects or reproductive harm. Styrene Information and Research Center v. Office of Environmental Health Hazard Assessment, 2012 Cal.App. LEXIS 1146.

The Office of Environmental Health Hazard Assessment (“OEHHA”), the agency charged with enforcing Proposition 65, relied exclusively on the IARC Monographs on the Evaluation of Carcinogenic Risks to Humans (“IARC”) to designate the two chemicals as carcinogens. However, IARC classifies styrene and vinyl acetate as Group 2B (those substances that are “possibly” carcinogenic.) The Court of Appeal concluded that because OEHHA did not propose any other basis for including those substances on the list, they had to be excluded. Chemicals may be included on the Proposition 65 list only if there is a sufficient showing that they in fact cause cancer or reproductive toxicity.

Proposition 65 regulates substances officially listed by California as causing cancer or birth defects or other reproductive harm in two ways. The first regulatory arm of Proposition 65 prohibits businesses from knowingly discharging listed substances into drinking water sources, or onto land where the substances can pass into drinking water sources. The second regulatory arm of Proposition 65 prohibits businesses from knowingly exposing individuals to listed substances without providing a clear and reasonable warning.

Proposition 65 has been the basis for numerous consumer action lawsuits against manufacturers whose products contain chemicals that are known or suspected to cause cancer. The Court of Appeal’s ruling should restrict future lawsuits to chemicals that are classified by IARC as Group 1 (when there is sufficient evidence of carcinogenicity in humans) or Group 2A (those substances determined to be “probably” carcinogenic to humans.) The decision will not provide a basis to prevent future civil tort lawsuits claiming that a chemical classified by IARC as 2B caused or contributed to an individual plaintiff developing cancer. In this situation Plaintiff’s attorneys may still rely on peer reviewed epidemiological and toxicological studies to prove that a chemical is an established risk factor for developing a particular form of cancer in humans.

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November 19, 2012