The National Toxicology Program (NTP) for the U.S. Department of Health and Human Services recently released a Technical Report that found evidence of carcinogenic activity in laboratory rats exposed to perfluorooctanoic acid (PFOA). The NTP Technical Report may result in the listing of PFOA under California's Proposition 65 as a carcinogen. Private toxic tort plaintiffs may also attempt to rely on the Technical Report in PFAS contamination lawsuits.

PFAS

Per- and polyfluoroalkyl substances (PFAS) are a family of synthetic chemicals that have been used for decades to make commonly used products, including nonstick cookware, food packaging, water- and wrinkle-resistant fabrics, and firefighting foam. They are known as "forever chemicals" because they resist degradation and are highly persistent in the environment. PFOA is one of the most widely produced and studied PFAS compounds. 

While PFOA was phased out of domestic production in 2002 and U.S. manufacturers eliminated PFOA emissions and product content at the end of 2015, PFOA is still found throughout the United States, including in drinking water supplies and in just about everyone's blood. Additionally, PFOA is still found in products imported into the U.S. 

Proposition 65

Prop. 65, officially known as the Safe Drinking Water and Toxic Enforcement Act of 1986, was enacted as a ballot initiative in November 1986. The proposition contains two substantive provisions. The first provision requires businesses to warn Californians about exposures to chemicals in the products they purchase, in their homes or workplaces, or that are released into the environment. The second provision prohibits businesses from discharging significant amounts of listed chemicals into sources of drinking water.

The California Office of Environmental Health Hazard Assessment (OEHHA) implements Prop. 65 and maintains the list of chemicals known to the state to cause cancer or reproductive toxicity. OEHHA has already listed PFOA as a reproductive toxicant, but it has not listed PFOA as a carcinogen. 

The statute defines several ways for chemicals to be added to the Prop. 65 list. For instance, a chemical will be added to the Prop. 65 list if any "authoritative body" (including the NTP) formally identifies it as causing cancer or other reproductive harm. 

The NTP Technical Report 

The NTP Technical Report analyzed prenatal and postweaning exposure to PFOA in laboratory rats. Under the conditions of the two-year studies, there was "clear evidence of carcinogenic activity" of PFOA in male rats. In addition, there was "some evidence of carcinogenic activity" of PFOA in female rats.

Because the NTP is an "authoritative body" under Prop. 65, the NTP Technical Report may lead to the listing of PFOA as a known carcinogen. 

However, there are limitations to applying animal studies, like the NTP Technical Report, to humans. As the report notes, "The actual determination of risk to humans from chemicals found to be carcinogenic in laboratory animals requires a wider analysis that extends beyond the purview of these studies." For instance, responses of laboratory animals and humans to chemicals may differ qualitatively and/or quantitatively, and many carcinogens are sex, strain and/or species specific. In addition, differences in pharmacokinetics (i.e., absorption, distribution, metabolism and excretion) are often responsible for interspecies differences in susceptibility to toxic agents. 

Unlike animal studies, data derived from human chemical exposure studies allow researchers (and regulators) to avoid issues and uncertainties that are inherent in interspecies extrapolations. This is why agencies like the Environmental Protection Agency, Food and Drug Administration and World Health Organization prefer high-quality human data for use in assessing the potential of chemicals to cause adverse health effects in humans. 

To date, very few studies have analyzed the carcinogenic effects of PFOA in human studies. The International Agency for Research on Cancer, for instance, concluded that PFOA was possibly carcinogenic to humans, based on limited evidence in humans that it can cause testicular and kidney cancer and limited evidence in laboratory animals. Other human studies have suggested possible links to kidney and thyroid cancer, but the increases in risk have been small and could have been due to chance. Thus, there is likely insufficient data from human studies for OEHHA to conclude that exposure to PFOA is carcinogenic to humans. 

However, assuming OEHHA proceeds to list PFOA as a carcinogen, there would be a few implications for businesses and litigants. 

Prop. 65 Compliance

First, businesses will have to warn consumers about potential exposures to PFOA in their products. Previously, businesses would have only had to warn consumers that PFOA is known to the state to cause reproductive harm. However, in order to obtain "safe harbor" protection under Prop. 65, businesses will have to warn consumers that PFOA can cause cancer and birth defects or reproductive harm. 

OEHHA typically develops "safe harbor levels" to guide businesses in determining whether a warning is necessary or whether discharges of a chemical into drinking water sources are prohibited. However, OEHHA has not yet set safe harbor levels for PFOA as a reproductive toxicant, and it is unclear whether it would do so for PFOA as a carcinogen. If there is no safe harbor level for the chemical, businesses must still comply with Prop. 65 and will be required to demonstrate through self-funded risk assessments that exposure at certain levels remain safe. OEHHA has adopted regulations that provide guidance for calculating levels in the absence of a safe harbor level. See Article 7 and Article 8 of the California Code of Regulations. 

PFAS Litigation

Outside the Prop. 65 realm, we anticipate private toxic tort plaintiffs to rely on the NTP Technical Report in PFAS contamination lawsuits to provide evidence of the carcinogenic effects of PFAS. In the past few years, there has been an explosion of PFAS litigation throughout the country. To date, many agencies have not yet formally evaluated whether PFOA can cause cancer. And some PFOA studies were sponsored by states or nongovernmental organizations and not peer reviewed. Thus, plaintiffs may look to the NTP Technical Report to support their claims. Whether their claims are successful, however, will of course depend on a number of factors separate from the studies cited in their pleadings.

Jeffrey Dintzer is a partner and Greg Berlin is an associate at Alston & Bird in Los Angeles.