In 2020, Jessica Trowbridge and colleagues published “Exposure to Perfluoroalkyl Substances in a Cohort of Women Firefighters and Office Workers in San Francisco,” hereafter “Exposure to PFAS in Women Firefighters,” in the journal Environmental Science & Technology. The researchers, affiliated with the University of California in Berkeley, California, aimed to investigate occupational exposure to perfluoroalkyl substances, or PFAS, by comparing blood samples between female firefighters and office workers. PFAS are synthetic chemicals found in firefighting foam, textiles, and many household products. Research has shown that exposure to PFAS can increase the risk of health complications, including cancer and reproductive concerns. Trowbridge and colleagues sought to address a gap in previous studies of PFAS, which primarily focused on male firefighters. Their study documented increased PFAS exposure in female firefighters compared to office workers and highlighted potential health risks, particularly for those who are pregnant.

Aqueous film-forming foam, or AFFF, is a chemical foam that fire departments and other organizations worldwide use to fight fires involving flammable liquids. AFFF contains per- and polyfluoroalkyl substances, or PFAS, as such chemicals serve as the backbone structure of the foam. PFAS pose health risks, mainly because they can accumulate in the body over time and can cause numerous health issues, such as hormonal dysfunctions. In the 1960s, the United States Naval Research Laboratory, in collaboration with a private chemical company, developed AFFF to enhance capabilities to fight fires involving jet fuel aboard naval ships. The effectiveness of the foam is mainly due to the structure of PFAS, which allows AFFF to spread quickly over burning fuel, suppressing vapors and cutting off the oxygen necessary for the fire. Since its development in the 1960s, many versions of AFFF have been marketed for firefighting purposes. Despite its effectiveness in suppressing flammable-liquid fires, AFFF poses risks for many groups, including firefighters, pregnant women, and their fetuses.

On 7 December 2018, the United States Judicial Panel on Multidistrict Litigation, or JPML, consolidated ninety lawsuits into the Aqueous Film-Forming Foams Products Liability Litigation, commonly called MDL No. 2873. Aqueous film-forming foams are substances that can smother fires, and they often contain toxic chemicals called per- and polyfluoroalkyl substances, or PFAS. MDL No. 2873, which originated in the District Court of South Carolina, addresses health and environmental concerns related to AFFF. Plaintiffs across the US claim that exposure to PFAS in AFFF causes various health issues, including cancer and birth defects. The litigation targets major manufacturers, including 3M, DuPont, and Chemours, who allegedly continued producing PFAS products despite known risks to human health. MDL No. 2873 consolidates nationwide PFAS claims and establishes a means to hold AFFF manufacturers responsible for environmental contamination with PFAS.