PFAS are a group of man-made chemicals used since the 1940s. PFAS were used to manufacture commercial products and firefighting foam. Some PFAS are no longer used. The potential source of PFAS present at the Town landfill, such as in waste water treatment residuals and municipal solid waste, are primarily from use of household cleaning products, food packaging, clothing, and beauty products that contained PFAS.
In 2019, Massachusetts Department of Environmental Protection (MassDEP) recognized the need for more information on PFAS characteristics in wastewater treatment residuals. Prior to 2020 on Nantucket, such residuals were mixed with municipal solid waste and leaf/yard waste to be used for compost. Waste Options, the Town Contractor, collected compost samples in 2019 to maintain a proactive approach to environmental quality on the island. Specific PFAS sampling protocols were not established at that time.