Step 1: What are PFAS and Where Did They Come From?

PFAS are a group of man-made chemicals (per- and polyfluoroalkyl substances) that have been used since the 1940s in household products and industrial settings.  They are used mainly for their ability to repel oil, grease, water, and heat. We are exposed to PFAS from a variety of sources in everyday life. Stain-resistant carpeting, nonstick cookware, grease- and water-proof food packaging, fabric softeners, waterproof clothing, cosmetics, and many other products contain this class of chemicals.

Due to their widespread use, PFAS have made their way into our waste stream. Since the 1980s, sludge from waste treatment facilities has been used in agriculture as a low-cost fertilizer source. This was considered a beneficial use at the time and farmers were unaware some of the sludge they were spreading contained PFAS.

PFAS are very resistant to breaking down in the environment, hence the name “forever chemicals”.  Therefore they have remained in the soil, been taken up into plants, and made their way into animals who eat those plants. In some cases, they have also leached into both surface and groundwater. 

Potential sources of PFAS for home gardens include:

  • Farmland with a history of sewage sludge application that was converted into residential lots with gardens
  • Topsoil obtained from farmland with a history of sludge application
  • Use of soil amendments containing sewage sludge (“biosolids”) containing PFAS or manure from animals fed PFAS contaminated feed or water
  • Irrigation with water from a source that contains PFAS 

PFOA and PFOS are two of the better studied PFAS compounds and are known to cause human harm in relatively small quantities. 

Studies suggest PFAS exposure can lead to:

  • Increased cholesterol levels
  • Changes in liver enzymes
  • Decreased vaccine response in children
  • Decreased birth weight
  • Thyroid disease
  • Increased risk of high blood pressure or preeclampsia in pregnant women
  • Increased risk of kidney or testicular cancer

Therefore, eating food contaminated with PFAS is a concern. For more information on the health effects of PFAS, visit the What are the health effects of PFAS? page (Agency for Toxic Substances and Disease Registry /ATSDR website). 

Currently, the Maine Department of Environmental Protection (DEP) is testing all known licensed land application sites statewide. Preliminary results show that PFAS levels are not uniform across all application sites in Maine. 

For more information about PFAS and how they ended up in our soil, visit the Guide to Investigating PFAS Risk on Your Farm (UMaine Extension)

To direct questions to University of Maine Cooperative Extension, please email:

Proceed to Step 2: Are There PFAS Compounds Already in My Garden? →