University researchers in Michigan are studying hemp for its potential to clean up soil contaminated with per- and polyfluoroalkyl substances (PFAS), manufactured chemicals that have drawn close scrutiny by environmental and health agencies.
A team at Northern Michigan University (NMU) said initial results show that hemp plants can draw up PFAS from the ground and may be able to degrade the chemicals.
Called “forever chemicals” because they do not break down in nature, PFAS have been found in humans, water, air, fish and soil, according to the Environmental Protection Agency (EPA).
How PFAS reach humans
SOURCE: Water Tectonics
The chemicals have been used in “Teflon” nonstick pans, fast food wrappers, water-resistant clothing, and carpeting that repels water, grease and stains. The chemicals have also been used in lubricants, firefighting foam used at military bases and airports, and even in personal care products such as waterproof mascaras and eyeliners, sunscreen, shampoo and shaving cream.
NMU Chemistry Professor Lesley Putman, who is leading the research, said growing hemp in polluted areas would be an advancement over typical and more costly remediation methods that use granular activated charcoal or reverse osmosis.
Putman’s team first experimented with PFBA, a small type of PFAS that is not considered toxic. She said the hemp took up PFBA into plant leaves, stems and flowers while not affecting plant growth. PFOS and PFOA, two toxic PFAS forms which appear in larger molecules, were sequestered mainly in the plant roots, and did not travel further up the plant, Putman said.
Wastewater from the sewage treatment plant at the former KI Sawyer Air Force Base in Michigan’s Upper Peninsula tested positive for PFOS, Putman said. The same substance has been reported at a military base in Maine, where a separate experiment is testing hemp’s ability to remediate contamination attributed to the longtime use of firefighting foam.
Carried in atmosphere
Despite a move by manufacturers to phase out PFAS, the chemicals have been detected on most continents regardless of the level of industrial development. Their presence far from potential sources indicates they may be carried in the atmosphere, according to a report from Elsevier ScienceDirect published earlier this year.
Growing hemp proved successful in removing PFAS chemicals from topsoil and purifying polluted groundwater in research supported by industrial giant 3M in Belgium.
The EPA is expected to classify certain PFAS chemicals as “hazardous substances” this year. The agency said it has plans to require companies to report releases of PFAS, and is seeking more power to pursue polluters as it analyzes sites and recovers remediation costs.