Contamination

Understanding Contamination

Although compost is overwhelmingly safe and beneficial for the environment, it is useful to know about potential contamination sources in order to make good choices when buying and using compost. Read on to better understand potential contaminants including persistent herbicides and manmade inerts.

Persistent Herbicides

The compost industry still contends with the lasting effect of a some chemical broadleaf weed killers that can survive the composting process and negatively affect plants grown in such compost. These Persistent Herbicides have active chemical ingredients that can persist on treated vegetation for years, even after composting.

The USCC recognizes the threat these chemicals pose to our compost manufacturers and the end users of compost products that could contain them. Use the resources below to fight this threat.

The USCC also has a permanent standing subcommittee, the Legislative and Environmental Affairs Committee, which focuses on fighting persistent herbicides.

Man-Made Inerts (Trash)

Man-made inerts refer to the trash that get mixed into the compost feedstocks and end up in compost. They can include plastic, textiles, glass and other objects that don’t decompose entirely during the compost manufacturing process. It is difficult to sift these out of compost after they arrive at the facility. While man-made inerts are not generally dangerous, they do decrease the quality of compost.

Man-made inerts is one of the characteristics measured during the STA certification process.

PFAs

Per- and Polyfluoroalkyl substances (known variously as PFAS, PFOs and PFOAs) are man-made fluorinated compounds that have been put into consumer products since the 1940s because of their stain- and grease-repelling properties. Two of the chemicals, PFOs and PFOAs, have been phased out in the U.S. due to USEPA rulings in 2002 and 2015 that restrict their manufacture.

Visit our PFAS Resources here.