PFHxS: The Case for a Class-Based Listing

PFHxS and related substances

Perfluorohexane sulfonic acid (PFHxS) and its related substances has been used as a toxic (so-called "regrettable") substitute for another PFAS, perfluorooctanesulfonic acid (PFOS), that was listed under the Stockholm Convention for global restriction in 2009. After its evaluation, the POPRC concluded that PFHxS is, as a result of long-range environmental transport, likely to lead to significant adverse effects on human health and the environment such that global action is warranted.

PFHxS is extremely persistent in the environment but is relatively water soluble. This means that it adsorbs less to soils and sediments and has a high mobility in the environment, leading to widespread, long-term contamination. It also means that standard adsorption and filtering methods to remove PFHxS from water are generally ineffective and that it is not removed during standard wastewater- or drinking water treatment processes.

The POPRC evaluation concluded that there are no justifications for any continued production and use of PFHxS since cost-effective alternatives are already in use. Therefore, the POPRC recommend listing PFHxS, its salts and relates substances for global elimination with no exemptions.

The consequences of the persistence of PFAS also provides justification for addressing all PFAS as a class based on precaution.