These are two compounds that have been made within the last 10 years to replace PFOA and PFOS. There are still health and environmental concerns about the safety of GenX (ammonium salt of hexafluoropropylene oxide dimer acid, or HFPO-DA, introduced in 2009), and PFBS (perfluorobutanesulfonic acid, released in 2003), and many environmental labs are beginning to test for them along with PFOA and PFOS.
