1 ppb corresponds to 1 microgram per kilogram of packaging, and 1 ppm to 1 milligram per kilogram. The 25 ppb threshold therefore sets the limit at 25 milligrams of a given PFAS per tonne of paper and the 50 ppm threshold at 50 grams of PFAS overall per tonne. The US and German authorisations identified by the OECD permitted up to 2 to 15 kilograms of fluorinated agent per tonne of paper, depending on the substance, or 40 to 300 times more.
Read the source article: PPWR PFAS food packaging limits: the 3 thresholds explained