The United States and Poland have the highest blood concentrations of PFOS, exceeding 30 ng/mL.

“Another article, "Perfluorooctane and related fluorochemicals in human blood from several countries." I've highlighted that they say among four perfluorochemicals measured, PFOS was the predominant compound found in blood. Concentrations of PFOS were the highest in samples collected from the United States and Poland. Moderate in Korea, Belgium, Malaysia, Brazil, Italy, and Colombia, and lowest in India. United States had the highest along with Poland, greater than 30 ng/mL of PFO S.”