It is estimated that it takes 4 years for half of this substance to be eliminated from the body. PFOS is detected in the blood serum of almost all people in the U.S., but concentrations have been decreasing over time. In contrast, PFOS blood levels appear to be rising in China where PFOS production continues. In people, the highest exposures to PFOS in blood have been 12,830 parts per billion for occupational exposure and 656 parts per billion—or possibly 1,656 parts per billion—in a consumer. Occupationally exposed individuals may have an average level of PFOS over 1000 parts per billion, and a small segment of individuals in the upper range of the general population may be over the 91.5 parts per billion level. PFOS exposure has been demonstrated as early as fetal development during pregnancy since PFOS can easily pass through the placenta. It has been shown that fetal exposure to PFOS is quite prevalent and has been shown to be detected in greater than 99% of umbilical cord serum samples. PFOS has been detected in municipal wastewater and drinking water samples, worldwide, at concentrations ranging between few ng/L and some μg/L. Levels in wildlife A variety of wildlife species have had PFOS levels measured in egg, liver, kidney, serum, and plasma samples and some of the highest recorded values as of January 2006 are listed below. Despite the global wide-ranging restriction, PFOS concentrations in air continued to increase at many monitoring stations between 2009 and 2017. Health effects in humans and wildlife There has been a growing body of evidence investigating the health effects of PFOS on the reproductive, developmental, liver, kidney, thyroid, and immunological effects in humans. Pregnancy outcomes Several studies have focused on pregnancy outcomes in infants and mothers who are exposed to PFOS during pregnancy. For developing offspring, exposure to PFOS occurs through the placenta. While the impact of PFOS compounds on fetal development continues to be an ongoing investigation, findings have demonstrated a relationship between PFOS exposure in pregnant mothers and negative birth outcomes. There has been some evidence to suggest that PFOS levels in pregnant women have been associated with preeclampsia, preterm labor, low birth weight and gestational diabetes. Although, the strongest association is between PFOS levels with preterm birth and preeclampsia. There has been some evidence to suggest that PFOS impairs fetal growth during pregnancy, although findings have been inconsistent. The specific physiological