Perfluoroalkyl acids in serum from nursing women living in an area in Sweden with drinking water contamination

Perfluoroalkyl acids (PFAAs) are a group of persistent organic substances that are surface active and water and fat/oil repellent. Due to the wide use and persistence of PFAAs they are present everywhere in the environment, and humans are exposed via food, drinking water and the use of products containing PFAAs and related compounds. We investigated blood serum levels of ten perfluoroalkyl carboxylic acids (PFCAs), four perfluoroalkane sulfonic acids (PFSAs), and perfluoroctane sulfonamide (FOSA) in 297 women from Uppsala County, Sweden, sampled three weeks after delivery during 1996-1999 and 2008-2011. The aim of the study was to determine if there were significant differences in PFAA serum levels between the women living in different districts in the City of Uppsala, in attempt to ascertain the impact of drinking water exposure on blood levels of PFAA. Earlier results on drinking water analyses suggested that the drinking water distributed mainly to the Southern district of Uppsala was contaminated with high levels of perfluorohexane sulfonic acid (PFHxS) and perfluorooctane sulfonic acid (PFOS), and lower levels of perfluorobutane sulfonic acid (PFBS). The contaminated water wells have now been taken out of production. Another aim was to evaluate associations between blood PFOS levels and fish consumption, suggested to be a significant source of PFOS exposure. When comparing serum levels of PFAA in women from different city districts, significantly higher concentrations PFBS and PFHxS were found in the Southern and/or the Western districts both in 1996-1999 and 2008-2011. Higher levels of PFHxS were observed in 2008-2011 than in 1996-1999 in all Uppsala districts, but not in women from areas outside of the City of Uppsala. These results suggest that drinking water exposure to PFHxS and PFBS gave a major contribution to the total exposure to the compounds mainly in the Southern district but also to some extent in other districts of Uppsala. Levels of PFOS in serum did not differ between districts, and the levels were lower in 2008-2011 than in 1996-1999 suggesting that the drinking water contamination of PFOS has not yet resulted in increased serum levels in women consuming the contaminated water. Total fish consumption and lean fish and shellfish consumption were positively associated with serum concentrations of lin-PFOS (p<0.05) in the group of women from 2008-2011. Our results strongly suggest that drinking water exposure to perfluorohexane sulfonic acid (PFHxS) and perfluorobutane sulfonic acid (PFBS) is an important factor behind the increasing temporal trends of the levels of these compounds in blood serum from young women in Uppsala. Our results further suggested that the relative importance of fish consumption as human exposure pathway for PFOS has increased since the 1990s.