ARTICLE pubs.acs.org/est
Trends in Exposure to Polyfluoroalkyl Chemicals in the U.S. Population: 1999 2008† Kayoko Kato, Lee-Yang Wong, Lily T. Jia, Zsuzsanna Kuklenyik, and Antonia M. Calafat* Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, Georgia, United States
bS Supporting Information ABSTRACT: Since 2002, practices in manufacturing polyfluoroalkyl chemicals (PFCs) in the United States have changed. Previous results from the National Health and Nutrition Examination Survey (NHANES) documented a significant decrease in serum concentrations of some PFCs during 1999 2004. To further assess concentration trends of perfluorooctane sulfonate (PFOS), perfluorooctanoate (PFOA), perfluorohexane sulfonate (PFHxS), and perfluorononanoate (PFNA), we analyzed 7876 serum samples collected from a representative sample of the general U.S. population g12 years of age during NHANES 1999 2008. We detected PFOS, PFOA, PFNA, and PFHxS in more than 95% of participants. Concentrations differed by sex regardless of age and we observed some differences by race/ethnicity. Since 1999 2000, PFOS concentrations showed a significant downward trend, because of discontinuing industrial production of PFOS, but PFNA concentrations showed a significant upward trend. PFOA concentrations during 1999 2000 were significantly higher than during any other time period examined, but PFOA concentrations have remained essentially unchanged during 2003 2008. PFHxS concentrations showed a downward trend from 1999 to 2006, but concentrations increased during 2007 2008. Additional research is needed to identify the environmental sources contributing to human exposure to PFCs. Nonetheless, these NHANES data suggest that sociodemographic factors may influence exposure and also provide unique information on temporal trends of exposure.
’ INTRODUCTION Polyfluoroalkyl chemicals (PFCs) have been manufactured for over 60 years and used in many industrial and commercial applications.1,2 Some PFCs, including perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA), are persistent compounds. Because of the widespread exposure to PFCs in wildlife and people and the potential adverse health impacts associated with such exposures,1,3 5 in 2002, 3M, the main manufacturer of PFOS worldwide, discontinued the production of PFOS precursors and related compounds in the United States; however, other manufacturers still produce PFOS abroad.6 Furthermore, PFOA, its salts, and precursors are still manufactured, although efforts exist to limit emissions of PFOA into the environment.2,7 These efforts appear to have reduced exposure to some of these PFCs in the environment 8 10 and in people.11 13 In the United States, general population data from the National Health and Nutrition Examination Survey (NHANES), conducted by the National Center for Health Statistics (NCHS), Centers for Disease Control and Prevention (CDC) 11,14 are reflective of this reduced exposure. Specifically, we reported before that in the sixyear period covered by NHANES 1999 2000 and 2003 2004, serum concentrations of PFOS and PFOA showed a downward trend.11 The present manuscript builds on those findings with †
Part of the Perfluoroalkyl Acid Special Issue This article not subject to U.S. Copyright. Published 2011 by the American Chemical Society
two main objectives: (1) to assess whether the trend in exposure to PFOS, PFOA, and two additional PFCs, perfluorononanoate (PFNA) and perfluorohexane sulfonate (PFHxS), has continued since 2004, and (2) to replicate, update, and expand upon our earlier work 11,14 by examining exposure to select PFCs by use of the most recent NHANES data from 2005 2008.
’ MATERIALS AND METHODS Sera analyzed for 12 PFCs was obtained from 7876 participants aged g12 years from NHANES 1999 2000 and 2003 2008. NCHS’s Institutional Review Board approved the NHANES protocol. All participants (parents/guardians for participants
