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Abstract
Whether perfluorooctanoate (PFOA) and perfluorooctanesulfonate (PFOS), two widely used and biopersistent synthetic chemicals, are immunotoxic in humans is unclear. Accordingly, this article systematically and critically reviews the epidemiologic evidence on the association between exposure to PFOA and PFOS and various immune-related health conditions in humans. Twenty-four epidemiologic studies have reported associations of PFOA and/or PFOS with immune-related health conditions, including ten studies of immune biomarker levels or gene expression patterns, ten studies of atopic or allergic disorders, five studies of infectious diseases, four studies of vaccine responses, and five studies of chronic inflammatory or autoimmune conditions (with several studies evaluating multiple endpoints). Asthma, the most commonly studied condition, was evaluated in seven studies. With few, often methodologically limited studies of any particular health condition, generally inconsistent results, and an inability to exclude confounding, bias, or chance as an explanation for observed associations, the available epidemiologic evidence is insufficient to reach a conclusion about a causal relationship between exposure to PFOA and PFOS and any immune-related health condition in humans. When interpreting such studies, an immunodeficiency should not be presumed to exist when there is no evidence of a clinical abnormality. Large, prospective studies with repeated exposure assessment in independent populations are needed to confirm some suggestive associations with certain endpoints.
Acknowledgements
We thank Ms. Laura Elkayam (Exponent, Inc.) for her review of the text and tables for accuracy.
Declaration of interest
This manuscript was supported by the 3M Company. 3M was not involved in the preparation of the manuscript. The sponsors were provided the opportunity to review draft versions and to offer suggestions, whose inclusion in the manuscript was left to the discretion of the authors. The authors retained sole control of the manuscript content and the findings, and statements in this paper are those of the authors and not those of the author’s employer or the sponsors.
No authors were directly compensated by 3M. This project was funded through a contract between 3M and Exponent, an international science and engineering company that provided salary compensation to J.S.M. and E.T.C. H.O.A. and P.B. were compensated with consulting fees from Exponent and had no direct correspondence with 3M related to this manuscript. H.J.W. was not financially compensated for his work on the manuscript. The team of authors was assembled based on existing professional connections (between E.T.C., H.O.A., P.B., and J.M.) and a colleague's referral to an expert in clinical immunology (H.J.W.).
H.J.W. declares no conflict of interest related to the subject of this manuscript. J.S.M. was a consultant to 3M and previously testified as an expert in legal proceedings related to PFOA and PFOS; he is now retired. E.T.C. is a consultant to 3M and other industry clients on issues related to perfluoroalkyl and polyfluoroalkyl substances, including PFOA and PFOS. P.B. was a consultant to other industry clients on issues related to PFOA. J.S.M., E.T.C., P.B., and H.O.A. co-authored a peer-reviewed, published manuscript on PFOA, PFOS, and cancer that was financially supported by 3M. None of the authors are currently engaged to testify as experts on behalf of the sponsors in litigation related to the compounds discussed in this manuscript.