Formerly called Perfluorinated Compounds (PFC)
Why is exposure to perfluoroalkyl and polyfluoroalkyl substances relevant to health?
Perfluoroalkyl and polyfluoroalkyl substances (PFAS), formerly called perfluorinated compounds (PFC), are used in the manufacture of lubricants, detergents, fire-fighting foams, inks, varnishes, stain-free coating formulations, waxes, and water and oil repellents. Common products containing PFAS include pizza boxes, microwavable popcorn bags, and stain-resistant coating on furniture and clothing. Exposure is thought to be primarily from ingestion of contaminated food and water, and for children – breast milk and house dust. However, exposures in the general U.S. population are declining since the phase-out of some PFAS production over the last few decades.
PFAS exposure has been associated with a variety of health outcomes including endocrine-disrupting effects, immune system alterations, and increases in cholesterol and liver enzymes. Prenatal exposure to PFAS has been associated with developmental delays including changes in growth, learning, and behavior. PFAS exposure can also lead to decreased fertility and hormonal changes in women. Other effects such as cancers are still being investigated.
What types of questions can be answered?
PFAS can be measured in blood serum or plasma to estimate exposure. Many published data exist with which to compare these exposures including general U.S. population data published in Centers for Disease Control and Prevention's (CDC) National Report on Human Exposure to Environmental Chemicals. PFAS can also be measured in air, drinking water, house dust, soil, or silicone wristbands.
How can exposure to PFAS be measured?
- Analytes: The PFAS most commonly detected in humans include perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate (PFHxS), and perfluorononanoic acid (PFNA). Other PFAS may be measured but are detected less frequently.
- Methods: Almost all methods couple liquid chromatography with mass spectrometry detection. Because sample contamination can occur during the analysis process if polytetrafluoroethylene (PTFE or Teflon®)-coated supplies are used, special care is taken to reduce contamination.
- Types of biospecimens: Serum or plasma are the primary matrices for measurement of PFAS. They also have been measured in breast milk and amniotic fluid, but interpretation, particularly in amniotic fluid, is not straightforward. They are not lipophilic but associate with albumin in tissue and blood.
- Types of environmental samples: Dust and silicone wristbands are the most common media analyzed.
How does HHEAR ensure the quality of its analyses?
Quality assurance procedures begin with avoiding preanalytic contamination. If possible, the inclusion of “field blanks” in a study can help identify contamination from collection/storage sources. PTFE-free tubes, vials, and other materials should ideally be used during collection. Breast milk samples should be collected by manual expression to avoid potential contamination from breast pump components. Positive and negative controls are included in each analytic run because background contamination can be problematic.
What sample quality and quantity are necessary?
Typically, 0.1-1.0 mL of biological material or one gram of dust, 100 mL water, or 5 grams soil are used. Less volume usually translates to lower frequency of detection. Samples should have been collected to minimize PFAS contamination as described above.
References
Agency for Toxic Substances and Disease Registry (ATSDR). Perfluorinated Chemicals and Your Health.
Kato K, Wong LY, Chen A, et al. Changes in serum concentrations of maternal poly- and perfluoroalkyl substances over the course of pregnancy and predictors of exposure in a multiethnic cohort of Cincinnati, Ohio pregnant women during 2003-2006. Environmental Science & Technology. 2014;48(16):9600-9608.
Kato K, Wong LY, Jia LT, et al. Trends in exposure to polyfluoroalkyl chemicals in the U.S. population: 1999-2008. Environmental Science & Technology. 2011;45(19):8037-8045.
Lei M, Zhang L, Lei J, et al. Overview of emerging contaminants and associated human health effects. BioMed Research International. 2015;2015:404796.