How We Did The Study
Each of our 10 participants wore a personal sampling device for an entire day during normal activities such as working, caring for their families, running errands, and socializing. The sampling device meets air particulate sampling protocols established by the U.S. government and key professional organization (see below for details). The sampling device used a pump to move air in the individual’s breathing zone through two filters designed to capture air particulates of two different sizes. Previous research has found that personal air sampling like this captures higher concentrations of flame retardants than sampling of room air, due to the “Pigpen effect”—the personal dust cloud each of us carries with us.
Air filters from the sampling device were shipped to a laboratory where our research collaborators at the Virginia Institute of Marine Science analyzed them for a wide range of toxic flame retardants including TCEP, TCPP, and TDCPP.
Air sampling method:
Air particulates were collected using an AirChek 2000 pump (flow rate 2 L min-1) with an Institute of Occupational Medicine (IOM) Sampler equipped with a stainless steel cassette assembly . Participants were instructed to wear the IOM sampler affixed to a collar continually during a 24-hour day during normal activities, including at home and at work, traveling to and from home and work, shopping, and socializing, and to wear or hang the sampler at breathing zone level during sleep. Time of collection ranged from 12.9 to 24.6 hours. The IOM sampler meets air particulate sampling criteria established by the American Conference of Governmental Industrial Hygienists (ACGIH) and the Occupational Safety and Health Administration (OSHA).Two size classes of air particulates were examined: 1) inhalable particulates (> 4 µm, nominal), that can either enter the lung airways (trachea, bronchi and their branches) or are trapped on the mucosa of the nose, mouth and lungs and then are expelled or swallowed. These were collected with a MultiDust® foam disc of a specific porosity (D50) of 4 µm (D50: the particle aerodynamic diameter for which 50% of the particles penetrate). This was placed inside the stainless steel cassette assembly, positioned at the IOM inlet; 2) smaller respirable air particulates (< 4 µm, nominal) which are able to penetrate deep inside the lung’s gas-exchange regions were collected on a 25-mm, 1.0 µm glass fiber filter placed in series behind the foam disc within the cassette. After collection, all sample cassettes were placed in SKC’s transportation clip with cover and stored <4o C in double sealed plastic bags until analyzed.
Analytical protocol (Extraction, purification and analysis):
Air particulate samples (disc and filter) were analyzed for ClOPFRs (i.e. TCEP, TCPP and TDCPP) as described by La Guardia et al.. Briefly, samples were spiked with a surrogate standard (deuterated tris (1,3-dichloro-2-propyl)phosphate (dTDCPP), Max Planck Institute for Biophysical Chemistry, Germany) and extracted with methylene chloride (DCM) in a Dionex ASE 200 accelerated solvent extractor (Sunnyvale, CA, USA) at 100o C and 68 atm. Each extract was then purified on a 2 gm silica solid phase extraction column (International Sorbent Tech.; Hengoed Mid Glamorgan, UK) eluted with 3.5-mL hexane (Fraction 1), followed by 6.5 mL of 60:40 hexane/DCM and then 8 mL DCM (Fraction 2) and 5 mL 50:50 acetone/DCM (Fraction 3). Fraction 3 containing the analytes of interest was reduced; solvent exchanged to methanol and decachlorodiphenyl ether (DCDE, AccuStandards, Inc.) was added as the internal standard. Analytes within each purified extract were further separated by ultra-performance liquid chromatography (UPLC, Waters Corp. Milford, MA, USA) and analyzed by atmospheric pressure photoionization tandem mass spectrometry (APPI/MS/MS, Q-Trap3200 MS, AB Sciex, Framingham, MA. USA).