Exposome analysis

Wristbands (MyExposome, Inc, Philadelphia, PA) were worn by each cyclist to collect environmental samples¹⁷. The participants wore wristbands for three consecutive days during summer, cycling for 6 hours per city. 2 hours per day in average, during 3 sequential days in each city, depending on the weather conditions. All measurements were performed in duplicates (n = 2 cyclists). At the end of sampling campaign, all samples of hair swatches and bracelets exposed during outdoors experimental campaigns were labeled and stored in air tight polytetrafluoroethylene (PTFE) bags (Welch Fluorocarbon,Dover, NH, USA) and stored at −20 °C until analysis After deployment, field staff shipped the wristbands to Oregon State University (OSU) in PTFE bags. The wristbands were cleaned twice with 18 MΩ cm water and once with isopropanol to remove particles on the surface. The wristbands were immediately stored in amber jars at −20 °C until extraction. Briefly, each was spiked with extraction surrogates to account for extraction efficiency, then extracted twice in 100 mL ethyl acetate at room temperature using an orbital shaker set at 60 rotations per minute and quantitatively concentrated using TurboVap® closed cell evaporators (Biotage LLC, Charlotte, NC, USA). All of the sample collections took place in 2016¹⁵.

Each wristband was analyzed and screened for 1,529 compounds as described previously¹⁸. Every chemical in the testing is classified into one or more of the categories presented in Table 1. The list was achieved by adding approximately 450 chemicals to libraries purchased with the deconvolution software. Single component standards (analytical grade) were prepared from neat or purchased in ethyl acetate, methylene chloride, n-hexane, or isooctane at a concentration between 0.5 and 10 ng/μL. Mass spectra and retention time for each new chemical were acquired using the GC-MS method described above and added to a new ChemStation probability-based matching library. Each entry included chemical name, retention time, retention index (retention time in seconds), mass spectra, molecular formula (from which the software generates MW) and Chemical Abstracts Service registration number (CASRN). After new chemicals were added, the new library was appended to the master library. AMDIS library files and an updated method file were then generated from this master library using ChemStation software¹⁶.

Wristband chemicals classification and description.