Operationalizing the Exposome Using Passive Silicone Samplers

Abstract

The exposome, which is defined as the cumulative effect of environmental exposures and corresponding biological responses, aims to provide a comprehensive measure for evaluating non-genetic causes of disease. Operationalization of the exposome for environmental health and precision medicine has been limited by the lack of a universal approach for characterizing complex exposures, particularly as they vary temporally and geographically. To overcome these challenges, passive sampling devices (PSDs) provide a key measurement strategy for deep exposome phenotyping, which aims to provide comprehensive chemical assessment using untargeted high-resolution mass spectrometry for exposome-wide association studies. To highlight the advantages of silicone PSDs, we review their use in population studies and evaluate the broad range of applications and chemical classes characterized using these samplers. We assess key aspects of incorporating PSDs within observational studies, including the need to preclean samplers prior to use to remove impurities that interfere with compound detection, analytical considerations, and cost. We close with strategies on how to incorporate measures of the external exposome using PSDs, and their advantages for reducing variability in exposure measures and providing a more thorough accounting of the exposome. Continued development and application of silicone PSDs will facilitate greater understanding of how environmental exposures drive disease risk, while providing a feasible strategy for incorporating untargeted, high-resolution characterization of the external exposome in human studies.

Silicone Foam for Passive Sampling and Nontarget Analysis of Air

“…In future real-world applications, incorporating diffusive barriers into the deployment casings around PDMS could reduce variability between people or locations, but such barriers must be designed to minimally interfere with collection of the airborne fine particulate fraction. PDMS personal samplers are already used without calibration or diffusive barriers for fundamental studies of the airborne exposome, , but calibration studies will be necessary for future quantitative applications with PDMS foam. Integration of high-throughput open-science nontarget workflows will be a major advancement beyond traditional target analysis or suspect screening, thereby allowing spatial, temporal, or interindividual trends and rank orders for thousands of substances, even in the absence of absolute quantification.…”

“…48−51 Comparison of PDMS Foam and Sheet by LC-HRMS. As highlighted in a recent perspective, 22 the LC-MS analysis of PDMS air samplers has been limited to studies of wristbands by target analysis of priority pesticides, phenols, and environmental tobacco smoke. Here, nontarget analysis of PDMS air sampler extracts by LC-HRMS in positive (ESI+) and negative (ESI−) ionization modes allowed detection of greater than 24 times molecular features (n = 8387) than GC-HRMS (n = 350), revealing a vast diverse range of airborne analytes containing oxygen, nitrogen, sulfur, and chlorine atoms (Figure 2a).…”

“…Yet, measurements of the personal airborne chemical exposome (e.g., to organic chemicals and elements) remain a challenge, and its complex dynamic nature was recently demonstrated by nontarget mass spectrometry (MS) in a study of 15 individuals wearing portable pumps . Unfortunately, such devices are expensive and not easily scalable to health studies, but great promise comes from simple and lightweight wearable passive air samplers which are based on silicone (i.e., polydimethylsiloxane (PDMS; [Si­(CH 3 ) 2 O] n )), including thin films, sheets, or bracelets. − PDMS allows the passive absorption of semivolatile organic substances from the gas phase, including polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), oxy-PAHs, phthalates, pesticides, and flame retardants. ,− Most applications have focused on target analysis with low-resolution gas chromatography (GC)-MS, ,,, but recently PDMS stir bars housed in wristbands , were analyzed by nontarget GC high-resolution mass spectrometry (HRMS). Fewer studies have performed target analyses of PDMS samplers using low-resolution liquid chromatography (LC)-MS, ,− and to our knowledge, no studies have yet applied nontarget LC-HRMS to PDMS air samplers.…”

“…9−14 PDMS allows the passive absorption of semivolatile organic substances from the gas phase, including polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), oxy-PAHs, phthalates, pesticides, and flame retardants. 12,14−21 Most applications have focused on target analysis with low-resolution gas chromatography (GC)-MS, 11,18,22,23 but recently PDMS stir bars housed in wristbands 13,24 were analyzed by nontarget GC high-resolution mass spectrometry (HRMS). Fewer studies have performed target analyses of PDMS samplers using low-resolution liquid chromatography (LC)-MS, 22,25−27 studies have yet applied nontarget LC-HRMS to PDMS air samplers.…”

Longitudinal Mapping of Personal Biotic and Abiotic Exposomes and Transcriptome in Underwater Confined Space Using Wearable Passive Samplers

“…The external exposome spans environmental exposures to chemical, biological, and physical factors as well as behavioral aspects like diet and drug use . While measurements of the internal exposome are precise to the individual, current techniques for estimating the external exposome are limited, lacking the precision to characterize complex spatiotemporal biotic and abiotic exposures at the individual level …”