Self-Collection Blood Test for PFASs: Comparing Volumetric Microsamplers with a Traditional Serum Approach

Low-Temperature Mineralization of Fluorotelomers with Diverse Polar Head Groups

Per- and polyfluoroalkyl substances (PFAS) are persistent environmental pollutants linked to harmful health effects. Currently employed PFAS destruction methods are energy-intensive and often produce shorter-chain and recalcitrant partially fluorinated byproducts. We report the mineralization of five fluorotelomer compounds via a base-mediated degradation using NaOH and mild temperatures (120 °C) in a mixture of DMSO:H2O (8:1 v/v). The studied fluorotelomers have varying polar head groups-carboxylic acids, sulfonic acids, alcohols, and phosphonic acids, which are the most common polar head groups used in commercial and industrial applications. The degradation intermediates and byproducts were characterized using 1H, 13C, and 19F NMR spectroscopy. Density functional theory computations at the M06-2X/6-311 + G(2d,p)-SMD-(DMSO) level were consistent with the observed intermediates and guided an overall mechanistic hypothesis. Degradation of each fluorotelomer occurs through a similar process, in which the nonfluorinated carbons and the first fluorinated carbon are cleaved from the remaining perfluoroalkyl fragment, which degrades through previously identified pathways. These findings provide important insight into PFAS degradation processes and suggest that PFAS containing at least one C-H bond within or adjacent to its fluoroalkyl chain can be degraded under these mild conditions. Many PFAS in current use as well as recalcitrant fluorinated byproducts generated from other PFAS degradation methods are candidates for this approach.

Quantifying levels of per- and polyfluoroalkyl Substances (PFAS) in water and serum after contamination from agricultural biosolid application

The National Academies of Sciences, Engineering, and Medicine recommends per- and polyfluoroalkyl substance (PFAS) blood testing for patients with risk of elevated exposure, and the Agency for Toxic Substances and Disease Registry (ATSDR) suggests PFAS blood testing based on exposure. Barriers to PFAS blood testing include cost, access to labs, and evolving laboratory methods. We quantify water and serum PFAS levels among a highly-exposed cohort in an area with groundwater contaminated by historical agricultural biosolid application. We compare the gold standard PFAS serum test with a commercial test and results from a one-compartment toxicokinetic model. Participants were adults (n = 30) whose household (n = 19) water had levels of the sum of six PFAS > 500 ng/L. Serum PFAS were measured using liquid chromatography-tandem mass spectrometry. Demographic and water consumption data were collected via telephone. Serum PFAS results from the commercial test were accessed via medical record. Statistical analysis included descriptive statistics and bivariate plots of serum levels. Perfluorohexanoic acid, perfluoroheptanoic acid (PFHpA), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorobutanesulfonic acid, perfluorohexanesulfonic acid (PFHxS), and perfluorooctanesulfonic acid (PFOS) were detected in 19 wells, and PFHpA, PFOA, PFNA, perfluorodecanoic acid, perfluoroundecanoic acid, PFHxS, and PFOS were detected in at least 19 participants' serum. In well water, PFOA and PFOS levels had geometric means (GMs) of 1749 ng/L (geometric standard deviation [GSD] 2.4) and 887 ng/L (GSD 19.7), respectively. In serum, PFOA and PFOS had GMs of 116.2 µg/L (GSD 13.5) and 58.3 µg/L (GSD 13.8), respectively. Our results are comparable with and had a wider mix of PFAS than other high-exposure cohorts. There was good agreement between the commercial and gold standard tests for PFOA, PFNA, and PFHxS, and mixed agreement between the gold standard test and modeled predictions, suggesting water-based toxicokinetic models of serum PFAS may be inadequate for assessing exposure in this population.

Comparison of maternal venous blood metabolomics collected as dried blood spots, dried blood microsamplers, and plasma for integrative environmental health research

Use of capillary blood devices for exposome research can deepen our understanding of the intricate relationship between environment and health, and open up new avenues for preventive and personalized medicine, particularly for vulnerable populations. While the potential of these whole blood devices to accurately measure chemicals and metabolites has been demonstrated, how untargeted metabolomics data from these samplers can be integrated with previous and ongoing environmental health studies that have used conventional blood collection approaches is not yet clear. Therefore, we performed a comprehensive comparison between relative-quantitative metabolite profiles measured in venous blood collected with dried whole blood microsamplers (DBM), dried whole blood spots (DBS), and plasma from 54 mothers in an ethnically diverse population. We determined that a majority of the 309 chemicals and metabolites showed similar median intensity rank, moderate correlation, and moderate agreement between participant-quantiled intraclass correlation coefficients (ICCs) for pair-wise comparisons among the three biomatrices. In particular, whole blood sample types, DBM and DBS, were in highest agreement across metabolite comparison metrics, followed by metabolites measured in DBM and plasma, and then metabolites measured in DBS and plasma. We provide descriptive characteristics and measurement summaries as a reference database. This includes unique metabolites that were particularly concordant or discordant in pairwise comparisons. Our results demonstrate that the range of metabolites from untargeted metabolomics data collected with DBM, DBS, and plasma provides biologically relevant information for use in independent exposome investigations. However, before meta-analysis with combined datasets are performed, robust statistical approaches that integrate untargeted metabolomics data collected on different blood matrices need to be developed.

Validation of Mitra® VAMS® as a blood collection technique for trace elements analysis using ICP-MS/MS

Background: Clinical dosage of toxic and essential elements in blood is well established and the collection method is still by venipuncture. This method has drawbacks and is not suited for everyone. Volumetric absorptive microsampling (VAMS) has been shown to have advantages over venipuncture. Materials & methods: Using inductively coupled plasma tandem mass spectrometry, a method for quantifying elements in whole blood sampled on VAMS was developed/validated. Method's performance was assessed by comparison with whole blood results. Results: Validation and performance assessment tests tend to show that most of the targeted elements provides accurate and reproducible results comparing to a method of reference. Conclusion: Overall, VAMS presents good preliminary results to eventually become an alternative to venipuncture for blood sampling for some trace elements analysis purposes.

Validating blood microsampling for per- and polyfluoroalkyl substances quantification in whole blood

Microsampling allows the collection of blood samples using a method which is inexpensive, simple and minimally-invasive, without the need for specially-trained medical staff. Analysis of whole blood provides a more holistic understanding of per- and polyfluoroalkyl substances (PFAS) body burden. Capillary action microsamplers (Trajan hemaPEN®) allow the controlled collection of whole blood as dried blood spots (DBS) (four 2.74 µL ± 5 %). The quantification of 75 PFAS from DBS was evaluated by comparing five common extraction techniques. Spiked blood (5 ng/mL PFAS) was extracted by protein precipitation (centrifuged; filtered), acid-base liquid-liquid extraction, trypsin protease digestion, and weak anion exchange (WAX) solid-phase extraction with analysis by high-performance liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Filtered protein precipitation was the most effective extraction method, recovering 72 of the 75 PFAS within 70 to 130 % with method reporting limit (MRL) for PFOS of 0.17 ng/L and ranging between 0.05 ng/mL and 0.34 ng/mL for all other PFAS. The optimised method was applied to human blood samples to examine Inter- (n = 7) and intra-day (n = 5) PFAS blood levels in one individual. Sixteen PFAS were detected with an overall Σ16PFAS mean = 6.3 (range = 5.7-7.0) ng/mL and perfluorooctane sulfonate (branched and linear isomers, ΣPFOS) = 3.3 (2.8-3.7) ng/mL being the dominant PFAS present. To the authors knowledge, this minimally invasive self-sampling protocol is the most extensive method for PFAS in blood reported and could be a useful tool for large scale human biomonitoring studies.

Analytical methods employed in the identification and quantification of per- and polyfluoroalkyl substances in human matrices - A scoping review

Persistent organic pollutants (POPs) represent a possible hazard for the ecosystems, with adverse outcomes on wildlife and humans. POPs have always received interest from the scientific community, and they have also been subject to legal restrictions worldwide on their application and commercialization. Among the broad spectrum of POPs, per- and polyfluoroalkyl substances (PFASs) are considered emerging contaminants due to their potential effect on the ecosystem and human health. These contaminants are widely employed in countless applications, from surfactants and building materials to food packaging. On the other hand, their chemical structure gives them the ability to interact with the environment, causing possible toxic effects for humans and environment. Human biomonitoring is a necessary instrument to indagate the impact of PFASs on human health: in recent years several studies have found detectable levels of PFASs in several biological matrices in humans (blood, hair, nails, and urine). Here, we review the most recent scientific literature concerning analytical methods employed in the identification and quantification of PFASs focusing on biological matrices. It has been noted that liquid chromatography coupled with mass spectrometry is the main analytical instrumentation employed, while blood and/or serum samples are the main employed human matrices whereas the use of non-invasive matrices is still at the beginning. Various issues directly related to human metabolism of PFASs and the effective amount of PFAS absorbed from the environment still need to be investigated.

Detail study on the interaction between perfluorooctanoic acid (PFOA) with human hemoglobin (Hb)

Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) are often referred to as legacy perfluoroalkyl substances (PFAS). Human exposure to PFAS leads to severe negative health impacts including cancers, infertility, and dysfunction in the kidneys. Steady-state absorbance, fluorescence, and circular dichroism (CD) methods were used to study the interactions between PFOA and Hb. The results demonstrate the presence of multiple PFOA binding sites on the Hb protein. The detailed analysis of the ferric hemoglobin protein (met Hb) absorbance data as a function of PFOA concentration indicates the presence of at least two binding sites with equilibrium dissociation constants of 0.8 ± (0.2) × 10-6 M and 63 ± (15) × 10-5 M. A competitive binding study with 1,8-ANS showed PFOA can bind to the same binding site as 1,8-ANS on the Hb protein. The titration curve for PFOA binding to Hb in its CO bound form (CO-Hb) yields a single equilibrium dissociation constant of 139 ± (20) × 10-6 M. PFOA binding at low concentrations occurs at the high-affinity sites leading to the destabilization of the protein structure as reflected by changes in the CD spectrum. PFOA interactions with Hb also interfere with the kinetics of CO association to this protein. The rate for CO association to Hb increases at low PFOA concentrations, whereas at elevated PFOA concentrations, the ligand association is biphasic as a new kinetic process with a different rate constant was observed. Overall, this study provides a detailed explanation of PFOA-induced structural and conformational changes to the Hb protein based on the spectroscopy data.