Is It Realistic to Propose Determination of a Lifetime Internal Exposome?

High-Resolution Mass Spectrometry for Human Exposomics: Expanding Chemical Space Coverage

In the modern "omics" era, measurement of the human exposome is a critical missing link between genetic drivers and disease outcomes. High-resolution mass spectrometry (HRMS), routinely used in proteomics and metabolomics, has emerged as a leading technology to broadly profile chemical exposure agents and related biomolecules for accurate mass measurement, high sensitivity, rapid data acquisition, and increased resolution of chemical space. Non-targeted approaches are increasingly accessible, supporting a shift from conventional hypothesis-driven, quantitation-centric targeted analyses toward data-driven, hypothesis-generating chemical exposome-wide profiling. However, HRMS-based exposomics encounters unique challenges. New analytical and computational infrastructures are needed to expand the analysis coverage through streamlined, scalable, and harmonized workflows and data pipelines that permit longitudinal chemical exposome tracking, retrospective validation, and multi-omics integration for meaningful health-oriented inferences. In this article, we survey the literature on state-of-the-art HRMS-based technologies, review current analytical workflows and informatic pipelines, and provide an up-to-date reference on exposomic approaches for chemists, toxicologists, epidemiologists, care providers, and stakeholders in health sciences and medicine. We propose efforts to benchmark fit-for-purpose platforms for expanding coverage of chemical space, including gas/liquid chromatography-HRMS (GC-HRMS and LC-HRMS), and discuss opportunities, challenges, and strategies to advance the burgeoning field of the exposome.

"Isocyanates and isocyanides - life-threatening toxins or essential compounds?"

Isocyanides and isocyanates are some of the most reactive compounds in organic chemistry, making them perceived as compounds with high potential for use in both the laboratory and industry. With their high reactivity also comes several disadvantages, most notably their potentially high toxicity. The following article is a collection of information on the toxic effects of the isocyanide group on the human body and the environment. Information on the mechanism of how these harmful substances affect living tissues and the environment, worldwide information on how to protect against these chemicals, current regulations, and exposure limits for specific countries is compiled. The latest research on the application uses of isocyanates and isocyanides is also outlined, as well as the latest safer and greener methods and techniques to work with these compounds. Additionally, the presented article can serve as a brief guide to the organic toxicity of a group of isocyanates and isocyanates.

Linking Toxicology and Human Health Through the Exposome

Current analytical technology and continuing maturation of -omics methodology have enabled detailed assessment of human exposure via the exposome. Topics exploring the connection between etiology of disease and toxicology were presented at the 2023 Fall American Chemical Society meeting.

Pathways to Identify Electrophiles In Vivo Using Hemoglobin Adducts: Hydroxypropanoic Acid Valine Adduct and Its Possible Precursors

Analytical methods and tools for the characterization of the human exposome by untargeted mass spectrometry approaches are advancing rapidly. Adductomics methods have been developed for untargeted screening of short-lived electrophiles, in the form of adducts to proteins or DNA, in vivo. The identification of an adduct and its precursor electrophile in the blood is more complex than that of stable chemicals. The present work aims to illustrate procedures for the identification of an adduct to N-terminal valine in hemoglobin detected with adductomics, and pathways for the tracing of its precursor and possible exposure sources. Identification of the adduct proceeded via preparation and characterization of standards of adduct analytes. Possible precursor(s) and exposure sources were investigated by measurements in blood of adduct formation by precursors in vitro and adduct levels in vivo. The adduct was identified as hydroxypropanoic acid valine (HPA-Val) by verification with a synthesized reference. The HPA-Val was measured together with other adducts (from acrylamide, glycidamide, glycidol, and acrylic acid) in human blood (n = 51, schoolchildren). The HPA-Val levels ranged between 6 and 76 pmol/g hemoglobin. The analysis of reference samples from humans and rodents showed that the HPA-Val adduct was observed in all studied samples. No correlation of the HPA-Val level with the other studied adducts was observed in humans, nor was an increase in tobacco smokers observed. A small increase was observed in rodents exposed to glycidol. The formation of the HPA-Val adduct upon incubation of blood with glycidic acid (an epoxide) was shown. The relatively high adduct levels observed in vivo in relation to the measured reactivity of the epoxide, and the fact that the epoxide is not described as naturally occurring, suggest that glycidic acid is not the only precursor of the HPA-Val adduct identified in vivo. Another endogenous electrophile is suspected to contribute to the in vivo HPA-Val adduct level.

New Method to Biomonitor Workers Exposed to 1,6-Hexamethylene Diisocyanate

Isocyanates such as 1,6-hexamethylene diisocyanate (HDI), 4,4'-methylenediphenyl diisocyanate, and toluene diisocyanate are highly reactive compounds that have a variety of commercial applications, including manufacturing polyurethane foam, elastomers, paints, adhesives, coatings, insecticides, and many other products. Their primary route of occupational exposure is through inhalation. Due to their high chemical reactivity, they are toxic and have adverse effects at the cellular and subcellular levels, leading to irritative and immunological reactions associated with lung disease. High concentrations of isocyanates are strong respiratory irritants. Bronchial sensitization and asthma are among the major adverse clinical reactions associated with low-level chronic exposure to isocyanates. Albumin adducts have been linked to the mechanism of occupational asthma caused by isocyanates. Isocyanates react in vivo with albumin, which is recognized by the immune system. Albumin adducts of isocyanates trigger immune responses and are probably the antigenic basis for isocyanate asthma. Sensitization to isocyanates is the main pathway for adverse health effects. Therefore, markers for the biologically effective dose such as albumin adducts of HDI are needed. A new isocyanate adduct of HDI with lysine─N^ε-[(6-amino-hexyl-amino)carbonyl]-lysine (HDI-Lys)─was synthesized and characterized by ¹H-NMR, ¹³C-NMR, and mass spectrometry (MS). Appropriate internal standards─HDI-Lys-4,4'-5,5'-d₄ (HDI-d₄-Lys) and N^ε-[(7-amino-heptyl-amino)carbonyl]-lysine (Hep-Lys)─were synthesized to establish a LC-MS/MS method for the analysis of HDI adducts in in vitro modified albumin and in workers. The presence of HDI-Lys was found after pronase digestion of albumin and confirmed by two independent chromatographic approaches: with a C8 reversed-phase column and with a hydrophilic interaction liquid chromatography column. Quantification was performed with positive electrospray ionization (ESI)-MS. The adduct peak found in vivo was confirmed with the less sensitive negative ESI-MS. In summary, these are new compounds and methods to determine isocyanate-specific adducts with albumin in workers exposed to HDI.

Literature review and evaluation of biomarkers, matrices and analytical methods for chemicals selected in the research program Human Biomonitoring for the European Union (HBM4EU)

Humans are potentially exposed to a large amount of chemicals present in the environment and in the workplace. In the European Human Biomonitoring initiative (Human Biomonitoring for the European Union = HBM4EU), acrylamide, mycotoxins (aflatoxin B1, deoxynivalenol, fumonisin B1), diisocyanates (4,4'-methylenediphenyl diisocyanate, 2,4- and 2,6-toluene diisocyanate), and pyrethroids were included among the prioritized chemicals of concern for human health. For the present literature review, the analytical methods used in worldwide biomonitoring studies for these compounds were collected and presented in comprehensive tables, including the following parameter: determined biomarker, matrix, sample amount, work-up procedure, available laboratory quality assurance and quality assessment information, analytical techniques, and limit of detection. Based on the data presented in these tables, the most suitable methods were recommended. According to the paradigm of biomonitoring, the information about two different biomarkers of exposure was evaluated: a) internal dose = parent compounds and metabolites in urine and blood; and b) the biologically effective = dose measured as blood protein adducts. Urine was the preferred matrix used for deoxynivalenol, fumonisin B1, and pyrethroids (biomarkers of internal dose). Markers of the biological effective dose were determined as hemoglobin adducts for diisocyanates and acrylamide, and as serum-albumin-adducts of aflatoxin B1 and diisocyanates. The analyses and quantitation of the protein adducts in blood or the metabolites in urine were mostly performed with LC-MS/MS or GC-MS in the presence of isotope-labeled internal standards. This review also addresses the critical aspects of the application, use and selection of biomarkers. For future biomonitoring studies, a more comprehensive approach is discussed to broaden the selection of compounds.

Comprehensive profiling and kinetic studies of glycated lysine residues in human serum albumin

Lysine residues of proteins slowly react with glucose forming Amadori products. In hyperglycemic conditions, such as diabetes mellitus, this non-enzymatic glycation becomes more pervasive causing severe medical complications. The structure and conformation of a protein predisposes lysine sites to differing reactivity influenced by their steric availability and amino acid microenvironment. The goal of our study was to identify these sites in albumin and measure glycation affinities of lysine residues. We applied a bottom-up approach utilizing a combination of three LC-MS instruments: timsTOF, Orbitrap, and QTRAP. To prove applicability to samples of varying glycemic status, we compared in vitro glycated and non-glycated HSA, as well as diabetic and non-diabetic individual samples. The analysis of lysine glycation affinities based on peptide intensities provide a semi-quantitative approach, as the results depend on the mass spectrometry platform used. We found that glycation levels based on multiple reaction monitoring (MRM) quantitation better reflect individual glycemic status and that the glycation percentage for each site is in linear relation to all other sites. To develop an approach which more accurately reflects glycation affinity, we developed a kinetics model which uses results from stable isotope dilution HPLC-MRM methodology. Through glycation of albumin at different glucose concentrations, we determine the rate constants of glycation for every lysine residue by simultaneous comparative analysis.

Merging the exposome into an integrated framework for “omics” sciences

The exposome concept encourages holistic consideration of the non-genetic factors (environmental exposures including lifestyle) that influence an individual’s health over their life course. However, disconnect between the concept and practical application has promoted divergent interpretations of the exposome across disciplines and reinforced separation of the environmental (emphasizing exposures) and biological (emphasizing responses) research communities. In particular, while knowledge of biological responses can help to distinguish actual (i.e. experienced) from potential exposures, the inclusion of endogenous processes has generated confusion about the position of the exposome in a multi-omics systems biology context. We propose a reattribution of “exposome” to exclusively represent the totality of contact with external factors that a biological entity experiences, and introduce the term “functional exposomics” to denote the systematic study of exposure-phenotype interaction. This reoriented definition of the exposome allows a more readily integrable dataset for multi-omics and systems biology research.

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Reattribution of exposome concept to exclusively represent environmental exposures

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Generalized the exposome concept for all levels of biological organization

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Functional exposome presented as the totality of exposure-phenotype interaction

How to design a national genomic project-a systematic review of active projects

An increasing number of countries are investing efforts to exploit the human genome, in order to improve genetic diagnostics and to pave the way for the integration of precision medicine into health systems. The expected benefits include improved understanding of normal and pathological genomic variation, shorter time-to-diagnosis, cost-effective diagnostics, targeted prevention and treatment, and research advances.We review the 41 currently active individual national projects concerning their aims and scope, the number and age structure of included subjects, funding, data sharing goals and methods, and linkage with biobanks, medical data, and non-medical data (exposome). The main aims of ongoing projects were to determine normal genomic variation (90%), determine pathological genomic variation (rare disease, complex diseases, cancer, etc.) (71%), improve infrastructure (59%), and enable personalized medicine (37%). Numbers of subjects to be sequenced ranges substantially, from a hundred to over a million, representing in some cases a significant portion of the population. Approximately half of the projects report public funding, with the rest having various mixed or private funding arrangements. 90% of projects report data sharing (public, academic, and/or commercial with various levels of access) and plan on linking genomic data and medical data (78%), existing biobanks (44%), and/or non-medical data (24%) as the basis for enabling personal/precision medicine in the future.Our results show substantial diversity in the analysed categories of 41 ongoing national projects. The overview of current designs will hopefully inform national initiatives in designing new genomic projects and contribute to standardisation and international collaboration.

A review of the impact of xenobiotics from dietary sources on infant health: Early life exposures and the role of the microbiota

Xenobiotics are worldwide distributed and humans are unavoidably exposed to multiple chemical compounds during life, from preconception to adulthood. The human microbiota is mainly settled during early life and modulate host health and fitness. One of the main routes for chemical exposure is by intake of contaminated food and water. Thus, the interplay between diet-xenobiotics-microbiota during pregnancy and perinatal period may have relevant consequences for infant and adult health. Maternal exposure to metal(oid)s, persistent organic pollutants, and some food additives can modify the infant's microbiota with unknown consequences for child or adult health. Toxicants' exposure may also modulate the maternal transfer of microorganisms to the progeny during birth and breastfeeding; however, scarce information is available. The rapid increase in releasing novel chemicals to the environment, the exposure to chemical mixtures, the chronic/low dose scenario, and the delay in science-stakeholders action call for novel and groundbreaking approaches to improve a comprehensive risk assessment in sensitive population groups like pregnant women and neonates, with emphasis on microbiota as modulating factor and target-organ of xenobiotic's toxicity.

Increase in aflatoxin exposure in two populations residing in East and West Texas, United States

Although aflatoxin (AF) exposure has not been recognized as a major problem in the United States and other developed nations, recent global climate change may have a profound impact on distribution of toxigenic fungi growth and production of AFs in grain and groundnuts. Alterations in the contamination pattern can increase human dietary exposure, and further invoke public health concerns and associated disease risks. In this study, two populations from East and West Texas, known for their high risk of liver cancer, were examined for their AF exposure at three different time periods from 2004 to 2014. Serum samples (n = 1124) were collected from participants recruited for various studies from Bexar County and Lubbock County, TX, over the span of 2004 through 2014. The exposure biomarker, serum AFB₁-lysine adduct, was analyzed by HPLC-FLD and confirmed by LC-MS. Both populations showed a significant increase in detection rate, as well as median levels of serum AFB₁-lysine adduct over time, from 2.35 to 4.34 pg/mg albumin in East Texas (2007-2014), and 0.63-3.98 pg/mg albumin in West Texas (2004-2010). This observed shift in exposure likely represents a shift in the AF contamination pattern in the State of Texas, and may warrant further studies on risk assessment for the potential etiological effects of such increased exposures.