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Chemometers for in situ risk assessment of mixtures of pollutants

Periodic Reporting for period 4 - CHEMO-RISK (Chemometers for in situ risk assessment of mixtures of pollutants)

Berichtszeitraum: 2021-11-01 bis 2023-07-31

The overall goal of CHEMO-RISK was to develop a novel framework to assess the entirety of chemicals that environmental organisms as well as humans are exposed to, i.e. the so-called “chemical exposome” and its potential effects in the Planetary Health context. The CHEMO-RISK team addressed this overall goal in four subprojects addressing the following questions: (A) Which processes drive the enrichment of pollutants from the abiotic environment to aquatic biota of different trophic levels? (B) How do pollutant patterns, levels and their mixture effects differ across key tissues of stranded marine mammals? (C) How useful are non-invasive “chemometers” applied in human cohort studies in describing the internal exposure of the study participants? (D) Can “chemometer” samplers combined with non-target screening elucidate unknown yet relevant bioaccumulative chemicals?

The totality of life-long chemical exposure has been coined in the exposome concept. At the same time, the Planetary Health concept acknowledges the interconnectedness of human and environmental health. We successfully established functional chemometers for subprojects A, B and C to transfer mixtures of environmental pollutants from diverse environmental media (sediment, suspended particulate matter, water, biota of different trophic levels) and body compartments (lipid tissue, brain, liver and kidney of marine mammals) to the laboratory. However, the exploration of the opportunities for broad nontarget screening for the identification of potentially problematic, yet unknown compounds (subproject D) is still in progress.
We published a feature article about “chemometers” and their applications that gives a very good overview of CHEMO-RISK and the diverse aspects and challenges addressed in subprojects A, B, C and D (Rojo-Nieto & Jahnke 2023, doi: https://doi.org/10.1039/D2CC06882F).
In (A) we developed chemometers for lean biota tissues (Rojo-Nieto et al. 2019 https://doi.org/10.1016/j.chemosphere.2018.12.134) and water that were applied for multimedia sampling at the Swedish background site Lake Angen. We sampled a diverse set of fish species, mussels and crayfish as well as sediment across the lake and sampled freely dissolved chemicals from water using two silicone “chemometers”. We compared Csilicone⇌medium for all media to assess trophic magnification factors (TMFs) and observed explicit biomagnification of hydrophobic, persistent organic pollutants, interpreted using stable isotope ratios of nitrogen. However, compared to sediments and water, the biota showed underequilibration, which may result from fast-growing and short-lived algae at the bottom of the food chain being below equilibrium partitioning regarding sediment. Rojo-Nieto et al. manuscript; Wernicke et al. 2022a (https://doi.org/10.1016/j.ecoenv.2022.113285); Wernicke et al. 2022b (https://doi.org/10.1186/s12302-022-00644-w).

In (B) we developed chemometers to assess the internal exposure and effects in liver, kidney, brain and lipid tissue of diverse marine mammal species from the German North and Baltic Sea. The chemometer extracts were submitted to bioanalytical screening in four cellular reporter gene bioassays, with liver samples usually eliciting the strongest effects. Furthermore, the chemometer extracts were submitted to chemical screening using gas chromatographic separation and high-resolution mass spectrometric determination of about 70 compounds (GC/HRMS, Muz et al. 2020 https://doi.org/10.1021/acs.est.0c05537). We also characterized the influence of co-dosed lipids on the response of the bioassays. These data served to extend a model to correct data for the reduced bioavailability in the bioassay system. Reiter et al. 2019 (https://doi.org/10.1021/acs.est.9b07850); Reiter et al. 2022 (https://doi.org/10.1016/j.envint.2022.107337); Reiter et al. 2023 (https://doi.org/10.1039/D3EM00033H).

In (C) we developed chemometer plasters for the chemicals eliminated via human skin. A “sandwich” experiment tested chemical transfer from a ”donor” to an ”acceptor”. We further assessed whether the uptake into the silicone occurred mainly from the skin or the surrounding air using activated carbon as shielding layer. A pilot study investigated exposure times of 1-5 days on the upper thigh, compared with established silicone wristbands and blood. A separate method using thermodesorption and GC-MS/MS was established for a set of relevant compounds. Then, 100 cohort study participants wore the optimized sampler format along with the established wristband format and donated a blood sample to compare the patterns and levels of pollutants. This high risk/high gain project is in manuscript form: Abel et al. manuscript a; Abel et al. in manuscript b.

In (D) we aimed for suspect and non-target profiling to (i) establish a multi-target method for 150 persistent organic chemicals (Muz et al. 2020 ii develop a non-discriminatory clean-up for silicone-based chemometer extracts (Muz et al. 2021 https://doi.org/10.1002/etc.5153) and (iii) screen chemometer samples for peak patterns of potentially problematic chemicals. Pattern analysis in ”chemometer” extracts of diverse fish species covering different trophic levels from a contaminated site (Muz et al. manuscript) and investigating the chemometer extracts from different tissues of marine mammals (Schacht et al. manuscript) has been performed to explore the pattern analysis. Furthermore, a method that allows for the challenging analysis of polychlorinated and polybrominated dibenzodioxins and furans in liver samples of deer from different German regions has been established.
The progress beyond the state-of-the-art covered: (i) a multi-target screening method for 150 legacy and emerging pollutants with diverse physico-chemical properties (ii a non-discriminatory clean-up method, a vital step to allow for GC/HRMS analysis without severely contaminating the analytical system (iii multimedia equilibrium passive samplers of a broad range of compounds using silicone-based „chemometers“ for sediments, diverse biota tissues (https://doi.org/10.1016/j.chemosphere.2018.12.134 https://doi.org/10.1016/j.envint.2022.107337) non-invasive human samples (Abel et al. manuscript a) and for some compounds also for the water phase (Rojo-Nieto et al. manuscript) to study diffusion, partitioning, bioaccumulation and fate including source/sink considerations between compartments/media; (iv) improved understanding of the role of co-dosed lipids from in tissue chemometers in bioassays (https://doi.org/10.1021/acs.est.9b07850) and characterization of chemometer extracts in bioassays (https://doi.org/10.1016/j.envint.2022.107337) and chemical profiling including linking the results to the observed effects using iceberg modeling (v application of the chemometers, comparing them with established samplers to assess their prediction power for the pollutant levels in human blood (Abel et al. manuscript b); (vi) pattern analysis for the identification of potentially problematic, yet unknown pollutants (Muz et al. manuscript, Schacht et al. manuscript).

More information can be found on the project website at www.ufz.de/chemo-risk.
CHEMO-RISK subprojects