Bioaccumulation of therapeutic drugs by human gut bacteria.

Bacteria in the gut can modulate the availability and efficacy of therapeutic drugs. However, the systematic mapping of the interactions between drugs and bacteria has only started recently1 and the main underlying mechanism proposed is the chemical transformation of drugs by microorganisms (biotransformation). Here we investigated the depletion of 15 structurally diverse drugs by 25 representative strains of gut bacteria. This revealed 70 bacteria-drug interactions, 29 of which had not to our knowledge been reported before. Over half of the new interactions can be ascribed to bioaccumulation; that is, bacteria storing the drug intracellularly without chemically modifying it, and in most cases without the growth of the bacteria being affected. As a case in point, we studied the molecular basis of bioaccumulation of the widely used antidepressant duloxetine by using click chemistry, thermal proteome profiling and metabolomics. We find that duloxetine binds to several metabolic enzymes and changes the metabolite secretion of the respective bacteria. When tested in a defined microbial community of accumulators and non-accumulators, duloxetine markedly altered the composition of the community through metabolic cross-feeding. We further validated our findings in an animal model, showing that bioaccumulating bacteria attenuate the behavioural response of Caenorhabditis elegans to duloxetine. Together, our results show that bioaccumulation by gut bacteria may be a common mechanism that alters drug availability and bacterial metabolism, with implications for microbiota composition, pharmacokinetics, side effects and drug responses, probably in an individual manner.

Uncovering global-scale risks from commercial chemicals in air.

Commercial chemicals are used extensively across urban centres worldwide1, posing a potential exposure risk to 4.2 billion people2. Harmful chemicals are often assessed on the basis of their environmental persistence, accumulation in biological organisms and toxic properties, under international and national initiatives such as the Stockholm Convention3. However, existing regulatory frameworks rely largely upon knowledge of the properties of the parent chemicals, with minimal consideration given to the products of their transformation in the atmosphere. This is mainly due to a dearth of experimental data, as identifying transformation products in complex mixtures of airborne chemicals is an immense analytical challenge4. Here we develop a new framework-combining laboratory and field experiments, advanced techniques for screening suspect chemicals, and in silico modelling-to assess the risks of airborne chemicals, while accounting for atmospheric chemical reactions. By applying this framework to organophosphate flame retardants, as representative chemicals of emerging concern5, we find that their transformation products are globally distributed across 18 megacities, representing a previously unrecognized exposure risk for the world's urban populations. More importantly, individual transformation products can be more toxic and up to an order-of-magnitude more persistent than the parent chemicals, such that the overall risks associated with the mixture of transformation products are also higher than those of the parent flame retardants. Together our results highlight the need to consider atmospheric transformations when assessing the risks of commercial chemicals.

Competition of Cd(II) and Pb(II) on the bacterial cells: a new insight from bioaccumulation based on NanoSIMS imaging.

Polymetallic exposure causes complex toxicity to microorganisms. In this study, we investigated the responses of Escherichia coli under co-existence of cadmium (Cd) and lead (Pb), primarily based on biochemical analysis and RNA sequencing. Cd completely inhibited bacterial growth at a concentration of 2.41 mmol/L, with its removal rate as low as <10%. In contrast, the Pb removal rate was >95% under equimolar sole Pb stress. In addition, the Raman analysis confirmed the loss of proteins for the bacterial cells. Under the co-existence of Cd and Pb, the Cd toxicity to E. coli was alleviated. Meanwhile, the biosorption of Pb cations was more intense during the competitive sorption with Cd. Transmission electron microscopy images showed that a few cells were elongated during incubation, i.e., the average cellular length increased from 1.535 ± 0.407 to 1.845 ± 0.620 µm. Moreover, NanoSIMS imaging showed that the intracellular distribution of Cd and Pb was coupled with sulfur. Genes regulating sulfate transporter were also upregulated to promote sulfate assimilation. Then, the subsequent production of biogenic sulfide and sulfur-containing amino acids was enhanced. Although this strategy based on S enrichment could resist the polymetallic stress, not all related genes were induced to upregulate under sole Cd stress. Therefore, the S metabolism might remodel the microbial resistance to variable occurrence of heavy metals. Furthermore, the competitive sorption (in contrast to sole Cd stress) could prevent microbial cells from strong Cd toxicity.IMPORTANCEMicrobial tolerance and resistance to heavy metals have been widely studied under stress of single metals. However, the polymetallic exposure seems to prevail in the environment. Though microbial resistance can alleviate the effects of exogenous stress, the taxonomic or functional response to polymetallic exposure is still not fully understood. We determined the strong cytotoxicity of cadmium (Cd) on growth, and cell elongation would be driven by Cd stress. The addition of appropriate lead (Pb) showed a stimulating effect on microbial bioactivity. Meanwhile, the biosorption of Pb was more intense during co-existence of Pb and Cd. Our work also revealed the spatial coupling of intracellular S and Cd/Pb. In particular, the S assimilation was promoted by Pb stress. This work elucidated the microbial responses to polymetallic exposure and may provide new insights into the antagonistic function during metal stresses.

Exposure to bisphenol A and fiber-type microplastics induce oxidative stress and cell damage in disk abalone Haliotis discus hannai: Bioaccumulation and toxicity.

Along with environmental pollution caused by rapid economic development and industrialization, plastic waste is emerging as a global concern in relation to marine ecosystems and human health. Among the microplastics, fiber-type microfibers (MF) and bisphenol A (BPA), which are widely used as plasticizers, do not decompose well in the ocean, and tend to accumulate in organisms, generating an increased oxidative stress response. This study investigated the abalones' antioxidant and cell death responses following exposure to the environmental pollutants MF and BPA. Levels of malondialdehyde (MDA) and DNA damage increased over time, demonstrating the degree of lipid peroxidation and DNA damage in abalones exposed to individual and combined environmental conditions of MF and BPA. Compared to the single MF and BPA exposure groups, the combined exposure group showed a higher expression of antioxidant enzymes. A similar pattern was seen in the expression of the apoptosis enzyme caspase-3. Both MF and BPA caused oxidative stress and antioxidant enzymes were expressed to alleviate it, but it is believed that cell damage occurred because the stress level exceeded the allowed range.

Integrated Transfer Learning and Multitask Learning Strategies to Construct Graph Neural Network Models for Predicting Bioaccumulation Parameters of Chemicals.

Accurate prediction of parameters related to the environmental exposure of chemicals is crucial for the sound management of chemicals. However, the lack of large data sets for training models may result in poor prediction accuracy and robustness. Herein, integrated transfer learning (TL) and multitask learning (MTL) was proposed for constructing a graph neural network (GNN) model (abbreviated as TL-MTL-GNN model) using n-octanol/water partition coefficients as a source domain. The TL-MTL-GNN model was trained to predict three bioaccumulation parameters based on enlarged data sets that cover 2496 compounds with at least one bioaccumulation parameter. Results show that the TL-MTL-GNN model outperformed single-task GNN models with and without the TL, as well as conventional machine learning models trained with molecular descriptors or fingerprints. Applicability domains were characterized by a state-of-the-art structure-activity landscape-based (abbreviated as ADSAL) methodology. The TL-MTL-GNN model coupled with the optimal ADSAL was employed to predict bioaccumulation parameters for around 60,000 chemicals, with more than 13,000 compounds identified as bioaccumulative chemicals. The high predictive accuracy and robustness of the TL-MTL-GNN model demonstrate the feasibility of integrating the TL and MTL strategy in modeling small-sized data sets. The strategy holds significant potential for addressing small data challenges in modeling environmental chemicals.

Biotransformation, Bioaccumulation, and Bioelimination of Triphenyl Phosphate and Its Dominant Metabolite Diphenyl Phosphate In Vivo.

Aryl phosphorus flame retardants (aryl-PFRs), such as triphenyl phosphate (TPHP) and diphenyl phosphate (DPHP), are widely used worldwide. Understanding the fates of aryl-PFRs in vivo is crucial to assessing their toxicity and the risks they pose. Seven TPHP metabolites, including Phase I hydrolysis and hydroxylation and Phase II glucuronidation products, were identified in C57BL/6J male mice following subacute dietary exposure to aryl-PFRs (70 µg/kg body weight (bw)/day) for 7 days. TPHP was almost completely metabolized by mice (∼97%), with DPHP the major metabolite formed (34%-58%). In addition, mice were exposed to aryl-PFRs (7 µg/kg bw/day) for 12 weeks. Both TPHP and DPHP occurred at higher concentrations in the digestive tract (intestine and stomach), liver and heart. The total concentration of DPHP in all organs was 3.55-fold greater than that of TPHP. Recovery analysis showed that the rate of TPHP elimination from mouse organs reached 38%, while only 3%-5% of DPHP was removed, suggesting that the rates of degradation and elimination of DPHP were slower than TPHP and its bioaccumulation potential was higher. These results highlight the critical role of DPHP in the biotransformation, bioaccumulation, and bioelimination of TPHP, providing valuable insights into the fate of aryl-PFRs in vivo.

Low Dietary Uptake Efficiencies and Biotransformation Prevent Biomagnification of Octamethylcyclotetrasiloxane (D4) and Decamethylcyclopentasiloxane (D5) in Rainbow Trout.

With octamethylcyclotetrasiloxane (D4) and decamethylcyclopentasiloxane (D5) being considered for evaluation under the UN Stockholm Convention on Persistent Organic Pollutants, which specifically acknowledges risks of biomagnification of persistent organic pollutants in traditional foods, a study into the mechanism of the biomagnification process of D4 and D5 in Rainbow trout was conducted by combining the absorption-distribution-metabolism-excretion for bioaccumulation (ADME-B) approach to determine intestinal and somatic biotransformation rates and radiochemical analyses to identify metabolite formation. High rates of intestinal biotransformation of D4 and D5 (i.e., 2.1 (0.70 SE) and 0.88 (0.67 SE) day-1, respectively) and metabolite formation [i.e., 52.0 (17 SD)% of D4 and 56.5% (8.2 SD)% of D5 were metabolized] were observed that caused low dietary uptake efficiencies of D4 and D5 in fish of 15.5 (2.9 SE)% and 21.0 (6.5 SE)% and biomagnification factors of 0.44 (0.08 SE) for D4 and 0.78 (0.24 SE) kg-lipid·kg-lipid-1 for D5. Bioaccumulation profiles indicated little effect of growth dilution on the bioaccumulation of D4 and D5 in fish and were substantially different from those of PCB153. The study highlights the importance of intestinal biotransformation in negating biomagnification of substances in organisms and explains differences between laboratory tests and field observations of bioaccumulation of D4 and D5.

First Evidence of the Bioaccumulation and Trophic Transfer of Tire Additives and Their Transformation Products in an Estuarine Food Web.

The discovery of the significant lethal impacts of the tire additive transformation product N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine quinone (6PPD-Q) on coho salmon has garnered global attention. However, the bioaccumulation and trophic transfer of tire additives and their transformation products (TATPs) within food webs remain obscure. This study first characterized the levels and compositions of 15 TATPs in the Pearl River Estuary, estimated their bioaccumulation and trophic transfer potential in 21 estuarine species, and identified priority contaminants. Our observations indicated that TATPs were prevalent in the estuarine environment. Eight, six, seven, and 10 TATPs were first quantified in the shrimp, sea cucumber, snail, and fish samples, with total mean levels of 45, 56, 64, and 67 ng/g (wet weight), respectively. N,N'-Diphenyl-p-phenylenediamine (DPPD) and N,N'-bis(2-methylphenyl)-1,4-benzenediamine (DTPD) exhibited high bioaccumulation. Significant biodilution was only identified for benzothiazole, while DPPD and DTPD displayed biomagnification trends based on Monte Carlo simulations. The mechanisms of bioaccumulation and trophodynamics of TATPs could be explained by their chemical hydrophobicity, molecular mass, and metabolic rates. Based on a multicriteria scoring technique, DPPD, DTPD, and 6PPD-Q were characterized as priority contaminants. This work emphasizes the importance of biomonitoring, particularly for specific hydrophobic tire additives.

Bioconcentration Assessment of Three Cationic Surfactants in Permanent Fish Cell Lines.

Cationic surfactants are used in many industrial processes and in consumer products with concurrent release into the aquatic environment, where they may accumulate in aquatic organisms to regulatoryly relevant thresholds. Here, we aimed to better understand the bioconcentration behavior of three selected cationic surfactants, namely N,N-dimethyldecylamine (T10), N-methyldodecylamine (S12), and N,N,N-trimethyltetradecylammonium cation (Q14), in the cells of fish liver (RTL-W1) and gill (RTgill-W1) cell lines. We conducted full mass balances for bioconcentration tests with the cell cultures, in which the medium, the cell surface, the cells themselves, and the plastic compartment were sampled and quantified for each surfactant by HPLC MS/MS. Accumulation in/to cells correlated with the surfactants' alkyl chain lengths and their membrane lipid-water partitioning coefficient, DMLW. Cell-derived bioconcentration factors (BCF) of T10 and S12 were within a factor of 3.5 to in vivo BCF obtained from the literature, while the cell-derived BCF values for Q14 were >100 times higher than the in vivo BCF. From our experiments, rainbow trout cell lines appear as a suitable conservative in vitro screening method for bioconcentration assessment of cationic surfactants and are promising for further testing.

Stimulated Raman Scattering Microscopy Reveals Bioaccumulation of Small Microplastics in Protozoa from Natural Waters.

Microplastics (MPs) are pollutants of global concern, and bioaccumulation determines their biological effects. Although microorganisms form a large fraction of our ecosystem's biomass and are important in biogeochemical cycling, their accumulation of MPs has never been confirmed in natural waters because current tools for field biological samples can detect only MPs > 10 µm. Here, we show that stimulated Raman scattering microscopy (SRS) can image and quantify the bioaccumulation of small MPs (<10 µm) in protozoa. Our label-free method, which differentiates MPs by their SRS spectra, detects individual and mixtures of different MPs (e.g., polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, polystyrene, and poly(methyl methacrylate)) in protozoa. The ability of SRS to quantify cellular MP accumulation is similar to that of flow cytometry, a fluorescence-based method commonly used to determine cellular MP accumulation. Moreover, we discovered that protozoa in water samples from Yangtze River, Xianlin Wastewater Treatment Plant, Lake Taihu and the Pearl River Estuary accumulated MPs < 10 µm, but the proportion of MP-containing cells was low (∼2-5%). Our findings suggest that small MPs could potentially enter the food chain and transfer to organisms at higher trophic levels, posing environmental and health risks that deserve closer scrutiny.

Bioaccumulation and Trophodynamics of Novel Brominated Flame Retardants (NBFRs) in Marine Food Webs from the Arctic and Antarctic Regions.

The pervasive contamination of novel brominated flame retardants (NBFRs) in remote polar ecosystems has attracted great attention in recent research. However, understanding regarding the trophic transfer behavior of NBFRs in the Arctic and Antarctic marine food webs is limited. In this study, we examined the occurrence and trophodynamics of NBFRs in polar benthic marine sediment and food webs collected from areas around the Chinese Arctic Yellow River Station (n = 57) and Antarctic Great Wall Station (n = 94). ∑7NBFR concentrations were in the range of 1.27-7.47 ng/g lipid weight (lw) and 0.09-1.56 ng/g lw in the Arctic and Antarctic marine biota, respectively, among which decabromodiphenyl ethane (DBDPE) was the predominant compound in all sample types. The biota-sediment bioaccumulation factors (g total organic carbon/g lipid) of NBFRs in the Arctic (0.85-3.40) were 4-fold higher than those in the Antarctica (0.13-0.61). Trophic magnification factors (TMFs) and their 95% confidence interval (95% CI) of individual NBFRs ranged from 0.43 (95% CI: 0.32, 0.60) to 1.32 (0.92, 1.89) and from 0.34 (0.24, 0.49) to 0.92 (0.56, 1.51) in the Arctic and Antarctic marine food webs, respectively. The TMFs of most congeners were significantly lower than 1, indicating a trophic dilution potential. This is one of the very few investigations on the trophic transfer of NBFRs in remote Arctic and Antarctic marine ecosystems, which provides a basis for exploring the ecological risks of NBFRs in polar regions.

Bioaccumulation and Male Reproductive Toxicity of the New Brominated Flame Retardant Tetrabromobisphenol A-Bis(2,3-dibromo-2-methylpropyl ether) in Comparison with Hexabromocyclododecane.

Tetrabromobisphenol A-bis(2,3-dibromo-2-methylpropyl ether) (TBBPA-DBMPE) has come into use as an alternative to hexabromocyclododecane (HBCD), but it is unclear whether TBBPA-DBMPE has less hazard than HBCD. Here, we compared the bioaccumulation and male reproductive toxicity between TBBPA-DBMPE and HBCD in mice following long-term oral exposure after birth. We found that the concentrations of TBBPA-DBMPE in livers significantly increased with time, exhibiting a bioaccumulation potency not substantially different from HBCD. Lactational exposure to 1000 µg/kg/d TBBPA-DBMPE as well as 50 µg/kg/d HBCD inhibited testis development in suckling pups, and extended exposure up to adulthood resulted in significant molecular and cellular alterations in testes, with slighter effects of 50 µg/kg/d TBBPA-DBMPE. When exposure was extended to 8 month age, severe reproductive impairments including reduced sperm count, increased abnormal sperm, and subfertility occurred in all treated animals, although 50 µg/kg/d TBBPA-DBMPE exerted lower effects than 50 µg/kg/d HBCD. Altogether, all data led us to conclude that TBBPA-DBMPE exerted weaker male reproductive toxicity than HBCD at the same doses but exhibited bioaccumulation potential roughly equivalent to HBCD. Our study fills the data gap regarding the bioaccumulation and toxicity of TBBPA-DBMPE and raises concerns about its use as an alternative to HBCD.

Wildfires Influence Mercury Transport, Methylation, and Bioaccumulation in Headwater Streams of the Pacific Northwest.

The increasing frequency and severity of wildfires are among the most visible impacts of climate change. However, the effects of wildfires on mercury (Hg) transformations and bioaccumulation in stream ecosystems are poorly understood. We sampled soils, water, sediment, in-stream leaf litter, periphyton, and aquatic invertebrates in 36 burned (one-year post fire) and 21 reference headwater streams across the northwestern U.S. to evaluate the effects of wildfire occurrence and severity on total Hg (THg) and methylmercury (MeHg) transport and bioaccumulation. Suspended particulate THg and MeHg concentrations were 89 and 178% greater in burned watersheds compared to unburned watersheds and increased with burn severity, likely associated with increased soil erosion. Concentrations of filter-passing THg were similar in burned and unburned watersheds, but filter-passing MeHg was 51% greater in burned watersheds, and suspended particles in burned watersheds were enriched in MeHg but not THg, suggesting higher MeHg production in burned watersheds. Among invertebrates, MeHg in grazers, filter-feeders, and collectors was 33, 48, and 251% greater in burned watersheds, respectively, but did not differ in shredders or predators. Thus, increasing wildfire frequency and severity may yield increased MeHg production, mobilization, and bioaccumulation in headwaters and increased transport of particulate THg and MeHg to downstream environments.

Occurrence, Spatial Distribution, and Bioaccumulation of Dissolved Synthetic Musks in Freshwaters across China.

Commercial chemicals, such as synthetic musks, are of global concern, but data on their occurrence and spatial distribution in aquatic environments of large scale are scarce. Two sampling campaigns were conducted in the present study to measure freely dissolved synthetic musks in freshwaters across China using passive samplers, along with biological coexposure at selected sites. Polycyclic musks (PCMs) dominated synthetic musks, with a detection frequency of 95%. Higher concentrations of PCMs were observed in densely populated Mid, East, and South China compared to less populated regions, indicating the significance of anthropogenic activities for synthetic musks in water. The concentration ratios of galaxolide (HHCB)/tonalide (AHTN) were significantly higher in low-latitude areas than in high-latitude areas from June to September, suggesting that solar radiation played an important role in the degradation of HHCB/AHTN. Significant correlations were found between dissolved concentrations of HHCB and AHTN and their lipid-normalized concentrations in coexposed fish and clam. The estimated hazard quotients for HHCB and AHTN in freshwater fish consumed by humans were less than 0.01 at all sampling sites except the Yangtze River Basin. These results help to understand the environmental fate and ecological risks of synthetic musks on a large geographical scale.

Bioaccumulation and Potential Endocrine Disruption Risk of Legacy and Emerging Organophosphate Esters in Cetaceans from the Northern South China Sea.

Despite the increasing health risks shown by the continuous detection of organophosphate esters (OPEs) in biota in recent years, information on the occurrence and potential risks of OPEs in marine mammals remains limited. This study conducted the first investigation into the body burdens and potential risks of 10 traditional OPEs (tOPEs) and five emerging OPEs (eOPEs) in 10 cetacean species (n = 84) from the northern South China Sea (NSCS) during 2005-2021. All OPEs, except for 2-ethylhexyl diphenyl phosphate (EHDPHP), were detected in these cetaceans, indicating their widespread occurrence in the NSCS. Although the levels of the ∑10tOPEs in humpback dolphins remained stable from 2005 to 2021, the concentrations of the ∑5eOPEs showed a significant increase, suggesting a growing demand for these new-generation OPEs in South China. Dolphins in proximity to urban regions generally exhibited higher OPE concentrations than those from rural areas, mirroring the environmental trends of OPEs occurring in this area. All OPE congeners, except for EHDPHP, in humpback dolphins exhibited a maternal transfer ratio >1, indicating that the dolphin placenta may not be an efficient barrier for OPEs. The observed significant correlations between levels of OPEs and hormones (triiodothyronine, thyroxine, and testosterone) in humpback dolphins indicated that OPE exposures might have endocrine disruption effects on the dolphin population.

Bioaccumulation of Titanium in diatom Cyclotella atomus Hust.

Diatomaceous earth or diatomite is a fossil rock deposit of diatoms made up of silica and other minerals. A distinguishing feature of diatoms that placed them in the single class of microalgae Bacillariophyceae, is the frustule, a transparent, hard-shelled cell wall. It's interesting to note that the diatom has specific proteins and enzymes for heavy metal detoxification and can intake and store more heavy metals in its frustule. Consequently, an attempt has been made in this study to determine the bioaccumulation of metals in the frustules of the diatom. Hence, a centric diatom was isolated from the freshwater sample collected from the Adyar River, Chennai, Tamil Nadu. The diameter of the cell was 5-7.5 µm and 20-23 striations with radial arrangement. A single, dark off-center fultoportula and marginal fultoportula on the striae are found in the diatom. Additionally, one rimoportula between two marginal fultoportula distributed on the striae between the costa was also seen. As a result, the isolated diatom was morphologically identified as Cyclotella atomus Hust. Simultaneously, the bioaccumulation study reveals that the Titanium (Ti) was found accumulated in the frustules of the diatom incubated in the Ti-supplemented culture medium based on the scanning electron microscope-energy-dispersive X-ray analysis (SEM-EDAX). Therefore, the biogenic accumulation and fabrication of Titanium frustules in diatom have advantages in enhancing the efficiency of solar cells.

Arthropods in landfills and their accumulation potential for toxic elements: A review.

Landfills, as a source of potentially toxic elements (PTEs), pose a threat to the environment and human health. A literature review was conducted to explore the diversity of arthropods inhabiting solid waste landfills, as well as on the bioaccumulation of PTEs by arthropods. This review presents scientific papers over the last 20 years. Their importance in landfill ecosystems has been the subject of research; however, the issue of the accumulation of compounds such as toxic elements is emphasized only in a few studies. The bioaccumulation of PTEs was studied for 10 arthropod species that founded in landfills: Orthomorpha coarctata and Trigoniulus corallinus (class Diplopoda), Armadillidium vulgare and Trachelipus rathkii (class Malacostraca), the 6 species of the class Insecta - Zonocerus variegatus, Anacanthotermes ochraceus, Macrotermes bellicosus, Austroaeschna inermis, Calathus fuscipes and Harpalus rubripes.

Mercury distribution, bioaccumulation, and biomagnification in riparian ecosystems from a neotropical savanna floodplain, Araguaia River, central Brazil.

Litterfall is the main source of dry deposition of mercury (Hg) into the soil in forest ecosystems. The accumulation of Hg in soil and litter suggests the possibility of transfer to terrestrial invertebrates through environmental exposure or ingestion of plant tissues. We quantified total mercury (THg) concentrations in two soil layers (organic: 0-0.2 m; mineral: 0.8-1 m), litter, fresh leaves, and terrestrial invertebrates of the Araguaia River floodplain, aiming to evaluate the THg distribution among terrestrial compartments, bioaccumulation in invertebrates, and the factors influencing THg concentrations in soil and invertebrates. The mean THg concentrations were significantly different between the compartments evaluated, being higher in organic soil compared to mineral soil, and higher in litter compared to mineral soil and fresh leaves. Soil organic matter content was positively related to THg concentration in this compartment. The order Araneae showed significantly higher Hg concentrations among the most abundant invertebrate taxa. The higher Hg concentrations in Araneae were positively influenced by the concentrations determined in litter and individuals of the order Hymenoptera, confirming the process of biomagnification in the terrestrial trophic chain. In contrast, the THg concentrations in Coleoptera, Orthoptera and Hymenoptera were not significantly related to the concentrations determined in the soil, litter and fresh leaves. Our results showed the importance of organic matter for the immobilization of THg in the soil and indicated the process of biomagnification in the terrestrial food web, providing insights for future studies on the environmental distribution of Hg in floodplains.

Metal cross-contamination relationships between sediments and loricariidae species (siluriform) in a neotropical riverine system.

Human activities have changed the natural rates at which metals are moved and accumulated in both land and water environments, resulting in negative impacts on local wildlife. In this study, concentrations of Cr, Ni, Cd, Pb, Cu, Mn, Co, and Zn were evaluated in water and riverbed sediment samples collected from the Verde River basin (VR), as well as in tissue samples from five native Loricariidae species. Sediment samples collected from the central section of the VR riverbed indicated the presence of metal concentrations, which were primarily attributed to scattered pollution sources linked to rural activities in the surrounding areas. The bioconcentration factor in the Loricariids liver presented the highest average values for Zn (1.27-58.21), Co (0.48-14.91) and Cu (1.15-11.14). The same pattern was observed in the muscle, but in a lower proportion. Regarding the bioaccumulation factor, Co (1.54-34.84), Cu (5.85-25.22) and Zn (0.64-18.08) attained the highest average values in the liver. The co-inertia analysis examined the spatial distribution of metal concentrations in riverbed sediments and in tissues of Loricariids from the upper, middle, and lower stretches of the river, including the river mouth. The analysis revealed varying patterns, with samples from some regions showing higher bioaccumulation levels. This suggests that riverbed sediments are a primary source of metal contamination in Loricariids from these areas. The pollution has had a significant impact on the bioaccumulation of metals in the VR' Loricariids, which are good indicators of sediment-associated metal bioaccumulation. The metal concentrations recorded in both the riverbed sediments and Loricariids surpassed international and Brazilian limits set for aquatic health and safe human consumption. Given the importance of the Verde River in terms of its ecological, social, cultural, and economic roles, it is essential to implement biomonitoring and control measures to safeguard both terrestrial and aquatic resources.

Predicting PFAS fate in fish: Assessing the roles of dietary, respiratory, and dermal uptake in bioaccumulation modeling.

An increasing number of per- and polyfluoroalkyl substances (PFAS) exposed to the environment may pose a threat to organisms and human beings. However, there is a lack of simulations comprehensively addressing and comparing the bioaccumulation of PFAS across all three major exposure routes (oral, inhalation, and dermal), especially for dermal uptake. In this study, we proposed a physiologically based kinetic (PBK) model for PFAS, aiming to predict bioaccumulation factors (BAF) in fish by considering these diverse exposure routes. 15 PFAS were used for model validation, and 11 PFAS from Taihu Lake were used for exposure contribution modeling. Approximately 64% of estimations fell within 10-fold model bias from measurements in Taihu Lake, underscoring the potential efficacy of the developed PBK model in predicting BAFs for fish. The dermal route emerges as a contributor to short-chain PFAS exposure. For example, it ranged widely from 46% to 75% (mean) for all modeling short-chain PFAS (C6-C7) in Taihu Lake. It indicated the criticality of considering dermal exposure for PFAS in fish, highlighting a gap in field studies to unravel cutaneous intake mechanisms and contributions. For longer carbon chains of PFAS (C8-C12), dermal exposure accounted for 2%-27% for all species of aquatic organisms. The fish's lipid fraction and water content played a significant role in the contribution of PFAS intake through cutaneous exposure and inhalation. Kow had a significant positive correlation with skin intake rate (p < 0.05) and gill intake rate (p < 0.001), while having a significant negative correlation with skin intake (p < 0.05) and skin intake contribution (p < 0.001). Based on the proposed modeling approach, we have introduced a simulation spreadsheet for projecting PFAS BAFs in fish tissues, hopefully broadening the predictive operational tool for a variety of chemical species.