Impact of environmental pollution on PCDD/F and PCB bioaccumulation in game animals

ChemFREE: a one-stop comprehensive platform for ecological and environmental risk evaluation of chemicals in one health world

Addressing health and safety crises stemming from various environmental and ecological issues is a core focus of One Health (OH), which aims to balance and optimize the health of humans, animals, and the environment. While many chemicals contribute significantly to our quality of life when properly used, others pose environmental and ecological health risks. Recently, assessing the ecological and environmental risks associated with chemicals has gained increasing significance in the OH world. In silico models may address time-consuming and costly challenges, and fill gaps in situations where no experimental data is available. However, despite their significant contributions, these assessment models are not web-integrated, leading to user inconvenience. In this study, we developed a one-stop comprehensive web platform for freely evaluating the eco-environmental risk of chemicals, named ChemFREE (Chemical Formula Risk Evaluation of Eco-environment, available in http://chemfree.agroda.cn/chemfree/). Inputting SMILES string of chemicals, users will obtain the assessment outputs of ecological and environmental risk, etc. A performance evaluation of 2935 external chemicals revealed that most classification models achieved an accuracy rate above 0.816. Additionally, the $Q_{F1}^2$ metric for regression models ranges from 0.618 to 0.898. Therefore, it will facilitate the eco-environmental risk evaluation of chemicals in the OH world.

Integrated transcriptomics and metabolomics analyses reveal the aerobic biodegradation and molecular mechanisms of 2,3',4,4',5-pentachlorodiphenyl (PCB 118) in Methylorubrum sp. ZY-1

2,3',4,4',5-pentachlorodiphenyl (PCB 118), a highly representative PCB congener, has been frequently detected in various environments, garnering much attention across the scientific community. The degradation of highly chlorinated PCBs by aerobic microorganisms is challenging due to their hydrophobicity and persistence. Herein, the biodegradation and adaptation mechanisms of Methylorubrum sp. ZY-1 to PCB 118 were comprehensively investigated using an integrative approach that combined degradation performance, product identification, metabolomic and transcriptomic analyses. The results indicated that the highest degradation efficiency of 0.5 mg L-1 PCB 118 reached 75.66% after seven days of inoculation when the bacteria dosage was 1.0 g L-1 at pH 7.0. A total of eleven products were identified during the degradation process, including low chlorinated PCBs, hydroxylated PCBs, and ring-opening products, suggesting that strain ZY-1 degraded PCB 118 through dechlorination, hydroxylation, and ring-opening pathways. Metabolomic analysis demonstrated that the energy supply and redox metabolism of strain ZY-1 was disturbed with exposure to PCB 118. To counteract this environmental stress, strain ZY-1 adjusted both the fatty acid synthesis and purine metabolism. The analysis of transcriptomics disclosed that multiple intracellular and extracellular oxidoreductases (e.g., monooxygenase, alpha/beta hydrolase and cytochrome P450) participated in the degradation of PCB 118. Besides, active efflux of PCB 118 and its degradation intermediates mediated by multiple transporters (e.g., MFS transporter and ABC transporter ATP-binding protein) might enhance bacterial resistance against these substances. These discoveries provided the inaugural insights into the biotransformation of strain ZY-1 to PCB 118 stress, illustrating its potential in the remediation of contaminated environments.

Exposure to Persistent Organic Pollutants in Australian Waterbirds

There is growing worldwide recognition of the threat posed by persistent organic pollutants (POPs) to wildlife populations. We aimed to measure exposure levels to POPs in a Southern Hemisphere aquatic waterbird species, the nomadic gray teal (Anas gracilis), which is found across Australia. We collected wings from 39 ducks harvested by recreational hunters at two sites (one coastal, one inland) in Victoria, southeastern Australia, in 2021. We examined three groups of POPs: nine congeners of polychlorinated biphenyls (PCBs), 13 organochlorine pesticides (OCPs), and 12 polycyclic aromatic hydrocarbons (PAHs). The PCBs, OCPs, and PAHs were detected at quantifiable levels in 13%, 72%, and 100% of birds, respectively. Of the congeners we tested for in PCBs, OCPs, and PAHs, 33%, 38%, and 100% were detected at quantifiable levels, respectively. The highest levels of exposure to POPs that we found were to the PAH benzo[b]fluoranthene, occurring at a concentration range of 1.78 to 161.05 ng/g wet weight. There were some trends detected relating to differences between geographical sites, with higher levels of several PAHs at the coastal versus inland site. There were several strong, positive associations among PAHs found. We discuss potential sources for the POPs detected, including industrial and agricultural sources, and the likely role of large-scale forest fires in PAH levels. Our results confirm that while Australian waterbirds are exposed to a variety of POPs, exposure levels are currently relatively low. Additional future investigations are required to further characterize POPs within Australian waterbird species. Environ Toxicol Chem 2024;43:736-747. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Occurrence of perfluoroalkyl substances in cow's, goat's and sheep's milk - dietary intake and risk assessment

Introduction

Milk from cows, goats and sheep was analysed in terms of content of fourteen perfluoroalkyl substances (PFASs).

Material and Methods

Altogether, 73 milk samples from cows (n = 38), goats (n = 20) and sheep (n = 15) were collected from various regions of Poland. Concentrations of analytes were determined using liquid chromatography-tandem mass spectrometry (LC-MS/MS).

Results

The lower-bound sum of four PFAS (∑4 PFASs) concentrations (perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid, perfluorononanoic acid and perfluorohexanesulfonic acid) were highest in sheep's (0.0055 μg/kg), lower in goat's (0.0046 μg/kg), and lowest in cow's milk (0.0008 μg/kg). Goat's and sheep's milk was statistically significantly more contaminated than cow's milk. None of the samples exceeded the indicative values set by Commission Recommendation (EU) 2022/1431, and even the maximum detected concentrations were an order of magnitude lower. The most frequently detected was linear PFOS, which was found in 33%, 76% and 93% of cow's, goat's and sheep's milk samples, respectively. Based on mean upper-bound ∑4 PFAS concentrations and average milk consumption, the estimated intake of ∑4 PFASs ranged from 0.153 to 0.266 ng/kg body weight (b.w.) for children and from 0.050 to 0.88 ng/kg b.w. for adults, which indicates that exposure is very low and is merely <7% of the tolerable weekly intake (TWI) for children and <2% of the TWI for adults.

Conclusion

Regardless of the milk type, the intake of PFASs via consumption of Polish milk does not contribute significantly to the overall PFAS intake of either adults or children.

Terrestrial animal livers as a source of PCDD/Fs, PCBs and PBDEs in the diet

The livers of terrestrial animals are an important source of vitamins and minerals, but with the liver being the major filtering and detoxifying organ, it retains xenobiotic material, especially persistent organic pollutants (POPs). The aim of the study was human health risk assessment related to the presence of certain POPs, namely polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs) in terrestrial animals' livers. HRGC-HRMS was used to determine analyte concentrations in 99 liver samples of chicken, pork, beef, and mutton livers obtained from Polish farms. The ovine livers were the most contaminated by ∑PCDD/F/dl-PCBs (0.06-2.21 pg WHO-TEQ g^-1 wet weight), ∑ndl-PCBs (0.036-1.54 ng g^-1 wet weight) and ∑PBDEs (0.21-2.27 ng g^-1 wet weight). Samples were found of ovine and pork livers that exceeded the maximum concentration limits established for PCDD/Fs. The Kruskal-Wallis test showed that there were statistical differences between regions in the concentrations of the ∑PCDD/Fs and ∑PCDD/F-PCBs, but none in those of the ∑dl-PCBs, ∑ndl-PCBs or ∑PBDEs. According to Dunnett's test results, ovine liver samples from the Podlaskie province contained fewer ∑PCDD/F than those from the Dolnośląskie (p < 0.027) and Małopolskie (p < 0.0342) voivodeships. Taking into account PCDD/F contents and Tolerable Weekly Intake (2 pg WHO-TEQ/kg BW) (TWI₂₀₁₈), the lowest risk was associated with chicken liver consumption (TWI up to 11 % in the 95th percentile), pork (62 %) and bovine (92 %) livers should be eaten in limited amounts for risk avoidance, while mutton liver (400 %) should not be eaten at all. Additionally, there is no risk of ingestion of a harmful amount of PBDEs associated with consumption of the livers of terrestrial animals from Poland based on the margin of exposure values (>15).

Bioaccumulation of PCDD/Fs and PCBs in free-range hens: Congener fingerprints and biotransfer factors

The bioaccumulation of lipophilic environmental contaminants in farm animals is an important issue to control and prevent human exposure to toxic pollutants. Free-range hens were used as a model to assess the transfer and the bioaccumulation of PCDD/Fs, DL-PCBs and NDL-PCBs from the soil to eggs in an area in the Campania region particularly affected by pollution, the "Land of Fires". We determined the following ranges of concentrations in eggs: 0.90-5.51 pg WHO-TEQ g^-1 fat for PCDD/Fs; 1.63-4.24 pg WHO-TEQ g^-1 fat for DL-PCBs; 2.77-9.75 pg WHO-TEQ g^-1 fat for the sum of PCDD/Fs and DL-PCBs and 12.53-30.94 ng g^-1 fat for NDL-PCBs. Higher contamination levels were observed in the eggs from free-range hens, compared to those of the control group, that is hens raised indoors; this indicates that soil remains a major source of contamination. Livers showed low levels of contamination for both outdoor and indoor reared hens. Biotransfer factors (BTFs) were calculated for each of the 35 PCDD/F and PCB congeners analysed. The BTFs highlighted that the transfer and bioaccumulation depend on chlorination degree and substitution pattern, in particular they increase with increasing chlorination degree up to the hexa-chlorinated congeners and then decrease. An exception to these finding was observed for 2,3,7,8 TCDD and 2,3,7,8 TCDF, which showed very high BTFs. These results demonstrate the importance of promoting studies on the environmental contaminants bioaccumulation as they provide an effective support for the risk assessment and management of exposure to toxic chemicals.

Levels, time trends, and distribution of dioxins and polychlorinated biphenyls in fishes from the Baltic Sea

Fish absorb dioxins from the environment through water and contact with sediments but the main source is food. These contaminants also enter the human body with food, including through the consumption of fish. This study presents the dioxin and polychlorinated biphenyl (PCB) concentrations in 145 samples of four fish species (herring, sprat, sea trout, salmon) caught in the southern Baltic Sea. The study results permit assessing whether the efforts made in recent years to reduce dioxin and PCB emissions into the environment have translated into decreases in concentrations of these pollutants in Baltic Sea fishes and whether these raw fish materials meet food law requirements. The safest fish species with regard to dioxins were designated, as were those of which consumption should be limited. The influence of fish age (length) and weight on dioxin and dioxin-like polychlorinated biphenyl (dl-PCB) concentrations was investigated. The correlation between fat content and dioxin concentration was determined. The Baltic Sea region and fishing ports from which the least contaminated fish come were also determined. The studies indicated that dioxin and PCB concentrationsin fishes from Polish fishing areas are currently lower than they were twenty years ago.

Toxicity of polychlorinated biphenyls in aquatic environments - A review

The assessment of polychlorinated biphenyls (PCBs) and their congeners resulting from the pollution of all environmental media is inherently related to its persistence and ubiquitous nature. In principle, determination of this class of contaminants are limited to the determination of their concentrations in the various environmental matrices. For solving many problems in this context, knowledge of the emission sources of PCBs, transport pathways, and sites of contamination and biomagnification is of great benefit to scientists and researchers, as well as many regulatory organizations. By far the largest amounts of PCBs, regardless of their discharged points, end up in the soil, sediment and finally in different aquatic environments. By reviewing relevant published materials, the source of origin of PCBs in the environment particularly from different pollution point sources, it is possible to obtain useful information on the nature of different materials that are sources of PCBs, or their concentrations and their toxicity or health effects and how they can be removed from contaminated media. This review focuses on the sources of PCBs in aquatic environments and critically reviews the toxicity of PCBs in aquatic animals and plants. The review also assesses the toxicity equivalency factors (TEFs) of PCBs providing valuable knowledge to other scientists and researchers that enables regulatory laws to be formulated based on selective determination of concentrations regarding their maximum permissible limits (MPLs) allowed. This review also supplies a pool of valuable information useful for designing decontamination technologies for PCBs in media like soil, sediment, and wastewaters.

Development and microbial characterization of Bio-RD-PAOP for effective remediation of polychlorinated biphenyls

Polychlorinated biphenyls (PCBs) as typical halogenated persistent organic pollutants are widely distributed in natural environments, and can be enriched and magnified in organisms via food webs. It is consequently urgent and necessary to develop techniques to completely remove these persistent organohalides. In this study, we developed a process (Bio-RD-PAOP) by integrating microbial reductive dechlorination (Bio-RD) with subsequent persulfate activation and oxidation process (PAOP) for effective remediation of PCBs. Results showed the synergistic combination of advantages of Bio-RD and PAOP in dechlorination of higher-chlorinated PCBs and of PAOP in degradation/mineralization of lower-chlorinated PCBs, respectively. For the PAOP, both experimental evidences and theoretical calculations suggested that degradation rate and efficiency decreased with the increased PCB chlorine numbers. Relative to the Bio-RD and PAOP, Bio-RD-PAOP had significantly higher PCB removal efficiencies, of which values were PCB congener-specific. For example, removal efficiency of Bio-RD-PAOP in removing PCB88 is 2.50 and 1.86 times of that of Bio-RD and PAOP, respectively. In contrast, the efficiency is 1.66 and 3.35 times of Bio-RD and PAOP, respectively, for PCB180 removal. The PAOP-derived oxidizing species (mainly sulfate free radical) significantly decreased microbial abundance, particularly of the organohalide-respiring Dehalococcoides. Notably, co-existence of other microorganisms alleviated the inhibitive effect of oxidizing species on the Dehalococcoides, possibly due to formation of microbial flocs or biofilm. This study provided a promising strategy for extensive remediation of organohalide-contaminated sites, as well as new insight into impact of PAOP-derived oxidizing species on the organohalide-respiring community.

Organochlorine pesticides and NDL-PCBs in wild boars from flatland region with intensive agricultural activities

The objective of this study was to analyse the content of OHCs and NDL-PCBs in wild boar population living in densely populated flatland region with intensive agricultural production. A total of 82 liver samples were analysed by GC-MS method, revealing the presence of minimum one residue in the liver of the majority of animals (92.7%). Most commonly detected residues included ∑ HCH (64.6%), ∑endrin (56.1%) and ∑dieldrin (32.3%). Mean concentrations were in the range ∑endrin > ∑dieldrin > ∑HCH > ∑NDL-PCB > ∑DDT > ∑CHL > ∑endosulfan > methoxychlor. The dominant compound within the total content of NDL-PCBs was PCB 153 (76%). The assessment of daily intake and determination of Health Index indicated that in 6.1% of the samples the consumption of one single portion of wild boar liver would be harmful to human health due to the presence of ∑endrin or NDL-PCBs.

Effects of curcumin on the bioavailability of dioxin-like pollutants in rats

The effects of curcumin on the bioavailability of polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (DL-PCBs) were investigated in Sprague–Dawley rats. Tetra- and penta-chlorinated PCDFs had the lowest bioavailability and hexa-chlorinated PCDD/Fs had the highest, while there was no obvious change in that of DL-PCBs. Curcumin markedly reduced the toxic equivalent (TEQ) of PCDD/Fs in rats, illustrating the potential to competitively inhibit absorption of PCDD/Fs by the epithelial cells of the small intestine due to the similar chemical structure (diphenyl) between curcumin and PCDD/Fs. Moreover, curcumin lowered the TEQ of DL-PCBs in the liver of male rats, but not female rats. The significant decrease in the bioavailability of PCDD/Fs and DL-PCBs demonstrates the potential detoxification mechanisms of curcumin.

Food Safety Considerations Related to the Consumption and Handling of Game Meat in North America

Emerging foodborne pathogens present a threat to public health. It is now recognized that several foodborne pathogens originate from wildlife as demonstrated by recent global disease outbreaks. Zoonotic spillover events are closely related to the ubiquity of parasitic, bacterial, and viral pathogens present within human and animal populations and their surrounding environment. Foodborne diseases have economic and international trade impacts, incentivizing effective wildlife disease management. In North America, there are no food safety standards for handling and consumption of free-ranging game meat. Game meat consumption continues to rise in North America; however, this growing practice could place recreational hunters and game meat consumers at increased risk of foodborne diseases. Recreational hunters should follow effective game meat food hygiene practices from harvest to storage and consumption. Here, we provide a synthesis review that evaluates the ecological and epidemiological drivers of foodborne disease risk in North American hunter populations that are associated with the harvest and consumption of terrestrial mammal game meat. We anticipate this work could serve as a foundation of preventive measures that mitigate foodborne disease transmission between free-ranging mammalian and human populations.

Recent advances in the biodegradation of polychlorinated biphenyls

Polychlorinated biphenyls (PCBs) are typical lasting organic pollutants. Persistence and recalcitrance to biodegradation of PCBs have hampered the transformation of PCB congeners from the environment. Biological transformation of polychlorinated biphenyls could take place through anaerobic dechlorination, aerobic microbial degradation, and a combination of transformation of anaerobic dechlorination and aerobic degradation. Under anaerobic conditions, microbial dechlorination is an important degradation mode for PCBs, especially high-chlorinated congeners. The low-chlorinated compounds formed after reductive dechlorination could be further aerobically degraded and completely mineralized. This paper reviews the recent advances in biological degradation of PCBs, introduces the functional bacteria and enzymes involved in the anaerobic and aerobic degradation of PCBs, and discusses the synergistic action of anaerobic reduction and aerobic degradation. In addition, the different ways to the microbial remediation of PCBs-contaminated environments are discussed. This review provides a theoretical foundation and practical basis to use PCBs-degrading microorganisms for bioremediation.