Exposure estimation and neurotoxicity inhibition of dioxins in sensitive populations near domestic waste incineration plant through adverse outcome pathway.

The neurotoxicity induced by dioxins has been recognized as a serious concern to sensitive population living near waste incineration plants. However, investigating the intracellular neurotoxicity of dioxin in humans and the corresponding mitigation strategies has been barely studied. Thus, a domestic waste incineration plant was selected in this study to characterize the neurotoxicity risks of sensitive populations by estimating the ratio of dioxin in human cells using membrane structure dynamics simulation; and constructing a complete dioxin neurotoxicity adverse outcome pathway considering the binding process of AhR/ARNT dimer protein and dioxin response element (DRE). Six dioxins with high neurotoxicity risk were identified. According to the composite neurotoxicity risk analysis, the highest composite neurotoxicity risk appeared when the six dioxins were jointly exposed. Dietary schemes were designed using 1/2 partial factor experimental design to mitigate the composite neurotoxicity risk of six dioxins and No. 16 was screened as the optimum combination which can effectively alleviate the composite neurotoxicity risk by 29.52%. Mechanism analysis shows that the interaction between AhR/ARNT dimer protein and DRE was inhibited under the optimal dietary scheme. This study provides theoretical feasibility and reference significance for assessing composite toxicity risks of pollutants and safety mitigation measures for toxic effects.

Improved microalgae carbon fixation and microplastic sedimentation in the lake through in silico method.

The impact of microplastics in lake water environments on microalgae carbon fixation and microplastic sedimentation has attracted global attention. The molecular dynamic simulation method was used to design microplastic additive proportioning schemes for improving microalgae carbon fixation and microplastic sedimentation. Results showed that the harm of microplastics can be effectively alleviated by adjusting the proportioning scheme of plastic additives. Besides, the decabromodiphenyl oxide (DBDPO) was identified as the main additive that affect the microalgae carbon fixation and microplastic sedimentation. Thus, a molecular modification based on CiteSpace visual analysis was firstly used and 12 DBDPO derivatives were designed. After the screening, DBDPO-2 and DBDPO-5 became the environmentally friendly DBDPO alternatives, with the highest microalgae carbon fixation and microplastic sedimentation ability enhancement of over 25 %. Compared to DBDPO, DBDPO derivatives were found easier to stimulate the adsorption and binding ability of surrounding hotspot amino acids to CO2 and ribulose-5-phosphate, increasing the solvent-accessible surface area of microplastics, thus improving the microalgae carbon fixation and microplastic sedimentation ability. This study provides theoretical support for simultaneously promoting the microalgae carbon fixation and microplastic sedimentation in the lake water environment and provides scientific basis for the protection and sustainable development of lake water ecosystem.

Synthesis of environmentally friendly neonicotinoid insecticide with proper functional properties by theoretical methodologies.

Modern insecticide substitutes using acetylcholine receptors (nAChR) as biochemical targets, such as neonicotinoid insecticides (NNIs), have been extensively researched. Only 12 compounds have been experimentally realized since the initial discovery of imidacloprid. Increasingly, the bottleneck in this field is to rapidly determine the synthesizability of NNI substitutes. Here, we designed a coupled evaluation system for synthesis prediction and validation, including the synthesis probability, reaction path difficulty, and electron transfer characteristics of NNIs and their substitutes. Firstly, a total of 1475 eigenvalues were generated and 52 critical eigenvalues were screened out through the Pearson's correlation coefficient. The positive and unlabeled (PU) machine learning was constructed using the critical eigenvalues NNIs, including 12 experimentally synthesized NNIs (positive samples) and 73 unsynthesized NNI substitutes (unlabeled samples). Results identified 3 NNI substitutes that were highly promising candidates for synthesis (synthesis probability > 0.5). The results of density functional theory demonstrated the ranking of their reaction ease was UN-1 (31.4 kcal/mol) > UN-2 (81.6 kcal/mol) > UN-3 (3.35 ×103 kcal/mol). Time-dependent density functional theory revealed that changes in the electron distribution and electron excitation type were critical factors affecting their synthesizability, and the local excitation type was more favorable for the synthesizability of NNI substituents. The findings provide significant guidance for NNIs synthesis, reducing the possible space of unlabeled samples to 95.89% of their original size, while also minimizing the cost of research on subsequent NNI substitutes.

Mitigating abortion risk of synthetic musk-contained body wash in pregnant women: Risk assessment and mechanism analysis.

Synthetic musks (SMs), the widely used odor component in personal care products have attracted attention due to their environmental impacts, especially the abortion risks. Given that women comprise a significant consumer demographic for personal care products, it is imperative to promptly initiate research on avoidance strategies for pregnant women concerning their exposure to synthetic chemicals (SMs). This study tried to establish novel theoretical approaches to eliminate the abortion risks of SM-contained body wash by designing the SM-contained proportioning scheme and analyzing the abortion risk mechanisms. The binding energy of SMs to estrogen-progesterone protein complex was used as an indicator of the abortion risk. A total of 324 SM-contained body wash proportioning schemes were designed using full factorial design and No. 218 was found as the most effective formula for body wash proportioning with the binding energy value of 68.6 kJ/mol. Results showed the abortion risk could be effectively alleviated (reduced 0.6%-163.4%) by regulating the proportioning scheme of SM-contained body wash. In addition, the mechanism analysis of SM-contained proportioning scheme proportioning scheme found that xanthan gum and disodium EDTA played essential roles in reducing the abortion risk in pregnant women after exposure. The selection of proper body wash components for reducing the abortion risk of SMs on pregnant women was first proposed. It sheds lights on the potential risks of people's daily life and proposes risk-eliminating strategies.

Reduced bacterial resistance antibiotics with improved microbiota tolerance in human intestinal: Molecular design and mechanism analysis.

Antibiotic selectivity and bacterial resistance are critical global public health issues. We constructed a multi-class machine learning model to study antibiotic effects on human intestinal microbiota abundance and identified key features. Binding energies of ß-lactam antibiotics with Escherichia coli PBP3 mutant protein were calculated, and a 2D-QSAR model for bacterial resistance was established. Sensitivity analysis identified key features affecting bacterial resistance. By coupling key features from the machine learning model and 2D-QSAR model, we designed ten flucloxacillin (FLU) substitutes that improved intestinal microbiota tolerance and reduced antibiotic bacterial resistance. Concurrently, the substitutes exhibited superior degradability in soil, aquatic environments, and under photolytic conditions, coupled with a reduced environmental toxicity compared to the FLU. Evaluations under combined medication revealed significant improvements in functionality and bacterial resistance for 80% of FLU substitutes, with 50% showing more than a twofold increase. Mechanistic analysis demonstrated enhanced binding to target proteins and increased biodegradability for FLU substitutes due to more concentrated surface charges. Reduced solvent hindrance and increased cell membrane permeability of FLU substitutes, mainly due to enhanced interactions with phospholipid bilayers, contributed to their functional selectivity. This study aims to address poor antibiotic selectivity and strong bacterial resistance, providing guidance for designing antibiotic substitutes.

Mechanism analysis of synthetic musks-induced miscarriage risk in pregnant women: Molecular and adverse outcome pathways perspectives.

Synthetic musks (SMs) with pleasant odor have been extensively used in personal care products. SMs are emerging contaminants due to the wide detection in human breast milk and blood, and even caused miscarriage to pregnant women. Aiming at this, the two-dimensional quantitative structure-activity relationship (2D-QSAR) coupling with three-dimensional quantitative structure-activity relationship (3D-QSAR) methods were first used to analyze the SM-induced risk of miscarriage in pregnant women, and the above two models were used to mutually authenticate each other. It was found that the critical volume, melting point and heat of formation of SMs were the key descriptors leading to miscarriage. In addition, the adverse outcome pathway (AOP) was used to assess the miscarriage risk of selected SMs and the environment-friendly SM derivatives with desired functional properties designed in previous studies. Results showed that the miscarriage risk of musk ketone derivative (M27) was reduced by approximately three times than that of MK. The miscarriage risk of galaxolide derivatives (i.e., D6 and D24) were about six times lower than that of galaxolide, which further confirmed that the theoretically designed SMs derivatives can effectively reduce the risk of miscarriage in pregnant women. This study provides a comprehensive analysis of the mechanism of SM-induced miscarriage, and provides an accurate and rapid theoretical evaluation method for the future risk assessment of SM-induced miscarriage.

Molecular Design and Mechanism Analysis of Phthalic Acid Ester Substitutes: Improved Biodegradability in Processes of Sewage Treatment and Soil Remediation.

Phthalic acid esters (PAEs) have the characteristics of environmental persistence. Therefore, improving the biodegradability of PAEs is the key to reducing the extent of ecological harm realized. Firstly, the scoring function values of PAEs docking with various degrading enzymes in sewage treatment were calculated. Based on this, a 3D-quantitative structure-activity relationship (3D-QSAR) model for PAE biodegradability was built, and 38 PAE substitutes were created. By predicting the endocrine-disrupting toxicity and functions of PAE substitutes, two types of PAE substitutes that are easily degraded by microorganisms, have low toxicity, and remain functional were successfully screened. Meanwhile, the differences in the mechanism of molecular degradation difference before and after PAE modification were analyzed based on the distribution characteristics of amino acid residues in the molecular docking complex. Finally, the photodegradability and microbial degradability of the PAE substitutes in the soil environment was evaluated. From the 3D-QSAR model design perspective, the modification mechanism of PAE substitutes suitable for sewage treatment and soil environment degradation was analyzed. We aim to improve the biodegradability of PAEs at the source and provide theoretical support for alleviating the environmental hazards of using PAEs.

In-silico study of reducing human health risk of POP residues' direct (from tea) or indirect exposure (from tea garden soil): Improved rhizosphere microbial degradation, toxicity control, and mechanism analysis.

The accumulation of potentially harmful substances in tea garden soils and tea leaves, especially persistent organic pollutants (POPs), is a special concern for tea consumers worldwide. However, their potential health and ecological risks in tea gardens have rarely been investigated. This study proposed measures to improve the degradation ability of POPs by the tea rhizosphere and to reduce the human health risks caused by POPs after tea consumption. In this study, the binding energy values of six types of POPs and the degraded protein were used to reflect the degradation ability and calculated using molecular dynamic simulations. The main root secretions (i.e., catechin, glucose, arginine, and oxalic acid) were selected and applied with a combination of tea fertilizer and trace element combination (i.e., urea, straw, and copper element), leading to an improved degradation ability (49.59 %) of POPs. To investigate the mechanisms of the factors that affect the degradation ability, molecular docking, tensor singular value decomposition methods, multivariate correlation analysis and 2D-QSAR model were used. The results showed that the solvation energy and solvent accessible surface area are the main forces, and the molecular weight, boiling point, and topological radius of the POPs were the key molecular features affecting their degradation ability. Based on the three key characteristics, a diet avoidance scheme (i.e., avoiding lysine, maslinic acid, ethanol, perfluorocaproic acid, and cholesterol with tea), which can reduce the binding ability of POP residues to aromatic hydrocarbon receptors by 506.13 %. This work will provide theoretical strategies to improve the quality and safety of tea production and reduce the potential risks of harmful substance residues in tea garden soils and tea leaves.

A new perspective to improve the treatment of Lianhuaqingwen on COVID-19 and prevent the environmental health risk of medication.

Lianhuaqingwen (LH), one traditional Chinese medicine (TCM), has been used to treat the coronavirus disease 2019 (COVID-19), but its ecotoxicity with potential human health security has not been well investigated. To overcome such adverse effects and improve its medication efficacy, an intelligent multi-method integrated dietary scheme, screening, and performance evaluation approach was developed. Thirteen LH compounds were selected, and the main protease (Mpro) was used as the potential drug target. Resulted information showed that the more compounds of LH added, the higher medication efficacy obtained using multi-method integrated screening system, expert consultation method, and molecular dynamics simulation. Pharmacodynamic mechanism analysis showed that low total energy and polar surface area of LH active compound (i.e., ß-sitosterol) will contribute to the best therapeutic effect on COVID-19 using quantitative structure-activity relationships (QSAR) and sensitivity models. Additionally, when mild COVID-19 patients take LH with the optimum dietary scheme (i.e., ß-lactoglobulin, α-lactalbumin, vitamin A, vitamin B, vitamin C, carotene, and vitamin E), the medication efficacy were significantly improved (23.58%). Pharmacokinetics and toxicokinetics results showed that LH had certain human health risks and ecotoxicity. This study revealed the multi-compound interaction mechanism of LH treatment on COVID-19, and provided theoretical guidance for improving therapeutic effect, evaluating TCM safety, and preventing human health risk.

Design of a Microbial Remediation Inoculation Program for Petroleum Hydrocarbon Contaminated Sites Based on Degradation Pathways.

This paper analyzed the degradation pathways of petroleum hydrocarbon degradation bacteria, screened the main degradation pathways, and found the petroleum hydrocarbon degradation enzymes corresponding to each step of the degradation pathway. Through the Copeland method, the best inoculation program of petroleum hydrocarbon degradation bacteria in a polluted site was selected as follows: single oxygenation path was dominated by Streptomyces avermitilis, hydroxylation path was dominated by Methylosinus trichosporium OB3b, secondary oxygenation path was dominated by Pseudomonas aeruginosa, secondary hydroxylation path was dominated by Methylococcus capsulatus, double oxygenation path was dominated by Acinetobacter baylyi ADP1, hydrolysis path was dominated by Rhodococcus erythropolis, and CoA path was dominated by Geobacter metallireducens GS-15 to repair petroleum hydrocarbon contaminated sites. The Copeland method score for this solution is 22, which is the highest among the 375 solutions designed in this paper, indicating that it has the best degradation effect. Meanwhile, we verified its effect by the Cdocker method, and the Cdocker energy of this solution is -285.811 kcal/mol, which has the highest absolute value. Among the inoculation programs of the top 13 petroleum hydrocarbon degradation bacteria, the effect of the best inoculation program of petroleum hydrocarbon degradation bacteria was 18% higher than that of the 13th group, verifying that this solution has the best overall degradation effect. The inoculation program of petroleum hydrocarbon degradation bacteria designed in this paper considered the main pathways of petroleum hydrocarbon pollutant degradation, especially highlighting the degradability of petroleum hydrocarbon intermediate degradation products, and enriching the theoretical program of microbial remediation of petroleum hydrocarbon contaminated sites.

Identification and regulation of ecotoxicity of polychlorinated naphthalenes to aquatic food Chain (green algae-Daphnia magna-fish).

Polychlorinated naphthalenes (PCNs) are widely distributed in the aquatic environment and can be transmitted through the food chain, which can amplify their toxic effects on human. To inhibit their transmission in the trophic level, this study aimed to predict the joint toxicity mechanism of polychlorinated naphthalenes (PCNs) to the key organisms and control scheme of its toxicity in the aquatic food chain (green algae-Daphnia magna-fish). The toxic effect grade and mode of action (MoA) of PCNs on the food chain were first predicted to guide the establishment of toxic mechanism model. QSAR models were constructed to quantify the mechanism of aquatic toxicity due to PCNs. The results showed the PCN compounds studied were highly toxic at all the trophic levels of the aquatic food chain. The binding ability of PCNs to the aquatic organisms was the main factor causing the toxicity of PCNs in the food chain, followed by electronic parameters EHOMO and ELUMO. Moreover, the binding ability between PCNs and food chain receptors was related to the molecular hydrophobicity, the hydrophobicity can be changed by adjusting the ability of PCNs to be adsorbed by sediment and their chlorine substituents, while the effect of PCNs electronic parameters (EHOMO and ELUMO) can be adjusted by their solvation effect. In addition, the macro-control scheme of PCN-based aquatic toxicity mechanism was established, and the molecular dynamics (MD) simulation confirmed its effectiveness and accessibility. The MD simulation showed the inhibition effect of nutrition-grade toxicity in the food chain was significant when the external stimulation conditions of solvation, anaerobic dechlorination and molecular adsorption were improved, with the decrease range of 66.26-263.16%, 198.93-323.98% and 189.24-549.48%, respectively. This work reveals new insights into the mechanism of PCNs joint toxicity to aquatic ecosystem food chain and develop appropriate strategies for its ecological risk management.

Application of a 2D-QSAR with a sine normalization method for the biodegradation of fluoroquinolones to poison cyanobacteria.

Cyanobacteria are photosynthetic autotrophic aquatic prokaryotes. One of the methods for controlling cyanobacterial blooms is to destroy the phycobiliproteins required for photosynthesis. In this study, to improve the biodegradation of the fluoroquinolones through inhibit cyanobacteria, the molecular docking scores of 32 fluoroquinolones (FQs) with four categories of phycobiliproteins from cyanobacteria were calculated after sine normalization to characterize the binding ability between them. A two-dimensional quantitative structure-activity relationship (2D-QSAR) model was constructed based on the comprehensive scores. Danofloxacin (DAN) with the highest comprehensive score was chosen for molecular modification. When docking with four categories of phycobiliproteins from cyanobacteria, the docking values of DAN-11 and DAN-16 were increased up to 35.75%. Moreover, their functional characteristics and environmentally friendly predictive values were improved. When the DAN-11 and DAN-16 molecules docked with the other cyanobacterial phycobiliproteins, indicating that the designed DAN derivatives had general applicability to poison cyanobacteria, the weak interaction forces might increase the binding ability between the DAN derivatives and the receptor phycobiliprotein compared with the target molecule.

A novel pharmacophore model on PAEs' estrogen and thyroid hormone activities using the TOPSIS and its application in molecule modification.

In the proposed model, the estrogen activity values and thyroid hormone activity values of PAEs molecules were normalized using the TOPSIS method by eliminating the dimension coefficients, and the comprehensive activity values of estrogen and thyroid hormone were obtained by analyzing the activity of each hormone and assigning the corresponding weight. The five pharmacophore models of hormone combined activity were constructed using the comprehensive activity values. Hypol 1 was the optimal pharmacophore model, showing good predictive power and significance. Then, the DBP, DNOP, and DMP molecules in environmental priority control pollutants were selected as the target molecules to perform common substitution reactions of hydrogen bond donor. Eleven PAEs derivative molecules with significantly reduced combined activity and single activity were screened. In analysis of the differences before and after modification of the docking parameters and amino acid residues before and after modification of PAEs and their derivatives, the reduced closeness between ligand and receptor leads to the decrease of thyroid hormones and estrogen activities. Moreover, the establishment of the models, not only shows that the PAEs hormone activity has certain linear relationships with the physical parameters of molecules but also shows that thyroid hormone activity and estrogen activity of PAEs is consistent with the hormone combined activity. The results confirmed the feasibility of the modified PAEs modification scheme with reduced combined activities of hormones, providing an important theoretical method for the construction of the pharmacophore model of combined activities of hormones and the study of PAEs derivative molecules.

Efficacy coefficient method assisted quadruple-activities 3D-QSAR pharmacophore model for application in environmentally friendly PAE molecular modification.

Phthalate acid esters (PAEs) are among the most widely used plasticizers in plastic products. They are easily diffused from plastic during use and seriously affect the environment and human health. Therefore, designing environmentally friendly PAE derivatives has important practical applications. In this paper, the environmentally friendly molecular modification of PAEs was carried out according to a comprehensive structural evaluation based on a three-dimensional quantitative structure-activity relationship (3D-QSAR) pharmacophore model of four activity modes. First, the efficacy coefficient method was used to process the mobility, toxicity, degradation and bioconcentration data of the PAEs to calculate comprehensive evaluation values. The PAE 3D-QSAR pharmacophore complex model was constructed based on the PAE four-activity comprehensive evaluation value (a comprehensive value representing the mobility, toxicity, degradation and bioconcentration of the PAEs), and a total of 4 PAE derivatives with reduced comprehensive evaluation values were obtained. Functional evaluation of the derivatives showed that the five PAEs with lower comprehensive evaluation values were stable in the environment, while the insulating properties of the derivative molecules were less affected. Following the four-activity pharmacophore model (Hypo 1) of the target molecules, dimethyl phthalate (DMP) and di-n-octyl phthalate (DNOP), comprehensive evaluation models and their mobility, toxicity, degradation and bioconcentration single-activity models, the substitution sites selected by the comprehensive evaluation model were demonstrated to be highly representative. By constructing a two-dimensional quantitative structure-activity relationship (2D-QSAR) model of the comprehensive evaluation values of the PAEs and the four single-effect 2D-QSAR models of their derivatives, the different effects of the five key parameters on the comprehensive evaluation values, toxicity, degradation, mobility and bioconcentration of molecules were analysed.

Combined 2D-QSAR, Principal Component Analysis and Sensitivity Analysis Studies on Fluoroquinolones' Genotoxicity.

In this paper, two-dimensional quantitative structure-activity relationship (2D-QSAR) and principal component analysis (PCA) methods were employed to screen the main parameters affecting the genotoxicity of fluoroquinolones (FQs), and the rules affecting the genetic toxicity of FQs were investigated by combining 2D-QSAR and PCA with the sensitivity analysis method. First, four types of parameters were calculated, namely, the geometric parameters (7), electronic parameters (5), physical and chemical parameters (8), and spectral parameters (7), but the physical and chemical parameters heat of formation (HF) and critical volume (CV) were excluded after the establishment of the 2D-QSAR model. Then, after PCA, it was found that the first principal component represented the main driving factors affecting the molecular genetic toxicity of FQs. In addition, after comprehensive analysis of the factor loading of the first, second, and third principal components, seven parameters affecting the genotoxicity of the FQs were screened out, namely, total energy (TE), critical temperature (CT), and molecular weight (Mol Wt) (increased with increasing genotoxicity of the FQs) and steric parameter (MR), quadrupole moment QXX (QXX), quadrupole moment QYY (QYY), and boiling point (BP) (decreased with increasing genotoxicity of the FQs); the above key parameters were also verified by sensitivity analysis. The obtained rules could be used to determine the substitution sites and the substitution groups associated with higher genotoxicity in the process of FQ modification, and these rules agreed well with the hologram quantitative structure-activity relationship (HQSAR) model. Finally, it was also found through SPSS analysis that the parameters screened in this paper were significantly correlated with FQ derivatives' genetic toxicity.

A Review of a Class of Emerging Contaminants: The Classification, Distribution, Intensity of Consumption, Synthesis Routes, Environmental Effects and Expectation of Pollution Abatement to Organophosphate Flame Retardants (OPFRs).

Organophosphate flame retardants (OPFRs) have been detected in various environmental matrices and have been identified as emerging contaminants (EC). Given the adverse influence of OPFRs, many researchers have focused on the absorption, bioaccumulation, metabolism, and internal exposure processes of OPFRs in animals and humans. This paper first reviews the evolution of various types of flame retardants (FRs) and the environmental pollution of OPFRs, the different absorption pathways of OPFRs by animals and humans (such as inhalation, ingestion, skin absorption and absorption), and then summarizes the environmental impacts of OPFRs, including their biological toxicity, bioaccumulation, persistence, migration, endocrine disruption and carcinogenicity. Based on limited available data and results, this study also summarizes the bioaccumulation and biomagnification potential of OPFRs in different types of biological and food nets. In addition, a new governance idea for the replacement of existing OPFRs from the source is proposed, seeking environmentally friendly alternatives to OPFRs in order to provide new ideas and theoretical guidance for the removal of OPFRs.

Modification of Hexachlorobenzene to Molecules with Lower Long-Range Transport Potentials Using 3D-QSAR Models with a Full Factor Experimental Design.

In this study, the hexachlorobenzene molecule was modified by three-dimensional quantitative structure-activity relationship (3D-QSAR) models and a full factor experimental design to obtain new hexachlorobenzene molecules with low migration ability. The 3D-QSAR models (comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA)) were constructed by SYBLY-X 2.0 software, using experimental data of octanol-air partition coefficients (KOA) for 12 chlorobenzenes (CBs) congeners as the dependent variable, and the structural parameters of CBs as independent variables, respectively. A target molecule (hexachlorobenzene; HCB: its long-distance migration capability leads to pollution of the marine environment in Antarctic and Arctic) was modified using the 3D-QSAR contour maps associated with resolution V of the 210-3 full-factorial experimental design method, and 11 modified HCB molecules were produced with a single chlorine atom (-Cl2) and three chlorine atoms (-Cl1, -Cl3, and -Cl5) replaced with electropositive groups (-COOH, -CN, -CF3, -COF, -NO2, -F, -CHF2, -ONO2, and -SiF3) to increase the logKOA. The new molecules had essentially similar biological enrichment functions and toxicities as HCB but were found to be more easily degraded. A 2D-QSAR model and molecular docking technology indicated that both dipole moments and highest occupied orbital energies of the substituents markedly affected migration and degradation of the new molecules. The abilities of the compounds to undergo long distance migration were assessed. The modified HCB molecules (i.e. 2-CN-HCB, 2-CF3-HCB, 1-F-3-COOH-5-NO2-HCB, 1-NO2-3-CN-5-CHF2-HCB and 1-CN-3-F-5-NO2-HCB) moved from a long-range transport potential of the modified molecules to a relatively low mobility class, and the transport potentials of the remaining modified HCB molecules (i.e. 2-COOH-HCB, 2-COF-HCB, 1-COF-3-ONO2-5-NO2-HCB, 1-F-3-CN-5-SiF3-HCB, 1-F-3-COOH-5-SiF3-HCB and 1-CN-3-SiF3-5-ONO2-HCB) also significantly decreased. These results provide a basic theoretical basis for designing environmentally benign molecules based on HCB.

Synthetic Musks: A Class of Commercial Fragrance Additives in Personal Care Products (PCPs) Causing Concern as Emerging Contaminants.

Synthetic musks (SMs) are promising fragrance additives used in personal care products (PCPs). The widespread presence of SMs in environmental media remains a serious risk because of their harmful effects. Recently, the environmental hazards of SMs have been widely reported in various environmental samples including those from coastal and marine regions. This paper provides a systematic review of SMs, including their classification, synthetic routes, analysis and occurrence in environmental samples, fate and toxicity in the environment, as well as the associated risk assessment and pollution control. Research gaps and future opportunities were also identified with the hope of raising interest in this topic.