Phthalate esters and their metabolites in paired soil-crop systems from farmland in major provinces of eastern China: Pollution characteristics and implications for human exposure

A narrative review of phthalates: From environmental release to kidney injury

Plastic products play an indispensable role in human daily lives, largely due to their low cost and unrivaled convenience. Phthalates (PAEs) are the most significant plastic additives due to their distinctive properties and are extensively utilized and produced in large quantities. Nevertheless, given their inability to form covalent bonds with plastics, these compounds are prone to leaching from plastic surfaces. As a result, the use of plastics in various industries has become a major source of PAEs in the environment, leading to increased risks to humans. The kidneys, which play a central role in the excretion of PAEs, are considered one of the primary target organs for PAEs accumulation and toxicity. A growing body of evidence supports an association between exposure to PAEs and adverse effects on the kidney. In environments, PAEs are often exposed simultaneously with other contaminants that may directly or indirectly modify the toxic effects of PAEs. This review focuses on the adverse effects of PAEs exposure on the kidney and their mechanisms of action, as well as the interactions between PAEs and other contaminants on the kidney. This review underscores the necessity for future toxicological studies to prioritize the mechanisms of renal injury caused by co-exposure to PAEs and other pollutants. The employment of advanced technologies, including network toxicology and molecular docking techniques, is imperative to enhance comprehension of the potential toxicity associated with co-exposures.

Uptake, translocation, and biotransformation of phthalate acid esters in crop plants: A comprehensive review

Phthalate acid esters (PAEs) are prevalent emerging contaminants in agricultural environments. The uptake of PAEs by crop plants has attracted extensive attention due to the risks posed to human health through transfer in food chains. Despite its importance, the interaction between PAEs and crop plants remains poorly understood. In this critical review, the occurrence of six priority control PAEs in various food crops grown in greenhouses and conventional farms is investigated, with detected concentrations reaching up to mg/kg (dry weight) levels. PAEs enter plants through roots, foliar gas, or foliar particle uptake. After entry, PAEs exhibit acropetal translocation from the root and basipetal translocation from the leaf. PAEs are transformed into various metabolites through hydroxylation, hydrolysis, and oxidation in phase I metabolism and further conjugated with biomolecules such as amino acids or sugars in phase II metabolism. Exposure to PAEs disrupts plant homeostasis and activated antioxidant enzymes to alleviate phytotoxicity. Dietary intake of PAEs-contaminated food crops presents potential risks to human health, particularly from fruit and root vegetables consumed by children, warranting specific attention. Furthermore, current knowledge gaps and future perspectives are proposed. This review provides a comprehensive assessment of the knowledge on the uptake, translocation, and transformation of PAEs in crop plants, emphasizing the need for an integrated investigation into the full life cycle of PAEs in plants to ensure food safety.

Bimetallic lanthanide metal-organic framework supported ratiometric molecularly imprinted fluorescence sensor: An innovation for selective and visual detection of dimethyl phthalate

Dimethyl phthalate (DMP) is a prototypical member of the phthalic acid ester class of plasticizers that may remain in food, posing a considerable risk to both food safety and human health. An innovative ratiometric fluorescence sensor (MIPs@BL-MOF) was constructed by incorporating bimetallic lanthanide terbium/europium metal-organic framework (BL-MOF) into molecularly imprinted polymers (MIPs) for the rapid selective and visual detection of DMP. In this work, BL-MOF prepared by the 'post-mixing' strategy was intelligently incorporated in the MIPs layer, giving the sensor the ability of rapid mass transfer, efficient binding, excellent anti-interference, and high selectivity. Based on the photoelectron transfer mechanism, high-affinity detection of DMP was realized by MIPs@BL-MOF with a good linear fitting (R2 = 0.9944) and theoretical detection limit of 3.29 nmol L-1 in the range of 1.0 × 10-8-1.0 × 10-3 mol L-1. More importantly, a portable visual sensing platform integrated by the MIPs@BL-MOF sensor and smartphone was successfully applied to DMP detection. Accordingly, the MIPs@BL-MOF-based ratiometric fluorescence sensing platform with desirable specificity, sensitivity, and portability holds great potential for the rapid and visual detection of plasticizers for ensuring environmental and food safety.

Transformation metabolites of phthalate esters (PAEs) inhibited rice growth through jasmonic acid signaling pathway

Phthalate esters (PAEs) were ubiquitous in agricultural soils and could be metabolized after being absorbed by crops, posing significant implications for crop yield and quality. We hypothesize that monophthalates (mPAEs), the hydrolyzed products of PAEs, might mimic phytohormone jasmonic acid (JA) to activate the JA signaling pathway, therefore enhancing the defense towards pests and inhibiting the rice plant growth. Taking dibutyl phthalate (DBP) as a representative PAE, our study discovered that DBP exposure significantly induced JA-related outcomes including decreased larval weight (9.58-18.8%), and rice biomass (11.7-34.2%). Under the conditions where the JA content remained unchanged, monobutyl phthalate (MBP), the hydrolyzed product of DBP, triggered the JA signaling pathway, evidenced by significantly upregulated genes encoding coronatine insensitive 1 (COI1) (1.56-1.73 fold), jasmonate ZIM-domain (JAZ) (4.33-7.71 fold), MYC2 transcription factor (2.07-2.87 fold), and promoted phytoalexins production in downstream signaling. MBP conjugated with isoleucine, and the conjugate subsequently mimicked a JA bioactivator (JA-isoleucine conjugate) to occupy the binding site of COI1-JAZ co-receptor protein, thereby initiating the JA signaling pathway. These JA-related outcomes and mechanism were consistently evidenced in rice exposed to other four typical PAEs, and the aliphatic chain length of selected PAEs indicated a negative contribution to these observations. In this study, we discovered a unconventional mechanism through which the transformation metabolites of PAEs elicit pest defense while simultaneously inhibiting rice growth, providing insights into the risk assessment of PAEs on crop yields and quality.

Bisphenol analogues in soils and lettuce (Lactuca sativa L.) around typical factories in eastern China: Occurrence, contamination characteristics, and health risks

Following the restrictions on bisphenol A (BPA), the production and environmental release of bisphenol analogues (BPs) have increased. However, knowledge about the occurrence of bisphenol analogues other than BPA, especially in farmland soils and edible plants, remains limited. This study investigated the occurrence, contamination characteristics, and human health risks of eight bisphenol analogues in paired soil-plant samples from areas near factories in eastern China. Results indicated that the concentrations of Σ8BPs in the collected soil and plant samples ranged from 1.4 to 897.1 ng/g dw and 2.5 to 586.2 ng/g dw, respectively. BPA, bisphenol AF (BPAF), bisphenol F (BPF), and bisphenol S (BPS) were the primary components of BPs, with BPA having the highest detection frequency (74 %). In addition, a positive correlation was observed between the root concentration factor and the log Kow of BPs (R2 = 0.471, P < 0.05), whereas the translocation factor exhibited a negative correlation with the log Kow (R2 = 0.405, P < 0.05). The hazard index (HI) values of BPs in paired soil-plant samples were <1, suggesting that the current contamination levels of BPs in soils and plants are unlikely to pose significant health risks to humans. However, potential risks from long-term exposure require careful monitoring. This study offers new insights into the spatial distributions and contamination status of BPs in farmland soils and plants, highlighting the environmental behavior and health risks of other bisphenol analogues.

Persistent effects of early-life exposure to dibutyl phthalate on zebrafish: Immune system dysfunction via HPA axis

The plasticizer dibutyl phthalate (DBP) is one of the common contaminants in the aquatic environment and has been verified to be detrimental to aquatic organisms. In this research, zebrafish was employed to explore the toxic mechanism of DBP at environmental concentrations. The findings indicated that DBP led to abnormal development of zebrafish larvae, encompassing an increase in heart rate and malformation rate, as well as a reduction in survival rate and hatching rate. DBP also induced HPA axis activation, increased glucocorticoid content and microglia activation in zebrafish larvae. Moreover, adult zebrafish in the early-life exposure and long-term exposure groups demonstrated anxiety-like and depression-like behaviors. RNA-seq analysis revealed that early embryonic exposure to DBP led to persistent damage in zebrafish that could not be recovered in adulthood. The HPA axis was more severely disorganized in males than in females, and sex-specific differences were also shown in immunotoxicity. It is speculated that the immune system disorder could partially attribute to the out-of-control HPA axis, while the activation of inflammatory cells and inflammatory factors will further exacerbate the situation of HPA axis dysregulation.

The occurrence and safety evaluation of phthalic acid esters in Oasis agricultural soils of Xinjiang, China

Soil pollution caused by plastic residues containing additives (e.g. phthalic acid esters (PAEs)) is ubiquitous and has become a global concern. However, the distribution, accumulation, and potential risks associated with PAEs in agricultural soils have not been fully explored. This study quantified the types, concentrations, and distribution patterns of common PAEs in 29 agricultural soil samples collected from the Xinjiang Oasis, China. The results indicated that no significant variation in PAE concentrations across the oasis farmlands in Xinjiang. The PAEs were predominantly concentrated in the topsoil layer (0-20 cm), with an average concentration of 102.3 μg/kg, with some migration observed to the deeper soil layer (20-40 cm). The most abundant PAEs detected were Di (2-ethylhexyl) phthalate (DEHP), diisobutyl phthalate (DIBP), and diethyl phthalate (DEP), which accounted for 49.82 %, 23.74 %, and 20.96 % of the total, respectively. Furthermore, the concentrations of all PAEs were below China's soil quality risk control standards, and the non-carcinogenic risks to both adults and children were below the current threshold, indicating relatively low risks to both the human health and the environment. These findings are crucial for understanding the presence and safety evaluation of PAEs in Xinjiang Oasis farmland, and they provide important reference data for managing and controlling PAE contamination in agricultural soils.

Phthalates in the environment of China: A scoping review of distribution, anthropogenic impact, and degradation based on meta-analysis

Phthalates (PAEs) are a group of endocrine-disrupting environmental chemicals (EEDs) that pose significant risks to human health. PAEs are widespread in various environmental media, including air, dust, water, and soil, and are subject to both horizontal and vertical migration. Human activities significantly influence the distribution of PAEs, yet current research on this relationship remains limited. In this study, we first describe the hot issues of PAEs in the environment through bibliometrics, and then review published related studies. We outline the global distribution of PAEs in different media and conducted a comparative analysis of their composition. Principal component analysis (PCA) revealed PAEs differences in environmental mediums and geographic locations. Correlation analysis between PAEs composition and human activities in China further demonstrated that PAE concentrations were closely linked to agricultural and industrial activities. We also discussed the biodegradation and abiotic degradation of PAEs, finding that bacteria play a crucial role in their degradation in soil. This study aims to assess the distribution, transfer, impact, and degradation of PAEs, providing insights for the prevention and remediation of PAE pollution.

Pollution Status, Ecological Effects, and Bioremediation Strategies of Phthalic Acid Esters in Agricultural Ecosystems: A Review

Phthalic acid esters (PAEs) are common organic contaminants in farmland soil throughout agricultural systems, posing significant threats to human health and thus closely associated with food safety concerns. Here, we consolidate the latest findings regarding the distribution, ecological effects, bioremediation methods, and microbial degradation pathways of PAEs in agricultural ecosystems. Generally, di(2-ethylhexyl) phthalate (DEHP), di-n-butyl phthalate (DnBP), and di-isobutyl phthalate (DiBP) exhibit the highest detection frequencies and concentrations in soil, air and agricultural products. The presence of these PAEs in agricultural ecosystems can significantly affect soil and plant-associated microbial communities, leading to decreased yield and quality of agricultural products. Bioremediation techniques, such as microbial degradation and phytoremediation, are frequently explored to address these issues. Overall, this review provides a comprehensive overview of current research on PAEs in China's agricultural systems and offers insights into potential problems and future research directions.

Occurrence and human exposure risk of antibiotic resistance genes in tillage soils of dryland regions: A case study of northern Ningxia Plain, China

Agricultural soils are important source and sink of antibiotic resistance genes (ARGs). However, little is known about the fate of ARGs in dryland soils, while its human exposure risks were seriously overlooked. Taking the northern Ningxia Plain as a case, this study explored the occurrence of ARGs and its relationship with mobile genetic elements (MGEs), pathogens, and environmental factors. Furthermore, the concentrations of airborne ARGs by soil wind erosion and the human exposure doses of soil ARGs were evaluated. The results showed the abundances of different regions ranged from 4.0 × 105 to 1.6 × 106 copies/g. Soil ARGs are driven by MGEs, but multiply impacted by soil properties, nutrition, and bacterial community. Vibrio metschnikovii, Acinetobacter schindleri, and Serratia marcescens are potential pathogenic hosts for ARGs. Further exploration revealed the concentration of ARGs loaded in dust by soil wind erosion reached more than 105 copies/m3, which were even higher than those found in sewage treatment plants and hospitals. Skin contact is the primary route of ARGs exposure, with a maximum dose of 24071.33 copies/kg/d, which is largely attributed to ARGs loaded in dust. This study bridged the gap on ARGs in dryland soils, and provided reference for human exposure risk assessment of soil ARGs.

Distribution and source analysis of soil toxic organic compounds of coal-electricity production base in arid and semi-arid region of China

The presence and distribution of toxic organic compounds in soil pose significant challenges. Whether their distributional characteristics are more complex, especially in arid and semi-arid regions with harsh climatic conditions? This study analyzed the composition, classification, spatial distribution, and sources of 123 toxic organic compounds in 56 soil samples of coal-electricity production base. Those compounds were classified into 11 categories, mainly pesticides (41 compounds), organic synthesis intermediates (31 compounds), and drugs (23 compounds). Seventeen of those compounds were detected over the rate of 30 %, with 13 of them being under the Toxic Substances Control Act (TSCA) inventory. The primary sources of toxic organic compounds were determined using Principal Component Analysis (PCA) and Positive Matrix Factorization (PMF), including the degradation of pesticide residues (22.03 %), emissions of plastic pellets (16.64 %), industrial waste emissions (12.80 %), emissions from livestock (12.74 %), plastic films (11.22 %) and coal-to-liquid projects (10.78 %). This research underscores the widespread presence of toxic organic compounds in soil, highlighting their origins and distribution patterns, which are essential for developing targeted environmental management strategies in arid and semi-arid regions.

Widespread phthalate esters and monoesters in the aquatic environment: Distribution, bioconcentration, and ecological risks

Field research on phthalate monoesters (MPEs) and their relationships with phthalate esters (PAEs) is limited, especially in wild fishes. Here, PAEs and MPEs were measured in surface water, sediment, and wild fish collected from a representative river basin with high economic development. Several metabolites of emerging plasticizers, such as mono(3,5,5-trimethyl-1-hexyl) phthalate and mono(6-oxo-2-propylheptyl) phthalate, have already existed in fish with high detection frequencies (95 % and 100 %). Monobutyl phthalate and mono(2-ethylhexyl) phthalate were the predominant MPEs in fish and natural environment (surface water and sediment), while bis(2-ethylhexyl) phthalate was the most abundant PAEs in all matrices. The total concentrations (median) of 9 PAEs and 16 MPEs were 5980 and 266 ng/L in water, 231 and 10.6 ng/g (dw) in sediment, and 209 and 32.5 ng/g (ww) in fish, respectively. The occurrence of MPEs was highly related to their parent PAEs, with similar spatial distribution characteristics in the aquatic environments. Moreover, municipal wastewater discharge was recognized as the main source of MPEs in the research area. Fish species can accumulate targeted chemicals, and it seems more MPEs were from the PAE degradation in fish other than the direct uptake of MPEs in water. Parent PAEs showed higher ecological risk than their corresponding metabolites.

Phthalate monoesters accumulation in residential indoor dust and influence factors

Phthalate monoesters (mPAEs) possess biological activity that matches or even exceeds that of their parent compounds, phthalate esters (PAEs), negatively impacting humans. Indoor dust is the main carrier of indoor pollutants. In this study, indoor dust samples were collected from 46 households in Changchun City, Jilin Province, in May 2019, and particulate and flocculent fibrous dust was used as the research target to analyze the concentration and compositional characteristics of mPAEs, primary metabolites of five significant PAEs. The influence of factors such as architectural features and living habits in residential areas on exposure to mPAEs was explored. Ten suspected enzyme genes along with two metabolic pathways with the ability to degrade PAEs were screened using PICRUSt2. The results showed that the total concentrations of the five mPAEs in the indoor dust samples were particulate dust (11.49-78.69 μg/g) and flocculent fibrous dust (21.61-72.63 μg/g), respectively. The molar concentration ratio (RC) of mPAEs to corresponding PAEs significantly differed among chemicals, with MMP/DMP and MEP/DEP sporting the highest RC values. Different bacterial types have shown distinct influences against mPAEs and PAEs. Enzyme function and metabolic pathway abundance had a significant effect on the concentration of some mPAEs, mPAEs are most likely derived from microbial degradation of PAEs.

Risk assessment of China's Eastern Route of the South-to-north Water Diversion Project from the perspective of Phthalate Esters occurrence in the impounded lakes

Phthalate esters (PAEs) are widely utilized and can accumulate in lacustrine ecosystems, posing significant ecological and human health hazards. Most studies on PAEs focus on individual lakes, lacking a comprehensive and systematic perspective. In response, we have focused our investigation on characteristic lakes situated along the Eastern Route of the South-to-north Water Diversion Project (SNWDP-ER) in China. We have detected 16 PAE compounds in the impounded lakes of the SNWDP-ER by collecting surface water samples using solid-phase extraction followed by gas chromatography analysis. The concentration of PAEs were found to between 0.80 to 12.92 μg L-1. Among them, Bis (2-ethylhexyl) phthalate (DEHP) was the most prevalent, with mean concentration of 1.56 ± 0.62 μg L-1 (48.44%), followed by Diisobutyl phthalate (DIBP), 0.64 ± 1.40 μg L-1 (19.87%). Spatial distribution showed an increasing trend in the direction of water flow. Retention of DEHP and DIBP has led to increased environmental risks. DEHP, Dimethyl phthalate (DMP) etc. determined by agriculture and human activities. Additionally, Dibutyl phthalate (DBP) and DIBP mainly related to the use of agricultural products. To mitigate the PAEs risk, focusing on integrated management of the lakes, along with the implementation of stringent regulations to control the use of plasticizes in products.

Biodegradation of phthalate acid esters and whole-genome analysis of a novel Streptomyces sp. FZ201 isolated from natural habitats

Di-n-butyl phthalate (DBP) is one of the most extensively used phthalic acid esters (PAEs) and is considered to be an emerging, globally concerning pollutant. The genus Streptomyces holds promise as a degrader of various organic pollutants, but PAE biodegradation mechanisms by Streptomyces species remain unsolved. In this study, a novel PAE-degrading Streptomyces sp. FZ201 isolated from natural habitats efficiently degraded various PAEs. FZ201 had strong resilience against DBP and exhibited immediate degradation, with kinetics adhering to a first-order model. The comprehensive biodegradation of DBP involves de-esterification, β-oxidation, trans-esterification, and aromatic ring cleavage. FZ201 contains numerous catabolic genes that potentially facilitate PAE biodegradation. The DBP metabolic pathway was reconstructed by genome annotation and intermediate identification. Streptomyces species have an open pangenome with substantial genome expansion events during the evolutionary process, enabling extensive genetic diversity and highly plastic genomes within the Streptomyces genus. FZ201 had a diverse array of highly expressed genes associated with the degradation of PAEs, potentially contributing significantly to its adaptive advantage and efficiency of PAE degradation. Thus, FZ201 is a promising candidate for remediating highly PAE-contaminated environments. These findings enhance our preliminary understanding of the molecular mechanisms employed by Streptomyces for the removal of PAEs.

Status of phthalate esters pollution in facility agriculture across China: Spatial distribution, risk assessment, and remediation measures

The pervasive utilization of phthalate esters (PAEs) in plastic products has led to an emergent concern regarding the PAEs contamination in environmental matrices. However, the overall understanding of PAEs pollution in facility agriculture and its relevant risks remain limited. In this paper, the characteristics, health risks, and remediation measures of PAEs pollution in facility agriculture across China were analyzed. In general, PAEs pollution in facility agriculture soil in SWC and vegetables in SC were more serious than that in the other six regions (p < 0.05). The total level of six PAEs ranged from 0.053 to 5.663 mg·kg-1 in soil samples, nd (not detectable) to 12.540 mg·kg-1 in vegetable samples, with mean values of 0.951 mg·kg-1 and 2.458 mg·kg-1, respectively. DEHP and DnBP were dominant in both soil and vegetable samples with a total contribution of over 70 % of the six PAEs, but their concentrations were a little lower in soil samples. The PAEs concentrations of leafy, root, and fruit vegetables exhibited a descending trend. Correlation analysis revealed that the relationships between soil and vegetable PAEs concentrations remained inconclusive, lacking clear correlations. Furthermore, risk assessments indicated that the hazard quotient (HQ) for both total and individual PAEs in the vast majority of vegetable samples remained within acceptable thresholds. Meanwhile, all values for carcinogenic risks (CR) were confined within the range of 10-4. In conclusion, the study outlines remediation measures aimed at precluding and mitigating the environmental risks associated with PAEs exposure. These findings furnish a scientific foundation for the targeted assessment and judicious management of PAEs pollution within facility agriculture landscape of China.

Composition, distribution, health risks, and drivers of phthalates in typical red paddy soils

The accelerated accumulation of phthalate esters (PAEs) in paddy soils poses a serious threat to human health. However, related studies mainly focus on facility vegetable fields, drylands, and orchards, and little is known about paddy soils. In this study, 125 samples were collected from typical red paddy fields to investigate the pollution characteristics, sources, health risks, and main drivers of PAEs. Soil physicochemical properties, enzyme activity, and bacterial community composition were also measured simultaneously. The results showed that eight PAE congeners were detected ranging from 0.17 to 1.97 mg kg-1. Di-n-butyl phthalate (DBP), di-(2-ethylhexyl) phthalate (DEHP), and di-isobutyl phthalate (DIBP) were the most abundant PAE congeners, accounting for 81% of the total PAEs. DEHP exhibited a potential carcinogenic risk to humans through the intake route. The main PAEs were positively correlated with soil organic matter (SOM) and soil water content (SWC) contents. Low levels of PAEs increased bacterial abundance. Furthermore, most PAE congeners were positively correlated with hydrolase activity. Soil acidity and nutrient dynamics played a dominant role in the bacterial community composition, with PAE congeners playing a secondary role. These findings suggest that there may be a threshold response between PAEs and organic matter and nutrient transformation in red paddy soils, and that microbial community should be the key driver. Overall, this study deepens the understanding of ecological risks and microbial mechanisms of PAEs in red paddy soils.