Effect of di-n-butyl phthalate (DBP) on the fruit quality of cucumber and the health risk

Responses of transcriptome and metabolome in peanut leaves to dibutyl phthalate during whole growth period

Introduction

The application of agricultural film mulching technology has significantly contributed to increasing crop yield and income, but the pollution caused by residual film has seriously affected agricultural production and the natural environment. Agricultural film is commonly employed to enhance the yield of peanuts; its use may lead to excessive dibutyl phthalate (DBP) residues in peanut kernels. But, limited investigations have been conducted on the regulatory mechanism of peanut leaves in response to DBP exposure throughout the entire growth period.

Methods

To bridge this knowledge gap, we investigated the differences in transcriptome and metabolome of peanut leaves under DBP stress.

Results

According to visual observations, the results of morphological response showed that the growth of peanut plants was significantly inhibited from seedling to pod stage under DBP treatment. Transcriptomic analysis results showed that the genes AH19G05510 (LRR receptor-like serine threonine-protein kinase) and AH20G31870 (disease resistance), belonging to the FAR1 family and bZIP family respectively, may be key genes involved in the resistance to DBP stress throughout its growth stages. Metabolomic analysis results showed that during the initial stage of DBP stress, the key metabolites in peanut leaves response to stress were carboxylic acids and derivatives, as well as fatty acyls. As peanut growth progressed, flavonoids gradually became more prominent in the resistance to DBP stress. By integrating metabolomics and transcriptomics analysis, we have identified that purine metabolism during seedling and flowering stages, as well as the flavone and flavonol biosynthesis pathways during pod and maturity stages, played a crucial role in response to DBP stress.

Discussion

These findings not only provide valuable key gene and metabolic information for studying anti-plasticizer pollution throughout the entire growth period of peanuts, but also offer reference for enhancing crop resistance to plasticizer pollution through genetic modification and metabolic regulation.

Phthalates and other organic chemicals in agricultural soils after use of different types of conventional and biodegradable plastics

Various plastic materials are used in contact with agricultural soil, like mulching films, crop covers, weed controlling fabrics and nets. Polyethylene (PE) mulches have already been recognized as a significant source of plastic in soil and they have been shown to contain additives like phthalates, known as endocrine disruptors. However, other agricultural plastics are less studied, and little is known on the substances potentially released from them endangering biodiversity and the human health. This research aims to assess whether different agricultural plastics release additives into soil and to compare the release among various materials. We collected soil samples from 38 agricultural fields where conventional mulching films (PE), weed controlling fabrics (PP), biodegradable mulches based on polybutylene adipate terephthalate (PBAT), frost covers (PP), and oxo-degradable films (at least OXO-PE) were used. We analyzed the soils for phthalates and acetyl tributyl citrate (ATBC), used as plastic additives, and for polycyclic aromatic hydrocarbons (PAH) and dodecane that have high affinity for plastics. In comparison to the control soils, dibutylphthalate (DBP) and ATBC concentrations were significantly higher in soils mulched with PE and, partly, with biodegradable films. DBP concentration found in soil samples ranged between below the limit of quantification at a control site (1.5 μg kg-1) to 135 μg kg-1 at a site mulched with OXO-PE. The highest ATBC concentration, 22 ± 6 μg kg-1, was registered in a site mulched with PE, showing a statistically significant difference not only in comparison to the controls but also when compared to sites mulched with OXO-PE (p = 0.029) and PBAT (p < 0.009). On the contrary, the use of agricultural plastics did not influence the concentration of PAHs and dodecane. Our results indicate that agricultural plastics are a source of some organic chemicals to agricultural soils, including phthalates that are known for posing threat to soil ecosystem and human health.

Revealing the metabolomics and biometrics underlying phytotoxicity mechanisms for polystyrene nanoplastics and dibutyl phthalate in dandelion (Taraxacum officinale)

Micro/nanoplastics (M/NPs) and phthalates (PAEs) are emerging pollutants. Polystyrene (PS) MPs and dibutyl phthalate (DBP) are typical MPs and PAEs in the environment. However, how dandelion plants respond to the combined contamination of MPs and PAEs remains unclear. In this study, we evaluated the individual and combined effects of PS NPs (10 mg L-1) and DBP (50 mg L-1) on dandelion (Taraxacum officinale) seedlings. The results showed that compared to control and individual-treated plants, coexposure to PS NPs and DBP significantly affected plant growth, induced oxidative stress, and altered enzymatic and nonenzymatic antioxidant levels of dandelion. Similarly, photosynthetic attributes and chlorophyll fluorescence kinetic parameters were significantly affected by coexposure. Scanning electron microscopy (SEM) results showed that PS particles had accumulated in the root cortex of the dandelion. Metabolic analysis of dandelion showed that single and combined exposures caused the plant's metabolic pathways to be profoundly reprogrammed. As a consequence, the synthesis and energy metabolism of carbohydrates, amino acids, and organic acids were affected because galactose metabolism, the citric acid cycle, and alanine, aspartic acid and glutamic acid metabolism pathways were significantly altered. These results provide a new perspective on the phytotoxicity and environmental risk assessment of MPs and PAEs in individual or coexposures.

Research progress and prospect of glomalin-related soil protein in the remediation of slightly contaminated soil

Soil pollution caused by organic pollutants and potentially toxic elements poses a serious threat to sustainable agricultural development, global food security and human health. Therefore, strategies for reducing soil pollution are urgently required. Arbuscular mycorrhizal fungi (AMF)-assisted phytoremediation is widely recognized for its ability to remediate slightly-contaminated soil. Glomalin-related soil protein (GRSP) production by AMF is considered a vital mechanism of AMF-assisted phytoremediation. GRSP is widespread in soils and may contribute to the remediation of slightly contaminated soils. GRSP facilitates stabilization of pollutants in soils by interacting with pollutants owing to its abundant functional groups, recalcitrance, and long turnover time. It also enhances soil bioremediation and phytoremediation by stimulating soil microbial activity, improving soil structure, and providing nutrients for plants. However, research on GRSP is still in its early stages, and studies on contaminated soil remediation are limited. The effectiveness of GRSP in situ remediation remains to be proved. This review summarizes current knowledge regarding the GRSP distribution and its contribution to the remediation of slightly contaminated soils. Additionally, we present strategies to increase the GRSP content in contaminated soils, as well as prospects for future studies on the use of GRSP in contaminated soil remediation. This study focuses on recent developments that aim to improve awareness of the role of GRSP in soil remediation and relevant future directions.

Contamination and ecological risk of microplastics and phthalates in the surface water of the Tha Dee Sub-River basin, Nakhon Si Thammarat Province, Thailand

Plastic waste has become a significant source of water pollution worldwide, releasing microplastics (MPs) and hazardous chemicals into aquatic environments. The purpose of this study was to determine the occurrence and ecological risk of MPs and phthalates (PAEs) in the surface water of the Tha Dee Sub-River basin in Nakhon Si Thammarat Province, Thailand. MPs, PAEs, and water quality parameters, including turbidity, pH, conductivity, dissolved oxygen, and salinity, were investigated simultaneously at 26 sampling stations. The average number of MPs per liter was 0.5 ± 0.4. Filaments were the most common MPs (59%), and transparent/white was the most prevalent color (51%). Four PAEs were found, with an average total concentration of 25.78 ± 93.87 µg/L, and diethyl phthalate was observed in the highest concentrations. Although there was no association between PAEs and other parameters, there was a significant correlation among particular PAEs (P < 0.05), indicating that they came from the same source. The pollution load index of MPs indicated a minor risk, but PAEs posed a medium risk to fish in the study area. This study's findings suggest that further research into the sources of PAEs and their contamination of aquatic life is needed.

Uptake of a plasticizer (di-n-butyl phthalate) impacts the biochemical and physiological responses of barley

BACKGROUND

DBP is one of the most commonly used plasticizers for imparting desirable properties to polymers. The introduction of phthalates is reported to have occurred in the late 1920s, and there has been a significant rise in their release into the environment in past decades due to a lack of covalent bonding with the parent matrix. Because of their numerous applications in day-to-day life, phthalates have become ubiquitous and also classified as endocrine disruptors. Hence, several studies have been conducted to investigate the phthalate-mediated toxicities in animals; however, plants have not been explored to the same amount.

METHODS

Therefore, in the present study, the accumulation and translocation along with morpho-physiological perturbations in barley plants after 15, 30, 60, and 120 days of exposure to di-n-butyl phthalate (DBP) are investigated using standard protocols.

RESULTS

The maximal accumulation and translocation of DBP in the roots and shoots of barley plants was observed after 60 days of exposure. The exposure of DBP from 15 to 120 days was recorded to decline all the morphological indices (i.e., dry weight, net primary productivity, seed number per spike, and seed weight) of barley plants. The pigments content declined under DBP treatment for all exposure durations except 120 days exposure. Carbohydrate content increased after 15-30 days of exposure afterward it was observed to be decreased under 60 and 120 days of exposure. The protein content was declined in DBP stressed plants for 15-120 days. Proline content was increased in all exposure durations and maximal percent increase was recorded in 120 days of exposure. MDA content showed an increase at earlier exposure durations then followed by a decline in long-term exposure. Hydrogen peroxide content increased at all exposure durations. There were significant alterations observed in the activities of all antioxidative enzymes in comparison to the control. Furthermore, DBP stressed plants after 60 days were analyzed for the macromolecular variations using Fourier transform infrared spectroscopy (FTIR).

CONCLUSION

Thus, the outcomes of the current work provide an appraisal of phthalates' uptake and translocation mediated phytotoxic responses in barley plants. These observations can help in developing genetically modified edible plants that are resistant to phthalates uptake, thereby ensuring food security.

DEHP-induced mitophagy and mitochondrial damage in the heart are associated with dysregulated mitochondrial biogenesis

Di(2-ethylhexyl) phthalate (DEHP) is a plasticizer widely used in agricultural and industrial plastic products. Many researchers have demonstrated that DEHP can cause varying degrees of harm to the heart. This research investigated the mechanism by which DEHP causes heart damage in quail. The quail were treated with DEHP (250 mg/kg BW/day, 500 mg/kg BW/day or 750 mg/kg BW/day) for 45 days. The present study suggested that DEHP could cause varying levels of heart damage, including disordered myocardial fiber arrangements, myocardial fiber breakage and myocardial cell swelling. The results showed that DEHP induced mitochondrial damage, such as cavitation lesions and mitochondrial crest breakage. DEHP damaged mitochondria and inhibited nuclear respiratory factor 1 (Nrf1)-mediated mitochondrial biogenesis, which led to mitochondrial damage. DEHP caused oxidative stress in the heart and activated the defense mechanism of the nuclear factor red blood cell 2 related factor 2 (Nrf2) system. DEHP-induced mitophagy was related to a decline in mitochondrial biogenesis and disordered mitochondrial dynamics. The data indicated that DEHP exposure damaged cardiac mitochondria and caused mitophagy and cardiotoxicity. Of note, this study showed that DEHP-induced mitophagy and mitochondrial damage are associated with the dysregulation of mitochondrial biogenesis.

Response of soil characteristics to biochar and Fe-Mn oxide-modified biochar application in phthalate-contaminated fluvo-aquic soils

Biochar (BC) derived from agricultural biomass is effective at immobilizing phthalate in the agricultural soil environment. In this study, we assessed the effects of 0.5%, 1%, and 2% BC and Fe-Mn oxide-modified biochar (FMBC) addition on dibutyl phthalate (DBP) and di-(2-ethylhexyl) phthalate (DEHP) residues and biochemical characteristics in the rhizosphere soil of mature wheat polluted with DBP and DEHP using a pot experiment. Scanning electron microscopy showed that the surfaces and pores of BC and FMBC adhered soil mineral particles after remediation. Therefore, DBP and DEHP residues were increased in BC- and FMBC-treated soils. Illumina HiSeq sequencing showed that, compared with the control, BC and FMBC addition significantly enhanced the relative abundance of Firmicutes and reduced Proteobacteria. The abundance of Sphenodons and Pseudomonas, which degrade phthalates, tended to be higher in FMBC-amended soils than in BC-amended and control soils. This result may be related to an increase in available nutrients and organic matter following BC and FMBC application. Subsequently, the changes in soil bacterial abundance and community structure induced an increase in polyphenol oxidase, β-glucosidase, neutral phosphatase, and protease activity in BC and FMBC remediation. In comparison with the BC treatment, FMBC addition had a significantly positive effect on enzyme activity, and the microbial structure and was therefore more effective at immobilizing DBP and DEHP in the soil. Thus, our findings strongly suggest that FMBC is a reliable remediation material for phthalate-contaminated soil.

Single-use plastics: Production, usage, disposal, and adverse impacts

Single-use plastics (SUPs), invented for the modern "throwaway society," are intended to be used only once. They are being increasingly produced and used globally, most notably as packaging or consumables, such as SUP shopping bags or disposable tableware. We discuss how most SUPs are landfilled or incinerated, which causes pollution, consumes valuable land, and squanders limited natural resources. Only relatively small amounts are currently recycled, a hindrance to the concept of a circular economy. Moreover, SUP litter aggregation in the natural environment is a major concern. This article briefly reviews SUP contamination in various environmental media including soil, rivers, lakes and oceans around the world. In the face of mounting evidence regarding the threat posed to plant growth, soil invertebrates and other land animals, (sea) birds, and marine ecosystems, there is a growing push to minimize SUPs. Regulatory tools and voluntary actions to reduce SUP usage have been put forward, with some suggestions for minimizing SUP waste.

Effects of Fe-Mn oxide-modified biochar composite applications on phthalate esters (PAEs) accumulation in wheat grains and grain quality under PAEs-polluted brown soil

Phthalate esters (PAEs), such as dibutyl phthalate (DBP) and di-(2-ethylhexyl) phthalate (DEHP), are used extensively as additives and plasticizers, and have become ubiquitous in the environment. PAEs in the soil could have adverse effects on crop plants as well as humans via accumulations in food chain. Thus, it is important to explore strategies to reduce the bioavailability of phthalate esters. We investigated the effects of Fe-Mn oxide-modified biochar composite (FMBC) applications on the quality of wheat grown in DBP- and DEHP-polluted brown soil. The application of FMBC and biochar (BC) increased the wheat grain biomass by 9.71-223.01% and 5.40-120.15% in the DBP-polluted soil, and 10.52-186.21% and 4.50-99.53% in the DEHP-spiked soil in comparison to the controls. All FMBC treatments were better than the BC treatments, in terms of decreasing DBP and DEHP bioavailability for the wheat grains. The activities of the glutamine synthetase and glutamic-pyruvic transaminase in the flag leaves at the filling stage and of granule-bound starch synthase, soluble starch synthase, and adenosine diphosphate-glucose pyrophosphorylase in the grains at maturity increased significantly with increases in either the BC or FMBC applications. This, in turn, increased the starch, protein, and amino acid content in the wheat grains. Compared with the BC treatment, the FMBC amendment induced only slight increases in the aforementioned factors. This study offers novel insights into potential strategies for decreasing PAEs bioavailability in soil, with potential positive implications for crop quality and environmental health improvements.

The Formation of Fruit Quality in Cucumis sativus L

Cucumber is one of the most widely grown vegetables in China and an indispensable fresh fruit in the diet. With the development of society, the demand of people for cucumber quality is higher and higher. Therefore, cultivating high-quality cucumber varieties is one of the main goals of cucumber breeding. With the rapid development of biotechnology such as molecular marker, cucumber quality control network is becoming clear. In this review, we describe the formation mechanism of cucumber fruit quality from three aspects: (1) the commercial quality of cucumber fruit, (2) nutritional quality formation, and (3) flavor quality of cucumber fruit. In addition, the determinants of cucumber fruit quality were summarized from two aspects of genetic regulation and cultivation methods in order to provide ideas for cucumber researchers and cultivators to improve fruit quality.

Physiological responses of Arthrobacter sp. JQ-1 cell interfaces to co-existed di-(2-ethylhexyl) phthalate (DEHP) and copper

Arthrobacter sp. JQ-1 can completely degrade 500 mg/L of DEHP within 3 days. The minimum inhibitory concentrations (MICs) of Cu²⁺ could reach 1.56 mM, however, 5.0 mg/L Cu²⁺ apparently inhibited DEHP degradation and bacterial growth. Consequently, JQ-1 was exposed to the DEHP-copper environment to verify the toxicity mechanism based on the physiological responses of cellular multiple interfaces (cellular surface, membrane and intracellular characteristics). The results showed the combination of 500 mg/L DEHP and 5.0 mg/L Cu²⁺ significantly decreased cell surface hydrophobicity (CSH) and the absolute value of zeta potential, which implied the bioavailability of DEHP was decreased. The cellular surface changes were mainly due to the interaction between Cu²⁺ and some functional groups (CH₂, CH₃, aromatic rings, and amide). The weakened proton-motive force (PMF) across the plasma membrane may interfere the formation and utilization of energy, which is not conducive to the repair process of cellular damages. In this study, Non-invasive micro-test technology (NMT) was applied to the research of combined toxicity of DEHP and heavy metal ions for the first time. DEHP-copper intensified K⁺ efflux and Ca²⁺ influx across the plasma membrane, which disturbed ion homeostasis of K⁺ and Ca²⁺ and might induce apoptosis and further inhibit DEHP degradation. The decline of intracellular esterase activity indicated that the metabolic capacity is apparently restrained. This study enhances our understanding of cellular different interface processes responding to combined pollutants.

Improving yield and quality of vegetable grown in PAEs-contaminated soils by using novel bioorganic fertilizer

Phthalate acid esters (PAEs) are ubiquitous pollutants in agricultural soils. Application of bioorganic fertilizer (BOF) containing beneficial microbes represents a promising approach to improve the yield and quality of crops grown in contaminated soils. In the present study, a novel multifunctional bioorganic fertilizer N-BOF was developed by using compost of sewage sludge and agricultural waste and inoculating with PAEs-degrading B. megaterium YJB3 and phosphate solubilizing B. megaterium YLYP1. Its feasibility of improving the yield and quality of vegetable grown in PAEs (including DBP and DEHP) contaminated soil was evaluated by pot experiments. The N-BOF could effectively promote plant growth, with biomass increasing by 4-66.9% and 19-110% compared to chemical (CF) and no fertilizer (CK), respectively. The concentrations of DBP and DEHP in shoots of chemically fertilised vegetable ranged 1.23-3.12 mg/kg (dry weight, DW) and 1.63-3.89 mg/kg (DW), respectively. Their concentrations were significantly decreased (p < 0.05) when N-BOF was applied (1%, 2%, 5% amendment), especially at higher application rate ranging 0.11-0.3 mg/kg (DW) and 0.16-0.32 mg/kg (DW), respectively. Meanwhile, vegetable quality attributes were also significantly improved when 2% N-BOF was applied, with increase in the contents of vitamin C, vitamin B1, total protein, and starch, and decrease in the contents of nitrite and nitrate. In this case, the human health risk from consumption of the vegetable grown in PAEs-contaminated soil could be significantly reduced. Thus, our study is expected to provide an efficient way of high-value utilization of organic substrates by producing low-cost but high quality N-BOF. Future studies on the effects of N-BOF in terms of fertilizer regimes on yield and quality of the vegetable are needed, and further field studies for assessing the long-term efficacy and reliability of this promising N-BOF are also warranted.

Metabolic process of di-n-butyl phthalate (DBP) by Enterobacter sp. DNB-S2, isolated from Mollisol region in China

The accumulation of phthalate acid esters (PAEs) in the environment has aroused a global concern. Microbial degradation is the most promising method for removing PAEs from polluted environment. Di-n-butyl phthalate (DBP) is one of the most widely used PAEs. In this study, a highly efficient DBP-degrading strain, Enterobacter sp. DNB-S2 was isolated from Mollisol in northeast China, and the degradation rate of 500 mg L^-1 DBP reached 44.10% at 5 °C and 91.08% at 50 °C within 7 days. A new intermediate, n-butyl benzoate BP, was detected, implying a new degradation pathway. The complete genome of the strain DNB-S2 was successfully sequenced to comprehensively understand of the entire DBP catabolic process. Key genes were proposed to be involved in DBP degradation, such as esterases, 3,4-dihydroxybenzoate decarboxylase and catechol 2,3-dioxygenase genes. Intermediate-utilization tests and real-time quantitative polymerase chain reaction (RT-qPCR) validated the proposed DBP catabolic pathway. The aboriginal bacterium DNB-S2 is a promising germplasm for restoring PAE-contaminated Mollisol regions at low temperature. This study provides novel insight into the catabolic mechanisms and abundant gene resources of PAE biodegradation.

Phthalate Ester Contamination in Intensively Managed Greenhouse Facilities and the Assessment of Carcinogenic and Non-Carcinogenic Risk: A Regional Study

The contamination status and the potential carcinogenic and non-carcinogenic health risks from six phthalate esters (PAEs), nominated as priority pollutants by the United States Environmental Protection Agency (USEPA), were investigated in 40 typical greenhouses in three large-scale intensive greenhouse production areas in Jingmen city, Hubei province, central China. The total concentrations of PAEs in 40 soil samples and 80 vegetable samples ranged from 919 ± 134 to 7015 ± 475 µg kg⁻¹ (dry weight, DW), and from 387 ± 63, to 11,683 ± 1313 µg kg⁻¹ (DW), respectively. No carcinogenic risk was detected. The heat-map of the hazard quotient (HQ) values indicates the non-carcinogenic risks to children from di-n-butyl phthalate (DBP), at two sampling sites out of the 40, and from diethylhexyl phthalate (DEHP) (20 to young children and three to older children and adults) at 23 of the sites. The contamination risk from PAEs at Pengdun is of concern because only two of the 14 sampling sites selected there showed the non-carcinogenic risk to humans was unclear. The results of this study help to close a long-term knowledge gap resulting from a shortage of experimental data on PAE contamination in intensive greenhouse vegetable production in central China. The inclusion of DEHP in the Chinese list of priority pollutants is recommended, due to its increasing contamination and risk. This study provides valuable information for protected agricultural soil management and risk avoidance. It is a timely reminder to take PAE contamination and associated health risks into consideration, during the planning and introduction of intensively-managed greenhouse production systems.

Plastic film mulching increased the accumulation and human health risks of phthalate esters in wheat grains

Plastic film mulching is a common practice to increase crop yield in dryland, while the wide use of plastic film has resulted in ubiquitous phthalate esters (PAEs) releasing into the soil. PAEs in soil could be taken up and accumulated by dietary intake of food crops such as wheat, thus imposing health risks to residents. In the present study, samples from a long-term location-fixed field experiment were examined to clarify the accumulation of PAEs in soil and wheat, and to assess the human health risks from PAEs via dietary intake of wheat grain under plastic film mulching cultivation in dryland. Results showed that concentrations of PAEs in grains from mulching plots ranged from 4.1 to 12.6 mg kg^-1, which were significantly higher than those in the control group. There was a positive correlation for the PAE concentrations between wheat grains and field soils. Concentrations of PAEs in the soil were in the range of 1.8-3.5 mg kg^-1 for the mulching treatment, and 0.9-2.7 mg kg^-1 for the control group. Di-n-butyl phthalate (DBP) and di-(2-ethylhexyl) phthalate (DEHP) were detected in all soil and grain samples, and DEHP was found to be the dominant PAE compound in grains. Based on DEHP concentrations in wheat grains, the values of carcinogenic risk for adults were higher than the recommended value 10^-4. Results indicated that wheat grains from film mulching plots posed a considerable non-carcinogenic risk to residents, with children being the most sensitive resident group. Findings of this work call the attention to the potential pollution of grain crops growing in the plastic film mulching crop production systems.

Modulation of biochemical and physiological parameters in Hordeum vulgare L. seedlings under the influence of benzyl-butyl phthalate

Background

Phthalates are man-made chemical compounds with numerous applications especially known for their use as plasticizers. They have weak bonding to the polymeric matrix or products in which they are used. Owing to this reason, they are readily released into the environment which makes them ubiquitous. The agricultural soils are also reported to be polluted with phthalates up to a considerable extent which causes adverse effects on flora and fauna. A few studies have been conducted on phthalate-induced phytotoxicity, which has revealed that phthalates affect the quality and yield of edible plants. In the last decades, some crops were analyzed for phthalate-induced adversities; among them, barley was the least explored.

Methods

The present study has investigated the impact of benzyl-butyl phthalate (BBP) on barley (Hordeum vulgare L.) seedlings to address the biochemical, physiological consequences, and toxicological implications. After the exogenous exposure of BBP (viz. 0, 25, 50, 100, 200, 400, 800, 1,600 mg/L) for 7 days, barley seedlings were analyzed for different indices.

Results

The exposure of BBP mediated a significant (p ≤ 0.05, 0.01) overall elevation in the contents of pigment, proline, soluble protein, carbohydrate, hydrogen peroxide (H₂O₂), and malondialdehyde (MDA) in shoots and roots of barley seedlings. The activities of superoxide dismutase (SOD), guaiacol peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR) were also stimulated significantly in shoots and roots of seedlings against BBP stress except for SOD activity which declined in the roots. The polyphenols (non-enzymatic antioxidants) content was also altered in all the treated concentrations as compared to the control. Furthermore, BBP caused stomatal abnormalities, induced cytotoxicity, and loss of plasma membrane integrity.

Conclusions

BBP disturbed the normal physiology of barley which could also affect the yield of the crop under field conditions.

Dibutyl phthalate contamination remolded the fungal community in agro-environmental system

Dibutyl phthalate (DBP) is a typical soil contaminant that is widely used as plasticizer in modern agricultural production. In this study, an experiment was conducted to evaluate fungal community succession in a soil-vegetable ecosystem under different DBP concentrations. By using high-throughput sequencing of the ribosomal internal transcribed spacer (ITS) region, it was shown that DBP contamination caused significant changes to the soil fungal community, in terms of both α and β diversities. The largest changes in fungal α and β diversities were detected under 50 mg/kg DBP concentration at the first day of addition. The bulk soils, rhizosphere soils and the phyllosphere harbored different fungal communities, while the abundance of saprotrophs and plant pathogens in the phyllosphere have been increased under DBP contamination. From correlation analysis and partial Mantel test, the change in fungal community α diversity was the result of multiple factors (DBP concentration, bacterial community and soil properties) while the β diversity of fungal community was mainly co-varied with the bacterial community after DBP contamination. Moreover, molecular ecological network analysis demonstrated that DBP contamination was detrimental to mutualistic relationships among fungal species and destabilized the network structure. Overall, the fungal communities in soils and around vegetables were largely remolded by DBP contamination that provides new insight into DBP contamination impacts on agricultural ecosystems.

One overlooked source of phthalate exposure - oral intake from vegetables produced in plastic greenhouses in China

With increasing consumption of Vegetables planted in Plastic Greenhouses (VPGs) in China, phthalate exposure from VPGs represents an overlooked source of total daily exposure, since VPGs are not included in current phthalate exposure scenarios. For this reason, current exposure scenario modeling may underestimate the daily phthalate exposure in relation to adverse health impacts. Thus, in this paper we estimated the oral intake exposure to phthalates from VPGs by studying four provinces ranging from the north to the south in eastern China, based on published data. Exposures to di(2-ethylhexyl)-phthalate (DEHP) and dibutyl phthalate (DBP) were assessed for various population groups differentiated by age, sex, income, and region. Younger children experienced the highest exposure from VPG intake (mean 1.55 (0.19 and 6.20) (2.5th and 97.5th percentiles) μg/kg/body weight (bw)/day), followed by older children, teenagers, and adults (0.53 (0.06 and 1.80)). Exposures in urban populations were significantly higher than those in rural areas, and when examined by income, urban populations with low-income had the lowest exposures and the upper-middle income group was associated with the highest levels. Exposures in northeastern and southern provinces were higher than the levels in middle provinces due to regional disparities in dietary habits. Proportions of the mean oral intake exposures to DEHP and DBP from VPGs to the total daily exposure by modeling different exposure pathways and media were over 10% for all age groups. The DEHP and DBP exposure from VPG intake in China were found to be much higher than the levels in western countries. For example, exposures of older children to DBP and DEHP were respectively 17 and 4 times higher than European levels. The authors recommend policy interventions to protect populations from future risk of phthalate exposure.

Responses of bacterial community to dibutyl phthalate pollution in a soil-vegetable ecosystem

Phthalate esters (PAEs) are a type of plasticizer that has aroused great concern due to their mutagenic, teratogenic, and carcinogenic effects, wherefore dibutyl phthalate (DBP) and other PAEs have been listed as priority pollutants. In this study, the impacts of DBP on a soil-vegetable ecosystem were investigated. The results showed that DBP could accumulate within vegetable tissues, and the accumulative effect was enhanced with higher levels of DBP contamination in soils. DBP accumulation also decreased vegetable quality in various ways, including decreased soluble protein content and increased nitrate content. The diversity of bacteria in soils gradually decreased with increasing DBP concentration, while no clear association with endophytic bacteria was observed. Also, the relative abundance, structure, and composition of soil bacterial communities underwent successional change during the DBP degradation period. The variation of bulk soil bacterial community was significantly associated with DBP concentration, while changes in the rhizosphere soil bacteria community were significantly associated with the properties of both soil and vegetables. The results indicated that DBP pollution could increase the health risk from vegetables and alter the biodiversity of indigenous bacteria in soil-vegetable ecosystems, which might further alter ecosystem functions in agricultural fields.

Occurrence and risk assessment of phthalate esters (PAEs) in agricultural soils of the Sanjiang Plain, northeast China

This study looks at the pollution status of six priority control phthalate esters (PAEs) under different cultivation of agricultural soils in the Sanjiang Plain, northeast China. Results show the total concentration of PAEs ranged from 162.9 to 946.9 μg kg^-1 with an average value of 369.5 μg kg^-1. PAE concentrations in three types of cultivated soils exhibited decreasing order paddy field (532.1 ± 198.1 μg kg^-1) > vegetable field (308.2 ± 87.5 μg kg^-1) > bean field (268.2 ± 48.3 μg kg^-1). Di-(2-ethylhexyl) phthalate (DEHP) and di-n-butyl phthalate (DnBP) were the most abundant PAEs congeners. Compared with previous studies, agricultural soils in the Sanjiang Plain showed relatively low contamination levels. Anthropogenic activities such as cultivation practices and industrial emissions were associated with the distribution pattern of PAEs. Furthermore, human health risks of PAEs were estimated and the non-cancer risk shown negligible but carcinogenic risk of DEHP exceeded the threshold limits value. PAE contaminants originated from cultivation practices and intense anthropogenic activities result in placing the agricultural soils under a potential risk to human health and also to ecosystems in the Sanjiang Plain. Therefore, the contamination status of PAEs in agricultural soil and potential impacts on human health should attract considerable attention.

Variation in accumulation and translocation of di-n-butyl phthalate (DBP) among rice (Oryza sativa L.) genotypes and selection of cultivars for low DBP exposure

Di-n-butyl phthalate (DBP) is a typical endocrine-disrupting chemical with higher detection frequency and concentration in agricultural soil (particularly in paddy-field soil of Guangdong Province) of China. In this study, a greenhouse experiment was conducted to investigate variation in uptake and accumulation of DBP by 20 rice cultivars and to screen low DBP-accumulating cultivars. DBP concentrations in plants varied greatly with rice cultivars, growth stages, and tissues. The highest DBP concentrations in both roots and shoots were observed at the ripening stage, with concentrations 2-100-fold higher than those at tillering, jointing, and flowering stages. At the ripening stage, DBP concentrations decreased in the order of leaf > root > stem > grain, and significant differences of DBP concentrations were observed among various rice cultivars. Moreover, the magnitude of variation in DBP concentrations among various cultivars was greater in stems and grains than in roots and leaves. The translocation factors of DBP from roots to stems and from shoots to grains were <1.0, and those from stems to leaves were almost >1.0. Overall, cultivars Yuxiangyouzhan, Jinnongsimiao, Tianyou 122, and Wuyou 380 accumulated relatively lower DBP in grains, resulting in lower DBP exposure. The DBP uptake and translocation pathways in rice require further investigation. Graphical abstract ᅟ.