Uptake and translocation of 14C-Carbamazepine in soil-plant systems

Unmasking Spatial Heterogeneity in Phytotoxicology Mechanisms Induced by Carbamazepine by Mass Spectrometry Imaging and Multiomics Analyses

Previous studies have highlighted the toxicity of pharmaceuticals and personal care products (PPCPs) in plants, yet understanding their spatial distribution within plant tissues and specific toxic effects remains limited. This study investigates the spatial-specific toxic effects of carbamazepine (CBZ), a prevalent PPCP, in plants. Utilizing desorption electrospray ionization mass spectrometry imaging (DESI-MSI), CBZ and its transformation products were observed predominantly at the leaf edges, with 2.3-fold higher concentrations than inner regions, which was confirmed by LC-MS. Transcriptomic and metabolic analyses revealed significant differences in gene expression and metabolite levels between the inner and outer leaf regions, emphasizing the spatial location's role in CBZ response. Notably, photosynthesis-related genes were markedly downregulated, and photosynthetic efficiency was reduced at leaf edges. Additionally, elevated oxidative stress at leaf edges was indicated by higher antioxidant enzyme activity, cell membrane impairment, and increased free fatty acids. Given the increased oxidative stress at the leaf margins, the study suggests using in situ Raman spectroscopy for early detection of CBZ-induced damage by monitoring reactive oxygen species levels. These findings provide crucial insights into the spatial toxicological mechanisms of CBZ in plants, forming a basis for future spatial toxicology research of PPCPs.

Congener-specific uptake and accumulation of bisphenols in edible plants: Binding to prediction of bioaccumulation by attention mechanism multi-layer perceptron machine learning model

Plant accumulation of phenolic contaminants from agricultural soils can cause human health risks via the food chain. However, experimental and predictive information for plant uptake and accumulation of bisphenol congeners is lacking. In this study, the uptake, translocation, and accumulation of five bisphenols (BPs) in carrot and lettuce plants were investigated through hydroponic culture (duration of 168 h) and soil culture (duration of 42 days) systems. The results suggested a higher bioconcentration factor (BCF) of bisphenol AF (BPAF) in plants than that of the other four BPs. A positive correlation was found between the log BCF and the log Kow of BPs (R2carrot = 0.987, R2lettuce = 0.801, P < 0.05), while the log (translocation factor) exhibited a negative correlation with the log Kow (R2carrot = 0.957, R2lettuce = 0.960, P < 0.05). The results of molecular docking revealed that the lower binding energy of BPAF with glycosyltransferase, glutathione S-transferase, and cytochrome P450 (-4.34, -4.05, and -3.52 kcal/mol) would be responsible for its higher accumulation in plants. Based on the experimental data, an attention mechanism multi-layer perceptron (AM-MLP) model was developed to predict the BCF of eight untested BPs by machine learning, suggesting the relatively high BCF of bisphenol BP, bisphenol PH, and bisphenol TMC (BCFcarrot = 1.37, 1.50, 1.03; BCFlettuce = 1.02, 0.98, 0.67). The prediction of BCF for ever-increasing varieties of BPs by machine learning would reduce repetitive experimental tests and save resources, providing scientific guidance for the production and application of BPs from the perspective of priority pollutants.

Biochemical and physiological changes in Zea mays L. after exposure to the environmental pharmaceutical pollutant carbamazepine

The presence of pharmaceuticals in the environment is a matter of great concern. They are consistently found in the environment, raising concerns regarding human exposure through dietary intake. In this study, we observed the effect of the application of carbamazepine at 0.1, 1, 10, and 1000 μg per kg of soil contamination levels to assess stress metabolism in Zea mays L. cv. Ronaldinio at the 4th leaf, tasselling, and dent phenological stages. The transfer of carbamazepine to the aboveground and root biomass was assessed, and uptake increased dose-dependently. No direct effect on biomass production was observed, but multiple physiological and chemical changes were observed. Major effects were consistently observed at the 4th leaf phenological stage for all contamination levels, including reduced photosynthetic rate, reduced maximal and potential activity of photosystem II, decreased water potential, decreased carbohydrates (glucose and fructose) and γ-aminobutyric acid in roots, and increased maleic acid and phenylpropanoids (chlorogenic acid and its isomer, 5-O-caffeoylquinic acid) in aboveground biomass. A reduction in net photosynthesis was observed for the older phenological stages, whereas no other relevant and consistent physiological and metabolic changes related to contamination exposure were detected. Our results indicate that Z. mays can overcome the environmental stress caused by the accumulation of carbamazepine with notable metabolic changes at the early phenological stage; however, older plants adapted and only exhibited minor effects in the presence of the contaminant. The potential implications for agricultural practice could be associated with the plant's response to simultaneous stresses due to metabolite changes associated with oxidative stress.

Understanding the metabolism of the novel plant antiviral agent dufulin by different positional 14C labeling in cherry radishes

Dufulin is a new type of plant antiviral agent. However, its metabolism in plants, which is very important for environmental risk assessment, is still unclear. In this study, we used ¹⁴C markers at different positions and high-performance liquid chromatography-quadrupole time-of-flight-mass spectrometry (HPLC-QTOF-MS) to qualitatively and quantitatively analyze dufulin metabolites in cherry radish. By combining ion pairs with unique abundance ratios, we clarified the metabolite structures, inferred the metabolic pathway of dufulin, and clarified the criteria for residues. The extractable residue of dufulin from cherry radish stem and leaf tissues was above 98 % and that in the succulent root was above 87 %. In the stem and leaf tissues and succulent root, dufulin underwent both phase I and phase II metabolism, and four metabolites were produced, including a conjugate of glucose malonate and hydroxylated dufulin, which was confirmed by comparison with a standard. However, the proportions and concentrations of the four metabolites did not meet the residue criteria, so only the dufulin precursor compound was included as a residue. This study provides reliable data for evaluating the impacts of dufulin on the environment and human health and for objectively examining the safety of dufulin.

Dissemination of antibiotics through the wastewater-soil-plant-earthworm continuum

Under the ongoing climate change scenario, treated municipal wastewater (TMW) is a potential candidate for irrigated agriculture but may result in the exposure of agricultural environments to antibiotics. We studied the transfers of trimethoprim, sulfamethoxazole, and sulfapyridine in the TMW-soil-plant-earthworm continuum under greenhouse/laboratory conditions. Irrigation of potted spinach and radish with as-collected TMW resulted in no transfers of antibiotics into soil or plants owing to their low concentrations in the tertiary-treated TMW. However, TMW spiked with higher antibiotic concentrations led to transfers through this continuum. High initial inputs, slow soil degradation, and chemical speciation of the antibiotics, coupled with an extensive plant-root distribution, were important factors enhancing the plant uptake of antibiotics. In microcosm studies, transfers from vegetable materials into earthworms were low but showed potential for bioaccumulation. Such food chain transfers of antibiotics may be a driver for antibiotic resistance in agricultural systems, which is an area worthy of future study. These issues can perhaps be mitigated through high levels of TMW purification to effectively remove antibiotic compounds.

Migration and toxicity of toltrazuril and its main metabolites in the environment

Veterinary drugs heavily used in livestock are passed into the environment through different ways, resulting in risks to terrestrial environments and humans. The migration of toltrazuril (TOL), an important anticoccidial drug used intensively in livestock, and its main metabolites between the chicken manure compost, soil and vegetables was investigated, and then the impacts of TOL on the soil bacterial community and ARGs, soil enzyme activities and phytotoxicity were detected. In the process of aerobic composting for 80 days, except for toltrazuril sulfoxide (the degradation half-life was 59.74 d), TOL and ponazuril (PON) were not significantly degraded. However, TOL and its metabolites were significantly degraded in fertilized soil, and the degradation half-life was 28.17-346.50 d. Among the three drugs, only PON could migrate from soil to vegetables, and the residual concentrations of PON in lettuce and radish were 2.64-70.02 μg kg-1 and 0-2.80 μg kg-1, respectively. Moreover, TOL and its main metabolisms had no significant effect on the bacterial community structure and the abundance of antibiotic resistance genes during composting, but affected the microbial activity in the soil. The presence of TOL and its main metabolites reduced soil urease activity, increased catalase activity, and decreased alkaline phosphatase activity at the beginning and then increased slightly. They had negative effects on plant growth. Compared with the control group, the inhibition rates of TOL and its metabolites on lettuce and radish seed germination were 8.33% and 26.74% respectively, and the inhibition rates of root elongation length were 25.88% and 34.45% respectively. These results showed that TOL and its main metabolites were ineffectively removed by aerobic composting, and could be migrated from composting to soil and vegetables, which had adverse effects on soil enzyme activity and plant growth. Therefore, its environmental ecological risk and human health risk needs to be further evaluated.

Reclaimed water driven lettuce cultivation in a hydroponic system: the need of micropollutant removal by advanced wastewater treatment

For a novel approach of resource-efficient water reuse, a municipal wastewater treatment plant was extended at pilot scale for advanced wastewater treatment, i.e., ozonation and biological activated carbon filtration, and a hydroponic system for reclaimed water driven lettuce cultivation. The treatment specific wastewater lines with the corresponding lettuce plants, differentiated into roots and shoots, were monitored for priority wastewater micropollutants, i.e., acesulfame (sweetener), caffeine (stimulant), carbamazepine, diclofenac, ibuprofen, sulfamethoxazole with acetyl-sulfamethoxazole (human pharmaceuticals), 1H-benzotriazole, and 4/5-methylbenzotriazole (industrial chemicals). As clearly demonstrated, conventional tertiary treatment could not efficiently clean up wastewater. Removal efficiencies ranged from 3% for carbamazepine to 100% for ibuprofen. The resulting pollution of the hydroponic water lines led to the accumulation of acesulfame, carbamazepine, and diclofenac in lettuce root systems at 32.0, 69.5, and 135 μg kg-1 and in the uptake of acesulfame and carbamazepine into lettuce shoots at 23.4 and 120 μg kg-1 dry weight, respectively. In contrast, both advanced treatment technologies when operating under optimized conditions achieved removal efficiencies of > 90% also for persistent micropollutants. Minimizing the pollution of reclaimed water thus met one relevant need for hydroponic lettuce cultivation.

Antioxidative response of lettuce (Lactuca sativa) to carbamazepine-induced stress

Carbamazepine (CBZ) is a widely used anti-epileptic drug that has been detected in wastewaters from sewage treating plants and thus appears in rivers, streams and other water bodies. As plants can absorb this compound, it can also appear in edible plants like lettuce, entering the food chain. In this study, the effect of carbamazepine in lettuce plants grown in hydroponic solution is analyzed. CBZ was detected both in roots and in leaves and is shown to induce oxidative stress. Hydrogen peroxide levels increased both in leaves and in roots while malondialdehyde increased only in leaves. Regarding the activity of antioxidative enzymes in the leaves, it is shown that superoxide dismutase (SOD), catalase (CAT), guaiacol peroxidase (GPOD) and ascorbate peroxidase (APX) have a relevant role in quenching reactive oxygen species induced by oxidative stress. In roots, the only enzymes that showed increased activity were CAT, GPOD and glutathione reductase (GR). Ascorbate and glutathione also appear to have an important role as antioxidants in response to increased concentrations of carbamazepine. Although the roots are in direct contact with the contaminant, the leaves showed the strongest oxidative effects.

Qualitative Risk Analysis for Contents of Dry Toilets Used to Produce Novel Recycling Fertilizers

Human excreta are a sustainable, economical source of nutrients, and can be used to produce recycling fertilizer for horticulture by collecting and processing the contents of dry toilets. Herein, we discuss the key categories of risk associated with the main groups of materials commonly found in dry toilets. The study was part of the development of a German product standard for marketable and quality-assured recycling fertilizers from human excreta for use in horticulture. Particular attention is paid to ensuring that the fertilizer is epidemiologically and environmentally harmless and that the quality of the recycling fertilizer is adequate in terms of low pollution and nutrient availability. In sum, the risk of transmissible human pathogens lies within the human excreta, particularly feces; plant materials added during composting are of particular phytosanitary relevance; pharmaceutical residues in excrements and chemical additives are potential sources of pollutants; non-biodegradable contaminants can cause pollution and injury; and the horticultural risks involve mainly the ammonia emission potential and in some cases the salinity effects of urine. These risks can be reduced significantly (i) with education of users around proper operation of dry toilets and the consequences of adding inappropriate waste, (ii) with facilitation of proper use with general waste bins and clear instructions, and importantly (iii) by using modern sanitization and cleaning processes and testing for harmful substances under the guidance of local laws and regulations, ensuring safe and high-quality fertilizers. In conclusion, the benefits of using dry toilet contents to produce fertilizers for use in horticulture are unquestionable. Our analysis highlights the need to support recycling optimization and awareness for the purpose of a sustainable circular economy and to minimize the risk of harm to humans and the environment overall.

Content of soil-derived carbon in soil biota and fauna living near soil surface: Implications for radioactive waste

¹⁴C is known as one of the radionuclides that have potential to be released into the biosphere from radioactive waste repositories and taken up by organisms. In this study, we used a novel approach to investigate the proportion of soil organic carbon (SOC) in invertebrates and microbial biomass. The study was conducted on a peatland site after the end of peat extraction. There was a large difference in the isotopic abundance of ¹⁴C between the 8000-year-old peat and air. We used a two-pool isotope mixing model to reveal the fraction of soil-derived C in the organisms and in dissolved organic carbon in soil water. The contribution of soil-derived C was found to be highest in microbial biomass (61%) and earthworms (22%). Some contribution of soil-derived C was detected in fungus gnats (2%), but not in other insects or in spiders. These findings are important for developing evidence-based radioecological models based on correct understanding of the relative contributions of atmospheric C vs. SOC in organisms.

Uptake, translocation and accumulation of 14C-triclosan in soil-peanut plant system

Triclosan is an antimicrobial agent that is ubiquitously present in water, biosolids and soil. Current agricultural practices, such as irrigation with treated wastewater and soil amendment with biosolids, often cause further triclosan contamination in agricultural fields. However, the fate and crop uptake of triclosan in agrofood systems and related human exposure are still not fully understood. In the present study, ¹⁴C-triclosan was used to trace the fate and distribution of triclosan in a soil-peanut plant system. ¹⁴C-triclosan in the system maintained an excellent mass balance ranging from 92.5% to 102.7%. ¹⁴C-triclosan uptake from soil to peanut plants at the harvest stage (120 d) was only 1.02 ± 0.17% of the applied ¹⁴C. The bioconcentration factors in different tissues followed the order of roots > stems > leaves > fruits. The concentration of ¹⁴C-triclosan in peanut fruits was 0.76-0.84 μg g^-1. ¹⁴C-triclosan was more easily accumulated in peanut kernels (69.2 ± 6.30%) than peanut hulls (27.5 ± 5.77%) and skin (3.28 ± 0.53%). The estimated daily intake (EDI) values suggested that peanut consumption represented a minimal risk to human health. The results of this study help to develop a better understanding of the fate of triclosan in the soil-peanut plant system and assess its environmental and human health risks.

Phytotransformation and Metabolic Pathways of 14C-Carbamazepine in Carrot and Celery

Carbamazepine (CBZ) is an anticonvulsant pharmaceutical compound of environmental concern due to its persistence, bioactive toxicity, and teratogenic effects. Studies on the kinetics and metabolic pathways of CBZ in plant tissues are still limited. In the present study, the phytotransformation of ¹⁴C-CBZ was explored. The ¹⁴C detected in bound residues was lower than in extractable residues (>85% of the uptaken ¹⁴C radioactivity) in plant tissues. CBZ underwent appreciable transformation in plants. A large portion of accumulated ¹⁴C radioactivity (80.3 ± 6.4%) in the cells was distributed in the cell water-soluble fraction. A total of nine radioactive transformation products of CBZ were identified, three of which were generated in vivo due to the contraction of the heterocycle ring. The proposed metabolic pathways revealed that conjugation with glutathione or phenylacetic acid was the major transformation pathway of CBZ in plants, with the contribution of epoxidation, hydroxylation, methoxylation, methylation, amination, and sulfonation.

Translocation of pharmaceuticals from wastewater into beehives

There has been a substantial research focus on the presence of pesticides in flowers and the subsequent exposure to honeybees. Here we demonstrate for the first time that honeybees can also be exposed to pharmaceuticals, commonly present in wastewater. Residues of carbamazepine (an anti-epileptic drug) up to 371 ng/mL and 30 µg/g were detected in nectar and pollen sampled from zucchini flowers (Cucurbita pepo) grown in carbamazepine spiked soil (0.5-20 µg/g). Under realistic exposure conditions from the use of recycled wastewater, carbamazepine concentrations were estimated to be 0.37 ng/L and 30 ng/kg in nectar and pollen, respectively. Incorporation of environmentally relevant carbamazepine residues in nectar and pollen into a modelling framework able to simulate beehive dynamics including the honeybee foraging activity at the landscape scale (BEEHAVE and BEESCOUT) enabled the simulation of carbamazepine translocation from zucchini fields into honeybee hives. Carbamazepine accumulation was modelled in 11 beehives across a 25 km2 landscape over three years chosen to represent distinct climatic conditions. During a single flowering period, carbamazepine concentrations were simulated to range between 0 and 2478 ng per beehive. The amount of carbamazepine gathered not only varied across the simulated years but there were also differences in accumulation of carbamazepine between beehives within the same year. This work illustrates a fundamental first step in assessing the risk of pharmaceuticals to bees through realistic scenarios by demonstrating a method to quantify potential exposure of honeybees at the landscape scale. Pharmaceuticals are being inadvertently but increasingly applied to agricultural lands globally via the use of wastewater for agricultural irrigation in response to water scarcity problems. We have demonstrated a route of pharmaceutical exposure to honeybees via contaminated nectar and pollen. Given the biological potency of pharmaceuticals, accumulation of these chemicals in nectar and pollen suggest potential implications for honeybee health, with unknown ecosystem consequences.