Fate of the antifungal drug clotrimazole in agricultural soil

Ecotoxicological risk assessment of wastewater irrigation on soil microorganisms: Fate and impact of wastewater-borne micropollutants in lettuce-soil system

The implementation of the new Water Reuse regulation in the European Union brings to the forefront the need to evaluate the risks of using wastewater for crop irrigation. Here, a two-tier ecotoxicological risk assessment was performed to evaluate the fate of wastewater-borne micropollutants in soil and their ecotoxicological impact on plants and soil microorganisms. To this end, two successive cultivation campaigns of lettuces were irrigated with wastewater (at agronomical dose (not spiked) and spiked with a mixture of 14 pharmaceuticals at 10 and 100 µg/L each) in a controlled greenhouse experiment. Over the two cultivation campaigns, an accumulation of PPCPs was observed in soil microcosms irrigated with wastewater spiked with 100 μg/L of PPCPs with the highest concentrations detected for clarithromycin, hydrochlorothiazide, citalopram, climbazole and carbamazepine. The abundance of bacterial and fungal communities remained stable over the two cultivation campaigns and was not affected by any of the irrigation regimes applied. Similarly, no changes were observed in the abundance of ammonium oxidizing archaea (AOA) and bacteria (AOB), nor in clade A of commamox no matter the cultivation campaign or the irrigation regime considered. Only a slight increase was detected in clade B of commamox bacteria after the second cultivation campaign. Sulfamethoxazole-resistant and -degrading bacteria were not impacted either. The irrigation regimes had only a limited effect on the bacterial evenness. However, in response to wastewater irrigation the structure of soil bacterial community significantly changed the relative abundance of Acidobacteria, Chloroflexi, Verrucomicrobia, Beta-, Gamma- and Deltaprotebacteria. Twenty-eight operational taxonomic units (OTUs) were identified as responsible for the changes observed within the bacterial communities of soils irrigated with wastewater or with water. Interestingly, the relative abundance of these OTUs was similar in soils irrigated with either spiked or non-spiked irrigation solutions. This indicates that under both agronomical and worst-case scenario the mixture of fourteen PPCPs had no effect on soil bacterial community.

Monitoring of Clotrimazole Degradation Pathway in Presence of its Co-formulated Drug

Two stability-indicating chromatographic methods for the determination of clotrimazole and its two acid induced degradation products, with dexamethasone acetate without prior separation. First method depends on RP-HPLC utilizing ODS-3 Inertsil C18 column. Mobile phase consists of acetonitrile:phosphate buffer (pH 6.0) in ratio (65:35, v/v) with flow rate 1.5 mL/min and UV-detection at 220 nm. Linearity range 1.0-75.0 μg/mL for clotrimazole and 2.0-75.0 μg/mL for dexamethasone with mean percentage recovery of 99.49 ± 1.10 for CLT and 99.60 ± 1.06 for DA. Second method depends on HP-TLC. Developing system is composed of chloroform:ethyl acetate in the ratio of (5:3.5, v/v), scanned at 220 nm. Linearity range 1.0-12.0 μg/band for clotrimazole and 1.0-20.0 μg/band for dexamethasone with mean R% of 99.33 ± 0.76 for clotrimazole and 99.77 ± 0.99 for dexamethasone. Conditions and parameters affecting the separation of the cited components without interference of the degradation products are tested and optimized. Suitability of the methods for quantization of the drugs concentrations is proven by validation as instructed from the ICH. Validation results and statistical treatment of the data demonstrate reliability of these methods. Kinetics of acid degradation process of clotrimazole are investigated by the proposed HPLC method and the order rate constant, half life and shelf life are computed.

Mycoremediation of azole antifungal agents using in vitro cultures of Lentinula edodes

Azole antifungal agents are widely used as active ingredients in antifungal pharmaceuticals and agricultural fungicides. An increase in the use of azole antifungals has resulted in an increase in the concentration of these compounds in wastewater and surface water, with potential implications for agriculture. In the present study, bifonazole (BIF) and clotrimazole (CTZ) were selected for investigation because of their widespread use in topical formulations and persistence in the environment. The mycoremediation capacity of BIF and CTZ by mycelia of Lentinula edodes in in vitro culture was evaluated. The main aim of this study was to identify the presumable biodegradation products of the investigated active pharmaceutical substances using the LC/MS/MS method. For this purpose, the media were enriched with the following active pharmaceutical ingredients selected for this study: BIF powder, CTZ powder, and BIF cream, each of them at the same concentration of 0.1 mg/mL. Subsequently, thin-layer chromatography coupled with densitometry was used to evaluate the content of BIF and CTZ in mycelium from in vitro cultures of L. edodes. The degradation process was found to affect primarily the imidazole moiety of both investigated compounds. In addition, the amounts of undegraded investigated compounds were found to be 4.98, 9.26, and 4.56 mg/g dry weight for BIF powder, CTZ powder, and BIF cream, respectively. Therefore, the findings of this study revealed that L. edodes could be considered for remediation of pollution caused by azole antifungal agents.

PBT assessment and prioritization of contaminants of emerging concern: Pharmaceuticals

The strong and widespread use of pharmaceuticals, together with incorrect disposal procedures, has recently made these products contaminants of emerging concern (CEC). Unfortunately, little is known about pharmaceuticals' environmental behaviour and ecotoxicity, so that EMEA (European Medicines Agency) released guidelines for the pharmaceuticals' environmental risk assessment. In particular, there is a severe lack of information about persistence, bioaccumulation and toxicity (PBT) of the majority of the thousands of substances on the market. Computational tools, like QSAR (Quantitative Structure Activity Relationship) models, are the only way to screen large sets of chemicals in short time, with the aim of ranking, highlighting and prioritizing the most environmentally hazardous for focusing further experimental studies. In this work we propose a screening method to assess the potential persistence, bioaccumulation and toxicity of more than 1200 pharmaceutical ingredients, based on the application of two different QSAR models. We applied the Insubria-PBT Index, a MLR (Multiple Linear Regression) QSAR model based on four simple molecular descriptors, implemented in QSARINS software, and able to synthesize the PBT potential in a unique cumulative value and the US-EPA PBT Profiler that assesses the PBT behaviour evaluating separately P, B and T. Particular attention was given to the study of Applicability Domain in order to provide reliable predictions. An agreement of 86% was found between the two models and a priority list of 35 pharmaceuticals, highlighted as potential PBTs by consensus, was proposed for further experimental validation. Moreover, the results of this computational screening are in agreement with preliminary experimental data in the literature. This study shows how in silico models can be applied in the hazard assessment to perform preliminary screening and prioritization of chemicals, and how the identification of the structural features, mainly associated with the potential PBT behaviour of the prioritized pharmaceuticals, is particularly relevant to perform the rational a priori design of new, environmentally safer, pharmaceuticals.

Occurrence, fate and ecological risk of five typical azole fungicides as therapeutic and personal care products in the environment: A review

Azole fungicides are widely used to treat fungal infection in human. After application, these chemicals may reach to the receiving environment via direct or indirect discharge of wastewaters, thus posing potential risks to non-target organisms. We aimed to review the occurrence, fate and toxicological effects of some representative household azole fungicides in the environment. Azole fungicides were widely detected in surface water and sediment of the aquatic environment due to their incomplete removal in wastewater treatment plants. These chemicals are found resistant to microbial degradation, but can undergo photolysis under UV irradiation. Due to different physiochemical properties, azole fungicides showed different environmental behaviors. The residues of azole fungicides could cause toxic effects on aquatic organisms such as algae and fish. The reported effects include regulation changes in expression of cytochrome P450-related genes and alteration in CYP450-regulated steroidogenesis causing endocrine disruption in fish. Further studies are essential to investigate the removal of azole fungicides by advanced treatment technologies, environmental fate such as natural photolysis, and toxic pathways in aquatic organisms.

Identification of antimycotic drugs transformation products upon UV exposure

The reactivity of three imidazolic, environmental persistent antimycotic drugs (clotrimazole, CTZ; ketoconazole, KTZ; and miconazole, MCZ) upon exposure to ultraviolet (UV) radiation is discussed. First, precursor compounds were immobilized in a silicone support which was further exposed to UV light at two different wavelengths: 254 and 365 nm. After solvent desorption, degradation kinetics of the precursor pharmaceuticals, identification of the arising transformation products (TPs) and evaluation of their time-course were investigated by liquid chromatography (LC) with quadrupole time-of-flight (QTOF) mass spectrometry (MS) detection. The three antimycotics displayed similar stabilities when exposed to 254 nm light; however, CTZ was significantly more stable than MCZ and KTZ when irradiated with the 365 nm lamp. TPs identified in silicone supports resulted from de-chlorination, cleavage, intra-molecular cyclization and hydroxylation reactions. Many of these species were also detected when exposing other solid matrices, such as sand and agricultural soil, previously spiked with target compounds, to UV light. The 50% estimated lethal concentration, calculated using the 48-h Daphnia magna test, for the two main TPs of CTZ and MCZ, at both wavelengths, were lower than those corresponding to the precursor drugs.

Typical azole biocides in biosolid-amended soils and plants following biosolid applications

Biosolid application on agricultural land may contaminate soils with various household chemicals and personal care products. This study investigated the occurrence and dissipation of typical azole biocides climbazole, clotrimazole, and miconazole in biosolid-amended soils as well as the uptake of these biocides by plants. The field trial includes two treatment groups: old groups with biosolid application at rates of 5, 10, 20, and 40 t/ha every year within 5 years, and new groups with only one biosolid application. The results showed that climbazole, clotrimazole, and miconazole were detected in biosolid-amended soils, but not detected in control soils. These biocides were not found in the crop plants collected from the trial plots. The dissipation half-lives for climbazole, clotrimazole, and miconazole under the field conditions were 175-179, 244, and 130-248 days, respectively. High biosolid application rates and repeated biosolid applications could lead to higher persistence of the biocides in the agricultural soils. An exposure model could effectively predict the residual concentrations of climbazole and miconazole in the biosolid-amended soils of the old treatments with different biosolid application rates. Thus, the field trial demonstrated high persistence of these three biocides in the soil environments.

Occurrence and dissipation of three azole biocides climbazole, clotrimazole and miconazole in biosolid-amended soils

This study investigated the occurrence and dissipation of three azole biocides climbazole, clotrimazole and miconazole in biosolid-amended soils of the three sites (Zhejiang, Hunan and Shandong) in China following three treatments (CK: control without biosolid application; T1: one biosolid application; T2: biosolid application every year). The results showed that climbazole, clotrimazole and miconazole were present in the biosolid and biosolid-amended soils, but absent in the control soils. In the soils treated with biosolids, the concentrations of climbazole, clotrimazole and miconazole were mostly lower in the Zhejiang soils than in the Shandong or Hunan soils, suggesting that these three biocides are more readily dissipated under the flooding condition. During the one year monitoring, the concentrations of climbazole, clotrimazole and miconazole in the biosolid-applied soils showed only slight variations. The dissipation half-lives for miconazole calculated under the field conditions of Shandong site were 440 days for T1 and the half-lives for clotrimazole were 365 days for T2. The results suggested the persistence of these three biocides in the soil environments.

Persistence of the tricyclic antidepressant drugs amitriptyline and nortriptyline in agriculture soils

Amitriptyline and nortriptyline are widely used tricyclic antidepressant drugs. They have been detected in wastewater, surface runoff, and effluents from sewage treatment plants. As such, they could potentially reach agriculture land through the application of municipal biosolids or reclaimed water. In the absence of data on their fate in the environment, the persistence and dissipation pathways of radiolabeled amitriptyline were determined in three agriculture soils varying widely in texture and chemical properties (loam soil, clay loam soil, and sandy loam soil). Tritiated amitriptyline was added to laboratory microcosms containing soils, and the metabolism of the extractable (3) H was monitored during incubation at 30°C. The total solvent extractable radioactivity decreased in all three soils with times to dissipate 50% of material (DT50) ranging from 34.1 ± 3.2 (loam soil) to 85.3 ± 3.2 d (sandy soil). Nortriptyline (N-desmethyl amitriptyline) and amitriptyline-N-oxide were identified as major transformation products in all three soils by high performance liquid chromatography with photodiode array detector and time-of-flight mass spectrometry (HPLC-TOF-MS/UV). The addition of liquid municipal biosolids to the loam soil had no effect on the dissipation of amitriptyline. The persistence of nortriptyline was evaluated in the loam soil. The DT50 of nortriptyline was 40.5 ± 3.2 d estimated with HPLC-TOF-MS/UV. Approximately 10% of added nortriptyline was converted to hydroxylated products after 50 d of incubation. In summary, amitriptyline persisted in agricultural soils with major dissipation mechanisms, including forming nonextractable residues and producing various transformation products including the psychoactive drug nortriptyline.

Accelerated Biodegradation of Veterinary Antibiotics in Agricultural Soil following Long-Term Exposure, and Isolation of a Sulfamethazine-degrading sp

The World Health Organization has identified antibiotic resistance as one of the top three threats to global health. There is concern that the use of antibiotics as growth promoting agents in livestock production contributes to the increasingly problematic development of antibiotic resistance. Many antibiotics are excreted at high rates, and the land application of animal manures represents a significant source of environmental exposure to these agents. To evaluate the long-term effects of antibiotic exposure on soil microbial populations, a series of field plots were established in 1999 that have since received annual applications of a mixture of sulfamethazine (SMZ), tylosin (TYL), and chlortetracycline (CTC). During the first 6 yr (1999-2004) soils were treated at concentrations of 0, 0.01 0.1, and 1.0 mg kg soil, in subsequent years at concentrations of 0, 0.1, 1.0, and 10 mg kg soil. The lower end of this concentration range is within that which would result from an annual application of manure from medicated swine. Following ten annual applications, the fate of the drugs in the soil was evaluated. Residues of SMZ and TYL, but not CTC were removed much more rapidly in soil with a history of exposure to 10 mg/kg drugs than in untreated control soil. Residues of C-SMZ were rapidly and thoroughly mineralized to CO in the historically treated soils, but not in the untreated soil. A SMZ-degrading sp. was isolated from the treated soil. Overall, these results indicate that soil bacteria adapt to long-term exposure to some veterinary antibiotics resulting in sharply reduced persistence. Accelerated biodegradation of antibiotics in matrices exposed to agricultural, wastewater, or pharmaceutical manufacturing effluents would attenuate environmental exposure to antibiotics, and merits investigation in the context of assessing potential risks of antibiotic resistance development in environmental matrices.

The antihistamine diphenhydramine is extremely persistent in agricultural soil

The widely used antihistamine diphenhydramine is present in municipal biosolids, and is detected in runoff from agricultural land fertilized with biosolids. In the present study the kinetics and major pathways of diphenhydramine dissipation in a loam, sandy loam, and clay loam soil were determined in laboratory incubations. The time to dissipate 50% (DT(50)) of (14)C-diphenhydramine residues at 30 °C ranged from 88 ± 28 days in the clay loam to 335 ± 145 days in the loam soil. Mineralization of (14)C was insignificant, and diphenhydramine-N-oxide was the only detected extractable transformation product elucidated by radioisotope and HPLC-MS methods. There were no significant effects of municipal biosolids on the kinetics or pathways of removal. Overall, diphenhydramine is quite persistent in soils, and formation of non-extractable soil-bound residues is the major mechanism of diphenhydramine dissipation.

Pharmaceutical and personal care products in groundwater, subsurface drainage, soil, and wheat grain, following a high single application of municipal biosolids to a field

Dewatered municipal biosolids (DMBs) were applied to a field at a rate of ~22 Mg dw ha(-1) in October 2008. Pharmaceuticals and personal care products (PPCPs) were monitored in groundwater, tile drainage, soil, DMB aggregates incorporated into the soil post-land application, and in the grain of wheat grown on the field for a period of ~1 year following application. Over 80 PPCPs were analyzed in the source DMB. PPCPs selected for in-depth monitoring included: antibiotics (tetracyclines, fluoroquinolones), bacteriocides (triclosan, triclocarban), beta-blockers (atenolol, propranolol, metaprolol), antidepressants (fluoxetine, citalopram, venlafaxine, sertraline), antifungals (miconazole), analgesics (acetaminophen, ibuprofen) and anticonvulsants (carbamazepine). PPCPs in tile were observed twice, ~3 weeks and 2 months post-application. Of all PPCPs measured in tile drainage, only carbamazepine, ibuprofen, acetaminophen, triclosan, triclocarban, venlafaxine, and citalopram were detected (5-74 ng L(-1)). PPCPs were not detected in groundwater >2 m depth below the soil surface, and concentrations above detection limits at 2 m depth were only observed once just after the first rain event post-application. In groundwater, all compounds found in tile, except carbamazepine, acetaminophen and citalopram, were detected (10-19 ng L(-1)). PPCPs were detected in DMB aggregates incorporated in soil up to 1 year post-application, with miconazole and fluoxetine having the lowest percent reductions over 1 year (~50%). For several compounds in these aggregates, concentration declines were of exponential decay form. No PPCPs were detected in the grain of wheat planted post-application on the field. No PPCPs were ever detected in water, soil or grain samples from the reference plot, where no DMB was applied.

Influence of moisture on the availability and persistence of clotrimazole and fluconazole in sludge-amended soil

Applying sewage sludge to soil is a common practice in many parts of the world. Thus, pharmaceutical compounds, such as azoles, can be released into the environment after sludge is applied to soil. To understand the fate of clotrimazole and fluconazole (pharmaceuticals used as antifungals in humans) in soil after its amendment with sludge, a reliable and sensitive method has been developed to determine these compounds in the solid and aqueous phases of soil. Desorption of clotrimazole from soil amended with sludge was negligible, whereas a rapid desorption of fluconazole was observed. Dissipation rates of these azoles were determined in amended soil incubated at 25°C with moisture contents ranging from 4.5 to 20%. Clotrimazole was more persistent than fluconazole in dry soil, whereas the contrary occurred in wet soil. Partitioning soil:soil solution of these azoles varied with time and moisture contents. Clotrimazole was found in soil with negligible amounts in soil solution, whereas fluconazole was approximately partitioned 50:50 during the assay time (60 d) at any soil moisture content. Occasional rainfall coupled with a relatively low binding soil capacity can result in the contamination of surface and groundwaters by fluconazole, whereas clotrimazole will remain in the soil.