Determination and Dietary Intake Risk Assessment of Pesticide Residues in Fritillariae Thunbergii Bulbs and Cultivated Soils.

BACKGROUND: Pesticide residues in traditional Chinese medicines pose a potential risk to human health. However, little is known about the characteristics of pesticide residues in the fritillariae thunbergii bulbs (FTB). OBJECTIVE: This study aims to establish a method for the determination of pesticide multi-residues in FTB and then measured their residual levels in the FTB collected from nine cultivation regions. METHODS: A modified QuEChERS method coupled with GC/UPLC was used to determine the residues of 24 pesticides in the FTB and soil samples. RESULTS: The recoveries of these pesticides at three concentrations were 72.17-112.48% in the FTB and 70.92-113.74% in the soil with RSD < 11.83%, and the LOD and LOQ ranged from 0.005-10 µg/kg and 0.011-22 µg/kg, respectively. A total of 13 pesticide residues were detected in the FTB samples with the residual levels of 0.0011-509.63 µg/kg, which were all below the referred MRLs in other Chinese herbs or food. Meanwhile, dietary intake risk assessment showed that the risk of pesticide residues in the FTB was acceptable to consumers. CONCLUSIONS: This study developed a method for the determination of pesticide multi-residues in the FTB and cultivated soil samples, and furthermore the dietary intake risk of pesticide residues in the FTB is safe. HIGHLIGHTS: A modified QuEChERS method was established for the determination of 24 pesticides in the FTB with high sensitivity, accuracy, and precision.

Deposition, dissipation, and minimum effective dosage of the fungicide carbendazim in the pepper-field ecosystem.

BACKGROUND: In order to reduce application dosage of carbendazim (CBD), the effects of different droplet sizes and application rate on initial deposition, retention rate, and field control efficacy of CBD in the pepper plant (Capsicum annuum L.) were studied under laboratory and field conditions. RESULTS: Based on eight types of nozzles at six concentrations of 646.8, 582.2, 517.5, 414.0, 310.5, and 258.7 g a.i./hm2 , the initial deposition amount of CBD in the pepper plant showed a first increased and then decreased trend with the increasing application dosages. The initial deposition amount of CBD in the pepper leaves and stems was highest when using the nozzle ST110-03 at 200 µm volume median diameter (VMD) and 350 L/hm2 application rate. HPLC-MS/MS analysis revealed that CBD was first converted to 2-aminobenzimidazole, which then transformed into benzimidazole and 2-hydroxybenzimidazole by deamination and hydroxylation, and ultimately mineralized to carbon dioxide and water via the cleavage of the imidazole ring in pepper plant. The dissipation rate of CBD was fruits > roots/stems > leaves > soils. After 7 days of application, the field efficacy of CBD at six concentrations on pepper anthracnose (Colletotrichum spp.) were 94.1%, 91.3%, 82.3%, 76.5%, 47.0%, and 41.2%, respectively. CONCLUSION: The results revealed the deposition and dissipation characteristics of CBD, and the minimum effective dosage on pepper anthracnose decreased to 80% of the minimum recommended dose in the open field pepper ecosystem. The study will contribute to the CBD reduction by improving its utilization rate in the pepper-field ecosystem. © 2019 Society of Chemical Industry.

Deposition, Distribution, Metabolism, and Reduced Application Dose of Thiamethoxam in a Pepper-Planted Ecosystem.

To decrease the application dose of thiamethoxam (TMX) to control the pepper whitefly (Bemisia tabaci Q), the deposition, dissipation, metabolism, and field efficacy of TMX were investigated in a pepper (Capsicum annuum var. grossum)-planted ecosystem using eight types of nozzles at six concentrations (56.25, 41.25, 26.25, 21.0, 15.75, and 10.5 g a.i./hm2). The initial deposition amount of TMX in the pepper plant first increased and then decreased with increasing application dose. The optimum spray conditions of TMX were found to be a droplet size of 200 µm volume median diameter and a spray volume of 350 L/hm2. Moreover, three metabolites, TMX-dm, clothianidin (CLO), and C5H8O2N3SCl, were detected in the pepper-planted system. The dissipation rate of TMX in the pepper-field ecosystem was leaves > stems > fruits > roots > soils. The results revealed the deposition and fate of TMX in the pepper-field ecosystem, and the application dose could be reduced by 20% based on the minimum recommended dose for controlling pepper whitefly.

Exploring microbial community structure and biological function in manured soil during ten repeated treatments with chlortetracycline and ciprofloxacin.

The changes of enzyme activities, microbial community structure and function, and the diversity and resistance level of antibiotic-resistant bacteria (ARB) were studied in soil during ten repeated treatments with chlortetracycline (CTC) and/or ciprofloxacin (CIP) together with organic manure (OM) under laboratory conditions. The activities of neutral phosphatase (NPA) and catalase (CAT) displayed the suppression-recovery-stimulation trend in the OM&CTC treatment but the stimulation trend in the OM&CTC&CIP treatment. The NPA was stimulated but the CAT was little affected in the OM&CIP treatment. Soil microbial functional diversity displayed the suppression-recovery-stimulation trend in the OM&CTC and OM&CTC&CIP treatments and the stimulation-suppression trend in the OM&CIP treatment with the treatment frequency. Metagenomic analysis showed that the relative abundances of Actinobacteria and Firmicutes in the antibiotic treatment significantly increased by 0.5-235.6%, but that of Proteobacteria decreased by 0.2-27.3% compared to the control with the treatment frequency. Furthermore, the relative abundances of dominant bacterial genera including Streptomyces, Actinomadura, Mycobacterium, and Streptococcus in the antibiotic treatment significantly increased by 1.1-10433.3% compared to the control. Meanwhile, repeated antibiotic treatments induced a significant increase in the diversity and resistance level of ARB isolates, especially in the OM&CTC treatment. It is concluded that repeated treatments with CTC and/or CIP can alter enzyme activities, microbial community structure and function, and increase the diversity and resistance level of ARB isolates.

Adsorption and Desorption of Carbendazim and Thiamethoxam in Five Different Agricultural Soils.

The adsorption and desorption behaviors of carbendazim (CBD) and thiamethoxam (TMX) were systematically studied in five different agricultural soils. The adsorption and desorption isotherms of CBD and TMX in the five different soils were fitted well by the Freundlich model. The Freundlich adsorption coefficient (Kfads) and Freundlich desorption coefficient (Kfdes) of CBD in the five different soils were 1.46-19.53 and 1.81-3.33, respectively. The corresponding values of TMX were 1.19-4.03 and 2.07-6.45, respectively. The adsorption affinity and desorption ability of the five different soils for CBD and TMX depended mainly on soil organic matter content (OMC) and cation exchange capacity (CEC). Desorption hysteresis occurred in the desorption process of CBD and TMX in the five different agricultural soils, especially for TMX. It is concluded that the adsorption-desorption ability of CBD was much higher than that of TMX in the five different agricultural soils, which was attributed to soil OMC and CEC.

Exploring bacterial communities and biodegradation genes in activated sludge from pesticide wastewater treatment plants via metagenomic analysis.

Activated sludge (AS) has been regarded as the main driver in the removal of organic pollutants such as pesticides due to a high diversity and abundance of microorganisms. However, little is known about the biodegradation genes (BDGs) and pesticide degradation genes (PDGs) harbored in the AS from wastewater treatment plants (WWTPs). In this study, we explored the bacterial communities and BDGs/PDGs in the AS from five WWTPs affiliated with pesticide factories across four consecutive seasons based on high-throughput sequencing. The AS in pesticide WWTPs exhibited unique bacterial taxa at the genus level. Furthermore, a total of 17 BDGs and 68 PDGs were explored with a corresponding average relative abundance of 0.002-0.046% and 2.078-7.143% in each AS sample, respectively, and some BDGs/PDGs clusters were also identified in the AS. The bacterial communities and BDGs/PDGs were season-dependent, and the total variations of 50.4% and 76.8% were jointly explained by environmental variables (pesticide types, wastewater characteristics, and temperature). In addition, network analysis and distribution patterns suggested that the potential hosts of BDGs/PDGs were Thauera, Stenotrophomonas, Mycobacterium, Hyphomicrobium, Allochromatium, Ralstonia, and Dechloromonas. Our findings demonstrated the linkages of bacterial communities and BDGs/PDGs in the AS, and depended on the seasons and the pesticide wastewater characteristics.

Biodegradability and ecological safety assessment of Stenotrophomonas sp. DDT-1 in the DDT-contaminated soil.

The biodegradability and ecological safety assessment of the previously isolated DDT-degrading bacterial strain Stenotrophomonas sp. DDT-1 were investigated in the DDT-contaminated soil under laboratory and field conditions. Under laboratory conditions, the degradation rates of fresh p,p'-DDT in soil were enhanced by 2.0-3.0-fold with the introduction of the strain DDT-1 compared to those of the control treatments. A similar enhancement in the dissipation of DDTs (p,p'-DDT, p,p'-DDE, p,p'-DDD, and o,p'-DDT) in the aged DDT-contaminated field plot soils resulted from the inoculation with this strain. Meanwhile, the degradation rates of DDTs increased by 2.9-5.5- and 2.8-7.6-fold in the inoculated greenhouse and open field soils, respectively, after field demonstration application of strain DDT-1 preparation. Moreover, no significant differences in the soil enzyme activity, microbial functional diversity, and bacterial community structure were observed between the inoculated and un-inoculated field soils, but several soil microbial genera exhibited some fluctuations in abundance. It is concluded that strain DDT-1 could accelerate the removal of DDTs residues in field soils, and furthermore, its inoculation was ecologically safe.

Repeated treatments of ciprofloxacin and kresoxim-methyl alter their dissipation rates, biological function and increase antibiotic resistance in manured soil.

The dissipation of ciprofloxacin (CIP, 1.0 and 10.0mg/kg) and kresoxim-methyl (KM, 1.0 and 2.0mg/kg) in manure-amended soil, the variations in soil enzyme activities and microbial functional diversities, and CIP-induced bacterial community tolerances were studied using a chromatographic analysis, enzyme colorimetric and titration analyses, and the BIOLOG EcoPlate method. Three successive treatments of individual and combined samples of CIP and KM at low and high concentrations were performed at 60d intervals. The dissipation half-life of CIP increased, but that of KM decreased in manured soil with treatment frequency; furthermore, the combined treatment altered the dissipation rates of CIP and KM. A stronger inhibitory effect on the activities of soil neutral phosphatase and urease was observed in the individual KM treatment than in the individual CIP treatment. A similar inhibitory trend was also found in soil neutral phosphatase activity in the combined treatment at high concentration compared to that at low concentration, but the activity of soil catalase was enhanced in the early stages of the KM or CIP treatments. Meanwhile, the inhibitory trend on the overall activity and functional diversity of soil microorganisms was observed in the individual KM or CIP treatment, and the combined treatment exerted a greater suppression effect than that in the individual treatment. Bacterial community resistance to CIP increased significantly with increasing treatment frequency and concentration, and furthermore antibiotic resistance developed faster in the combined treatment than in the individual treatment. It was concluded that the repeated treatments of CIP and KM could alter their dissipation rates and soil enzyme activities, suppress microbial functional diversity, and increase bacterial community resistance to CIP in manured soil.

Computed tomography fluoroscopy versus conventional computed tomography guidance for biopsy of intrathoracic lesions: a retrospective review of 1143 consecutive procedures.

PURPOSE: To compare the success rates, complication rates, and radiation doses of conventional computed tomography (CCT) versus computed tomography with fluoroscopy (CTF) during image-guided percutaneous needle biopsies of intrathoracic lesions. MATERIALS AND METHODS: We conducted a retrospective analysis of 1143 consecutive intrathoracic biopsies performed under computed tomography guidance at a single tertiary care center. For each procedure we recorded patient age and sex, lesion size and location, and radiation dose administered to the patient. Thereafter, appropriate tests of statistical significance were applied to compare rates of success, complications, and radiation between CCT and CTF guidance. RESULTS: After correcting for lesion size, CTF was associated with an odds ratio (OR) of 6.07 [95% confidence interval (CI): 2.23-16.50] for technical procedural success, an OR of 0.79 (95% CI: 0.55-1.15) for fine-needle aspiration success, an OR of 2.11 (95% CI: 1.02-4.38) for core-needle biopsy success, and an OR of 1.45 (95% CI: 1.00-2.21) for overall success when compared with CCT. CTF was associated with an OR of 1.10 (95% CI: 0.35-3.48) for complications when compared with CCT. Mean dose-length product per procedure was 1332 mGy cm for CCT and 1730 mGy cm for CTF (P=0.027). CONCLUSIONS: CCT and CTF are both valuable tools for intrathoracic biopsy. CTF improves technical and core-needle biopsy success at the expense of higher radiation doses to the patient. Operator confidence with CCT and CTF in light of lesion characteristics should guide the choice to select one over the other.