Quantum criticality enabled by intertwined degrees of freedom.

Strange metals appear in a wide range of correlated materials. Electronic localization-delocalization and the expected loss of quasiparticles characterize beyond-Landau metallic quantum critical points and the associated strange metals. Typical settings involve local spins. Systems that contain entwined degrees of freedom offer new platforms to realize unusual forms of quantum criticality. Here, we study the fate of an SU(4) spin-orbital Kondo state in a multipolar Bose-Fermi Kondo model, which provides an effective description of a multipolar Kondo lattice, using a renormalization-group method. We show that at zero temperature, a generic trajectory in the model's parameter space contains two quantum critical points, which are associated with the destruction of Kondo entanglement in the orbital and spin channels, respectively. Our asymptotically exact results reveal an overall phase diagram, provide the theoretical basis to understand puzzling recent experiments of a multipolar heavy fermion metal, and point to a means of designing different forms of quantum criticality and strange metallicity in a variety of strongly correlated systems.

Peri-treatment adverse events of primary mediastinal non-seminomatous germ cell tumors.

Primary mediastinal non-seminomatous germ cell tumors (PMNSGCT) are rare but life-threatening thoracic cancers. We report our experience from eight patients with peri-treatment adverse events. By analyzing changes in tumor extent, serum tumor markers, and pathologies between diagnosis and transfer, those events could be attributed to postbiopsy respiratory insufficiency, growing teratoma syndrome, secondary histiocytic malignancy, and PMNSGCT progression. Subjecting patients to respiratory therapy, conventional or high-dose chemotherapy, and surgery controlled the disease, with five of the eight patients surviving disease free. These outcomes indicate that integrated appropriate and timely approaches are important in tackling peri-treatment adverse events.

Is there a role for lung surgery in initially unresectable non-small cell lung cancer after tyrosine kinase inhibitor treatment?

BACKGROUND: The role of lung surgery in initially unresectable non-small cell lung cancer (NSCLC) after tyrosine kinase inhibitor (TKI) treatment remains unclear. We aimed to assess the survival benefits of patients who underwent surgery for regressed or regrown tumors after receiving TKI treatment. METHODS: The details of patients diagnosed with unresectable NSCLC treated with TKI followed by lung resection from 2010 to 2020 were retrieved from our database. The primary endpoint was 3-year overall survival (OS), whereas the secondary endpoints were a 2-year progression-free survival (PFS), feasibility, and the safety of pulmonary resection. The statistical tests used were Fisher's exact test, Kruskal Wallis test, Kaplan-Meier method, Cox proportional hazards model, and Firth correction. RESULTS: Nineteen out of thirty-two patients were selected for the study. The patients underwent lung surgery after confirmed tumor regression (17 [89.5%]) and regrowth (two [10.5%]). All surgeries were performed via video-assisted thoracoscopic surgery: 14 (73.7%) lobectomies and five (26.3%) sublobar resections after a median duration of 5 months of TKI. Two (10.5%) postoperative complications and no 30-day postoperative mortality were observed. The median postoperative follow-up was 22 months. The 2-year PFS and 3-year OS rates were 43.9% and 61.5%, respectively. Patients who underwent surgery for regressed disease showed a significantly better OS than for regrowth disease (HR=0.086, 95% CI 0.008-0.957, p=0.046). TKI-adjuvant demonstrated a better PFS than non-TKI adjuvant (HR=0.146, 95% CI 0.027-0.782, p=0.025). CONCLUSION: Lung surgery after TKI treatment is feasible and safe and prolongs survival via local control and directed consequential therapy. Lung surgery should be adopted in multimodality therapy for initially unresectable NSCLC.

Sequential localization of a complex electron fluid.

Complex and correlated quantum systems with promise for new functionality often involve entwined electronic degrees of freedom. In such materials, highly unusual properties emerge and could be the result of electron localization. Here, a cubic heavy fermion metal governed by spins and orbitals is chosen as a model system for this physics. Its properties are found to originate from surprisingly simple low-energy behavior, with 2 distinct localization transitions driven by a single degree of freedom at a time. This result is unexpected, but we are able to understand it by advancing the notion of sequential destruction of an SU(4) spin-orbital-coupled Kondo entanglement. Our results implicate electron localization as a unified framework for strongly correlated materials and suggest ways to exploit multiple degrees of freedom for quantum engineering.

Neoadjuvant Chemoradiation Versus Upfront Esophagectomy in Clinical Stage II and III Esophageal Squamous Cell Carcinoma.

BACKGROUND: The benefits of neoadjuvant chemoradiation (NCRT) compared to upfront esophagectomy (UE) in esophageal squamous cell carcinoma (ESCC) is controversial. Our purpose was to determine whether clinical stages based on the 8th edition American Joint Committee on Cancer Tumor-Node-Metastasis staging system could guide treatment decision. METHODS: Data from 2503 patients with clinical stages II and III ESCC diagnosed between 2008 and 2014 were obtained from a nationwide database. Propensity score matching was used to identify well-balanced pairs of patients. Cox proportional hazards regression and log-rank test were used in the survival analysis. The outcomes of patients receiving "NCRT followed by surgery" or "UE" strategies were compared. RESULTS: The treatment modality (UE or NCRT) was not a prognostic factor in clinical stage II ESCC (HR: 0.97; p = 0.778). In contrast, the UE group demonstrated a significantly worse outcome compared with the NCRT group in clinical stage III ESCC (HR: 1.39; p < 0.001). After matching, patients who underwent UE for clinical stage II ESCC had median survival/3-year overall survival (OS) rates of 27.8 months/39.2% compared with 32.7 months/49.8% in the NCRT group (p = 0.508). The patients who underwent UE for clinical stage III ESCC had median survival/3-year OS rates of 17.9 months/28.2% in the UE group compared with 24.0 months/41.8% in the NCRT group (p < 0.001). CONCLUSIONS: Our data suggest that NCRT strategy improved survival compared with UE in clinical stage III ESCC but not in clinical stage II tumors.

A Nomogram for Predicting Cancer-Specific Survival of TNM 8th Edition Stage I Non-small-cell Lung Cancer.

BACKGROUND: Models for predicting the survival outcomes of stage I non-small-cell lung cancer (NSCLC) defined by the newly released 8th edition TNM staging system are scarce. This study aimed to develop a nomogram for predicting the cancer-specific survival (CSS) of these patients and identifying individuals with a higher risk for CSS. METHODS: A total of 30,475 NSCLC cases were extracted from the Surveillance, Epidemiology, and End Results (SEER) database. We identified and integrated the risk factors to build a nomogram. The model was subjected to bootstrap internal validation with the SEER database, and external validation with a multicenter cohort of 1133 patients from China. The difference in the impact of adjuvant chemotherapy on model-defined high- and low-risk patients was examined using the National Cancer Database (NCDB). RESULTS: Eight independent prognostic factors were identified and integrated into the model. The calibration curves showed good agreement. The concordance index (C-index) of the nomogram was higher than that of the staging system (IA1, IA2, IA3, and IB) (internal validation set 0.63 vs. 0.56; external validation set 0.66 vs. 0.55; both p < 0.01). Specifically, 21.7% of stage IB patients (7.5% of all stage I) were categorized into the high-risk group (score > 30). There was a significant interaction effect between the adjuvant chemotherapy and risk groups in the NCDB cohort (p = 0.003). CONCLUSIONS: We established a practical nomogram to predict CSS for 8th edition stage I NSCLC. A prospective study is warranted to determine its role in identifying adjuvant chemotherapy candidates.

Early Oral Feeding Following McKeown Minimally Invasive Esophagectomy: An Open-label, Randomized, Controlled, Noninferiority Trial.

OBJECTIVE: Our objective was to evaluate the impact of early oral feeding (EOF) on postoperative cardiac, respiratory, and gastrointestinal (CRG) complications after McKeown minimally invasive esophagectomy for esophageal cancer. SUMMARY BACKGROUND DATA: Nil-by-mouth with enteral tube feeding is routinely practiced after esophagectomy. METHODS: Patients were randomly allocated to receive oral feeding on the first postoperative day (EOF group) or late oral feeding (LOF group) 7 days after surgery. The primary endpoint was the occurrence of postoperative CRG complications, and the secondary outcomes included bowel function recovery and short-term quality of life (QOL). RESULTS: Between February 2014 and October 2015, 280 patients were enrolled in this study. There were 140 patients in the EOF group and 140 patients in the LOF group. EOF was noninferior to LOF for CRG complications (30.0% in the EOF group vs. 32.9% in the LOF group; 95% confidence interval of the difference: -13.8% to 8.0%). Compared with the LOF group, the EOF group showed significantly shorter time to first flatus (median of 2 days vs. 3 days, P = 0.001) and bowel movement (median of 3 vs. 4 days, P < 0.001). Two weeks after the operation, patients in the EOF group reported higher global QOL and function scores and lower symptom scores than patients in the LOF group. CONCLUSIONS: In patients after McKeown minimally invasive esophagectomy is noninferior to the standard of care with regard to postoperative CRG complications. In addition, patients in the EOF group had a quicker recovery of bowel function and improved short-term QOL.

Cost-Effectiveness of Minimally Invasive Esophagectomy for Esophageal Squamous Cell Carcinoma.

INTRODUCTION: The cost-effectiveness of minimally invasive esophagectomy (MIE) versus open esophagectomy (OE) for esophageal squamous cell carcinoma (ESCC) has not been established. Recent cost studies have shown that MIE is associated with a higher surgical expense, which is not consistently offset by savings through expedited post-operative recovery, therefore suggesting a questionable benefit of MIE over OE from an economic point of view. In the current study, we compared the cost-effectiveness of MIE versus OE for ESCC. MATERIALS AND METHODS: Between April 2000 and December 2013, a total of 251 consecutive patients undergoing MIE or OE for ESCC were enrolled. After propensity score (PS)-matching the MIE group with the OE group for clinical characteristics, 95 patients from each group were enrolled to compare the peri-operative outcomes, long-term survival, and cost. RESULTS: After PS-matching, the baseline characteristics were not significantly different between groups. Perioperative outcomes were similar in both groups. MIE was superior to OE with respect to a shorter intensive care unit (ICU) stay, while the complication rate (except for hoarseness) and survival were similar. Post-operative cost was significantly less in the MIE group due to a shorter ICU stay; however, reduced post-operative cost failed to offset the higher surgical expense of MIE. CONCLUSIONS: MIE for ESCC failed to show cost-effectiveness regarding overall expense in our study, but costs less in the postoperative care, especially for ICU care. More cost studies on MIE in other health care systems are warranted to verify the cost-effectiveness of MIE.

A Propensity-matched Analysis Comparing Survival After Esophagectomy Followed by Adjuvant Chemoradiation to Surgery Alone for Esophageal Squamous Cell Carcinoma.

BACKGROUND: The role of adjuvant chemoradiation in esophageal cancer has been underestimated in the literature. This study was undertaken to determine whether adjuvant chemoradiation improves survival compared with surgery alone. METHODS: Data of 1095 esophageal squamous cell carcinoma (ESCC) patients, including 679 in surgery alone group (group 1) and 416 in surgery followed adjuvant chemoradaition group (group 2), were obtained from the Taiwan Cancer Registry database. Propensity score matching (PSM) analysis was used to identify 147 well-balanced patients in each group for overall survival comparison. RESULTS: After PSM, the 3-year survival rates and median survival were 44.9% and 27.2 (95% confidence interval [CI]: 17.6-40.3) months in group 2, which is significantly higher than that in group 1 (28.1% and 18.2 [95% CI: 14.3-24.5] months, P = 0.0043). In the multivariate survival analysis, pT3/4 stage (Hazard Ratio [HR]: 2.03, 95% CI: 1.38-2.97, P < 0.001), pN+ stage (HR: 1.83, 95% CI: 1.31-2.57, P = 0.0004), tumor length more than 32 mm (HR: 1.93, 95% CI: 1.33-2.79, P < 0.001), R1/2 resection (HR: 1.75, 95% CI: 1.15-2.66, P = 0.009), and adjuvant chemoradiation (HR: 0.57, 95% CI: 0.42-0.78, P < 0.0001) were independent prognostic factors. Subgroup analysis suggested patients with pT3/4 stage, pN+ stage tumors, larger tumor size, poorly differentiated tumors, and R1/2 resections were more likely to demonstrate survival benefit from adjuvant chemoradiation. CONCLUSIONS: Compared with surgery alone, adjuvant chemoradiation provides a survival benefit to ESCC patients, especially those with pT3/4 stage, N+ tumors, larger tumor size, poorly differentiated tumors, and R1/2 resections.

Dissimilatory Arsenate Reduction and In Situ Microbial Activities and Diversity in Arsenic-rich Groundwater of Chianan Plain, Southwestern Taiwan.

Although dissimilatory arsenic reduction (DAsR) has been recognized as an important process for groundwater arsenic (As) enrichment, its characterization and association with in situ microbial activities and diversity in As-rich groundwater is barely studied. In this work, we collected As-rich groundwater at depths of 23, 300, and 313 m, respectively, from Yenshui-3, Budai-Shinwen, and Budai-4 of Chianan plain, southwestern Taiwan, and conducted incubation experiments using different electron donors, acceptors, and sulfate-reducing bacterial inhibitor (tungstate) to characterize DAsR. Moreover, bacterial diversity was evaluated using 454-pyrosequencing targeting bacterial 16S rRNAs. MPN technique was used to enumerate microorganisms with different in situ metabolic functions. The results revealed that DAsR in groundwater of Chianan plain was a biotic phenomenon (as DAsR was totally inhibited by filter sterilization), enhanced by the type of electron donor (in this case, lactate enhanced DAsR but acetate and succinate did not), and limited by the availability of arsenate. In addition to oxidative recycling of As(III), dissolution of As(V)-saturated manganese and iron minerals by indigenous dissimilatory Mn(IV)- and Fe(III)-reducing bacteria, and abiotic oxidation of As(III) with Mn(IV) regenerated As(V) in the groundwater. Sulfate-respiring bacteria contributed 7.4 and 28.2 % to the observed DAsR in groundwater of Yinshui-3 and Budai-Shinwen, respectively, whereas their contribution was negligible in groundwater of Budai-4. A noticeable variation in dominant genera Acinetobacter and Bacillus was observed within the groundwater. Firmicutes dominated in highly As-rich groundwater of Yenshui-3, whereas Proteobacteria dominated in comparatively less As-rich groundwater of Budai-Shinwen and Budai 4.

Feasibility of Subxiphoid Anatomic Pulmonary Lobectomy in a Canine Model.

Purpose Transthoracic thoracoscopic approach is the gold standard in surgical treatment for thoracic disease. However, it is associated with significant chronic postoperative wound discomfort. Currently, limited data are available regarding the subxiphoid approach to the thoracic cavity. The present study is aimed to evaluate the performance of a subxiphoid anatomic pulmonary lobectomy (SAPL) in a canine model. Methods The SAPL procedure was performed in 10 beagle dogs using a 3-cm incision over the xiphoid process. After thoracic exploration, SAPL was performed under flexible bronchoscopy guidance. The pulmonary vessel was divided with Ligasure and secured with a suture ligature. The bronchus was divided with endostapler. Surgical outcomes were evaluated by the success of SAPL and operative complications. Results SAPL was successfully completed in 9 animals. One animal required conventional thoracotomy to resuture the pulmonary artery stump. Another animal encountered small middle lobe laceration after SAPL and died at 8 days postoperation due to respiratory distress. Conclusion Subxiphoid anatomic pulmonary lobectomy is technically feasible. Refinement of endoscopic instruments combined with more research evidences may facilitate the development of subxiphoid platform in thoracic surgery.

Single-incision versus multiple-incision thoracoscopic lobectomy and segmentectomy: a propensity-matched analysis.

OBJECTIVE: To compare the perioperative outcomes of single-incision and multiple-incision thoracoscopic lobectomy and segmentectomy. BACKGROUND: Reports of single-incision thoracoscopic lobectomy and segmentectomy for lung cancer are limited, and a comparison between single-incision and multiple-incision thoracoscopic lobectomy or segmentectomy for lung cancer has not been previously reported. METHODS: From January 2005 to June 2013, a total of 233 patients with lung cancer underwent thoracoscopic lobectomy or segmentectomy via a single-incision or multiple-incision technique. A propensity-matched analysis, incorporating preoperative variables, was used to compare the short-term outcomes between single-incision and multiple-incision thoracoscopic lobectomy and segmentectomy. RESULTS: Overall, 50 patients underwent single-incision thoracoscopic pulmonary resections, including 35 lobectomies and 15 segmentectomies, and 183 patients underwent multiple-incision thoracoscopic lobectomy or segmentectomy between January 2005 and December 2011. Propensity matching produced 46 patients in each group. The length of hospital stay and the complication rate were not significantly different between the 2 groups. Single-incision thoracoscopic lobectomy and segmentectomy were associated with shorter operative time (P = 0.029), more numbers of lymph nodes (P = 0.032), and less intraoperative blood loss (P = 0.017) than with the multiple-incision approach. No in-hospital mortality occurred in either group. CONCLUSIONS: Single-incision thoracoscopic lobectomy and segmentectomy are feasible, and perioperative outcomes are comparable with those of the multiple-incision approach.

Comparison of pathologic stage in patients receiving esophagectomy with and without preoperative chemoradiation therapy for esophageal SCC.

The prognostic value for the post-chemoradiation therapy (CRT) pathologic stage is uncertain. The purpose of this study was to compare the pathologic stage in patients undergoing esophagectomy with and without preoperative CRT for esophageal squamous cell carcinoma (ESCC). This study retrospectively reviewed the data from 2151 patients with ESCC who underwent esophagectomy with or without preoperative CRT between 2008 and 2011 in Taiwan. Patients were divided into 2 groups. Group A consisted of patients treated with primary surgery without prior treatments (n=1301), and group B consisted of patients receiving preoperative CRT followed by esophagectomy (n=850). In group A, 679 patients received surgery alone, 92 received postoperative chemotherapy, 416 received postoperative chemoradiation therapy, and 114 received postoperative radiation therapy. In group A, the 3-year survival rates by pathologic stage were 82.2% for stage 0, 67.6% for stage I, 50.7% for stage II, 21.5% for stage III, and 14.8% for stage IV (P<.001). In group B, the 3-year survival rates of post-CRT pathologic stages 0, I, II, III, and IV were 59.4%, 46.0%, 40.3%, 19.1%, and 8.2%, respectively (P<.001). In multivariate analysis, the pathologic T, N, and M were all independent prognostic factors in both group A (esophagectomy alone) and B (CRT plus esophagectomy). The current, 7th edition of the esophageal TNM staging system could adequately stratify prognostic groups in patients with squamous cell carcinoma who were treated with preoperative CRT and esophagectomy.

Learning thoracoscopic lobectomy in resident training.

BACKGROUND: Thoracoscopic lobectomy is a safe and effective procedure; however, the ways by which to incorporate this technically demanding procedure into residency training is still unknown. We reported on the outcomes of thoracoscopic lobectomies performed by a single thoracic resident, who was simultaneously undergoing training for both open and thoracoscopic lobectomies. PATIENTS AND METHODS: Between January 2010, and May 2011, data from 87 consecutive thoracoscopic lobectomies that were performed by a trainee surgeon (B.-Y.W.) were prospectively obtained. Data were grouped into the first 30 and subsequent 57 cases. Patient characteristics, operative data, complications, and surgical pathology were analyzed. RESULTS: The mean operating time in group 2 was significantly lower compared with group 1 (264.0 ± 45.9 min in group 1 vs. 197.5 ± 57.7 min in group 2; p<0.001). There were no mortalities in both the groups and no significant differences in postoperative complications. CONCLUSIONS: Thoracoscopic lobectomy can be taught to a nonexperienced thoracic resident during an open procedure without compromising the safety of patients. It appears that surgical performance reaches a plateau after the completion of 30 cases.

Automatic detection and vascular territory classification of hyperacute staged ischemic stroke on diffusion weighted image using convolutional neural networks.

Automated ischemic stroke detection and classification according to its vascular territory is an essential step in stroke image evaluation, especially at hyperacute stage where mechanical thrombectomy may improve patients' outcome. This study aimed to evaluate the performance of various convolutional neural network (CNN) models on hyperacute staged diffusion-weighted images (DWI) for detection of ischemic stroke and classification into anterior circulation infarct (ACI), posterior circulation infarct (PCI) and normal image slices. In this retrospective study, 253 cases of hyperacute staged DWI were identified, downloaded and reviewed. After exclusion, DWI from 127 cases were used and we created a dataset containing total of 2119 image slices, and separates it into three groups, namely ACI (618 slices), PCI (149 slices) and normal (1352 slices). Two transfer learning based CNN models, namely Inception-v3, EfficientNet-b0 and one self-derived modified LeNet model were used. The performance of the models was evaluated and activation maps using gradient-weighted class activation mapping (Grad-Cam) technique were made. Inception-v3 had the best overall accuracy (86.3%), weighted F1 score (86.2%) and kappa score (0.715), followed by the modified LeNet (85.2% accuracy, 84.7% weighted F1 score and 0.693 kappa score). The EfficientNet-b0 had the poorest performance of 83.6% accuracy, 83% weighted F1 score and 0.662 kappa score. The activation map showed that one possible explanation for misclassification is due to susceptibility artifact. A sufficiently high performance can be achieved by using CNN model to detect ischemic stroke on hyperacute staged DWI and classify it according to vascular territory.

Asia expert consensus on segmentectomy in non-small cell lung cancer: A modified Delphi study.

Objective: Segmentectomy as a parenchymal-sparing surgical approach has been recommended over lobectomy in select patients with early-stage non-small cell lung cancer. This study aimed to address 3 aspects of segmentectomy ("patient indication"; "segmentectomy approaches"; "lymph node assessment") where there is limited clinical guidance. Methods: A modified Delphi approach comprising 3 anonymous surveys and 2 expert discussions was used to establish consensus on the aforementioned topics among 15 thoracic surgeons (2 Steering Committee; 2 Task Force; 11 Voting Experts) from Asia who have extensive segmentectomy experience. Statements were developed by the Steering Committee and Task Force based on their clinical experience, published literature (rounds 1-3), and comments received from Voting Experts through surveys (rounds 2-3). Voting Experts indicated their agreement with each statement on a 5-point Likert scale. Consensus was defined as ≥70% of Voting Experts selecting either "Agree"/"Strongly Agree" or "Disagree"/"Strongly Disagree." Results: Consensus from the 11 Voting Experts was reached on 36 statements (11 "patient indication" statements; 19 "segmentation approaches" statements; 6 "lymph node assessment" statements). In rounds 1, 2, and 3, consensus was reached on 48%, 81%, and 100% of drafted statements, respectively. Conclusions: A recent phase 3 trial reported significantly improved 5-year overall survival rates for segmentectomy compared with lobectomy, proposing thoracic surgeons to consider segmentectomy as a surgical option in suitable patients. This consensus serves as a guidance to thoracic surgeons considering segmentectomy in patients with early non-small cell lung cancer, outlining key principles that surgeons should consider in surgical decision-making.

The potential for reductive mobilization of arsenic [As(V) to As(III)] by OSBH(2) (Pseudomonas stutzeri) and OSBH(5) (Bacillus cereus) in an oil-contaminated site.

Microbial reduction of arsenate [As(V)] plays an important role in arsenic (As) mobilization in aqueous environments. In this study, we investigated reduction of arsenate by different bacterial isolates such as OSBH(1) (GU329913), OSBH(2) (GU329914), OSBH(3) (GU329915), OSBH(4) (GU329916) and OSBH(5) (GU329917), isolated from the oil sludge of a sewage treatment plant operated by the China Petroleum Refinery Company in Kaohsiung, southern Taiwan. Bacterial strains of pure culture were identified by 16S rRNA analysis (≥99 % nucleotide similarity). Morphological and 16S rRNA analysis show that the isolate OSBH(1) is similar to E. coli, OSBH(2) is similar to P. stutzeri, OSBH(3) is similar to P. putida, OSBH(4) is similar to P. aeruginosa, and OSBH(5) is similar to B. Cereus. The As(V) was transformed to As(III) in the presence of isolates OSBH(2) and OSBH(5) by a detoxification process. The potential reduction rates of As(V) were higher in the presence of isolate OSBH(5) compared to the isolate OSBH(2). The microbial growth (cell/mL) of isolate OSBH(5) was significantly higher in culture medium compared to OSBH(2). The bacterial isolates such as OSBH(1), OSBH(3) and OSBH(4) were found to be incapable of transforming the As(V). It is concluded that the activity of the oil-degrading bacterial isolates described in this work contributes to the mobilization of As in the more toxic As(III) form that affects biotic life.

Health risks for human intake of aquacultural fish: Arsenic bioaccumulation and contamination.

Aquacultural tilapia (Oreochromis mossambicus L.) and shrimp (Penaeus monodon L.) from groundwater-cultured ponds in southwestern Taiwan were analyzed to estimate arsenic (As) bioaccumulation and the potential health risk to human intake. Most of aquacultural ponds exhibited higher arsenic than maximum allowed concentrations (50 µg L(-1)) in pond water of Taiwan. Arsenic levels in tilapia in Budai, Yichu and Beimen were 0.92 ± 0.52 µg g(-1), 0.93 ± 0.19 µg g(-1) and 0.76 ± 0.03 µg g(-1), respectively and in shrimp was 0.36 ± 0.01 µg g(-1) in Beimen. Total arsenic in tilapia is highly correlated (R(2) = 0.80) with total arsenic concentration of pond water. Total arsenic in fish showed high correlation with that in bone (R(2) = 0.98), head (R(2) = 0.97) and tissue (R(2) = 0.96). Organic arsenic species (DMA) was found higher relative to inorganic species of As(III) and As(V). The average percent contribution of inorganic arsenic to total arsenic in fish samples was 12.5% and ranged between 11.7 to 14.2%. Bioaccumulation factors (BAFs) for total arsenic in fish ranged from 10.3 to 22.1, whereas BAF for inorganic arsenic ranged from 1.33 to 2.82. The mean human health cancer risk associated with the ingestion of inorganic arsenic in the fish was estimated at 2.36 × 10(-4) ± 0.99 × 10(-4), which is over 200 times greater than a de Minimus cancer risk of 1 × 10(-6). The mean human health hazard quotient associated with ingesting inorganic arsenic in the fish was 1.22 ± 0.52, indicating that expected human exposure exceeds the reference dose for non-cancer health effects by 22%. These results suggest that the inhabitants in this region are being subjected to moderately elevated arsenic exposure through the consumption of tilapia and shrimp raised in aquaculture ponds.

A comparative study on arsenic and humic substances in alluvial aquifers of Bengal delta plain (NW Bangladesh), Chianan plain (SW Taiwan) and Lanyang plain (NE Taiwan): implication of arsenic mobilization mechanisms.

Humic substances in groundwater and aquifer sediments from the arsenicosis and Blackfoot disease (BFD) affected areas in Bangladesh (Bengal delta plain) and Taiwan (Lanyang plain and Chianan plain) were characterized using fluorescence spectrophotometry and Fourier transform infrared (FT-IR) spectroscopy. The results demonstrate that the mean concentration of As and relative intensity of fluorescent humic substances are higher in the Chianan plain groundwater than those in the Lanyang plain and Bengal delta plain groundwater. The mean As concentrations in Bengal delta plain, Chianan plain, and Lanyang plain are 50.65 µg/l (2.8-170.8 µg/l, n=20), 393 µg/l (9-704 µg/l, n=5), and 104.5 µg/l (2.51-543 µg/l, n = 6), respectively. Average concentrations and relative fluorescent intensity of humic substances in groundwater are 25.381 QSU (quinine standard unit) and 17.78 in the Bengal delta plain, 184.032 QSU and 128.41 in the Chianan plain, and 77.56 QSU and 53.43 in the Lanyang plain. Moreover, FT-IR analysis shows that the humic substances extracted from the Chianan plain groundwater contain phenolic, alkanes, aromatic ring and amine groups, which tend to form metal carbon bonds with As and other trace elements. By contrast, the spectra show that humic substances are largely absent from sediments and groundwater in the Bengal delta plain and Lanyang plain. The data suggest that the reductive dissolution of As-adsorbed Mn oxyhydroxides is the most probable mechanism for mobilization of As in the Bengal delta plain. However, in the Chianan plain and Lanyang plain, microbially mediated reductive dissolution of As-adsorbed amorphous/crystalline Fe oxyhydroxides in organic-rich sediments is the primary mechanism for releasing As to groundwater. High levels of As and humic substances possibly play a critical role in causing the unique BFD in the Chianan plain of SW Taiwan.