Long-Term Efficacy of Ultrasound-Guided Laser Ablation for Papillary Thyroid Microcarcinoma: Results of a 10-Year Retrospective Study

Background: The aim of this study was to evaluate the 10-year efficacy and safety of laser ablation (LA) for the treatment of solitary papillary thyroid microcarcinoma (PTMC). Methods: LA was performed on patients with low-risk PTMC (diagnosed using fine-needle aspiration cytology) who refused or were ineligible for surgery between 2008 and 2011. Ultrasonography was performed to evaluate the ablated volumes and potential recurrences on the day after the procedure, as well as at 1 week, 1, 3, and 6 months, and every 6 months thereafter for 10 years. Computed tomography (CT) with contrast enhancement and positron emission tomography/CT was performed to evaluate local recurrences and distant metastases. Results: A total of 90 PTMCs in 90 patients were treated in a single session of LA, and the procedure was well tolerated by the patients. The mean follow-up duration was 112 months. By 3-10 months after the LA, all the ablation areas had disappeared or presented as scars. The disappearance rate was 100% after 12 months. Thyroid hormone and autoantibody levels did not change significantly after the treatment. Three patients experienced transient voice changes, but each recovered within 1 month. Additional PTMC foci were subsequently detected in previously untreated areas in five patients (5.5%) 17-56 months after the treatment. A metastatic lymph node was detected in one patient (1.1%) within two months of the treatment; however, it was determined to be an undetected cancer metastasis, rather than a recurrence. All the patients with recurrence underwent surgery, and there were no instances of recurrence after >5 years. Conclusions: LA is effective and safe for the treatment of low-risk PTMCs. A thorough examination of multifocality and lymph node metastasis status is required before considering LA treatment.

Difference in F-18 FDG Uptake After Esophagogastroduodenoscopy and Colonoscopy in Healthy Sedated Subjects

PURPOSE

We aimed to evaluate the difference in fluorodeoxyglucose (FDG) uptake in sedated healthy subjects after they underwent esophagogastroduodenoscopy (EGD) and colonoscopy procedures.

METHODS

The endoscopy group (n = 29) included healthy subjects who underwent screening via F-18 FDG positron emission tomography/computed tomography (PET/CT) after an EGD and/or colonoscopy under sedation on the same day. The control group (n = 35) included healthy subjects who underwent screening via PET/CT only. FDG uptake in the tongue, uvula, epiglottis, vocal cords, esophagus, stomach, duodenum, liver, cecum, colon, anus, and muscle were compared between the two groups.

RESULTS

Maximum standardized uptake value (SUVmax) in the tongue, pharynx, larynx, and esophagus did not significantly differ between the endoscopy and control groups. In contrast, mean SUVmax in the whole stomach was 18 % higher in the endoscopy group than in the control group (SUVmax: 2.96 vs. 2.51, P = 0.010). In the lower gastrointestinal track, SUVmax from the cecum to the rectum was not significantly different between the two groups, whereas SUVmax in the anus was 20 % higher in the endoscopy group than in the control group (SUVmax: 4.21 vs. 3.50, P = 0.002). SUVmax in the liver and muscle was not significantly different between the two groups. Mean volume of the stomach and mean cross section of the colon was significantly higher in the endoscopy group than in the control group (stomach: 313.28 cm³ vs. 209.93 cm³, P < 0.001, colon: 8.82 cm² vs. 5.98 cm², P = 0.001).

CONCLUSIONS

EGD and colonoscopy under sedation does not lead to significant differences in SUVmax in most parts of the body. Only gastric FDG uptake in the EGD subjects and anal FDG uptake in the colonoscopy subjects was higher than uptake in those regions in the control subjects.

Radioiodine Scan Index: A Simplified, Quantitative Treatment Response Parameter for Metastatic Thyroid Carcinoma

PURPOSE

We aimed to develop and validate a simplified, novel quantification method for radioiodine whole-body scans (WBSs) as a predictor for the treatment response in differentiated thyroid carcinoma (DTC) patients with distant metastasis.

METHODS

We retrospectively reviewed serial WBSs after radioiodine treatment from 2008 to 2011 in patients with metastatic DTC. For standardization of TSH simulation, only a subset of patients whose TSH level was fully enhanced (TSH > 80 mU/l) was enrolled. The radioiodine scan index (RSI) was calculated by the ratio of tumor-to-brain uptake. We compared correlations between the RSI and TSH-stimulated serum thyroglobulin (TSH_s_Tg) level and between the RSI and Tg reduction rate of consecutive radioiodine treatments.

RESULTS

A total of 30 rounds of radioiodine treatment for 15 patients were eligible. Tumor histology was 11 papillary and 4 follicular subtypes. The TSH_s_Tg level was mean 980 ng/ml (range, 0.5-11,244). The Tg reduction rate after treatment was a mean of -7 % (range, -90 %-210 %). Mean RSI was 3.02 (range, 0.40-10.97). RSI was positively correlated with the TSH_s_Tg level (R(2) = 0.3084, p = 0.001) and negatively correlated with the Tg reduction rate (R(2) = 0.2993, p = 0.037). The regression equation to predict treatment response was as follows: Tg reduction rate = -14.581 × RSI + 51.183.

CONCLUSIONS

Use of the radioiodine scan index derived from conventional WBS is feasible to reflect the serum Tg level in patients with metastatic DTC, and it may be useful for predicting the biologic treatment response after radioiodine treatment.

Prediction for recurrence using F-18 FDG PET/CT in pathologic N0 lung adenocarcinoma after curative surgery

BACKGROUND

The aim of this study was to investigate risk factors for recurrence in patients with lung adenocarcinoma (LAD) who were pathologically N0 (pN0) after curative surgical resection.

METHODS

A total of 102 LAD patients (M/F = 55/47, mean age, 62.6 ± 9.4 years) diagnosed as pN0 after curative surgery were included in this study. Clinical, biochemical, radiologic, and pathologic findings were reviewed and analyzed for recurrence. Metabolic parameters [SUVmax, metabolic tumor volume (MTV), total lesion glycolysis (TLG)] on pretreatment F-18 FDG PET/CT were also obtained and analyzed for recurrence.

RESULTS

Of 102 patients, 38 (37.3%) were found to experience recurrence for 33.6 ± 16.3 months. SUVmax, MTV, and TLG were significantly higher in patients with recurrence. The optimal cutoff values determined using a receiver-operating characteristic curve were 6.90 for SUVmax, 10.78 cm(3) for MTV, and 39.68 for TLG. Univariate analysis showed that tumor size, tumor marker, SUVmax, MTV, and TLG were prognostic factors for recurrence. In multivariate analyses, after adjusting for age, sex, tumor size, pathologic T stage, and tumor marker, high SUVmax, MTV, and TLG showed an association with an increased risk of recurrence.

CONCLUSIONS

Metabolic parameters on pretreatment F-18 FDG PET/CT can predict recurrence in pN0 LAD patients who underwent curative surgery. Therefore, patients with high metabolic parameters on PET can be considered as candidates for adjuvant therapy to reduce recurrence and should be monitored carefully for early detection of possible recurrence.

Intratumoral Metabolic Heterogeneity for Prediction of Disease Progression After Concurrent Chemoradiotherapy in Patients with Inoperable Stage III Non-Small-Cell Lung Cancer

PURPOSE

We evaluated the value of variable (18)F-FDG PET/CT parameters for the prediction of disease progression after concurrent chemoradiotherapy (CCRT) in patients with inoperable stage III non-small-cell lung cancer (NSCLC).

METHODS

One hundred sixteen pretreatment FDG PET/CT scans of inoperable stage III NSCLC were retrospectively reviewed (stage IIIA: 51; stage IIIB: 65). The volume of interest was automatically drawn for each primary lung tumor, and PET parameters were assessed as follows: maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV) using the boundaries presenting SUV intensity exceeding 3.0, and the area under the curve of the cumulative SUV-volume histograms (AUC-CSH), which is known to reflect the tumor heterogeneity. Progression-free survival (PFS), locoregional recurrence-free survival (LRFS), and distant metastasis-free survival (DMFS) were compared with each PET and clinical parameters by univariate and multivariate survival analysis.

RESULTS

In the ROC analysis, the optimal cutoff values of SUVmax, MTV (cm(3)), and AUC-CSH for prediction of PFS were determined as 21.5, 27.7, and 4,800, respectively. In univariate analysis, PFS was statistically significantly reduced in those with AUC-CSH < 4,800 (p = 0.004). In multivariate analysis, AUC-CSH and SUVmax were statistically significant independent prognostic factors (HR 3.35, 95 % CI 1.79-6.28, p < 0.001; HR 0.25, 95 % CI 0.09-0.70, p = 0.008, respectively). Multivariate analysis showed that AUC-CSH was the most significant independent prognostic factor for LRFS and DMFS (HR 3.27, 95 % CI 1.54-6.94, p = 0.002; HR 2.79, 95 % CI 1.42-5.50, p = 0.003).

CONCLUSIONS

Intratumoral metabolic heterogeneity of primary lung tumor in (18)F-FDG PET/CT can predict disease progression after CCRT in inoperable stage III NSCLC.

False-positive uptake on radioiodine whole-body scintigraphy: physiologic and pathologic variants unrelated to thyroid cancer

Radioiodine whole-body scintigraphy (WBS), which takes advantage of the high avidity of radioiodine in the functioning thyroid tissues, has been used for detection of differentiated thyroid cancer. Radioiodine is a sensitive marker for detection of thyroid cancer; however, radioiodine uptake is not specific for thyroid tissue. It can also be seen in healthy tissue, including thymus, breast, liver, and gastrointestinal tract, or in benign diseases, such as cysts and inflammation, or in a variety of benign and malignant non-thyroidal tumors, which could be mistaken for thyroid cancer. In order to accurately interpret radioiodine scintigraphy results, one must be familiar with the normal physiologic distribution of the tracer and frequently encountered physiologic and pathologic variants of radioiodine uptake. This article will provide a systematic overview of potential false-positive uptake of radioiodine in the whole body and illustrate how such unexpected findings can be appropriately evaluated.

Ga-68 Somatostatin Receptor PET/CT in von Hippel-Lindau Disease

Von Hippel-Lindau (VHL) disease is a dominantly inherited familial cancer syndrome with a variety of benign and malignant tumors such as retinal and central nervous system hemangioblastomas, endolymphatic sac tumors, renal cysts and tumors, pancreatic cysts and tumors, pheochromocytomas, and epididymal cystadenomas. Cross-sectional modalities (computed tomography and magnetic resonance imaging) as well as ultrasound play a major role in the initial evaluation and follow-up of the various manifestations of VHL disease. Ga-68-labeled somatostatin receptor analogs already have a significant role in the diagnosis, staging, and therapy management of neuroendocrine neoplasms and neural crest tumors. Herein, we report a case presenting a variety of malignancies in VHL and showing the usefulness of Ga-68 somatostatin receptor PET/CT as a one-stop-shop imaging modality in the management of VHL disease.

The Clinical Usefulness of (18)F-FDG PET/CT in Patients with Systemic Autoimmune Disease

PURPOSE

Individuals with systemic autoimmune disease have an increased susceptibility to both inflammation and malignancy. The aim of this study was to evaluate the clinical usefulness of (18)F-FDG PET/CT in patients with systemic autoimmune disease.

METHODS

Forty patients diagnosed with systemic autoimmune disease were enrolled. Diagnostic accuracy of FDG PET/CT for detecting malignancy was assessed. FDG PET/CT findings, including maximum standardized uptake (SUVmax) of lymphadenopathy (LAP), liver, bone marrow, spleen, joint and muscles, were considered for the characterization of LAPs.

RESULTS

FDG PET/CT could detect metabolically activated lesions in 36 out of 40 patients (90%) including inflammatory lesions in 28 out of 32 patients (88%). The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of FDG PET/CT for the detection of malignancy were 100, 67, 70, 25, and 100%, respectively. Multiple LAPs were found in 25 of 40 patients (63%), and comprised three malignancies, four cases of tuberculosis, and 18 reactive changes. A SUVmax ratio of bone marrow to liver below 0.78 could distinguish malignancy from tuberculosis + reactive change (AUC = 1.000, sensitivity: 100%, specificity: 100%). The SUVmax ratio of spleen to liver in the reactive group was also significantly higher than that in the malignancy group (P = 0.014). SUVmax of LAP in the TB group was significantly higher than that in the reactive group (P = 0.040).

CONCLUSIONS

PET/CT is useful in detecting and differentiating inflammation and malignancy in patients with systemic autoimmune disease. Frequent false-positive interpretations can be minimized by consideration of FDG uptake in bone marrow and spleen.

Comparison of ¹³¹I whole-body imaging, ¹³¹I SPECT/CT, and ¹⁸F-FDG PET/CT in the detection of metastatic thyroid cancer

PURPOSE

The aim of this study was to compare (131)I whole-body scintigraphy (WBS), WBS with (131)I single photon emission computed tomography/computed tomography (SPECT/CT), and (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT in the detection of distant metastases of differentiated thyroid cancer (DTC).

METHODS

A total of 140 patients with 258 foci of suspected distant metastases were evaluated. (131)I WBS, (131)I SPECT/CT, and (18)F-FDG PET/CT images were interpreted separately. The final diagnosis was obtained from histopathologic study, serum thyroglobulin level, other imaging modalities, and/or clinical follow-up.

RESULTS

Of the 140 patients with 258 foci, 46 patients with 166 foci were diagnosed as positive for distant metastasis. The sensitivity, specificity, and diagnostic accuracy of each imaging modality were 65, 55, and 59%, respectively, for (131)I WBS; 65, 95, and 85% for (131)I SPECT/CT, respectively; and 61, 98, and 86%, respectively, for (18)F-FDG PET/CT in patient-based analyses. Lesion-based analyses demonstrated that both SPECT/CT and PET/CT were superior to WBS (p<0.001) in all patient groups. SPECT/CT was superior to WBS and PET/CT (p<0.001) in patients who received a single challenge of radioiodine therapy, whereas PET/CT was superior to WBS (p=0.005) and SPECT/CT (p=0.013) in patients who received multiple challenges.

CONCLUSION

Both SPECT/CT and PET/CT demonstrated high diagnostic performance in detecting metastatic thyroid cancer. SPECT/CT was highly accurate in patients who underwent a single challenge of radioiodine therapy. In contrast, (18)F-FDG PET/CT presented the highest diagnostic performance in patients who underwent multiple challenges of radioiodine therapy.

Improved detection of lung or bone metastases with an I-131 whole body scan on the 7th day after high-dose I-131 therapy in patients with thyroid cancer

PURPOSE

The purpose of this study is to compare post-therapy third day and seventh day I-131 whole body scans (3DWBS and 7DWBS) in detecting lung or bone metastasis from well-differentiated thyroid cancer.

MATERIALS AND METHODS

We enrolled 52 patients with lung or bone metastasis out of 1,152 patients who were treated with high-dose I-131 therapy from January 2008 to June 2009. All patients underwent 3DWBS and 7DWBS. I-131 avidity was classified into three grades: no uptake, suspicious for uptake, and definite uptake. We compared the presence and grades of metastatic lesions on each scan. We categorized all cases into three groups based on I-131 uptake on each scan and compared several clinical parameters including FDG uptake and thyroglobulin (Tg) level among the groups.

RESULTS

Sixty metastatic cases from 52 patients (45 lung and 15 bone metastases) were included. In 35 cases, I-131-avid metastatic lesions were detected by both 3DWBS and 7DWBS (group A). In 15 cases, metastatic lesions were missed on 3DWBS but detected on 7DWBS (group B). In 10 cases, I-131 uptake was not detected on either 3DWBS or 7DWBS (group C). Ten of 45 cases (22.2%) of lung metastasis that were negative on 3DWBS were detected on 7DWBS (p = 0.002). Five of 15 cases (33.3%) of bone metastasis that were negative on 3DWBS were detected on 7DWBS (p = 0.0625). The serum Tg level (TSH stimulated) was significantly different among groups A, B, and C (p = 0.0030). However, after exclusion of cases without a history of I-131 therapy, there was no significant difference in serum Tg level among the groups (p = 0.2330). The number of cases with a prior history of metastasis was higher in group A than in group B (p = 0.0069). However, there was no significant difference in prior history of metastasis between groups A and C (p = 0.8107).

CONCLUSION

7DWBS showed more lung or bone metastatic lesions than 3DWBS. After high-dose I-131 therapy, 7DWBS should be considered regardless of the results of the 3DWBS for the diagnosis of lung or bone metastasis from well-differentiated thyroid cancer.

Persistent organochlorine residues in estuarine and marine sediments from Ha Long Bay, Hai Phong Bay, and Ba Lat Estuary, Vietnam

To assess the organochlorine contamination in the northeast coastal environment of Vietnam, a total of 41 surface sediments were collected from Ha Long Bay, Hai Phong Bay, and Ba Lat estuary, and analyzed for their organochlorine content. Organochlorine compounds (OCs) were widely distributed in the Vietnamese coastal environment. Among the OCs measured, DDT compounds predominated with concentrations ranging from 0.31 to 274 ng g(-1). The overall contamination level of DDTs in coastal sediments from northern Vietnam is comparable with those from other Asian countries. However, concentrations exceeding 100 ng g(-1) are comparable with high concentrations reported from India and China, the largest DDT consumers in the world. The overall concentrations of PCBs, HCHs, and chlordanes in surface sediments were in the ranges of 0.04-18.71 ng g(-1), not detected (n.d.) - 1.00 ng g(-1), and n.d. - 0.75 ng g(-1), respectively. Ha Long Bay and Hai Phong Bay were relatively more contaminated with DDTs and PCBs than other regions, respectively. In contrast, the distribution of HCHs was relatively homogeneous. OCs contamination in the coastal environment of Vietnam is closely related to shipping and industrial activities. The levels of DDT compounds in harbors and industrial areas exceeded their sediment quality guideline values suggested by Environment Canada [CCME (Canadian Council of Ministers of the Environment), 2002. Canadian sediment quality guidelines for the protection of aquatic life. In: Canadian Environmental Quality Guidelines. Canadian Council of Ministers of the Environment, Winnipeg, MB] and Australian and New Zealand [ANZECC and ARMCANZ, 2000. National water quality management strategy. Paper No. 4, Australian and New Zealand Guidelines for Fresh and Marine Water Quality, vol. 1, The Guidelines. Australia. Document: http://www.deh.gov.au/water/quality/nwqms/volume1.html], indicating that adverse effects may occur to marine species in that areas.

Nationwide monitoring of polychlorinated biphenyls and organochlorine pesticides in sediments from coastal environment of Korea

To assess the organochlorine contamination in the Korean marine environment, a nationwide monitoring study was conducted. A total of 138 surface sediments, covering the whole Korean coast, were collected and analyzed. Organochlorine compounds (OCs) were widely distributed in the Korean coastal environment, with PCB and DDT contamination being particularly prevalent. The overall concentrations of PCBs, DDTs, HCHs, CHLs, and HCB in surface sediments were in the range of 0.088-199ngg(-1) (median value: 1.56ngg(-1)), 0.006-135ngg(-1) (0.68ngg(-1)), not detected (ND)-5.46ngg(-1) (0.32ngg(-1)), ND-3.26ngg(-1) (0.14ngg(-1)), and ND-2.59ngg(-1) (0.05ngg(-1)), respectively. The southeastern coast was found to be highly contaminated. Overall contamination status of Korean coastal sediments with regard to OCs is lower than that of USA. With the exception of highly industrialized sites, Korean coastal areas in general showed similar OC concentrations to those of other Asian countries. There was a significant correlation between distributions of most organochlorine contaminants with each other. OC contamination is closely related to shipping and industrial activities. Of the 7 sites categorized as highly polluted, 4 are in a harbor zone. Adverse effects to benthic communities are expected at the levels of OC contamination observed from harbor and industrial areas.

Levels of persistent organochlorine contaminants in fish from Korea and their potential health risk

Organochlorine contaminants in the muscles of sport and market fish were determined to understand the potential risks to humans consuming fish originating in Korea's coastal waters. Polychlorinated biphenyls (PCBs; sum of 22 congeners) and DDTs were the dominant contaminants, and their concentrations were in the range of 2.96 to 96.6 and 0.84 to 27.0 ng/g (wet weight basis), respectively. The highest PCB concentrations were found in samples taken from an industrial complex. Hexachlorocyclohexanes, chlordane-related compounds, and hexachlorobenzene concentrations were relatively low and ranged from 0.64 to 5.6, 0.17 to 4.24, and 0.08 to 1.58, respectively. Sport fish had levels of PCBs and DDTs approximately two times higher than market fish, implying that sport fish posed high potential risk of contamination with OCs. Risk-based screening value (SV) based on U. S. Environmental Protection Agency (USEPA) method was calculated using the USEPA approach to identify the primary chemicals of concern. Total PCB concentrations in all sport and market fish exceeded the SV (5.04 ng/g based on total PCBs), but the other compounds were mostly below SV values. Based on the estimated SVs, PCB compounds were identified as potential chemicals of concern.

Spatio-temporal distribution and characteristics of PAHs in sediments from Masan Bay, Korea

The distribution of polycyclic aromatic hydrocarbons (PAHs) has been investigated in the surface and core sediments from Masan Bay, Korea. Total PAHs in the surface sediments ranged from 207 to 2670 ng/g dry weight with a mean value of 680 ng/g. Qualitative similarity and quantitative difference between inner and outer bay indicate that the main sources of PAHs are located in the inner bay and outer bay is also affected by the same sources. Vertical distribution of PAHs revealed that three distinctive stages could be differentiated with the help of PCA analysis. The highest concentration (industrialization stage) appeared between late 1950s and 1980, which was 10 years later than other developed countries. A strong pyrolytic source fingerprint has been detected with slight influence of petrogenic sources, and diagenetic PAH, perylene also contributed. Total organic carbon normalized PAHs (sum of 13 PAHs, 8.85-88.0 microg/g OC) were under the threshold effects concentration (TEC, 290 microg/g OC).

Accumulation of tributyltin in olive flounder, Paralichthys olivaceus: its effect on hepatic cytochrome P450

Accumulation of tributyltin (TBT) was determined in liver of olive flounder exposed to TBT (3.65, 36.5, 365, 3,650, and 7,300 ng Sn/L) for 10 or 30 days, followed by 60 days depuration. Effect of TBT on hepatic cytochrome P450 content was also measured in liver of olive flounder. TBT was highly accumulated in liver of fish during the 10- to 30-day exposures, and hepatic cytochrome P450 content decreased with increasing TBT concentration. Hepatic cytochrome P450 contents were affected in olive flounder exposed to even environmentally relevant TBT concentrations, such as 3.65 ng Sn/L. In addition, the liver TBT levels demonstrated strong negative correlation to the hepatic cytochrome P450 content. The effects started to appear from 20 ng Sn/g dry weight of TBT in liver. Tributyltin concentrations and hepatic cytochrome P450 were also determined in feral fine-spotted flounder. The relationship between other organic pollutants known as cytochrome P450 inducers (e.g., polychlorinated biphenyls) as well as TBT and hepatic cytochrome P450 in the feral fish implied that TBT even at ppt level could impose antagonistic effects on hepatic cytochrome P450 induction.

PCB and PCDD/F totals, TEQs, and congener patterns in Korean coastal marine environments, 1987, 1988, 1990, and 1996-1999

Various mussel and oyster samples and select top sediment samples were taken over 27 industrial and pristine coastal sites form South Korea's west, south, and east coasts. Site-specific total PCB, PCDD/F, and organochlorine TEQ levels in biota were 1-306 ng/g ww, 3-9,400 pg/g ww, and 0.3-200 pg/g ww, respectively. Temporal trends showed a general decrease in total TEQ with an increase in TEQ contribution by PCDD/Fs at most locations over the past decade. Linear regression was used to establish a relationship between each contaminant total and the respective TEQ contribution. Principal component analysis was used to model the congener-specific PCB and PCDD/F data, and two three-component models were developed that describe the congener-specific patterns based on the variance between samples over the entire data set. Unique PCDD/F patterns were identified and discussed with respect to outliers identified in the previously established TEQ regressions and a distinct PCDD/F pattern was found that related to a single industrial source (i.e., steel mill). PCB patterns were explored in relation to those of common commercial mixtures of PCBs (i.e., Aroclors) and patterns were discussed with respect to TEQ. It was found that sites with relatively high PCB-TEQs showed an Aroclor 1254-like contamination.

Horizontal and vertical distribution of butyltin compounds in sediments from shipyards in Korea

Butyltin compounds were quantitatively determined in surface sediment and sediment core samples near shipyards in the south coast of Korea, which is one of the major ship building industries in the world. Tributyltin (TBT) concentrations reached up to 46100 ng Sn/g on a dry-weight basis at the front of the shipyard. Horizontal distribution of butyltin compounds was closely related to dry-docking activities. Butyltin concentrations were relatively low where remote from the sources. The vertical distribution of TBT in sediment cores showed active use of TBT in Korean peninsula for the past decades. The increase of TBT concentrations in sediment core according to estimated sediment age demonstrated a positive correlation with the increase of gross tonnage of ships built in the shipyard for 20 years. High TBT residue levels in sediment core samples raise concerns over persistence of the compound in the marine environment.

Geographical distribution and accumulation features of organochlorine residues in bivalves from coastal areas of South Korea

As a part of Mussel Watch Program in Korea, the contamination levels and accumulation features of polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) were assessed for 82 bivalve samples collected from 66 sites along the entire coast of Korea. The dry weight based sigmaPCBs and sigmaOCPs ranged from 4.4 ng g(-1) to 422.0 ng g(-1) (geometric mean = 36.9 ng g(-1)) and from 9.95 ng g(-1) to 131.37 (34.88) ng g(-1), respectively. PCB was predominant in Korean coast, followed by DDTs, HCHs, and Chlordanes. From the observed log normal distribution of PCB and each OCP, low- and high-levels were defined as geometric mean +/- 1 S.D., respectively. The levels at the sites near urban and/or industrial areas often exceeded the high-levels and the spatial distributions of sigmaDDTs and sigmaCHLs were correlated with that of sigmaPCBs, indicating terrestrial input pathways. Even distribution of sigmaHCHs suggested a possibility of atmospheric input pathway of HCHs. The observed isomer ratios of DDTs, HCHs, and CHLs indicated that aging has occurred.

Silyl derivatization of alkylphenols, chlorophenols, and bisphenol A for simultaneous GC/MS determination

A fast silyl derivatization technique for simultaneous GC/ MS analysis of alkylphenols, chlorophenols, and bisphenol A was developed. The analytes were silylized with an excess amount of bis(trimethylsilyl)trifluoroacetamide (BSTFA) followed by hydrolysis of excess silyl reagent with water. Reaction rates of derivatization were studied in various solvents and found to be fastest in acetone. Derivatization reaction in acetone was completed quantitatively within 15 s at room temperature while it took more than 1 h in other solvents studied. Similar results were obtained in mixed solvents with acetone if the content of acetone was higher than 60% (v/v). Since water-immiscible solvents such as dichloromethane or hexane are frequently used in the extraction of phenolic analytes in various sample matrixes, acetone can be added to the extracts in order to accelerate the reaction rate of derivatization. Stability of the derivatives in sample for long-term storage was ensured by hydrolyzing excess derivatizing reagent, BSTFA, with a spike of water followed by dehydration using anhydrous sodium sulfate. On the basis of the above results, a derivatizing treatment kit was designed to improve the convenience of analysis. It was possible to treat sample within several minutes successfully by using the kit. So fast simultaneous determination of those anlaytes by GC/MS was possible with improved convenience as well as sensitivity and reproducibility.

Horizontal distribution of butyltins in surface sediments from an enclosed bay system, Korea

Tributyltin (TBT), dibutyltin (DBT), and monobutyltin (MBT) compounds were quantitatively determined from surface sediment samples (total 59 stations) covering a whole basin where harbors, shipyards, and aquaculture farms were located. Butyltin compounds were detected from all the stations covering 640 km(2) of an enclosed bay system. TBT concentrations ranged from 4 to 382 ng/g as tin on a dry weight basis, and total butyltin concentrations, from 27 to 1763 ng/g. Horizontal distribution of TBT concentration showed apparent negative gradients from harbors and shipyards, indicating that its contamination was closely related to boating and dry-docking activities. However, TBT concentrations were decreased steeply from source areas. Elevated DBT and MBT levels in creeks imply the possible input of DBT from industrial wastewater. Total butyltin concentrations in sediments are significantly correlated with particulate organic carbon concentration for the subset of stations that are distant from source areas.

Accumulation of tributyl- and triphenyltin compounds in Pacific oyster, Crassostrea gigas, from the Chinhae Bay System, Korea

Butyl- and phenyltin residues were quantified in seawater and Pacific oyster (Crassostrea gigas) from the Chinhae Bay System, Korea. Butyltin compounds were detected in all the seawater and C. gigas samples, whereas phenyltin compounds were not detected in any seawater samples. Tributyltin (TBT) concentrations in seawater ranged <8-35 ng Sn L-1. TBT and triphenyltin (TPhT) concentrations in oysters ranged 95-885 and 155-678 ng Sn g-1, respectively. Spatial distribution of TBT was closely related to boating and dry-docking activities. However, spatial distribution of TPhT was not consistent with that of TBT. The estimated biological concentration factor (BCF) for TBT in C. gigas was about 25,000. Furthermore, 19 and 28% of total body burdens of TBT and TPhT were found in gonadal mass of C. gigas just prior to the spawning period, indicating that a proportional amount of TBT and TPhT would be released with a following reproductive process.