Relationship between Dietary Mercury Intake and Blood Mercury Level in Korea

This study was performed to evaluate the effect of dietary factors for mercury exposure by comparing with blood mercury concentration. Study population consisted of 1,866 adults (839 men and 1,027 women) in randomly-selected 30 districts in southeast Korea. Dietary mercury intake was calculated from food frequency questionnaire (FFQ) on seafood items and 24 hr recall record. Blood mercury concentration was measured with atomic absorption spectrometry. Mean age of the subjects was 43.5 +/- 14.6 yr. The FFQ showed that mercury-laden fish (tuna, shark) and frequently-eating fish (squid, belt fish, mackerel) were important in mercury intake from fish species. The recall record suggested that fish and shellfish was a highest group (63.1%) of mercury intake and had a wide distribution in the food groups. In comparison with the blood mercury concentration, age group, sex, household income, education, drinking status and coastal area were statistically significant (P < 0.001). In multiple regression analysis, coefficient from the FFQ (beta = 0.003) had greater effect on the blood mercury than the recall record (beta = 0.002), but the effect was restricted (adjusted R2 = 0.234). Further studies with more precise estimation of dietary mercury intake were required to evaluate the risk for mercury exposure by foods and assure risk communication with heavily-exposed group.

Association between Low-level Mercury Exposure and Neurobehavioral Functions in Korean Adults Living in a Coastal City

OBJECTIVES: The aim of this study was to determine the association between low-level mercury exposure and neurobehavioral functions in adults living in coastal regions of Korea. METHODS: We selected 172 adults aged 20-65 years living in a city in the coastal region of Korea. A sociodemographic survey was conducted, mercury levels in the blood, urine, and hair were measured, and the associations according to computerized neurobehavioral tests were determined using univariate analysis. After adjustment for associated variables, a multivariate linear regression analysis was performed. RESULTS: The geometric mean mercury levels in the blood, urine, and hair were 5.41 microg/L (range, 0.00-15.84 microg/L), 1.17 microg/g-creatinine (range, 0.00-32.86 microg/g-creatinine), and 1.37 mg/kg (range, 0.42-6.56 mg/kg), respectively. Variables that were associated with simple reaction time according to the neurobehavioral test results were age and urine mercury level. Variables associated with choice reaction time were the recent use of Korean traditional medicine and urine mercury level. Variables associated with the right-hand finger tapping speed test were age, gender, smoking behavior, education level, monthly household income, and urine mercury level. Variables associated with the left-hand finger tapping speed test were age, gender, education level, and urine mercury level. After adjustment for associated variables, there was no significant association between urine mercury level and simple reaction time (beta=25.96; p=0.47), choice reaction time (beta=50.37; p=0.32), or the number of left-hand finger taps (beta=-1.54; p=0.21). However, urine mercury level was significantly associated with the number of right-hand finger taps (beta=-3.86; p=0.01). CONCLUSIONS: We found no evidence that low-level mercury exposure in adults is associated with deficits in neurobehavioral functions. A longer follow-up study is required to confirm this conclusion.

Quantitative Analysis of Cancer-associated Gene Methylation Connected to Risk Factors in Korean Colorectal Cancer Patients / 예방의학회지

OBJECTIVES: The purpose of this paper was to elucidate the potential methylation levels of adjacent normal and cancer tissues by comparing them with normal colorectal tissues, and to describe the correlations between the methylation and clinical parameters in Korean colorectal cancer (CRC) patients. METHODS: Hypermethylation profiles of nine genes (RASSF1, APC, p16INK4a, Twist1, E-cadherin, TIMP3, Smad4, COX2, and ABCB1) were examined with 100 sets of cancer tissues and 14 normal colorectal tissues. We determined the hypermethylation at a given level by a percent of methylation ratio value of 10 using quantitative methylation real-time polymerase chain reaction. RESULTS: Nine genes' hypermethylation levels in Korean CRC patient tissues were increased more higher than normal colorectal tissues. However, the amounts of p16INK4a and E-cadherin gene hypermethylation in normal and CRC tissues were not significantly different nor did TIMP3 gene hypermethylation in adjacent normal and cancer tissues differ significantly. The hypermethylation of TIMP3, E-cadherin, ABCB1, and COX2 genes among other genes were abundantly found in normal colorectal tissues. The hypermethylation of nine genes' methylation in cancer tissues was not significantly associated with any clinical parameters. In Cohen's kappa test, it was moderately observed that RASSF1 was related with E-cadherin, and Smad4 with ABCB1 and COX2. CONCLUSIONS: This study provides evidence for different hypermethylation patterns of cancer-associated genes in normal and CRC tissues, which may serve as useful information on CRC cancer progression.

Corrigendum: The authors found errors in our published article: Quantitative Analysis of Cancer-associated Gene Methylation Connected to Risk Factors in Korean Colorectal Cancer Patients / 예방의학회지

On pages 252, 253, 254, Method, Table 1 and Figure 1 have been misspelled. The reverse transcriptase should be corrected as 'realtime'.

Relationship Between Blood Mercury Concentration and Waist-to-Hip Ratio in Elderly Korean Individuals Living in Coastal Areas / 예방의학회지

OBJECTIVES: This study investigated the relationship between the blood mercury concentration and cardiovascular risk factors in elderly Korean individuals living in coastal areas. METHODS: The sample consisted of 477 adults (164 males, 313 females) aged 40 to 65 years who visited a Busan health promotion center from June to September in 2009. The relationship between blood mercury concentration and cardiovascular risk factors including metabolic syndrome, cholesterol profiles, blood pressure, body mass index (BMI), waist circumference and waist-to-hip ratio (WHR), was investigated. Variables related to blood mercury concentration were further evaluated using multiple regression analysis. RESULTS: The blood mercury concentration of the study population was 7.99 (range, 7.60 to 8.40) microg/L. In males, the blood mercury concentration was 9.74 (8.92 to 10.63) microg/L, which was significantly higher than that in females (7.21, [6.80 to 7.64] microg/L). The blood mercury concentration of the study population was related to several cardiovascular risk factors including low-density lipoprotein (LDL) cholesterol (p=0.044), high-density lipoprotein (HDL) cholesterol (p=0.034), BMI (p = 0.006), waist circumference (p = 0.031), and WHR (p < 0.001). In males, the blood mercury concentration was significantly correlated with WHR in the multiple regression analysis. CONCLUSIONS: In males, the blood mercury concentration was related to waist-to-hip ratio, which is a central obesity index and cardiovascular risk factor. Our finding suggests that cardiovascular disease risk in males was increased by mercury exposure via an obesity-related mechanism.

Association Between MicroRNA196a2 rs11614913 Genotypes and the Risk of Non-Small Cell Lung Cancer in Korean Population / 예방의학회지

OBJECTIVES: The microRNA (miRNA) miR-196a2 may play an important role in lung cancer development and survival by altering binding activity of target mRNA. In this study, we evaluated their associations with the susceptibility of non-small cell lung cancers (NSCLC) by case-control study in a Korean population. METHODS: We performed genotyping analyses for miR-196a2 rs11614913 T/C at miRNA regions in a case-control study using blood samples of 406 NSCLC patient and 428 cancer-free control groups. RESULTS: The total C allele frequencies for miR-196a2 were 48.8% for the patients and 45.6% for the controls; and the genotype frequencies of TT, TC, and CC were 23.7%, 55.2%, and 21.1% for the patients and 31.1%, 46.35%, and 22.4% for the controls (p<0.05). Participants who possesses TC/CC genotypes showed high risk for NSCLC compared to those possessed TT genotypes (OR, 1.42; 95% CI, 1.03 to 1.96). The association was persisted in 60 and older age group, male, smokers, those without family history for cancer. However, no significant association of CC genotypes in recessive genetic model was observed. CONCLUSIONS: In conclusion, this case-control study provides evidence that miR-196a2 rs11614913 C/T polymorphisms are associated with a significantly increased risk of NSCLC in a dominant model, indicating that common genetic polymorphisms in miR-196a2 rs11614913 are associated with NSCLC. The association of miR196a2 rs11614913 polymorphisms and NSCLC risk require confirmation through additional larger studies.

Blood Mercury Concentration and Related Factors in an Urban Coastal Area in Korea / 예방의학회지

OBJECTIVES: This study was carried out for the purpose of evaluating the blood mercury concentration of the residents of Busan, Korea, as well as the relationship between the mercury concentration and the pattern of fish consumption along with other epidemiological factors. METHODS: Two hundred ninety-three subjects (147 men and 146 women), who were aged 40 years or more, were recruited into this study between June and October 2009. The mean age of the subjects was 54.3 years (with a range of 40-70 years). Mercury concentrations in blood samples were measured using a gold-amalgam collection method. RESULTS: The geometric mean concentration of mercury in the total subjects was 8.63 microgram/L [range: 1.48~45.71 microgram/L]. The blood mercury concentration of the men (9.55 microgram/L) was significantly higher than that of the women (7.76 microgram/L). The blood mercury concentration of those who eat fish more than 4 times per week was higher than others, and was statistically significant (male p = 0.0019, female p = 0.0002). According to the multiple analysis, the blood mercury concentration was significantly affected by the consumed fish but other epidemiological factors were not related. CONCLUSIONS: It was found that the subjects who have consumed a large amount of fish may have high blood mercury concentration. It appears that fish consumption can influence blood mercury concentration. Therefore, guidelines for fish consumption that will decrease blood mercury concentration might be necessary in Korea.

Usefulness of High Resolution Computed Tomography (HRCT) in the Diagnosis of Asbestos-Related Lung Diseases / 대한산업의학회지

OBJECTIVES: This study was carried out to improve the medical surveillance program of workers exposed to asbestos by examining the usefulness of High Resolution Computed Tomography (HRCT) in the diagnosis of asbestos-related lung disease. METHODS: The study subjects comprised 162 workers in a ship-repairing yard, 68 of whom had been directly exposed to asbestos and 94 indirectly exposed. The 'Occupational Safety & Health Administration (OSHA) asbestos standard, medical surveillance program' and HRCT were conducted to analyze the aspects of the asbestos-related lung disease. The OSHA asbestos standard, medical surveillance program consists of simple chest x-ray, spirometry and medical questionnaire. RESULTS: Seventeen (10.5%) of the 162 subjects, 10 (14.7%) directly exposed and 7 (7.4%) indirectly exposed, revealed asbestos-related lung disease on HRCT. The sensitivity and specificity of simple chest x-ray for asbestos-related lung disease were 70.6% and 98.6%, and the positive and negative predictive values were 85.7% and 96.6% respectively, as compared with HRCT. HRCT was an effective diagnostic tool especially to detect early asbestos-related lung disease. The study results indicated a relative significant association between the results of spirometry and HRCT. The variables significantly associated with asbestos-related lung disease on HRCT were work duration, smoking history (pack-years), past history of respiratory disease, cough and dyspnea. CONCLUSIONS: In the diagnosis of asbestos-related lung disease, HRCT should be considered not only for workers with positive findings on simple chest x-ray, but also workers with specific findings on spirometry, occupational history, smoking history, and past history of respiratory disease, or with respiratory symptoms such as cough and dyspnea.