Suicide mortality following the implementation of tobacco packaging and pricing policies in Korea: an interrupted time-series analysis.

BACKGROUND: To prevent tobacco use in Korea, the national quitline number was added to tobacco packages in December 2012, tobacco prices were raised by 80% in January 2015, and graphic health warning labels were placed on tobacco packages in December 2016. This study evaluated the association of these tobacco packaging and pricing policies with suicide mortality in Korea. METHODS: Monthly mortality from suicide was obtained from Cause-of-Death Statistics in Korea from December 2007 to December 2019. Interrupted time-series analysis was performed using segmented Poisson regression models. Relative risks (RRs) and 95% confidence intervals (CIs) were calculated adjusted for suicide prevention strategies. RESULTS: Suicide mortality was 20 per 1,000,000 in December 2007 and showed a downward trend over the study period. After the implementation of tobacco packaging and pricing policies, suicide mortality immediately declined by - 0.09 percent points (95% CI = - 0.19 to 0.01; P > 0.05) for the national quitline number, - 0.22 percent points (95% CI = - 0.35 to - 0.09; P < 0.01) for tobacco prices, and - 0.30 percent points (95% CI = - 0.49 to - 0.11; P < 0.01) for graphic health warning labels. The corresponding RRs for these post-implementation changes compared with the pre-implementation level were 0.91 (95% CI = 0.83 to 1.00), 0.80 (95% CI = 0.70 to 0.91), and 0.74 (95% CI = 0.61 to 0.90), respectively. Significant associations between tobacco control policies and suicide mortality were observed even when stratified by sex and region. CONCLUSIONS: The findings of this study provide new evidence for an association between tobacco control policies and deaths by suicide. An array of effective tobacco control policies should be considered for prevention programs targeting suicide.

Association between endocrine-disrupting chemical mixtures and non-alcoholic fatty liver disease with metabolic syndrome as a mediator among adults: A population-based study in Korea.

Endocrine-disrupting chemicals (EDCs) may play a role in non-alcoholic fatty liver disease (NAFLD); however, studies on the combined effects of EDC mixtures on NAFLD development are limited. Here, we explored the association between exposure to EDC mixtures and NAFLD and investigated the potential mediating role of metabolic syndrome (MetS). We included participants from the Korean National Environmental Health Survey Cycle 4 (2018-2020) and quantified the urinary concentrations of various EDCs-eight phthalate metabolites, three phenols, one antibacterial compound, four parabens, four polycyclic aromatic hydrocarbons, and one pyrethroid pesticide metabolite-as well as serum concentrations of five perfluorinated compounds (PFCs). NAFLD was defined as a hepatic steatosis index (HSI) ≥36 or a fatty liver index (FLI) ≥60. Weighted quantile sum (WQS) regression was employed to evaluate the associations between EDC mixtures and the risk of MetS or NAFLD. Causal mediation analysis was conducted to explore the potential mediating effect of MetS on the association between mixtures of EDCs and NAFLD risk. All estimates were adjusted for age, sex, educational level, physical activity, smoking status, involuntary smoking, and drinking habits. A total of 2942 adults were included in the analysis. Moderate-to-high positive correlations were identified between phthalate metabolites and PFCs. Higher WQS scores were associated with an elevated risk of MetS and NAFLD. The sex-stratified WQS regression model showed that the interactions between the WQS index and sex were significant for MetS and NAFLD. According to the causal mediation analysis, both the direct and indirect effects of EDC mixtures on NAFLD, with MetS as a mediator, were significant in females. Collectively, these findings highlight the need for interventions that could address both EDC mixture exposure and metabolic status to effectively reduce the risks associated with NAFLD and its related complications.

Cancer Risk Following Smoking Cessation in Korea.

Importance: Tobacco smoking is associated with increased risk of various cancers, and smoking cessation has been associated with reduced cancer risks, but it is still unclear how many years of smoking cessation are required to significantly reduce the cancer risk. Therefore, investigating the association of smoking cessation with cancer is essential. Objective: To investigate the time course of cancer risk according to the time elapsed since smoking cessation and the benefits of smoking cessation according to the age at quitting. Design, Setting, and Participants: This population-based, retrospective cohort study included Korean participants aged 30 years and older who underwent 2 or more consecutive health examinations under the National Health Insurance Service since 2002 and were followed-up until 2019. Data analysis was performed from April to September 2023. Exposures: Exposures included (1) time-updated smoking status based on biennial changes in smoking status, defined as complete quitters, transient quitters, relapsed quitters, continuous smokers, and never smokers; (2) duration of smoking cessation, defined as years since quitting; and (3) categorical variable for age at quitting. Main Outcomes and Measures: The primary cancer was ascertained using the cancer registry data: all-site cancer (International Statistical Classification of Diseases and Related Health Problems, Tenth Revision [ICD-10] codes C00-43, C45-96, or D45-D47), lung cancer (ICD-10 code C34), liver cancer (ICD-10 code C22), stomach cancer (ICD-10 code C16), and colorectal cancer (ICD-10 codes C18-20). Hazard ratios (HRs) and 95% CIs were estimated using a Cox proportional hazards regression model with follow-up years as the timescale. Results: Of the 2 974 820 participants, 1 727 340 (58.1%) were men (mean [SD] age, 43.1 [10.0] years), and 1 247 480 (41.9%) were women (mean [SD] age, 48.5 [9.9] years). Over a mean (SD) follow-up of 13.4 (0.1) years, 196 829 cancer cases were confirmed. Compared with continuous smokers, complete quitters had a lower risk of cancer, with HRs of 0.83 (95% CI, 0.80-0.86) for all cancer sites, 0.58 (95% CI, 0.53-0.62) for lung, 0.73 (95% CI, 0.64-0.82) for liver, 0.86 (95% CI, 0.79-0.93) for stomach, and 0.80 (95% CI, 0.72-0.89) for colorectum. The cancer risk exhibited a slightly higher value for 10 years after quitting compared with continued smoking and then it decreased over time, reaching 50% of the risk associated with continued smoking after 15 or more years. Lung cancer risk decreased 3 years earlier than that of other cancer types, with a larger relative reduction. Regardless of quitting age, a significant reduction in the cancer risk was observed. Quitting before the age of 50 years was associated with a greater reduction in lung cancer risk (HR, 0.43; 95% CI, 0.35-0.53) compared with quitting at age 50 years or later (HR, 0.61; 95% CI, 0.56-0.66). Conclusions and Relevance: In this population-based retrospective cohort study, sustained smoking cessation was associated with significantly reduced risk of cancer after 10 years since quitting. Quitting at any age helped reduce the cancer risk, and especially for lung cancer, early cessation before middle age exhibited a substantial risk reduction.

Environmental exposure to lead and cadmium are associated with triglyceride glucose index.

The triglyceride glucose (TyG) index was suggested as a novel reliable surrogate marker for insulin resistance and related cardiovascular-metabolic diseases. We aimed to evaluate the association between the TyG index and environmental exposure to lead (Pb), mercury (Hg), and cadmium (Cd). A total of 9645 adults who enrolled in the Korea National Health and Nutrition Examination Survey in 2005, 2008-2013, and 2016 were included. Fasting plasma glucose and triglyceride levels were used to calculate the TyG index. Multivariate logistic regression model was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs). We noted an increasing trend in the TyG index with increment of blood Pb and Cd concentrations. Participants in the highest quartile of blood Pb and Cd concentrations had higher TyG index values than those in the lowest quartile, with ORs (95% CIs) of 1.32 (1.07-1.63) and 1.29 (1.04-1.59) for Pb and Cd, respectively. Strong associations between blood Pb and Cd concentrations and the TyG index were found in men. Blood Hg concentrations did not show a significant association with the TyG index. Our study suggests that public health strategies for cardiovascular-metabolic disorder prevention should be directed toward individuals exposed to priority heavy metals.

Gastroesophageal reflux disease and risk of cancer: Findings from the Korean National Health Screening Cohort.

AIM: Little is known about the association of cancers other than esophageal adenocarcinoma with gastroesophageal reflux disease (GERD). This study aimed to examine the association between GERD and the risk of different types of cancer. METHODS: A cohort study was conducted using data from the National Health Screening Cohort. We included 10,261 GERD patients and 30,783 non-GERD individuals who were matched in a 1:3 ratio by age and sex. All participants were followed-up until cancer diagnosis, death, or end of the study (December 31, 2015). Hazard ratios were calculated using the Cox proportional hazards model, adjusting for smoking and alcohol consumption, physical activity, body mass index, income, area, and Charlson Comorbidity Index. RESULTS: The median follow-up time was 9.9 years. GERD was associated with an increased risk of esophageal (adjusted hazard ratios [aHR] = 3.20 [1.89-5.41]), laryngeal (aHR = 5.42 [2.68-10.96]), and thyroid cancers (aHR = 1.91 [1.55-2.34]) after controlling for all covariates. The results were consistent when examining GERD with esophagitis (K210) and without esophagitis (K219) separately. For thyroid cancer, the results were insignificant after controlling for having ever-received thyroid biopsy procedures. A dose-response relationship was found between GERD and esophageal cancer as well as laryngeal cancer, with patients with a longer duration of GERD treatment showing a stronger effect. In contrast, GERD was associated with a reduced risk of colorectal (aHR = 0.73 [0.59-0.90]), liver (aHR = 0.67 [0.51-0.89]), and pancreatic cancers (aHR = 0.43 [0.24-0.76]), which might have resulted from differences in healthcare utilization between GERD and non-GERD groups. CONCLUSION: GERD was associated with an increased risk of esophageal and laryngeal cancers. Additionally, early detection and treatment of precancerous lesions among the GERD group could lead to a lower risk of colorectal, liver, and pancreatic cancers.

Interaction between blood cadmium and lead concentration and physical activity on hypertension from the Korean national health and nutrition examination survey in 2008-2013.

BACKGROUND: Previous studies have suggested that blood Cd, Pb exposure, and physical activity levels may influence the development of hypertension. This study aimed to investigate the relationship between blood Cd, Pb levels, and hypertension by the level of physical activity in Korean adults using The Korea National Health and Nutrition Examination Survey (KNHANES). METHODS: We used data from the KNHANES (2008-2013), a nationally representative, cross-sectional, population-based study. We included 8,510 participants who had records of blood Cd, Pb and, blood pressure measurements. Multiple logistic regression was used to examine the association between blood Cd and Pb exposure and the development of hypertension, as well as the modifying effects of physical activity levels. Additive interaction was estimated using relative excess risk due to interaction (RERI), attributable proportion due to interaction (AP) and synergy index (S). RESULTS: Following covariates adjustments, we found significant associations of blood Cd and Pb with higher hypertension prevalence. This association was more apparent in low physical activity while blood Cd and Pb concentrations were not significantly associated with hypertension in participants with more activity. Additionally, there was a significant interaction between blood Cd and physical activity on hypertension risk (RERI = 0.17, 95% CI: -0.36-0.7; AP = 0.12, 95% CI: -0.28-0.52; S = 1.75, 95% CI:1.36-2.14). CONCLUSIONS: Our results suggest that low physical activity may substantially amplify the adverse effects of blood Pb and Cd exposure on hypertension risk. However, interactions were only found for Cd. Further studies are needed to confirm these findings.

Nonlinear Associations between Blood Cadmium Concentration and Thyroid Hormones According to Smoking Status in Korean Adults: The Korea National Health and Nutrition Examination Survey (KNHANES).

Research on the association between blood cadmium (BCd) exposure and thyroid hormone levels in the general population has been inconclusive. Therefore, we examined the associations between BCd and thyroid hormones according to smoking status in Korean adults (N = 1170, Men = 722, Women = 448) using multiple linear regression and restricted cubic splines analysis with data from the Korean National Health and Nutrition Examination Survey (2013). The geometric mean of BCd was 0.74 µg/L in all study participants and was higher in smokers (1.01 µg/L) than in nonsmokers (0.65 µg/L). Restricted cubic splines analysis revealed nonlinear trends between BCd and free thyroxine in smokers (p for nonlinearity = 0.02). By contrast, there were no significant associations between BCd and thyroid hormones in either men or women. In conclusion, nonlinear associations may exist between BCd and free thyroxine in smokers. Our study provides empirical support for the future formulation of an acceptable concentration range of BCd and offers a new concept for preventing thyroid problems.

Adherence to Cancer Prevention Guidelines and Cancer Incidence and Mortality: A Population-Based Cohort Study.

PURPOSE: This study aimed to estimate the risk of cancer incidence and mortality according to adherence to lifestyle-related cancer prevention guidelines. MATERIALS AND METHODS: Men and women who participated in the general health screening program in 2002 and 2003 provided by the National Health Insurance Service were included (n=8,325,492). Self-reported smoking, alcohol consumption, and physical activity habits and directly measured body mass index were collected. The participants were followed up until the date of cancer onset or death or 31 December 2018. The Cox proportional hazard model was used to evaluate the hazard ratio (HR) for cancer incidence and mortality according to different combinations of lifestyle behaviors. RESULTS: Only 6% of men and 15% of women engaged in healthy behavior at baseline, such as not smoking, not drinking alcohol, being moderately or highly physically active, and within a normal body mass index range. Compared to the best combination of healthy lifestyle behaviors, the weak and moderate associations with increased all cancer incidence (HR < 1.7) and mortality (HR < 2.5) were observed in those with heavy alcohol consumption and in former or current smokers. HRs of cancer mortality were significantly increased among current smokers in most combinations. CONCLUSION: Compared to full adherence to cancer prevention recommendations, unhealthy behaviors increase cancer risk. As few people meet these recommendations, there is a great opportunity for cancer prevention.

Awareness of and practice toward cancer prevention recommendations: results of the Korean National Cancer Prevention Awareness and Practice Survey in 2021.

OBJECTIVES: This study reports data regarding the awareness and practice of cancer prevention among Koreans in 2021 and behavioral changes during the coronavirus disease 2019 (COVID-19) pandemic. METHODS: We collected Cancer Prevention Awareness and Practice Survey data through face-to-face interview surveys using a structured questionnaire completed by 4,000 randomly selected men and women aged between 20 years and 74 years in 17 provinces. We examined the awareness and practice of 10 cancer prevention recommendations and evaluated their associations with potential risk factors through multiple logistic regression analysis adjusted for age, gender, residence, marital status, education, and income. RESULTS: Eighty percent of participants knew that cancer is preventable, while 45% practiced cancer prevention. Cancer prevention practice tended to be more common among older participants (adjusted odds ratio [aOR], 1.39 per 10-year increment; 95% confidence interval [CI], 1.29 to 1.49) and less common among rural inhabitants (aOR, 0.66; 95% CI, 0.51 to 0.86) than among urban residents and among single people (aOR, 0.55; 95% CI, 0.45 to 0.66) than among married people. Practices were the highest for avoiding burned or charred foods (87.6%) and lowest for vaccination against human papillomavirus (14.5%). Refusal to follow recommendations was most common for avoiding alcohol consumption (7.9%). The most difficult recommendations to follow were (1) regular exercise (57.7%); (2) maintaining a healthy body weight (46.1%); and (3) avoiding alcohol (40.1%). The most significant COVID-19-related changes were less exercise (32.5%) and increased body weight (25.6%). CONCLUSIONS: The awareness of cancer prevention was high, but the practice was low. Recommendations targeting awareness and practice need to be further promoted.

Low-Level Environmental Mercury Exposure and Thyroid Cancer Risk Among Residents Living Near National Industrial Complexes in South Korea: A Population-Based Cohort Study.

Background: Previous studies suggested that mercury may be linked to thyroid cancer due to its bioaccumulation in the thyroid gland, but no studies have evaluated the association between mercury exposure and thyroid cancer risk. We examined the relationship between mercury exposure and thyroid cancer risk, with the potential modification of hematological parameters. Methods: We performed a secondary analysis of a prospective cohort study among residents living near industrial complexes in South Korea (recruited from 2003 to 2011). Incident thyroid cancer cases (C73, ICD-10 code) were identified from the National Cancer Registry and Statistics Korea. Urinary mercury concentrations were measured using thermal decomposition amalgamation atomic absorption spectrometry (TDA-AAS). Cox proportional hazards regression models (adjusted for age, sex, educational level, smoking status, and employment) were used to estimate the hazard ratio (HR) and confidence interval [CI] between mercury exposure and the incidence of thyroid cancer. Results: We documented 69 cases of thyroid cancer in a total of 5213 participants during follow-up (median 8.7 years). The geometric mean of urinary mercury concentration was 1.8 µg/L for thyroid cancer cases and 1.2 µg/L for noncases (p for difference = 0.001). After adjusting for potential confounders, those in the highest tertile of urinary mercury levels had a twofold higher risk of thyroid cancer (HR = 1.97 [CI 1.03 - 3.80] in the highest tertile vs. the lowest tertile, p for trend = 0.043). This association was stronger for those with lower mean corpuscular volume and mean corpuscular hemoglobin status. Conclusions: Urinary mercury concentration was positively associated with the risk of thyroid cancer among residents living near national industrial complexes, and this association was influenced by red blood cell indices status. These results provide some evidence suggesting the adverse effects of environmental metal pollution in the development of thyroid cancer.

Influence of serum ferritin combined with blood cadmium concentrations on blood pressure and hypertension: From the Korean National Health and Nutrition Examination Survey.

BACKGROUND: Previous studies have suggested that cadmium (Cd) exposure and serum ferritin levels may influence the development of hypertension. OBJECTIVE: We evaluated whether the association between blood Cd levels and the development of hypertension could be modified by serum ferritin levels in a representative sample of the adult population of South Korea. METHODS: We used data from the Korean National Health and Nutrition Examination Survey (2008-2012), a nationally representative, cross-sectional, population-based study. We included 5752 adults aged 19 years and older who had records of blood Cd and ferritin levels and blood pressure measurements. Multiple logistic regression was used to examine the association between Cd exposure and the development of hypertension, as well as the modifying effects of serum ferritin. RESULTS: Men had higher levels of serum ferritin, and women had higher levels of Cd. Smoking in men was significantly associated with high blood pressure and risk of hypertension. Significantly fewer women were smokers, and the combination of abnormal serum ferritin levels and high Cd levels was significantly associated with high systolic blood pressure [odds ratio (OR) = 2.11; 95% confidence interval (CI) = 1.04-4.28], high diastolic blood pressure (OR = 2.07; 95% CI = 1.04-4.12), and increased hypertension risk (OR = 1.83; 95% CI = 1.03-3.25) in women who never smoked. CONCLUSIONS: Our results provide further evidence that individuals with abnormal serum ferritin levels should limit their exposure to Cd to prevent hypertension.

Occupational Exposure to Pesticides and Lung Cancer Risk: A Propensity Score Analyses.

PURPOSE: Occupational exposure to pesticides is thought to be associated with lung cancer, but studies have yielded conflicting results. We performed a propensity score (PS) based analyses to evaluate the relationship between occupational exposure to pesticides and lung cancer risk in the Korea National Cancer Center community-based cohort study (KNCCCS). MATERIALS AND METHODS: During the follow-up period, 123 incidental lung cancer cases were identified, of the 7,471 subjects in the final statistical analysis. Information about occupational exposure to pesticides and other factors was collected at enrollment (2003-2010). Cox proportional hazards regression analyses were conducted. Four PS-based approaches (i.e., matching, stratification, inverse probability-of-treatment weighting, and the use of the PS as a covariate) were adopted, and the results were compared. PS was obtained from the logistic regression model. Absolute standardized differences according to occupational exposure to pesticides were provided to evaluate the balance in baseline characteristics. RESULTS: In the Cox proportional hazards regression model, the hazard ratio (HR) for lung cancer according to occupational exposure to pesticides was 1.82 (95% confidence interval [CI], 1.11 to 2.98). With all the propensity score matching (PSM) methods, the HRs for lung cancer based on exposure to pesticides ranged from 1.65 (95% CI, 1.04 to 2.64) (continuous term with PSM) to 2.84 (95% CI, 1.81 to 4.46) (stratification by 5 strata of the PS). The results varied slightly based on the method used, but the direction and statistical significance remained the same. CONCLUSION: Our results strengthen the evidence for an association between occupational exposure to pesticides and the risk of lung cancer.

Toluene concentrations in the blood and risk of thyroid cancer among residents living near national industrial complexes in South Korea: A population-based cohort study.

BACKGROUND: Toluene is classified as a possible carcinogen, but its role on thyroid cancer is not well established. Vehicle emissions are one of the largest contributed sources of toluene, but no studies evaluating the influence of living near a road on the association between toluene and the incidence of thyroid cancer have been reported. Therefore, we examined potential associations between blood toluene concentrations and incidence risk of thyroid cancer, and an effect modification of living near a road. METHODS: We conducted a prospective cohort study using data from South Korean "Monitoring Project for Exposure to Environmental Pollutants and Health Effects among Residents Living near Industrial Complexes" survey. Study participants living near national industrial complexes were recruited from January 2003 to 2011. Incidence and mortality cases of thyroid cancer (C73, ICD-10 code) were identified using the National Cancer Registry and Statistics Korea, respectively. Blood toluene concentrations were measured using gas chromatography mass spectrometry. We used Cox proportional hazards regression models to estimate the hazard ratios (HR) and the 95% confidence interval (CI) between blood toluene concentrations and thyroid cancer risk. RESULTS: During the follow-up (median 8.6 years), 33 cases of thyroid cancer were diagnosed. The geometric mean of the toluene concentration in the blood was 0.56 µg/L for cases and 0.29 µg/L for non-cases. After adjusting for potential confounders, a positive association between blood toluene concentrations and thyroid cancer was found (HR = 2.77, 95% CI = 1.00-7.65 in the highest tertile vs. the lowest tertile, p for trend = 0.044). This positive association was stronger in people living near a road (≤50 m). CONCLUSIONS: Blood toluene concentrations may be positively associated with the incidence risk of thyroid cancer. Moreover, this association may be stronger among people living near a road.

Serum concentrations of persistent organic pollutants and colorectal cancer risk: A case-cohort study within Korean National Cancer Center Community (KNCCC) cohort.

BACKGROUND & AIMS: Recent prospective cohort studies have suggested that circulating persistent organic pollutants (POPs) may be associated with the development of cancers. We investigated the association between pre-diagnostic serum concentrations of POPs and colorectal cancer (CRC) risk. METHODS: A case-cohort study within a community-based prospective cohort was performed, including 104 CRC cases and 235 subcohort participants. Serum concentrations of POPs were measured by high resolution gas chromatography/high-resolution mass spectrometry. Multivariable Cox proportional hazards regression models were used. RESULTS: The association between serum concentrations of organochlorine pesticides (OCs) and CRC risk was significant (cis-heptachlor epoxide: 3rd tercile [HR (95% CI): 2.76 (1.25-6.07); trans-nonachlor: 2nd tercile [HR (95% CI): 3.90 (1.56-9.75)], 3rd tercile [HR (95% CI): 4.86 (1.95-12.16)]); p,p'-DDD: 2nd tercile [HR (95% CI): 6.02 (2.05-17.70)], 3rd tercile [HR (95% CI): 7.43 (2.42-22.84)]). Certain polychlorinated biphenyls (PCBs) congeners were significantly associated with CRC risk (PCB-105: 3rd tercile HR [95% CI]: 3.15 [1.38-7.19], PCB-118: 3rd tercile HR [95% CI]: 2.68 [1.22-5.92]; PCB-138: 2nd tercile [HR (95% CI): 2.51 (1.19-5.28)], 3rd tercile [HR (95% CI): 3.27 (1.50-7.12)]; PCB-153: 2nd tercile [HR (95% CI): 3.93 (1.81-8.54)], 3rd tercile [HR (95% CI): 5.02 (2.09-12.07)]; PCB-156: 2nd tercile [HR (95% CI): 2.61 (1.21-5.59)], 3rd tercile [HR (95% CI): 4.07 (1.73-9.61)]; PCB-180: 2nd tercile [HR (95% CI): 2.58 (1.15-5.78)], 3rd tercile [HR (95% CI): 4.01 (1.68-9.59)]).results CONCLUSIONS: This study suggests that serum concentrations of POPs could increase the CRC risk in the general population.

Association between environmental exposure to cadmium and risk of suspected non-alcoholic fatty liver disease.

AIM: We evaluated the associations between blood Cadmium (Cd) concentrations and risk of suspected NAFLD using nationally representative data from the Korea National Health and Nutrition Examination Survey (KNHANES) 2008-2013, 2016 and 2017. METHODS: This cross-sectional study included 12,099 adults for the serum alanine aminotransferase (ALT) and hepatic steatosis index (HSI) analyses and 2,904 adults for the serum gamma-glutamyl transferase (GGT) and fatty liver index (FLI) analyses, without significant alcohol consumption. Blood Cd concentrations were measured by graphite furnace atomic absorption spectrometry. Data were analyzed using survey logistic regression models. RESULTS: Odds ratios (ORs) of suspected NAFLD increased significantly per unit of natural log-transformed blood Cd concentration (OR [95% (CI)], for ALT, overall: 1.50 [1.34, 1.68], men: 1.64 [1.40, 2.10] and women: 1.29 [1.08, 1.47]; for GGT, overall: 1.77 [1.33, 2.35], men: 2.28 [1.53, 3.41] and women: 1.27 [0.82, 1.97]; for FLI, overall: 1.84 [1.32, 2.57], men: 1.91 [1.24, 2.94] and women: 1.58 [0.87, 2.86]; for HSI, overall: 1.19 [1.07, 1.32], men: 1.17 [1.01, 1.37] and women: 1.14 [0.99, 1.32]). The blood Cd concentrations associated with risk of suspected NAFLD were lower than those previously reported (for ALT, > 0.64 µg/L, for GGT, > 1.41 µg/L, for FLI, > 0.96 µg/L, and for HSI, > 1.41 µg/L). CONCLUSIONS: This study suggests that the reference level of blood Cd should probably be lower than the previously recommended value to prevent adverse health effects due to Cd exposure.

Environmental exposure to cadmium and risk of thyroid cancer from national industrial complex areas: A population-based cohort study.

BACKGROUND: Cadmium is known to act as a thyroid disruptor and carcinogen in humans. Recent evidence suggests that cadmium may play a role as a thyroid carcinogen due to its endocrine-disrupting activity, but this characterization remains unclear. OBJECTIVE: We investigated the association between urinary cadmium and primary thyroid cancer, and the modifying effect of diabetes on this association. METHODS: We included 5406 participants over 19 years old with measured urinary cadmium from samples collected at eight National Industrial Complex areas from 2003 to 2011. Among 5406 participants, 68 cases were diagnosed with thyroid cancer between enrollment and the end of follow-up (December 31, 2016). Incidence rate ratios for thyroid cancer were estimated using random-effects Cox proportional hazards models with follow-up time as the time scale. In addition, we conducted a stratified analysis by diabetes status. RESULTS: Compared with the lowest tertile, the middle and highest tertiles had higher risks of thyroid cancer, respectively (HRmiddle vs. lowest = 1.90, 95% CI = 0.93 to 3.91; HRhighest vs. lowest = 2.28, 95% CI = 1.09 to 4.78), with a significant dose-response relationship (P for trend = 0.03). There was no linear association between cadmium level and risk of thyroid cancer. Higher cadmium levels increased thyroid cancer risk in participants without diabetes (HRmiddle vs. lowest = 2.35, 95% CI = 1.05 to 5.24; HRhighest vs. lowest = 2.70, 95% CI = 1.18 to 6.19); although, an association between cadmium levels and thyroid cancer risk in participants with diabetes was not found. CONCLUSION: Low-level exposure to cadmium is associated with thyroid cancer risk. Our results provide the evidence to limit exposure to cadmium for cancer prevention in the general population. Further studies are needed to investigate the consequence of diabetes and antidiabetic drugs between cadmium and thyroid cancer.

Metabolic Syndrome and Colorectal Cancer Risk: Results of Propensity Score-Based Analyses in a Community-Based Cohort Study.

BACKGROUND: This study aimed to determine the effects of metabolic syndrome (MetS) on colorectal cancer (CRC) using propensity score (PS) methods. METHODS: The study subjects were 2417 men and 4568 women from the Korean National Cancer Center (KNCC) Community Cohort enrolled between 2003 and 2010. Odds risks (ORs) and 95% confidence intervals (CIs) using PS matching analysis, regression models adjusted by the PS or stratified into five strata according to PS, and PS weighting methods were calculated. RESULTS: In women, MetS and abnormally high triglyceride (TG) levels were associated with CRC risk using the PS matching analysis (ORs, for MetS, 2.19 (95% CI, 1.10-4.33); for abnormal TG levels, 2.08 (95% CI, 1.07-4.02)). However, there were no significant associations between MetS and TG levels and CRC risk in men. CONCLUSIONS: Our study might provide additional evidence that deteriorated metabolic profiles increase the risk of CRC in women rather than men. Thus, this may have an important role in effective population-level interventions for deteriorated metabolic profiles at an early stage.

Impact of environmental exposure to persistent organic pollutants on lung cancer risk.

BACKGROUND: Recent studies suggest that high pre-diagnostic serum concentrations of persistent organic pollutants (POPs) might result in the development of cancers in the general population. However, the association between pre-diagnostic serum POP concentrations and lung cancer risk has not been studied. Here, we evaluated associations between low-dose environmental exposure to POPs and risk of lung cancer using pre-diagnostic serum samples in a case-cohort study based on a population-based prospective cohort. METHODS: We conducted a case-cohort study based on the Korean National Cancer Center Community Cohort, from which we included 118 lung cancer cases and 252 controls. Serum concentrations of POPs were measured by high resolution gas chromatography/high-resolution mass spectrometry, and data were analyzed using multivariable Cox proportional-hazards regression models. RESULTS: Risk of lung cancer increased per unit increase in the natural log-transformed concentrations of the sum of chlordane congeners, total PCBs, and all PCBs subgrouped by the number of chlorines or ortho- substituted chlorines on the molecules, except for tri/tetrachlorobiphenyls, in all models. Among individual POP analytes with a detection rate >80%, after Bonferroni adjustment, only trans-nonachlor was associated with lung cancer risk. In categorical models, risk of lung cancer was associated with serum concentration of chlordane (4th vs. 1st quartile, hazard ratio [95% confidence interval], 8.79 [2.77-27.97]). Dose-dependent relationships were also found between risk of lung cancer and serum concentrations of PCBs regardless of their degree of chlorination, substitution pattern, or binding affinity to receptors (total PCBs, P = 0.002; mid-chlorinated PCBs, P = 0.004; high-chlorinated PCBs, P < 0.001; non- and mono-ortho PCBs, P = 0.031; di-ortho PCBs, P = 0.003; PCBs with dioxin-like activity, P = 0.011; non-dioxin-like non-/mono-ortho PCBs, P = 0.060). CONCLUSIONS: Serum concentrations of chlordane and PCBs are associated with risk of lung cancer in the general population, even decades after the ban on their production and use.

Neurodevelopment in Early Childhood Affected by Prenatal Lead Exposure and Iron Intake.

No safe threshold level of lead exposure in children has been recognized. Also, the information on shielding effect of maternal dietary iron intake during pregnancy on the adverse effects of prenatal lead exposure on children's postnatal neurocognitive development is very limited. We examined the association of prenatal lead exposure and neurodevelopment in children at 6, 12, 24, and 36 months and the protective action of maternal dietary iron intake against the impact of lead exposure. The study participants comprise 965 pregnant women and their subsequent offspring of the total participants enrolled in the Mothers and Children's environmental health study: a prospective birth cohort study. Generalized linear model and linear mixed model analysis were performed to analyze the effect of prenatal lead exposure and mother's dietary iron intake on children's cognitive development at 6, 12, 24, and 36 months. Maternal late pregnancy lead was marginally associated with deficits in mental development index (MDI) of children at 6 months. Mothers having less than 75th percentile of dietary iron intake during pregnancy showed significant increase in the harmful effect of late pregnancy lead exposure on MDI at 6 months. Linear mixed model analyses showed the significant detrimental effect of prenatal lead exposure in late pregnancy on cognitive development up to 36 months in children of mothers having less dietary iron intake during pregnancy. Thus, our findings imply importance to reduce prenatal lead exposure and have adequate iron intake for better neurodevelopment in children.

Factors Related to Relapse After 6 Months of Smoking Cessation Among Men in the Republic of Korea: A Cross-Sectional Study.

We identified factors associated with relapse after 6 months of smoking cessation (late relapse) among males of the Republic of Korea. Of the 222,707 smokers who visited public health center-based smoking cessation clinics (SCCs) between January 1, 2009 and mid-December 2009, we included 1720 individuals who successfully completed a 6-month smoking cessation program at an SCC. These participants were selected via a random stratified sampling design and completed an SCC user satisfaction survey between December 31, 2009 and January 6, 2010. Multiple logistic regression was used to identify factors associated with late relapse, and path analysis was employed to explore relationships among these factors. The frequency of late relapse was 21.6% (n = 372). Residence in a metropolitan area, low socioeconomic status, and the use of nicotine replacement therapy (NRT) were associated with statistically significant increases in late relapse, whereas greater access to counseling and more satisfaction with the SCC were associated with reduced late relapse. The path analysis showed that a greater number of cigarettes smoked daily and a younger age at smoking initiation exerted significant indirect effects on late relapse when NRT was employed. Residence in a metropolitan area indirectly prevented late relapse as counseling frequency increased. NRT use, counseling frequency, and SCC user satisfaction were affected by both smoking behavior and socioeconomic status. Relapse prevention efforts should concentrate on increasing both counseling frequency and SCC user satisfaction. Future studies should focus on the effect of NRT on the maintenance of long-term cessation at the population level in real-world settings.