National estimates of blood lead, cadmium, and mercury levels in the Korean general adult population

Association between Liver and Kidney Function and Birth Outcomes in Pregnant Surinamese Women Exposed to Mercury and Lead in the Caribbean Consortium for Research in Environmental and Occupational Health (CCREOH) Environmental Epidemiologic Cohort Study

Exposure to mercury (Hg) and lead (Pb), in combination with liver and kidney impairment, may result in adverse birth outcomes. From 408 women in the age range of 16 to 46 years, living in rural and urban areas in the interior of Suriname, we looked at the association between adverse birth outcomes and exposure to Hg and Pb in combination with liver and kidney function. This group of women represented a subcohort of pregnant women who participated in the Caribbean Consortium for Research in Environmental and Occupational Health (CCREOH)-Meki Tamara study. Liver function was assessed by measuring aspartate amino transferase (AST), alanine amino transferase (ALT), and gamma-glutamyl transferase (GGT). Kidney function was assessed by measuring creatinine, urea, and cystatin C. We defined preterm births as birth before 37 weeks of gestation, low birthweight as birthweight < 2500 g, and low Apgar score as a score < 7 at 5 min, and these were used as indicators for adverse birth outcomes. Small size for gestational age was defined as gestational age < -2SD weight for GA. We found significant statistical associations between biomarkers for liver and kidney functions and adverse birth outcomes Apgar score and gestational age. No significant association was found between heavy metals Hg and lead and adverse birth outcomes.

Blood Pb levels are associated with prostate cancer prevalence among general adult males: Linking National Cancer Registry (2002-2017) and KNHANES (2008-2017) databases of Korea

BACKGROUND

Exposure to heavy metals may increase the risk of developing prostate cancer. However, these observations are often inconsistent and not based on clinically diagnosed cases.

OBJECTIVE

To investigate the association of lead (Pb), cadmium (Cd), and mercury (Hg) exposure with clinically determined prostate cancer cases among adult males in South Korea.

METHODS

Metal biomonitoring data and cancer information from the general Korean population were extracted by linking National Cancer Center (NCC) cancer registration data (2002-2017) with Korea National Health and Nutrition Examination Survey (KNHANES) data (2008-2017). Among them, 46 prostate cancer cases (designated as 'all-prostate'), including 25 diagnosed after heavy metal measurement (designated as 'post-prostate'), and 93 matching controls were chosen. Logistic regression analysis was used to calculate the odds ratios (ORs) and 95% confidence intervals (CIs) between the heavy metal levels and prostate cancer.

RESULTS

Post-prostate patients exhibited higher blood Pb levels than controls (median 3.1 μg/dL vs. 2.38 μg/dL, p = 0.01). For all-prostate cancer, the OR of prostate cancer increased by 2.04-fold for every doubling of Pb levels (95% CI = 1.08-3.87, p = 0.03). The OR was also significantly elevated when comparing the third quartile (Q3) to the lowest quartile (Q1), with ORs ranging from 3.38 to 7.95, depending on model (p < 0.05). Blood Pb levels maintained a positive association with inconsistent significance for post-prostate cancer patients. For Cd and Hg, no statistically significant association was established.

SIGNIFICANCE

By linking two national health databases for the first time, we constructed an unbiased database of prostate cancer cases and matching controls. We found that blood Pb concentrations were associated with the risk of prostate cancer in Korean men at the current level of exposure.

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.

Metal concentrations in the whole blood of farmers in southeast Brazil

In this study, we measured Ni, Co, Cd, and Pb concentrations in the whole blood of farmers from southeast Brazil to address the factors influencing human exposure in this population. The factors included smoking, alcohol consumption, aging, body composition, gender, and feeding preferences, which were measured through carbon and nitrogen isotopic composition. We also calculated and compared the reference values (RVs) of the measured elements to evaluate ongoing exposure levels. We observed the influence of lifestyle habits on metal exposure; Cd levels were statistically higher in smokers, and alcohol consumption affected only Pb concentrations, with an association also observed with the frequency of alcohol ingestion. The metal levels were positively associated with both isotope values, indicating that feeding may be the dominant source of these elements in this population. We also observed the effect of endogenous sources measured through age, as increased Pb concentrations in both genders and higher Cd levels in older women, which is related to bone, kidney, and liver accumulation. The body mass index was negatively associated with Ni, Co, and Cd in women and positively in men. The negative associations may indicate that body fat may act as a reservoir for metals, reducing their availability in the blood in individuals with higher body mass and possibly influencing the assessment of exposure levels. The evaluated population presented elevated RVs for all elements: Ni 36, Co 3.3, Cd 16, and Pb 149 μg L-1. These values point to higher exposure in this population compared to other studies in Brazil and worldwide. These results emphasize an urgent need for monitoring programs for toxic substances in Brazil and evaluating possible health effects, given the ongoing environmental exposure associated with endogenous exposure and lifestyle habits that promote higher metal levels in this population.

Current Levels of Environmental Exposure to Cadmium in Industrialized Countries as a Risk Factor for Kidney Damage in the General Population: A Comprehensive Review of Available Data

The growing number of reports indicating unfavorable outcomes for human health upon environmental exposure to cadmium (Cd) have focused attention on the threat to the general population posed by this heavy metal. The kidney is a target organ during chronic Cd intoxication. The aim of this article was to critically review the available literature on the impact of the current levels of environmental exposure to this xenobiotic in industrialized countries on the kidney, and to evaluate the associated risk of organ damage, including chronic kidney disease (CKD). Based on a comprehensive review of the available data, we recognized that the observed adverse effect levels (NOAELs) of Cd concentration in the blood and urine for clinically relevant kidney damage (glomerular dysfunction) are 0.18 μg/L and 0.27 μg/g creatinine, respectively, whereas the lowest observed adverse effect levels (LOAELs) are >0.18 μg/L and >0.27 μg/g creatinine, respectively, which are within the lower range of concentrations noted in inhabitants of industrialized countries. In conclusion, the current levels of environmental exposure to Cd may increase the risk of clinically relevant kidney damage, resulting in, or at least contributing to, the development of CKD.

The Association between Mercury and Lead Exposure and Liver and Kidney Function in Pregnant Surinamese Women Enrolled in the Caribbean Consortium for Research in Environmental and Occupational Health (CCREOH) Environmental Epidemiologic Cohort Study

Exposure to mercury (Hg) and lead (Pb) may have an effect on pregnant women. We assessed the effect of exposure to mercury and lead on liver and kidney functions in a subcohort of pregnant women who participated in the Caribbean Consortium for Research in Environmental and Occupational Health (CCREOH)—Meki Tamara, study. From 400 women aged 16−46 living in rural, urban, and interior regions of Suriname, we measured blood mercury and blood lead levels. Creatinine, urea, and cystatin C were measured to assess kidney function, and aspartate amino transferase (AST), alanine amino transferase (ALT), and gamma-glutamyl transferase (GGT) were measured to assess liver function. Education, region, and ethnicity showed significant differences for both blood mercury and lead levels, which all had p-values < 0.001. Creatinine and urea were elevated with higher mercury blood levels. Our findings also suggest a relationship between high mercury blood levels and potential harmful effects on liver and kidney function.

Blood Lead Monitoring in a Former Mining Area in Euskirchen, Germany-Volunteers across the Entire Population

After centuries of mining in the district of Euskirchen, that is, in the communities of Mechernich and Kall, the lead concentration in the soil remains high, often exceeding regulatory guidelines. To clarify the lead body burden among residents in the region, a human biomonitoring study on a voluntary basis was initiated in which the blood lead level (BLL) was assessed. A questionnaire was distributed to evaluate lead exposure routes and confounders. Overall, 506 volunteers participated in the study, of whom 7.5% were children and adolescents, 71.9% were adults from 18 to 69 years, and 19.4% were residents 70 years or older. While the BLLs in the adult population were inconspicuous, among the children and adolescents investigated, 16.7% of the children between 3 and 17 years had BLLs above the recently revised German reference values for BLL in children. These results point towards a higher lead exposure in children living in the region. The hierarchical regression analysis based on the BLL and the questionnaire revealed the significant influence of the factors age, sex, smoking, construction age of the real estate, occupancy, and intensive contact with soil on the BLL. Measures to reduce lead exposure include a focus on improved personal and domestic hygiene to minimize lead intake.

Profile of Environmental Chemicals in the Korean Population-Results of the Korean National Environmental Health Survey (KoNEHS) Cycle 3, 2015-2017

The Korean National Environmental Health Survey (KoNEHS) program provides useful information on chemical exposure, serves as the basis for environmental health policies, and suggests appropriate measures to protect public health. Initiated on a three-year cycle in 2009, it reports the concentrations of major environmental chemicals among the representative Korean population. KoNEHS Cycle 3 introduced children and adolescents into the analysis, where the blood and urine samples of 6167 participants were measured for major metals, phthalates, phenolics, and other organic compounds. Lead, mercury, cadmium, metabolites of DEHP and DnBP, and 3-phenoxybenzoic acid levels of the Korean adult population tended to decrease compared to previous survey cycles but remained higher than those observed in the US or Canada. Both bisphenol A (BPA) and trans,trans-muconic acid concentrations have increased over time. Heavy metal concentrations (blood lead, and cadmium) in children and adolescents were approximately half that of adults, while some organic substances (e.g., phthalates and BPA) were high. BPA showed higher levels than in the US or Canada, whereas BPF and BPS showed lower detection rates in this cycle; however, as these are increasingly used as a substitute for BPA, further research is necessary. As environmental chemicals may affect childhood health and development, additional analyses should assess exposure sources and routes through continuous observations.

Association between Blood Mercury Concentration and Prevalence of Borderline Hypercholesterolemia among Adolescents: The Korea National Health and Nutrition Examination Survey (KNHANES) 2010-2013 and 2016

There is limited evidence on the association between blood mercury (Hg) concentration and the risk of borderline dyslipidemia in adolescents. Here, we investigated the association between blood Hg concentration and the prevalence of borderline dyslipidemia among Korean adolescents. A total of 1559 participants (806 boys and 753 girls) aged 10–18 years who cross-sectionally enrolled in the Korea National Health and Nutrition Examination Survey (KNHANES) 2010–2013 and 2016 were included in this study. Hg concentrations (µg/L) in whole blood samples were measured. The geometric mean (GM) of the blood Hg concentration was 1.88 µg/L. It showed a 63% higher prevalence of borderline hypercholesterolemia (total cholesterol (TC) 170–199 mg/dL) per unit of natural log-transformed blood Hg concentration in boys (95% CI = 1.10–2.41), but not in girls. When a categorical model was applied, the positive association with the prevalence of borderline hypercholesterolemia was also persistant in boys (OR (95% CI) for 2nd and 3rd tertiles (Hg concentration 1.532–11.761 µg/L) vs. 1st tertile (Hg concentration 0.192–1.531 µg/L): 1.92 (1.19–3.10)), but not in girls. This finding suggests that blood Hg concentration might result in a higher prevalence of borderline hypercholesterolemia among adolescents and more stringent public health actions should be taken for the reduction of Hg exposure to prevent dyslipidemia from early-childhood, despite the need of further study to evaluate a causal relationship between blood Hg concentration and the risk of dyslipidemia.

Association between Pb, Cd, and Hg Exposure and Liver Injury among Korean Adults

BACKGROUND

Exposure to lead (Pb), cadmium (Cd), and mercury (Hg) has been reported to be associated with liver-related diseases. However, studies examining the association between heavy metal exposure and liver injury in a large population are scant and characterized by inconsistent results. This study aimed to evaluate the association between levels of heavy metal exposure and liver injury in the general population.

METHODS

Data for 2953 participants aged 19 years or more obtained from the Korean National Environmental Health Survey (KoNEHS) Cycle 3 (2015-2017) were used. The associations between levels of blood or urine heavy metals (Pb, Cd, and Hg) and liver function biomarkers [aspartate aminotransferase (AST), alanine aminotransferase (ALT), and gamma-glutamyl transferase (GGT)] were evaluated using multiple linear regression analysis.

RESULTS

Regarding the blood Pb (BPb), AST was higher in those of the 4th quartile, ALT was higher in those of the 2nd and 4th quartiles, and GGT was higher in those of the 3rd and 4th quartiles than in the 1st quartile. For urinary Cd (UCd), AST was higher in those of the 4th quartile; ALT was higher in those of the 2nd, 3rd, and 4th quartiles; and GGT was higher in the 4th quartile than in the 1st quartile. For the blood Hg (BHg), AST was higher in those of the 2nd and 4th quartile, ALT was higher in those of the 2nd, 3rd, and 4th quartiles; and GGT was higher in those of the 3rd and 4th quartiles than in the 1st quartile. There was no significant difference between urinary Hg (UHg) and liver function markers.

CONCLUSION

Heavy metal exposure showed an association with liver injury among the general adult population in Korea. Further studies are required to clarify the relationship between heavy metals and liver injury.

Relationship between heavy metal exposure and type 2 diabetes: a large-scale retrospective cohort study using occupational health examinations

OBJECTIVES

To investigate the associations between heavy metal exposure and serum ferritin levels, physical measurements and type 2 diabetes mellitus (DM).

DESIGN

A retrospective cohort study.

SETTING

Changwon, the location of this study, is a Korean representative industrial city. Data were obtained from medical check-ups between 2002 and 2018.

PARTICIPANTS

A total of 34 814 male subjects were included. Of them, 1035 subjects with lead exposure, 200 subjects with cadmium exposure and the 33 579 remaining were assigned to cohort A, cohort B and the control cohort, respectively. Data including personal history of alcohol and smoking, age, height, weight, the follow-up duration, haemoglobin A1c (HbA1c), fasting blood sugar (FBS), ferritin levels, and lead and cadmium levels within 1 year after exposure were collected.

PRIMARY OUTCOME MEASURE

In subjects without diabetes, changes in FBS and HbA1c were analysed through repeated tests at intervals of 1 year or longer after the occupational exposure to heavy metals.

RESULTS

In Cohort A, DM was diagnosed in 33 subjects. There was a significant difference in lead concentrations between the subjects diagnosed with DM and those without DM during the follow-up period (3.94±2.92 mg/dL vs 2.81±2.03 mg/dL, p=0.002). Simple exposure to heavy metals (lead and cadmium) was not associated with DM in Cox regression models (lead exposure (HR) 1.01, 95% CI: 0.58 to 1.77, p 0.971; cadmium exposure HR 1.48, 95% CI: 0.61 to 3.55, p=0.385). Annual changes in FBS according to lead concentration at the beginning of exposure showed a positive correlation (r=0.072, p=0.032).

CONCLUSION

Our findings demonstrated that simple occupational exposure to heavy metals lead and cadmium was not associated with the incidence of DM. However, lead concentrations at the beginning of the exposure might be an indicator of DM and glucose elevations.

Chronic Exposure to Lead and Cadmium in Residents Living Near a Zinc Smelter

This study aimed to measure lead (Pb) and cadmium (Cd) exposure levels in residents living near a zinc (Zn) smelter in Seokpo-myeon, Bonghwa-gun, South Korea, and identify factors affecting exposure. Residents aged ≥20 years living within 3 km and ≥30 km away from the smelter were classified as the exposure group (n = 549), and the control group (n = 265), respectively. Data were obtained through a questionnaire survey. Blood Pb levels in the exposure group (4.19 µg/dL) were higher than in the control group (2.70 µg/dL). The exposure group (1.32 µg/L) also had higher urinary Cd concentrations than the control group (0.80 µg/L). Male sex, older age, previous work at the smelter, smoking, and proximity to the smelter were associated with higher blood Pb levels on multivariate analysis; urinary Cd concentration was significantly higher in women, those who were older, those with experience of working in a Zn smelter or mine, those with proximity to the Zn smelter, and those who consumed locally grown vegetables. In conclusion, Zn smelters are major source of Pb and Cd pollution and require ongoing public health management to prevent potential adverse health effects.

Blood lead concentration and exposure related factors in Korea from the National Environmental Health Survey (KoNEHS) II (2012-2014)

This study evaluated lead concentrations in blood and related factors among the South Korean population based on data from the Korea National Environmental Health Survey (KoNEHS) II (2012-2014) conducted by the National Institute of Environmental Research and the Ministry of Environment. Personal data were obtained from non-institutionalized civilian Korean individuals in an interview with trained community surveyors using a structured questionnaire (n = 6,455, aged 19 or older, mean age 49.7 years). The lead concentrations in whole blood were analyzed by atomic absorption spectrophotometry (AAS) with a Zeeman-effect-based background corrector. The precision and accuracy of the analytical methods were verified by internal and external quality controls (G-EQUAS, Germany). Statistical analysis was performed using weighted KoNEHS II data separated by sex, and the lead concentration was expressed as a geometric mean (GM). Multiple linear regression was performed using the SPSS 23.0 software package (SPSS Inc., Chicago, IL, USA). The total GM of lead concentrations was 19.5 µg/L. Lead concentrations increased with age and were higher in males (22.8 µg/L) than in females (16.6 µg/L). Smokers and drinkers had higher concentrations than non-smokers and non-drinkers of both sexes. People who used herbal medications had higher concentrations than those who did not among females. People of both sexes living in rural areas had higher lead concentrations than those in urban areas. Lead concentrations also varied with educational level, total family income, the type of water regularly consumed, and occupation. The average lead concentration of the general adult population in Korea has rapidly decreased over time from 45.8 µg/L (1999) to 19.45 µg/L (2012-2014); however, it remains higher than that of the United States, Germany, and Canada. The factors significantly related to lead concentration in South Korea were age, sex, smoking and alcohol drinking status, herbal medication usage by females, residential area, drinking water at home, and occupation. These factors could be used to improve occupational and environmental hygiene among the Korean population.

The reference value of blood lead level among the general adult population of eastern Iran

The aim of this study to the estimate the lead concentrations in the blood of the adult population in South Khorasan Province, evaluate factors related to high lead blood concentrations and establish lead reference values (RVs) in our study population. In cross-sectional study, 400 people who lived in the province of South Khorasan in 2017 were selected. Demographic information was collected and clinical examinations were performed. As the geometric means, blood lead concentration (BLC) was expressed, 10th, 50th, 90th, and 95th percentiles, and 95% confidence intervals (CI) of the 95th percentile. The upper limits rounded values of the 95% CI with the 95th percentile were applied to calculate RVs. Mean BLC was 6.02 ± 7.41 µg dL^-1, median of BLC was 4.4 µg dL^-1 (IQR: 2.9-6.5; range 0.9-54.7 µg dL^-1). One hundred and twenty-five (31.2%) participants had BLCs between 5 and 10.0 µg dL^-1, 40 (10.0%) between 10 and 20.0 µg dL^-1, and 15 (3.8%%) over 20 µg dL^-1. The RVs for BLC for men and women were 16 [95% CI: 10.13-15.96] µg dL^-1 and 15 [95% CI: 9.81-14.45] µg dL^-1, respectively. Higher BLCs were significantly associated with age, gender, hemoglobin, white blood cell count, and serum phosphorus concentration. This bio-monitoring study of BLCs in the general population of South Khorasan Province offers important demographic and lifestyle factors-stratified reference data. It is essential to continue efforts to reduce lead exposure.

Blood lead level risk factors and reference value derivation in a cross-sectional study of potentially lead-exposed workers in Iran

OBJECTIVES

This exploratory investigation aimed to measure blood lead levels and associated risk factors in exposed workers in Iran, and to derive appropriate reference values for blood lead in this population as a means of epidemiological comparison.

DESIGN

Cross-sectional.

SETTING

Manufacturing plants with potential lead exposure in Southern Khorasan Province, Iran.

PARTICIPANTS

The study included 630 workers, selected through stratified random sampling.

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary measures in this exploratory investigation were venous blood lead concentration (BLC) and associated risk factors of age, gender, work experience, cigarette smoking and history of opium use. The secondary measures were symptoms associated with lead toxicity. Data analyses were conducted using Student's t-test, Mann-Whitney U test, one-way analysis of variance, Kruskal-Wallis test, Spearman correlation coefficient and regression analysis.

RESULTS

Mean and median BLCs were 6.5±8.1 μg/dL and 3.9 μg/dL (IQR: 2.9-5.8), respectively. Of the subjects, 85 (13.5%) had BLC ≥10 μg/dL. The derived reference BLC value in this study was 30 μg/dL for men and 14 μg/dL for women. Increasing work experience and age were associated with BLC >10 μg/dL. Radiator manufacturers were up to 12.9 times (95% CI 4.6 to 35, p<0.005) more likely than painters to have BLC >10 μg/dL. Most subjects reported multiple symptoms.

CONCLUSIONS

The mean BLC was above the maximum recommended concentration. There was a significant relationship between higher BLC and age or working in a printing factory or radiator manufacturing. These findings can direct efforts towards reducing occupational lead exposure.

Heavy metals in maternal and cord blood in Beijing and their efficiency of placental transfer

This study aimed to determine the effect of exposure to heavy metals in pregnant women in Beijing, China. We also evaluated the association of these heavy metals with birth weight and length of newborns. We measured the levels of 10 heavy metals, including lead (Pb), titanium (Ti), manganese (Mn), nickel (Ni), cadmium (Cd), chromium (Cr), antimony (Sb), stannum (Sn), vanadium (V), and arsenic (As), in 156 maternal and cord blood pairs. An inductively coupled plasma mass spectrometry method was used for measurement. Pb, As, Ti, Mn, and Sb showed high detection rates (>50%) in both maternal and cord blood. Fourteen (9%) mothers had blood Pb levels greater than the United States Center for Disease Control allowable threshold limit for children (50 μg/L). In prenatal exposure to these heavy metals, there was no significant association between any heavy metal and birth weight/length. Moreover, we estimated the placental transfer efficiency of each heavy metal, and the median placental transfer efficiency ranged from 49.6% (Ni) to 194% (Mn) (except for Cd and Sn). The level and detection rate of Cd in maternal blood were much higher than that in cord blood, which suggested that Cd had difficulty in passing the placental barrier. Prospective research should focus on the source and risk of heavy metals in non-occupationally exposed pregnant women in Beijing.

Type 2 diabetes occurrence and mercury exposure - From the National Nutrition and Health Survey in Taiwan

BACKGROUND

The global prevalence of type 2 diabetes continues to increase in both developed and developing countries. Environmental exposure to mercury may be an important and modifiable risk factor for type 2 diabetes. However, the epidemiological results are controversial.

OBJECTIVES

This study aimed to examine the association between blood mercury levels and prevalence of type 2 diabetes.

METHODS

A total of 646 adult participants were selected from the National Nutrition and Health Survey in Taiwan (NAHSIT) 2005-2008. The participants were interviewed using structured questionnaires to record data on basic demographics, socioeconomic status, lifestyle, medical history, and 24-h dietary recall. Specimens of blood and urine were collected at the health examination. Type 2 diabetes was defined as a fasting blood glucose level ≥ 126 mg/dL or intake of hypoglycemic medications. The mercury concentration in red blood cells (RBC-Hg) was quantified by cold vapor atomic absorption spectrometry.

RESULTS

Participants with type 2 diabetes had a significantly higher RBC-Hg than those without type 2 diabetes. A significant association between the RBC-Hg and prevalence of type 2 diabetes was observed [odds ratio (OR): 1.64; 95% confidence intervals: 1.14-2.35] after potential confounders were well considered, including age, sex, body mass index (BMI), hypertension, total cholesterol, saltwater fish consumption, geographical strata, seasonality and hemoglobin (Hb) level.

CONCLUSION

Our findings showed that elevated RBC-Hg is significantly associated with type 2 diabetes prevalence. Future research, particularly for longitudinal cohort studies with suitable specimens, needs to be performed to verify our findings.

Prevalence of rheumatoid arthritis in relation to serum cadmium concentrations: cross-sectional study using Korean National Health and Nutrition Examination Survey (KNHANES) data

OBJECTIVES

It has been suggested that exposure to heavy metal cadmium (Cd) may contribute to a high risk of developing rheumatoid arthritis (RA). This study was to investigate the association of RA prevalence and serum concentrations of Cd and other heavy metals through large survey data analysis.

DESIGN

A retrospective cross-sectional survey study.

SETTING

Large population survey in Korea.

PARTICIPANTS

53 829 subjects participated in Korean National Health and Nutrition Examination Survey (KNHANES) from 2008 to 2013.

INTERVENTIONS

Heavy metals were measured in different time periods of the survey programme which resulted in three different data sets for analysis: Cd, mercury (Hg) and lead (Pb) from 2008 to 2012 survey; serum manganese (Mn) and urine arsenic (As) from 2008 to 2009 survey; and serum zinc (Zn) from 2010 survey. RA prevalence and its associations with serum heavy metals were analysed using a general linear/logistic regression model of complex sample design.

RESULTS

Serum Cd was elevated in patients with RA (RA vs control: 1.30±0.07 µg/L vs 1.17±0.01 µg/L, p<0.01). There were no significant differences in urine levels of As or serum levels of Pb, Hg, Mn or Zn between patients with RA and controls. OR (95% CI) of RA prevalence according to 1 µg/L increase of serum Cd level was 1.28(95% CI 1.03 to 1.61). Prevalence of RA in women was increased with increasing quartiles of Cd levels, with a 19-fold difference in female RA prevalence between individuals in the lowest quartile of serum Cd level and those in the highest quartile (0.18% vs 3.42%). Cubic spline curve of prevalence OR showed increased risk of RA according to increased serum Cd level. Increased risk of RA in men was not observed with increased serum Cd levels.

CONCLUSION

There was an increased prevalence of RA in females associated with increased serum levels of Cd in the Korean population.

Environmental and Body Concentrations of Heavy Metals at Sites Near and Distant from Industrial Complexes in Ulsan, Korea

BACKGROUND

Industrial pollution may affect the heavy metal body burden of people living near industrial complexes. We determined the average concentrations of atmospheric heavy metals in areas close to and distant from industrial complexes in Korea, and the body concentrations of these heavy metals in residents living near and distant from these facilities.

METHODS

The atmospheric data of heavy metals (lead and cadmium) were from the Regional Air Monitoring Network in Ulsan. We recruited 1,148 participants, 872 who lived near an industrial complex ("exposed" group) and 276 who lived distant from industrial complexes ("non-exposed" group), and measured their concentrations of blood lead, urinary cadmium, and urinary total mercury.

RESULTS

The results showed that atmospheric and human concentrations of heavy metals were higher in areas near industrial complexes. In addition, residents living near industrial complexes had higher individual and combined concentrations (cadmium + lead + mercury) of heavy metals.

CONCLUSION

We conclude that residents living near industrial complexes are exposed to high concentrations of heavy metals, and should be carefully monitored.

Trends in and factors affecting the observed levels of urinary inorganic and total blood mercury among US children, adolescents, adults, and senior citizens over 2005-2012

Data from National Health and Nutrition Examination Survey (NHANES) for 2005-2012 were used to (i) study adjusted and unadjusted trends in the levels of urinary inorganic mercury (UIHG) and total blood mercury (TBHG) and (ii) factors that affect the observed levels of UIHG and TBHG among children aged 1-5 (CHLD15) and 6-11 (CHLD611) years, adolescents aged 12-19 years (ADOL), adults aged 20-64 years (ADLT), and senior citizens aged >=65 years (SNR). Decrease in adjusted levels of UIHG for each 2-year NHANES cycle for CHLD611 was 0.08114ng/L, 0.08379ng/L for ADOLs, and 0.12ng/L for ADLTs. Decreases in adjusted levels (AGM) of TBHG for each 2-year NHANES cycle were: 0.0632ng/L for CHLD15, 0.10239ng/L for CHLD611, 0.06424ng/L for ADOLs, and 0.056088ng/L for ADLTs. Among CHLD15 (0.34 vs. 0.39μg/L, p<0.01) and CHLD611 (0.42 vs. 0.44μg/L, p=0.04), males had lower AGMs for TBHG than females but among ADLTs (0.84 vs. 0.80μg/L, p<0.01) and SNRs (0.82 vs. 0.71μg/L, p<0.01) the reverse was true. For UIHG, for ADLTs (0.33 vs. 0.45μg/L, p<0.01) and SNRs (0.27 vs. 0.35μg/L, p<0.01) males had lower AGMs than females. Irrespective of age, those who were in unclassified race/ethnic group had the highest AGMs when compared with non-Hispanic whites, non-Hispanic blacks, and Mexican Americans and the differences, more often than not, were statistically significant (p<0.01). Irrespective of age, fish and shellfish consumption during the last 30days was associated with higher AGMs for both UIHG and TBHG than when fish and shellfish were not consumed and the differences were always statistically significant (p<0.01). Nonsmoker ADLTs (0.86 vs. 0.78μg/L, p<0.01) and SNRs (0.83 vs. 0.71μg/L, p<0.01) were found to have higher adjusted levels of TBHG than smokers. It is hypothesized that constituents in tobacco smoke may accelerate excretion of mercury from the body.

The Cut-off Value of Blood Mercury Concentration in Relation to Insulin Resistance

Background

Increased blood mercury concentration is associated with inflammation, and chronic inflammation can cause insulin resistance. We examined the cut-off value of blood mercury in relation to an increased score on the homeostasis model assessment for insulin resistance (HOMA-IR).

Methods

We used data from the Korean National Health and Nutrition Examination Survey (2008-2010). Relevant data from 5,184 subjects (2,523 men and 2,661 women) were analyzed cross-sectionally. General linear analysis was performed to evaluate the relationship between HOMA-IR score and blood mercury concentration. In addition, we determined the cut-off value of blood mercury concentration in relation to increased HOMA-IR score (> 2.34) using an ROC curve.

Results

The mean value of blood mercury concentration in men and women was 5.88 μg/L and 4.11 μg/L, respectively. In men, comparing to the first quartile, HOMA-IR score increased significantly in the third and fourth blood mercury quartiles. In women, however, the increase in HOMA-IR score was not significant. The cut-off value that best represented the association between increased HOMA-IR score and blood mercury concentration in men was found to be 4.71 μg/L.

Conclusion

Blood mercury concentration was associated with increased HOMA-IR score in men, and the cut-off value of blood mercury concentration that was correlated with increased HOMA-IR score was around 4.71 μg/L.

Fish consumption, mercury exposure, and the risk of cholesterol profiles: findings from the Korea National Health and Nutrition Examination Survey 2010-2011

In this study, the associations between mercury (Hg) exposure and cholesterol profiles were analyzed, and increased Hg levels and cholesterol profiles according to the amount of fish consumption were evaluated. Data on levels of blood Hg, the frequency of fish consumption, total blood cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and triglyceride (TG) in 3951 adults were obtained from the Korea National Health and Nutrition Examination Survey 2010-2011 database. To compare the distribution for each log-transformed indicator, Student's t-test and analysis of variance were carried out, and the groups were classified according to the frequency of fish consumption through linear regression analysis; the association between Hg level and cholesterol profiles in each group was analyzed. The blood Hg levels (arithmetic mean, median, and geometric mean) for all target participants were 4.59, 3.66, and 3.74 µg/L, respectively. The high cholesterol group, low HDL-C group, and high TG group showed a statistically and significantly higher blood Hg level than the low-risk group. In both sexes, as the frequency of fish consumption increased, blood Hg level also increased, but TC, HDL-C, LDL-C, and TG did not show a similar trend. Increased blood Hg level showed a significant association with increased TC and LDL-C. This statistical significance was maintained in the group with less frequent fish consumption (<4 times per month), but the group with frequent fish consumption (>8 times per month) did not show a similar trend. The results of this study suggest that fish consumption increases the level of Hg exposure, and that as the level of Hg exposure increases, the levels of cholesterol profiles increase. However, this study also suggests that the levels of cholesterol profiles in those with frequent fish consumption can be diminished.

Determination of Trace Metal Levels in the General Population of Korea

The purpose of this study was to determine the levels of trace metals in the blood of the general Korean population. A total of 258 healthy individuals, according to their regular medical check-ups, (119 males and 139 females, age ranging from 12 to 78 years old) were enrolled from December 2014 to December 2016. Levels of 10 trace elements were determined using inductively coupled plasma mass spectrometry (ICP-MS). The geometric mean (GM) levels for lead, arsenic, cesium, mercury, aluminum, cadmium, copper, manganese, selenium, and zinc were 15.97 μg/L, 7.19 μg/L, 2.39 μg/L, 3.41 μg/L, 10.57 μg/L, 0.78 μg/L, 979.8 μg/L, 11.06 μg/L, 111.37 μg/L, and 872.7 μg/L, respectively. There were significant gender-related differences in the levels of several metals; male individuals had higher Pb, As, Cs, Hg, and Se than females, while females had higher Cd, Cu, and Mn than males. We noticed remarkably high blood levels of Hg, As and Al in the Korean population. The element concentrations reported represent a new contribution to the knowledge of the blood chemistry for the Korea population. The data can be used to assess the clinical health of this population.

The distribution of blood concentrations of lead (Pb), cadmium (Cd), chromium (Cr) and manganese (Mn) in residents of the German Ruhr area and its potential association with occupational exposure in metal industry and/or other risk factors

OBJECTIVE

This study investigated the metal distribution in blood samples from the general population and the risk of having high metal concentration for metal workers.

METHODS

Metal concentrations were determined in archived blood samples from 1411 men and 1410 women (median age 59 and 57 years, respectively) collected at baseline (2000-2003) of the prospective Heinz Nixdorf Recall Study. Retrospective information on working in metal industry was obtained from previous follow-up survey (2011-2014). Odds ratios (ORs) with 95% confidence intervals (CI) of having a metal concentration >90th percentile (P90) for working in metal industry were calculated using logistic regression with adjustment for covariates.

RESULTS

More men than women worked in metal industry (57 vs. 3 at baseline). Male metal workers had increased blood lead (Pb) (OR: 2.86; 95% CI: 1.38-5.91) and manganese (Mn) (OR: 2.92; 95% CI: 1.46-5.81). Smoking (≥30 cigarettes/day) strongly influenced cadmium (Cd) in blood (OR: 168; 95% CI: 55-510). Women had higher Mn (8.92μg/L) and Cd (0.36μg/L) concentrations than men (Mn: 8.11μg/L; Cd: 0.29μg/L). Blood Pb in women (29.2μg/L) was lower than in men (33.2μg/L). None of the studied risk factors was significantly associated with chromium and nickel concentrations above their 90th percentiles.

CONCLUSIONS

In this population-based cohort we found evidence that working in metal industry was predictive for having elevated blood Pb and Mn concentrations. However, the 95th percentiles of all investigated metals were not significantly influenced by metal-related occupations. The present study is supportive for gender-specific reference values to limit occupational exposure to Mn and Pb. The strong influence of smoking on blood Cd hinders establishing reference values.

The Association between Involuntary Smoking Exposure with Urine Cotinine Level and Blood Cadmium Level in General Non-Smoking Populations

Unintentional environmental exposure to toxicants is associated with an aggravated health status of the general population. Involuntary smoking (IS) exposure is one of the main routes to involuntary toxicants exposure. However, few studies have attempted to understand the environmental cadmium exposure by IS exposure in the general, non-smoking population. The purpose of the current study was to examine the relationship between blood cadmium level and IS level according to gender and age. We used the Korea National Health and Nutrition Examination Survey (KNHANES) IV-VI data that included heavy metal and urine cotinine sampling with IS exposure history. The final analysis comprised 3,493 adults (1,231 males and 2,262 females) and 395 adolescents (210 males and 185 females). Linear regression was performed to estimate the association between self-reported IS exposure with urine cotinine level and blood cadmium level in non-smokers with gender and age group stratification. In final regression model, the effect values (B) (standard errors [SE]) between blood cadmium and urine cotinine level in men was 0.0004 (0.0001) and 0.0006 (0.0002) in adults and adolescents, the B (SE) in women was 0.0006 (0.0002) and 0.0016 (0.0006) in adults and adolescents. Our study revealed, for the first time, a significant association between blood cadmium and IS exposure in non-smokers. Greater efforts are needed to improve environmental justices of the general population from IS, considering the severe harmful effects of involuntary exposure to even a low level of cadmium.

Association between Blood Mercury Level and Visceral Adiposity in Adults

BACKGROUND

Few studies have examined the association between mercury exposure and obesity. The aim of this study is to investigate the association between blood mercury concentrations and indices of obesity in adults.

METHODS

A total of 200 healthy subjects, aged 30 to 64 years, who had no history of cardiovascular or malignant disease, were examined. Anthropometric and various biochemical profiles were measured. Visceral adipose tissue (VAT) was measured using dual-energy X-ray absorptiometry (DXA).

RESULTS

All subjects were divided into three groups according to blood mercury concentrations. Compared with the subjects in the lowest tertile of mercury, those in the highest tertile were more likely to be male; were current alcohol drinkers and smokers; had a higher body mass index (BMI), waist circumference (WC), and VAT; had higher levels of blood pressure, fasting glucose, and insulin resistance; and consumed more fish. The blood mercury concentration was significantly associated with anthropometric parameters, showing relationships with BMI, WC, and VAT. After adjusting for multiple risk factors, the odds ratios (ORs) for high mercury concentration was significantly higher in the highest VAT tertile than in the lowest VAT tertile (OR, 2.66; 95% confidence interval, 1.05 to 6.62; P<0.05).

CONCLUSION

The blood mercury concentration was significantly associated with VAT in healthy adults. Further studies are warranted to confirm our findings.

Association of Blood Pressure with Exposure to Lead and Cadmium: Analysis of Data from the 2008-2013 Korean National Health and Nutrition Examination Survey

We examined the association of blood pressure with blood levels of cadmium, lead, and their combination in a representative sample of adults from South Korea (Korean National Health and Nutrition Examination Survey, 2008-2013). This cross-sectional study enrolled subjects who were at least 19 years-old, completed a health examination survey, and had blood measurements of lead and cadmium. We estimated the adjusted mean differences in diastolic and systolic blood pressure associated with doubling of blood lead and cadmium by regression of blood pressure against log₂-transformed blood metals and their tertiles after covariate adjustment. Adjusted odds ratios for hypertension and prehypertension were calculated for log₂-transformed blood levels of lead and cadmium and their tertiles. In the general population of Korea, blood lead level was associated with increased BP and risk of hypertension. Blood cadmium levels had a stronger association with elevated blood pressure and risk of hypertension than blood lead levels, and these associations remained significant after statistical adjustment for blood lead. The combination of blood lead and cadmium was more strongly associated with elevated blood pressure than exposure to each individual metal. In females, there was a stronger relationship between blood pressure and blood levels of these metals by analyzing interaction model. After adjustment for confounding factors, there were significant associations of blood pressure with the level of blood lead, cadmium, and their combination in adults from South Korea.

Blood cadmium concentrations in Korean adolescents: From the Korea National Health and Nutrition Examination Survey 2010-2013

OBJECTIVE

To assess blood cadmium levels in Korean adolescents with respect to demographic and lifestyle factors.

METHODS

We analyzed data from the Korea National Health and Nutrition Examination Survey from 2010 to 2013, totaling 1472 adolescents aged 10-18 years. Geometric means of blood cadmium were calculated using a complex samples general linear model to compare blood levels in different demographic and lifestyle groups. Multivariate logistic regression analyses were also used to find predictors for high blood cadmium (>90th percentile).

RESULTS

The geometric mean of the blood cadmium concentrations was 0.30μg/L in Korean adolescents. Older age, type of housing (multifamily house and commercial building), smoking and alcohol consumption, and iron deficiency/iron deficiency anemia (IDA) were significantly associated with higher blood cadmium concentrations (P<0.05). Blood cadmium concentrations were not significantly affected by gender, region, body mass index status, or household income. In multivariate logistic regression analysis, independent predictors for higher blood cadmium levels included current smoker (OR=7.77), alcohol consumption (OR=4.31), living in a multifamily house or commercial building (OR=3.11-3.46), and IDA (OR=2.64).

CONCLUSIONS

Possible associations between blood cadmium levels and type of housing or alcohol consumption in adolescents are suggested for the first time in this study. Further studies are needed to elucidate the mechanism of these findings.

The association of relational and organizational job stress factors with sleep disorder: analysis of the 3rd Korean working conditions survey (2011)

BACKGROUND

Sleep disorder is a disease that causes reduction in quality of life and work efficiency of workers. This study was performed to investigate the relationship between job-related stress factor and sleep disorder among wageworkers in Korea.

METHODS

This study was based on analysis of the 3rd Korean working conditions survey. We analyzed 35,902 workers whose employment status is wageworker. We classified the job-related stress factor into 12 sections. Logistic regression was performed to estimate the relationship between job-related stress factor and sleep disorder and Odds ratio and 95 % CI were calculated using the SPSS version 23.0 program.

RESULTS

Many categories of Job-related stress factor were correlated with sleep disorder (8 of 12 for women, 10 of 12 for men). The results of the regression analysis, corrected for general and occupational characteristics, indicated that sleep disorder was significantly correlated with the following categories of job-related stress: discrimination experience (OR 3.37, 95 % CI = 2.49 ~ 4.56 in women, OR 1.96, 95 % CI = 1.53 ~ 2.51 in men), direct customer confrontation (OR 2.72, 95 % CI = 1.91 ~ 3.86 in women, OR 1.99, 95 % CI = 1.45 ~ 2.72 in men), emotional stress (OR 2.01, 95 % CI = 1.30 ~ 3.09 in men), work dissatisfaction (detailed) (OR 1.99, 95 % CI = 1.36 ~ 2.93 in men), work dissatisfaction (overall) (OR 2.30, 95 % CI = 1.66 ~ 3.20 in women, OR 2.40, 95 % CI = 1.88 ~ 3.08 in men), expression of opinion difficulty (OR 0.66, 95 % CI = 0.48 ~ 0.92 in women, OR 0.57, 95 % CI = 0.45 ~ 0.73 in men).

CONCLUSION

A number of studies have reported that stress affects sleep disorder. In this study, many factors suspected to increase the risk of sleep disorder were added to previously known job stress factors. In particular, this study found a strong correlation between work-associated sleep disorder and relational and organizational job stress factors. Sleep disorder may lead to large decreases in workers' quality of life and work efficiency. Awareness and interventions are therefore required to reduce workplace stress; additional research of this topic is also required.

Cadmium levels in a representative sample of the Spanish adult population: The BIOAMBIENT.ES project

Urinary cadmium levels (U-Cd) were measured in 1770 adults (aged 18-65 years) as a representative sample of the Spanish workforce. The geometric mean (GM) was 0.28 μg/l with 95% CI: 0.27-0.32 μg/l (GM: 0.20 μg/g 95% CI: 0.18-022 μg/g creatinine). The 95% percentile was 1.03 μg/l. U-Cd increased with age, with women showing higher U-Cd than men (p<0.001; 0.24 μg/g vs 0.17 μg/g). A multivariate analysis confirmed that sex, age and smoking habit significantly influence U-Cd. Smoking habit increases U-Cd by ∼90% per 10 years of age, almost twice the increase observed for non-smoking. Female smokers had 85% higher U-Cd than non-smokers, whereas the corresponding value for male smokers and non-smokers was 45%. No regional differences were observed with respect to the national reference level. The Spanish population studied here exhibits similar urinary cadmium levels to its European counterparts in Germany and slightly lower levels than in France, the Czech Republic, Italy and the United Kingdom. This paper provides the first baseline information concerning cadmium exposure in the Spanish adult population on a national scale. As such, these findings will help us to establish reference levels, follow temporal trends and identify high-exposure groups, thereby enabling comparisons with other countries and contributing to the improvement of public health and environmental quality.

Allele Frequencies of the Single Nucleotide Polymorphisms Related to the Body Burden of Heavy Metals in the Korean Population and Their Ethnic Differences

This study was performed to select single nucleotide polymorphisms (SNPs) related to the body burden of heavy metals in Koreans, to provide Korean allele frequencies of selected SNPs, and to assess the difference in allele frequencies with other ethnicities. The candidate-gene approach method and genome-wide association screening were used to select SNPs related to the body burden of heavy metals. Genotyping analysis of the final 192 SNPs selected was performed on 1,483 subjects using the VeraCode Goldengate assay. Allele frequencies differences and genetic differentiations between the Korean population and Chinese (CHB), Japanese (JPT), Caucasian (CEU), and African (YIR) populations were tested by Fisher’s exact test and fixation index (F_ST), respectively. The Korean population was genetically similar to the CHB and JPT populations (F_ST < 0.05, for all SNPs in both populations). However, a significant difference in the allele frequencies between the Korean and CEU and YIR populations were observed in 99 SNPs (60.7%) and 120 SNPs (73.6%), respectively. Ten (6.1%) and 26 (16.0%) SNPs had genetic differentiation (F_ST > 0.05) among the Korean-CEU and Korean-YIR comparisons, respectively. The SNP with the largest F_ST value between the Korean and African populations was cystathionine-β-synthase rs234709 (F_ST: KOR-YIR, 0.309; KOR-CEU, 0.064). Our study suggests that interethnic differences exist in SNPs associated with heavy metals of Koreans, and it should be considered in future studies that address ethnic differences in heavy-metal concentrations in the body and genetic susceptibility to the body burden of heavy metals.

Physical Activity and Blood Lead Concentration in Korea: Study Using the Korea National Health and Nutrition Examination Survey (2008-2013)

Physical activity normally has a positive influence on health, however it can be detrimental in the presence of air pollution. Lead, a heavy metal with established adverse health effects, is a major air pollutant. We evaluated the correlation between blood lead concentration and physical activity using data collected from the Korea National Health and Nutrition Examination Survey. Multivariate logistic regression analysis was performed after dividing participants according to whether they were in the top 25% in the distribution of blood lead concentration (i.e., ≥ 2.76 µg/dL), with physical activity level as an independent variable and adjusting for factors such as age, sex, drinking, smoking, body mass index, region, and occupation. The high physical activity group had greater odds of having a blood lead concentration higher than 2.76 µg/dL (odds ratio 1.29, 95% CI 1.11-1.51) compared to the low physical activity group. Furthermore, blood lead concentration is correlated with increasing physical activity.

The Association Between Blood Mercury Levels and Risk for Overweight in a General Adult Population: Results from the Korean National Health and Nutrition Examination Survey

The primary objective of this study was to estimate the association between blood mercury levels and overweight in Korean adults. We analyzed cross-sectional data from 9228 participants (4283 men and 4945 women) who completed the Korean National Health and Nutrition Examination Survey (KNHANES), 2007-2013. The population was divided into two groups according to the body mass index (BMI) and waist circumference (WC). Blood mercury levels were analyzed using a gold amalgam method with a DMA-80 instrument, categorized into quartiles, and stratified by sex. After adjusting for all covariates, blood mercury was significantly associated with overweight in all subjects. According to the BMI criteria, the adjusted odds ratio of being in the highest blood mercury quartile was 1.75 (95 % confidence interval [CI], 1.53-2.01) overall, 2.09 (95 % CI, 1.71-2.55) in men, and 1.58 (95 % CI, 1.32-1.89) in women. According to the WC criteria, the adjusted odds ratio of being in the highest blood mercury quartile was 1.85 (95 % CI, 1.49-2.30) in men and 1.96 (95 % CI, 1.62-2.36) in women compared to the lowest quartile. Additionally, a trend in overweight across increasing blood mercury levels was observed by the p for trend test in the multiple diagnostic criteria.

Reference values of lead in blood and related factors among Korean adolescents: the Korean National Health and Nutrition Examination Survey 2010-2013

Purpose

This study aimed to assess the reference values and factors influencing blood lead levels among Korean adolescents.

Methods

The study population consisted of 1,585 adolescents (801 males, 784 females; aged 10-19 years) who participated in the Korea National Health and Nutrition Examination Survey 2010-2013. We analyzed blood lead concentrations in relation to demographic/lifestyle characteristics for all participants. "Reference values" of blood lead levels were calculated as the upper limit of the 95% confidence interval of the 95th percentile.

Results

The average "reference value" for blood lead concentrations among Korean adolescents was 2.25 µg/dL (2.49 µg/dL for males, 2.07 µg/dL for females), and the geometric mean of the blood lead concentrations was 1.34 µg/dL. Males had higher blood lead concentrations than females (male, 1.48 µg/dL; female, 1.19 µg/dL; P<0.001). Elementary school students had higher blood lead concentrations than junior and senior high school students (1.44 µg/dL vs. 1.31 µg/dL, P<0.001). Participants living in detached houses had higher blood lead concentrations than those living in apartments (P<0.001) and current smokers had higher concentrations than nonsmokers or participants with secondhand smoke exposure (P<0.05). Additionally, participants with excessive alcohol consumption had higher levels than non-drinkers (P<0.001).

Conclusion

This study provides national reference data on blood lead concentrations stratified by demographic and lifestyle factors among Korean adolescents. Further studies are needed to elucidate the relationship between increased lead exposure and demographic factors including type of housing.

Representative levels of blood lead, mercury, and urinary cadmium in youth: Korean Environmental Health Survey in Children and Adolescents (KorEHS-C), 2012-2014

BACKGROUND

This study examined levels of blood lead and mercury, and urinary cadmium, and associated sociodemographic factors in 3-18 year-old Korean children and adolescents.

MATERIALS AND METHODS

We used the nationally representative Korean Environmental Health Survey in Children and Adolescents data for 2012-2014 and identified 2388 children and adolescents aged 3-18 years. The median and 95th percentile exposure biomarker levels with 95% confidence intervals (CIs) were calculated. Multivariate regression analyses were performed on log transformed exposure biomarker levels adjusted for age, sex, area, household income, and father's education level. The median exposure biomarker levels were compared with data from Germany, the US, and Canada, as well as the levels of Korean children measured at different times.

RESULTS

The median levels of blood lead and mercury, as well as urinary cadmium were 1.23μg/dL, 1.80μg/L, and 0.40μg/L (95% CIs, 1.21-1.25, 1.77-1.83, and 0.39-0.41, respectively). The blood lead levels were significantly higher in boys and younger children (p<0.0001) and children with less educated fathers (p=0.004) after adjusting for covariates. Urinary cadmium level increased with age (p<0.0001). The median levels of blood mercury and urinary cadmium were much higher in Korean children and adolescents than those in their peers in Germany, the US, and Canada. Blood lead levels tended to decrease with increasing age and divergence between the sexes, particularly in the early teen years. Median levels of blood lead and urinary cadmium decreased since 2010.

CONCLUSION

Sociodemographic factors, including age, sex, and father's education level were associated with environmental exposure to heavy metals in Korean children and adolescents. These biomonitoring data are valuable for ongoing surveillance of environmental exposure in this vulnerable population.

Occupational Lead Exposure from Indoor Firing Ranges in Korea

Military personnel often use ammunitions that contain lead. The present study aimed to identify the risks for lead exposure and lead poisoning among workers at indoor firing ranges. A special health examination, including blood lead level (BLL) testing, was performed for all 120 workers at the indoor firing ranges of the Republic of Korea's Air Force, Navy, and Armed Forces Athletic Corps. The overall mean BLL was 11.3 ± 9.4 µg/dL (range: 2.0-64.0 µg/dL). The arithmetic mean of the BLL for professional shooters belong to Armed Forces Athletic Corps was 14.0 ± 8.3 µg/dL, while those of shooting range managers and shooting range supervisors were 13.8 ± 11.1 µg/dL and 6.4 ± 3.1 µg/dL, respectively. One individual had a BLL of 64 µg/dL, and ultimately completed chelation treatment (with CaNa2-ethylenediaminetetraacetic acid) without any adverse effects. These findings indicate that indoor firing range workers are exposed to elevated levels of lead. Therefore, when constructing an indoor firing range, a specialist should be engaged to design and assess the ventilation system; and safety guidelines regarding ammunition and waste handling must be mandatory. Moreover, workplace environmental monitoring should be implemented for indoor firing ranges, and the workers should undergo regularly scheduled special health examinations.

Environmental Exposure to Arsenic, Lead, and Cadmium in People Living near Janghang Copper Smelter in Korea

Concentrations of heavy metals exceed safety thresholds in the soil near Janghang Copper Refinery, a smelter in Korea that operated from 1936 to 1989. This study was conducted to evaluate the level of exposure to toxic metals and the potential effect on health in people living near the smelter. The study included 572 adults living within 4 km of the smelter and compared them with 413 controls group of people living similar lifestyles in a rural area approximately 15 km from the smelter. Urinary arsenic (As) level did not decrease according to the distance from the smelter, regardless of gender and working history in smelters and mines. However, in subjects who had no occupational exposure to toxic metals, blood lead (Pb) and cadmium (Cd) and urinary Cd decreased according to the distance from the smelter, both in men and women. Additionally, the distance from the smelter was a determinant factor for a decrease of As, Pb, and Cd in multiple regression models, respectively. On the other hands, urinary Cd was a risk factor for renal tubular dysfunction in populations living near the smelter. These results suggest that Janghang copper smelter was a main contamination source of As, Pb, and Cd, and populations living near the smelter suffered some adverse health effects as a consequence. The local population should be advised to make efforts to reduce exposure to environmental contaminants, in order to minimize potential health effects, and to pay close attention to any health problems possibly related to toxic metal exposure.

Effects of Dendropanax morbifera Léveille extracts on cadmium and mercury secretion as well as oxidative capacity: A randomized, double-blind, placebo-controlled trial

In this randomized, double-blind, placebo controlled clinical trial, the effects of Dendropanax morbifera (D. morbifera) Léveille on heavy metal (cadmium and mercury) excretion as well as on lipid peroxidation and Cu, Zn-superoxide dismutase (SOD1) activity were investigated. For this study, tablets containing placebo or 300 mg of the leaf extract from D. morbifera Léveille were used. A total of 60 eligible healthy subjects were enrolled in this randomized, double-blind, placebo-controlled study. The differences in cadmium, mercury, and malondialdehyde (MDA) levels and SOD1 activity were measured in the serum 60 days after treatment with placebo or D. morbifera Léveille extracts. No significant differences between baseline characteristics and biochemical values were identified in subjects in the placebo and D. morbifera Léveille groups. Serum levels of cadmium, mercury and MDA decreased following consumption of D. morbifera Léveille extracts; however, no significant differences were identified. In addition, female, but not male, subjects who consumed D. morbifera Léveille extracts showed a significant increase in SOD1 activity. This result suggests that chronic consumption of D. morbifera Léveille extract can help to facilitate excretion of cadmium and mercury from serum and increase the antioxidant capacity in humans.

Time trend of cadmium intake in Korea

OBJECTIVES

The aim of this study was to elucidate past and current levels of cadmium (Cd) intake among the general populations in Korea.

METHODS

For this purpose, publications reporting dietary intake of cadmium (Cd-D), cadmium concentration in blood (Cd-B) and that in urine (Cd-U) in Korea were retrieved through literature survey for a period from 1975 to 2015.

RESULTS

In practice, 9, 21 and 14 articles were available on Cd-D, Cd-B and Cd-Ucr (Cd-U as corrected for creatinine concentration), respectively. Linear regression analyses of the reported values as a function of years (i.e., the year when each survey was conducted) showed steady decreases in all of the three exposure markers of Cd-D, Cd-B and Cd-U(cr). Factors possibly contributing for the reduction were discussed including the government-set guideline of 0.2 mg/kg for rice and changes in food habits among general populations.

CONCLUSIONS

There have been steady decreases in Cd-D, Cd-B and Cd-U(cr). The current estimates for Cd-D, Cd-B and Cd-Ucr were 6.0-7.4 μg/day, 0.73-0.83 μg/L and 0.60-0.95 μg/g cr, respectively.

Associated factors for higher lead and cadmium blood levels, and reference values derived from general population of São Paulo, Brazil

Human activities are associated with emissions of various metals into the environment, among which the heavy metals lead and cadmium stand out, as they pose a risk to human life even at low concentrations. Thus, accurate knowledge of the levels of these metals exhibited by the overall population, including children, is important. The aim of this study was to estimate the concentrations of lead and cadmium in the blood of adults, adolescents and children residing in the city of São Paulo, assess factors associated with higher lead and cadmium blood levels, and to establish reference values for this population. The study sample consisted of 669 adults over 20 years old, 264 adolescents aged 12 to 19 years old and 391 children under 11 years old from both genders. The samples were collected at the end of 2007 and during 2008 in different city zones. Higher blood lead concentration was significantly associated with gender, smoking, offal intake, area of residence and age. The blood cadmium concentration was significantly associated with gender, smoking, consumption of distilled beverages and age. The reference values of lead and cadmium established for adults above 20 years old were 33 μg/L and 0.6 μg/L, respectively, for adolescents (12 to 19 years old) were 31 μg/L and 0.6 μg/L, respectively and for children under 11 years old were 29 μg/L and 0.2 μg/L, respectively. The results of this study indicate that the exposure levels of the investigated population to lead and cadmium are low.

The association between blood lead level and clinical mental disorders in fifty thousand lead-exposed male workers

BACKGROUND

While there has been research into the relationship between blood lead (BPb) level and mental disorders, there have been few investigations that use clinically diagnosed mental disorders in the adult population with a retrospective cohort study design. Hence, our study investigated the association between BPb level and risk of clinically diagnosed mental disorders.

METHODS

The data of male workers exposed to lead (Pb; n=54,788) were collected from annual Pb associated medical check-ups from 2000 to 2004 in Korea. The workers' hospital admission histories due to mental disorders (International Classification of Diseases, 10th revision, F00-F99) were used to identify clinically diagnosed mental disorders. After merging the data, the hazard ratio (HR) with a 95% confidence interval (95% CI) was calculated by survival analysis using the Cox proportional hazards model according to the quartile level of BPb (1st quartile<4.10 μg/dl, 2nd quartile<6.04 μg/dl, 3rd quartile<10.00 μg/dl, and 4th quartile≥10 μg/dl).

RESULTS

In a total of 54,788 workers, there were 223 admission cases of mental disorders (F00-F99) during the follow-up period. The HR (95% CI) of total mental and behavioral disorders (F00-F99) was 1.63 (1.12-2.39) in the 4th quartile group compared to the HR of the 1st quartile group after adjusting for age. The HR (95% CI) of the 4th quartile group was 2.59 (1.15-5.82) for mood (affective) disorders (F30-F39).

LIMITATION

The hospital admission data, not outpatient data, were used for current study while almost affective disorder treated at outpatient clinic level.

CONCLUSION

Our study highlighted that Pb exposure can cause clinical mental disorders that require hospital admission in adult male workers. Our relatively large sample size strengthens the evidence of the association between BPb level and risk of clinically diagnosed mental disorders.

Current sources of lead exposure and their relative contributions to the blood lead levels in the general adult population of Northern France: The IMEPOGE Study, 2008-2010

There is justification for limiting lead (Pb) exposure as much as possible, given its impact on health at low concentrations. Consequently, the aim of this study was to measure blood lead levels (BLL) and examine exposure factors related to BLL variations in the general adult population of northern France, a current and past industrial area. Two thousand inhabitants of northern France, aged between 20 and 59 years, were recruited using the quota method with caution. Blood lead levels were quantified by inductively coupled plasma-mass spectroscopy (ICP-MS), and variation factors were studied separately in men and women using multivariate stepwise linear and logistic regression models. The geometric mean of the BLL was 18.8 μg/L (95% confidence interval [CI]: 18.3-19.3). Occupational factors affected BLL only in men and represented 14% of total explained variance of BLL. External occupational factors significantly increasing mean levels of BLL were tobacco, consumption of some beverages (wine, coffee, tea, and/or tap water), raw vegetables, housing characteristics (built prior to 1948, Pb piping in the home) and do-it-yourself or leisure activities (paint stripping or rifle shooting). Consumption habits accounted together for 25% and 18% of the total explained variance, respectively, in men and women. Industrial environment did not significantly contribute to BLL variations. Blood lead levels observed in the general population of this industrial part of France did not appear to be excessively elevated compared to values found internationally. Nonetheless, these BLL remain a public health issue in regard to nonthreshold toxicity attributed to Pb.

The associations between metals/metalloids concentrations in blood plasma of Hong Kong residents and their seafood diet, smoking habit, body mass index and age

The concentrations of metals/metalloids in blood plasma collected from 111 healthy residents (51 female, 60 male) in Hong Kong (obtained from the Hong Kong Red Cross Blood Transfusion Service, from March to April 2008) were quantified by means of a double-focusing sector field inductively coupled plasma optical emission spectrometer (ICP-OES). Results showed that concentrations of these toxic metals such as Hg, Cd, and Pb in Hong Kong residents were not serious when compared with other countries. Males accumulated significantly higher (p < 0.05 or 0.01) Fe (female 0.92 mg/L; male 1.28), Sn (0.44 μg/L; 0.60), Cr (0.77; 0.90), Hg (1.01; 1.73), and Pb (23.4; 31.6) than females. Smokers accumulated significantly higher (p < 0.05) Cd (smoker 0.27 μg/L; nonsmoker 0.17) and Pb (32.8; 17.6) than nonsmokers. Positive correlations were found between concentrations of As, Cd, Pb, and Hg, with respect to seafood diet habit, body mass index (BMI), and age. More intensive studies involving more samples are needed before a more definite conclusion can be drawn, especially on the causal relationships between concentrations of metals/metalloids with dietary preference and lifestyle of the general public.

Blood Mercury and Insulin Resistance in Nondiabetic Koreans (KNHANES 2008-2010)

PURPOSE

Blood mercury levels are associated with inflammation, and chronic low-grade inflammation is a cause of insulin resistance. This study aimed to investigate the association between serum mercury and insulin resistance.

MATERIALS AND METHODS

Subjects from the 2008-2010 Korean National Health and Nutrition Examination Survey were selected (n=29235) and the relevant data of 5388 subjects (2643 males and 2745 females) were analyzed cross-sectionally. Homeostasis Model Assessment for Insulin Resistance (HOMA-IR) was compared according to blood mercury quartiles, and the odds ratio (OR) of having the highest quartile of HOMA-IR according to blood mercury quartiles was calculated.

RESULTS

Blood mercury levels in men and women were 29.4 nmol/L and 20.5 nmol/L, respectively, and fasting blood sugar (FBS), insulin, and HOMA-IR were significantly correlated with blood mercury levels. The correlation was stronger in men than in women. In men, FBS and HOMA-IR showed step-wise increases as the quartiles of blood mercury increased; only HOMA-IR differed significantly in the third and fourth blood mercury quartiles, compared to the first quartile. In women, however, both FBS and HOMA-IR differed significantly in the third and fourth blood mercury quartiles, compared to the first quartile. Among men, the OR of being in the highest HOMA-IR quartile was greatest for the highest blood mercury quartile (OR=1.720, 95% CI; 1.172-2.526), compared with the lowest quartile.

CONCLUSION

In this large population-based study, blood mercury levels were weakly correlated with HOMA-IR and may be a risk factor for insulin resistance in nondiabetic Koreans.