Development of sarcopenia assessment system using balance and gait ability: Preliminary tests in the elderly.

BACKGROUND: Sarcopenia is a disease that has recently become an issue, and research on various assessment methods is being conducted based on guidelines published for the diagnosis of sarcopenia. However, most assessments are complex because the inspector must measure each device to collect data, or the elderly must directly manipulate and get assessment. OBJECTIVE: In this study, we developed an sarcopenia assessment system to assess and analyze various sarcopenia in one system. METHODS: The system consists of a scaffold sensor for balance ability assessment, a chair sensor for assessing the walking and lower extremity function, and a hand-held dynamometer for assessing grip strength. The balance pad consists of 326 FSR (Force Sensitive Resistor) sensors, and the accuracy is 10 kg/± 10%. The chair sensor applied four weight sensors (Loadcells) to the corner of the hip of the chair, and the accuracy is up to 150 kg ± 10%, and the resolution is 1 kg ± 10%. All data is transmitted to the software through a USB cable to assess sarcopenia through data analysis. The software has built a database to manage user-specific data. The assessment items consisted of "Short Physical Performance Battery (SPPB) Test" and "Hand Grip Strength Test." After completion, the software automatically terminates the assessment results and classifies sarcopenia according to the presented reference value. RESULTS: The average value of the total SPPB test scores, including the balance test, gait speed test, and chair stand test, of all participants was 9.06 ± 1.97. The average values of the balance test, gait speed test, and chair stand test scores of all participants were 8.48 ± 2.80 sec (score 3.28 ± 1.23), 1.05 ± 0.26 m/sec (score 3.69 ± 0.79), and 16.05 ± 4.62 sec (score 2.08 ± 1.13). The average value of the hand grip test of all participants was 28.57 ± 2.94 kgf. CONCLUSIONS: A preliminary assessment was conducted on the elderly in their 60 s or older with the developed system, and its performance confirmed that the assessment and result analysis were conducted well without any errors in software or hardware. Future studies intend to verify the reliability and accuracy of the assessment results compared to the existing direct measurement methods. In addition, we would like to conduct a study to establish data on the muscle reduction index by age group of Koreans.

One-step hydrothermal synthesis of CuS/MoS2 composite for use as an electrochemical non-enzymatic glucose sensor.

Early diagnosis may be crucial for the prevention of chronic diabetes mellitus. For that herein, we prepared a CuS/MoS2 composite for a non-enzymatic glucose sensor through a one-step hydrothermal method owing to the synergetic effect of CuS/MoS2. The surface morphology of CuS/MoS2 was studied by Field Emission Scanning Electron Microscopy (FESEM) and Cs-corrected Scanning Transmission Electron Microscopy (Cs-STEM). The crystallinity and surface composition of CuS/MoS2 were analyzed by X-ray Diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS) respectively. The working electrode was prepared from CuS/MoS2 electrocatalyst, and for that dispersed solution of electrocatalyst was used to fabricate the material-loaded glassy carbon electrode (GC). CuS/MoS2 composite shows the viability of electrocatalyst to oxidize glucose in an alkaline solution with sensitivity and detection limit of 252.71 µA mM-1 cm-2 and 1.52 µM respectively. The proposed glucose sensor showed reasonable stability and potential selectivity during electrochemical analysis. Accordingly, the CuS/MoS2 composite has potential as a viable material for glucose sensing in diluted human serum.

Copper nanoparticles/polyaniline/molybdenum disulfide composite as a nonenzymatic electrochemical glucose sensor.

A Cu@Pani/MoS2 nanocomposite was successfully synthesized via combined in-situ oxidative polymerization and hydrothermal reaction and applied to an electrochemical nonenzymatic glucose sensor. The morphology of the prepared Cu@Pani/MoS2 nanocomposite was characterized using FE-SEM and Cs-STEM, and electrochemical analysis was performed using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and chronoamperometry techniques. Electrostatic interaction between Cu@Pani and MoS2 greatly enhanced the charge dispersion, electrical conductivity, and stability, resulting in excellent electrochemical performance. The Cu@Pani/MoS2 was used as an electrocatalyst to detect glucose in an alkaline medium. The proposed glucose sensor exhibited a sensitivity, detection limit, and wide linear range of 69.82 µAmM-1cm-2, 1.78 µM, and 0.1-11 mM, respectively. The stability and selectivity of the Cu@Pani/MoS2 composite for glucose compared to that of the potential interfering species, as well as its ability to determine the glucose concentration in diluted human serum samples at a high recovery percentage, demonstrated its viability as a nonenzymatic glucose sensor.

Nanoarchitectonics of Three-Dimensional Carbon Nanofiber-Supported Hollow Copper Sulfide Spheres for Asymmetric Supercapacitor Applications.

Three-dimensional carbon nanofiber (3D-CNF)-supported hollow copper sulfide (HCuS) spheres were synthesized by the facile hydrothermal method. The morphology of the as-synthesized HCuS@3D-CNF composite clearly revealed that the 3D-CNFs act as a basement for HCuS spheres. The electrochemical performance of as-synthesized HCuS@3D-CNFs was evaluated by cyclic voltammetry (CV) tests, gravimetric charge-discharge (GCD) tests, and Nyquist plots. The obtained results revealed that the HCuS@3D-CNFs exhibited greater areal capacitance (4.6 F/cm2) compared to bare HCuS (0.64 F/cm2) at a current density of 2 mA/cm2. Furthermore, HCuS@3D-CNFs retained excellent cyclic stability of 83.2% after 5000 cycles. The assembled asymmetric device (HCuS@3D-CNFs//BAC) exhibits an energy density of 0.15 mWh/cm2 with a working potential window of 1.5 V in KOH electrolyte. The obtained results demonstrate that HZnS@3D-CNF nanoarchitectonics is a potential electrode material for supercapacitor applications.

Toxicokinetic analyses of naphthalene, fluorene, phenanthrene, and pyrene in humans after single oral administration.

Polycyclic aromatic hydrocarbons (PAHs) are generated by incomplete combustion of organic matter. They have health effects in multiple organs and can cause lung, skin, and bladder cancers in humans. Although data regarding their toxicity is available, information on the absorption, distribution, metabolism, and excretion of PAHs in humans is very limited. In the present study, deuterium-labeled naphthalene (Nap), fluorene (Flu), phenanthrene (Phe), and pyrene (Pyr) were orally administered as a single dose (0.02-0.04 mg/kg) to eight healthy adults. Both serum and urine samples were monitored for 72 h after the exposure. Parent compounds and PAH metabolites (monohydroxy-PAHs; OH-PAHs) were measured by headspace-solid phase microextraction coupled with gas chromatography-mass spectrometry and high-performance liquid chromatography-tandem mass spectrometry, respectively. Based on the time-concentration profiles in serum and urine, non-compartmental analysis was performed, and two-compartment models were constructed and validated for each PAH. Subsequently, all of the parent compounds were rapidly absorbed (Tmax: 0.25 to 1.50 h) after oral administration and excreted in urine with a biological half-life (T1/2) of 1.01 to 2.99 h. The fractional urinary excretion (Fue) of OH-PAHs ranged from 0.07 % to 11.3 %; their T1/2 values ranged from 3.4 to 11.0 h. The two-compartment models successfully described the toxicokinetic characteristics of each PAH and its metabolites. Fue and the two-compartment models could be useful tools for exposure simulation or dose-reconstruction of PAHs. The results of this study will provide useful information for interpreting biomonitoring data of PAHs.

Pharmacokinetics of transdermal methyl-, ethyl-, and propylparaben in humans following single dermal administration.

Parabens are common chemicals used as preservatives in foods, cosmetics, and personal care products. Although transdermal exposure to parabens occurs, studies on human pharmacokinetics (PK) following dermal exposure to parabens are scarce. In this study, the PK following dermal exposure to parabens was determined and compared with our previous findings on oral exposure. A paraben mixture cream containing 0.8% deuterated methyl-, ethyl-, and propylparaben (MeP-d4 0.26%; EtP-d4 0.26%, and PrP-d4 0.28%) was dermally applied to the whole arm of five male volunteers at a dose of 24 g/person over 30 min. Blood and urine samples were collected at several intervals over the course of 48 h to measure the levels of MeP-d4, EtP-d4, and PrP-d4 and their conjugated metabolites using HPLC-MS/MS. As a result of non-compartmental analysis, the average peak values of total (sum of conjugated and unconjugated metabolites) MeP-d4, EtP-d4, and PrP-d4 were reached at 7.8 h, 10.5 h, and 5.3 h, indicating a slower absorption rate compared to that of oral exposure (<2 h). The terminal elimination half-lives of MeP-d4, EtP-d4, and PrP-d4 were 12.2 h, 12.0 h, and 9.3 h, respectively. Fractional urinary excretion (Fue) of total MeP-d4, EtP-d4, and PrP-d4 was 1.7%, 2.3%, and 1.9%, respectively. The Fue of total and unconjugated PrP-d4 following dermal exposure was five times lower and three times higher, respectively, compared with those after oral exposure, suggesting that PrP is relatively less metabolized to the conjugated form after dermal exposure. Taken together, dermal exposure to paraben leads to a longer apparent half-life and results in higher proportions of biologically active unconjugated parabens in the systemic circulation as compared to oral exposure. This study provides insights into the kinetic properties of parabens and their metabolites in humans.

Concentrations of blood and urinary arsenic species and their characteristics in general Korean population.

Arsenic (As) exposure has been extensively studied by investigating As species (e.g., inorganic arsenic (iAs), monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA)) in urine, yet recent research suggests that blood could be a possible biomarker of As exposure. These investigations, however, were conducted on iAs-contaminated areas, and evidence on populations exposed to low levels of iAs is limited. This study aimed to describe the levels and distributions of As species in urine and blood, as well as to estimate methylation efficiency and related factors in the Korean population. Biological samples were obtained by the Korean Ministry of Food and Drug Safety. A total of 2025 urine samples and 598 blood samples were utilized in this study. Six As species were measured using ultra-high-performance liquid chromatography with inductively coupled plasma mass spectrometry (UPLC-ICP-MS): As(V), As(III), MMA, DMA, arsenobetaine (AsB), and arsenocholine (AsC). Multiple linear regression models were used to examine the relationship between As species (concentrations and proportions) and covariates. AsB was the most prevalent species in urine and blood. The relative composition of iAs, MMA, DMA, and AsC in urine and blood differed significantly. Consumption of blue-backed fish was linked to higher levels of AsB in urine and blood. Type of drinking water and multigrain rice consumption were associated with increased iAs concentration in urine. Except for iAs, every species had correlations in urine and blood in both univariate and multivariate analyses. Adolescents and smokers presented a lower methylation efficiency (higher %MMA and lower %DMA in urine) and females presented a higher methylation efficiency (lower %iAs, %MMA, and higher %DMA in urine). In conclusion, blood iAs concentration cannot represent urinary iAs; nonetheless, different compositions of urine and blood might reflect distinct information about iAs exposure. Further investigations on exposure factors and health are needed using low-exposure groups.

Chitosan polymer matrix-derived nanocomposite (CuS/NSC) for non-enzymatic electrochemical glucose sensor.

In this study, N and S co-doped chitosan polymer matrix-derived composite (CuS/NSC) was synthesized via a one-step hydrothermal technique using a low-cost copper complex of chitosan polymer. Cyclic voltammetry and chronoamperometry revealed excellent electrocatalytic performance. The glucose sensor exhibited a linear range of 160 µM to 11.76 mM, a low detection limit 2.72 µM and a sensitivity of 13.62 mA mM-1 cm-2 with an excellent linear response. Furthermore, the sensor also displayed selectivity for glucose over potential interfering agents and exhibited a satisfactory recovery percentage using real sample in human serum. The results demonstrate that, CuS/NSC is an efficient nanocomposite material for non-enzymatic glucose sensors and is applicable for glucose detection in biological fluids.

Mercury Exposure and Associations with Hyperlipidemia and Elevated Liver Enzymes: A Nationwide Cross-Sectional Survey.

Mercury (Hg) has obesogenic properties. However, the associated health outcomes of population-level mercury exposure were unclear. This study investigated the relationships between blood mercury levels and obesity-related outcomes such as hyperlipidemia and elevated liver enzymes. Using the second cycle of the Korean National Environmental Health Survey (n = 6454), we performed logistic regression to examine the effects of Hg on hyperlipidemia and elevated liver enzymes. The blood mercury levels were significantly higher in the hyperlipidemia group (n = 3699, male: 4.03 µg/L, female: 2.83 µg/L) compared to the non-hyperlipidemia group (n = 2755, male: 3.48 µg/L, female: 2.69 µg/L), and high blood mercury levels were associated with an 11% higher risk of hyperlipidemia. The elevated liver enzymes group had higher mean blood mercury levels (n = 1189, male: 4.38 µg/L, female: 3.25 µg/L) than the normal group (n = 5265, male: 3.64 µg/L, female: 2.70 µg/L), and elevated blood mercury was associated with a 35% higher risk of elevated liver enzymes. Moreover, the effect was constant after adjusting for personal medications. These results indicate that mercury exposure is significantly associated with hyperlipidemia and elevated liver enzymes.

Pharmacokinetic profile of propyl paraben in humans after oral administration.

Parabens are commonly used as antimicrobial preservatives in consumer products. Because of their possible endocrine-disrupting activities, their safety has become a public concern. Although pharmacokinetic studies on parabens have been conducted in animals, limited information exists on their pharmacokinetic profiles in humans. In the present study, we determined the pharmacokinetic characteristics of propyl paraben (PP) in humans following a single oral administration of 0.6 mg/kg bw of deuterium labeled-PP. We also conducted experiment with similar design but different exposure amount (2.5 mg/kg bw) to verify the validity of the model to be developed. Blood and urine were collected at several intervals over the course of 48 h to measure levels of PP and its metabolites (conjugates and hydrolysates) in 12 male volunteers. The unconjugated parent compound (free PP), glucuronide and sulfate conjugates, p-hydroxybenzoic acid, and p-hydroxyhippuric acid were measured using HPLC-MS/MS. It was found that PP was rapidly absorbed via ingestion within 2 h and quickly eliminated (terminal half-life, 2.9 h). The fraction of administered dose excreted in the urine was 0.05% for free PP, 8.6% for total PP (free + conjugates), 23.2% for p-hydroxyhippuric acid, and 7.0% for p-hydroxybenzoic acid. Utilizing this pharmacokinetic profile, we successfully constructed a multi-compartment model where the disposition of PP was well described with two compartments and that of its metabolites was explained with first-order reactions. The present pharmacokinetic model provides insights into the kinetic properties of the disposition of PP and its metabolites in humans, and it can be used for risk assessment with biomonitoring of PP.

Risk assessment for phthalate exposures in the elderly: A repeated biomonitoring study.

Recent studies indicated that exposure to phthalates affects the development of a variety of diseases in the elderly population. However, limited information was available about the variability of phthalate daily intakes (DIs) and the proportion of the population that is highly exposed to phthalates. Therefore, we measured the levels of three phthalate metabolites, mono-(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), mono-(2-ethyl-5-oxohexyl) phthalate (MEOHP), and mono-n-butyl phthalate (MnBP) in 4014 urine samples repeatedly collected from 1646 elderly people. The DIs of di(2-ethylhexyl) phthalate (DEHP) and di-n-butyl phthalate (DnBP) were calculated using urinary MEHHP, MEOHP, and MnBP levels, and then the proportion of the population that was highly exposed to DEHP and DnBP was calculated. The intra-class correlation (ICC) for MEHHP, MEOHP, and MnBP levels was 0.07, 0.02, and 0.03, respectively, and exposures to DEHP and DnBP were strongly correlated with each other (correlation coefficient=0.89 and p-value<0.0001). The geometric mean of estimated DI was 8.8µg/kgbody-weight/day (range 0.005-3382.0) for DEHP and 1.5µg/kgbody-weight/day (range 0.0002-1076.8) for DnBP. The percentages of urine samples with DEHP > reference dose (RfD, 20µg/kgbody-weight/day) and DnBP > tolerable daily intake (TDI, 10µg/kgbody-weight/day) were 20.2% and 3.6%, respectively. The Korean elderly were co-exposed to DEHP and DnBP, and the variation of DEHP and DnBP metabolite levels was mainly attributed to intra-individual variation, rather than inter-individual variation. Furthermore, Korean elderly were exposed to the hazards of DEHP and DnBP based on the high level of the exceedance rate over TDI or RfD for DEHP and DnBP. Since the elderly are very susceptible to environmental pollutants, the harmful effects of DEHP and DnBP in the elderly population should be further studied in the future.

Prenatal contribution of 2, 2', 4, 4'-tetrabromodiphenyl ether (BDE-47) to total body burden in young children.

Many scientists made estimates of the body burden of PBDEs from breastmilk and house dust. Interestingly, they have not included the prenatal contribution to the body burden in young children after birth. In order to address how the prenatal contribution is important in the risk assessment of PBDEs in infants up to five years old, we used the median measurements of BDE-47 as a model chemical in 108 neonates in Korea, and made simulations of its disposition out of body from birth to five years. During the simulation periods, the environmental exposure was considered for house dust, babyfood, breastmilk consumption, etc., with assumption of typical exposure scenario applicable to general infants in Korea. About 22% of the total amounts of BDE-47 in newborn remained up to 5years after birth. The relative amounts of BDE-47 from the prenatal source were 20%, 14%, 10%, 8%, 6%, and 4% of the total body burden for 1-, 2-, 3-, 4- and 5-year after birth, respectively. The contribution from breastfeeding was 95.2% and 92.2% of the total postnatal exposure amounts at 6-month and 1-year after birth, respectively. After cease of breastfeeding at 1-yr, house dust and food were the important sources of exposure up to 5-yr; however, their contributions to the bodyburden were negligible with consideration of the remaining amounts of the analytes from the breastmilk and prenatal exposure. Suggestively, the innate amounts and pharmacokinetics should be counted in estimating bodyburden of BDE-47.

Placental and lactational transfer of decabromodiphenyl ether and 2,2',4,4'-tetrabromodiphenyl ether in dam-offspring pairs of Sprague-Dawley rats.

Although several studies have conducted maternal transfer of individual PBDE congener in experimental animals, there is a paucity of research on differences in maternal transfer of PBDE congeners. The purpose of the study was to investigate and compare placental and lactational transfer of BDE 47, -209 and its metabolites in rat dam-offspring pairs following repeated administration of BDE 47 and -209. 13C-BDE 47, BDE 209 and its debrominated congeners were detected both in dam serum and offspring body, which indicates that PBDEs can be maternally transferred. In addition, BDE 196 and -197 appeared in offspring body earlier than in maternal serum, which suggests that debromination can be occur in offspring body. BDE 209 increased in both dam and offspring while levels of 13C-BDE 47 was not increased in dam serum. 13C-BDE 47 seems to be stored in breast milk rather than in maternal serum, which can be assumed through the drastic increase of the congener in suckling pups. The magnitude of lactational transfer of the administered congeners was greater than that of placental transfer. And 13C-BDE 47 was relatively more transferred to suckling pups than BDE 209 through breastfeeding.

Temporal variability of blood lead, mercury, and cadmium levels in elderly panel study (2008-2014).

BACKGROUND: Biological measurements have been employed as useful biomarkers for exposure. Because of its property of reflecting toxicokinetic differences, however, within-subject variability leads to biased results in epidemiologic studies. METHOD: We examined the variability of lead (Pb), mercury (Hg), and cadmium (Cd) levels in blood samples from 1429 participants among 1677 elderly individuals aged over 60 years who lived in an urban area from August 2008 to April 2015. RESULTS: The geometric means of blood Pb, Hg, Cd were 1.92µg/dL, 2.48µg/L, and 1.33µg/L, and the intra-class correlations (ICCs) were 0.81, 0.71, and 0.83, respectively. The mean values of Pb and Hg levels in this study were lower than the results from single spot samples in other national biomonitoring surveys in Korea, with the exception of Cd was higher than those in other studies. Moreover, the predicted exceedances over the guidance levels for Pb, Hg, and Cd were 1.9%, 4.2%, and 0.3%, respectively. CONCLUSION: Korean elderly were exposed to high levels of Pb, Hg and Cd. Especially, those who had high levels of Cd were continuously exposed to Cd during study period with the 6 collection intervals. Therefore, factors affecting environmental Cd exposure should be further studied in the future.

Polybrominated Diphenyl Ethers in Maternal Serum, Breast Milk, Umbilical Cord Serum, and House Dust in a South Korean Birth Panel of Mother-Neonate Pairs.

Polybrominated diphenyl ethers (PBDEs) have been used as flame retardants. Although many reports have indicated an association between exposure to PBDEs and developmental neurotoxicity, the relative contributions of different sources of dust PBDE congeners to the levels in various tissues of mother-baby pairs is not well understood. The aims of this study were thus to measure the quantitative relationship between the level of PBDEs in house dust and tissues of mother-neonate pairs, and to investigate the chemical sources of the PBDEs. Forty-one mother-neonate pairs were recruited and provided samples of maternal serum (n = 29), umbilical cord serum (n = 25), breast milk (n = 50), and house dust (n = 41), where PBDEs were determined with high-resolution gas chromatography coupled with high-resolution mass spectrometry. While deca- (e.g., BDE 209, detected 100%), nona- (BDE 206/207, 95.1%), octa- (BDE 183, 100%), penta- (BDE 99/153, 100%, 98%) and tetra-BDEs (BDE 47, 100%) were detected abundantly in dust, penta- (BDE 99, 76%, 92%) and tetra-BDEs (BDE 47, 84%, 98%) were detected abundantly in umbilical cord serum and breast milk, respectively; tetra-BDEs (BDE 47, 86%) were detected more often relative to other congeners in maternal serum. Spearman's pairwise comparison showed that the levels of BDE 47 (ρ = 0.52, p < 0.001) and -99 (ρ = 0.64, p < 0.01) in umbilical cord serum were associated with BDE 209 levels in dust; BDE 47 in maternal serum also showed correlation with BDE 99 in cord serum (ρ = 0.48, p < 0.01) but there was no significant correlation between maternal BDE 47 and dust BDE 209. On the other hand, a comparison of the distribution among congeners suggested probable associations of BDE 47 in maternal serum, breast milk, and umbilical cord serum with BDE 209 in dust; and of BDE 99 in maternal and umbilical cord serum, breast milk, and dust with BDE 209 in dust. Although further studies are needed, a radar chart-based distributional comparison among congeners supported associations between BDE 47 or -99 in human tissues and BDE 209 in dust.

Validation of the Korean version of the Eating Disorder Inventory-2: psychometric properties and cross-cultural comparison.

PURPOSE: The purpose of the present study was to examine the validity and reliability of the Korean version of the Eating Disorder Inventory-2 (EDI-2) in Korean patients with eating disorders and healthy controls, and to investigate cultural differences of EDI-2 between a Korean group and a North American standardization sample. MATERIALS AND METHODS: The Korean version of the EDI-2 was prepared after comprehensive clinical assessment of Korean patients with eating disorders (n=327) as well as female undergraduates (n=176). Results were compared between eating disorder subgroups (anorexia nervosa, bulimia nervosa and eating disorders not otherwise specified) and those of a North American standardization sample and healthy controls. RESULTS: The results showed that the Korean EDI-2 had adequate internal consistency (0.77-0.93) and discriminated well between patients with eating disorders and healthy controls on all subscales. Significant differences in EDI-2 subscale scores between the eating disorder groups and the healthy control group were observed; however, there was no discernible difference among the eating disorder subgroups. When compared with a North American standardization sample, the Korean control group showed significantly higher scores for drive for thinness and asceticism. When patient groups were compared, the Korean group showed significantly lower scores for perfectionism. CONCLUSION: As expected, the results accurately reflected psychometric properties of the Korean version of EDI-2 for eating disorder patients in Korea. These findings also suggest that common characteristics for the eating disorder exist as a whole rather than with significant difference between each subgroup. In addition, significant differences between the Korean and the North American groups for both patients and controls also demonstrated specific cultural differences.

Sleep disturbance in women with eating disorder: prevalence and clinical characteristics.

The prevalence of sleep disturbance among 400 patients, diagnosed with anorexia nervosa (AN) or bulimia nervosa (BN), was assessed via structured interviews. Sleep disturbance was reported in 50.3% of patients, especially among those with the binge-eating/purging subtype. Patients with sleep disturbance had more disturbing symptoms; including higher binge frequency and vomiting frequency. Additional differences were also identified.

Seasonal variation in dissolved gaseous mercury and total mercury concentrations in Juam Reservoir, Korea.

Dissolved gaseous mercury (DGM) and total mercury (TM) concentrations were measured in Juam Reservoir, Korea. DGM concentrations were higher in spring (64+/-13pgL(-1)) and summer (109+/-15pgL(-1)), and lower in fall (20+/-2pgL(-1)) and winter (23+/-6pgL(-1)). In contrast, TM concentrations were higher in fall (3.2+/-0.1ngL(-1)) and winter (3.3+/-0.1ngL(-1)) than in spring (2.3+/-0.1ngL(-1)) and summer (2.2+/-0.4ngL(-1)). DGM concentrations were correlated with water temperature (p<0.0001), ORP (p<0.0001), UV intensity (UV-A: p=0.008; UV-B: p=0.003), and DOC concentration (p=0.0107). DGM concentrations varied diurnally with UV intensity. The average summer DGM (109+/-15pgL(-1)) and TM (2.2+/-0.4ngL(-1)) concentrations in Juam Reservoir were higher than the averages for North American lakes (DGM=38+/-16pgL(-1); TM=1.0+/-1.2ngL(-1)), but lower than levels reported for Baihua Reservoir in China.