Dae-Won Kang

Determination of arsenic species in rice grains using HPLC-ICP-MS

Determination of As species in rice is necessary because inorganic As species (arsenate (AsV) and arsenite (AsIII)) are more toxic than organic As (monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA)). This study evaluated the As species in Korean and USA rice grains. Levels were determined using microwave extraction and high performance liquid chromatography coupled with inductively coupled plasma-mass spectrometry (HPLC-ICPMS). Arsenite and DMA were the major species detected in Korean and USA rice. The percentage of inorganic As was 76.94% (54.50–87.86%) for Korean rice and 69.28% (52.94–72.92%) for USA samples. The order and percentage of As species observed in Korean and USA rice were AsIII (70%)>DMA (24%)>AsV (5%)>MMA (1%), and AsIII (64%)>DMA (28%)>AsV(5%)>MMA (3%), respectively. The AsIII concentrations were not significantly different in Korean rice grains, compared to USA grains. The high AsIII predominance indicates an elevated toxic effect of As in rice grains and needs further attention.

Transfer Factor of Heavy Metals from Agricultural Soil to Agricultural Products

BACKGROUND: The Transfer Factor (TF) of heavy metals from soil to plant is important, because TF is an indicator of heavy metal in soils and a factor that quantifies bioavailability of heavy metals to agricultural products. This study was conducted to investigate the transfer ability of Arsenic (As), Cadmium (Cd), and Lead (Pb) from soil to agricultural products. METHODS AND RESULTS: We investigated heavy metals (As, Cd and Pb) concentrations in 9 agricultural products (rice, barely, corn, pulse, lettuce, pumpkin, apple, pear, tangerin) and soil. TF of agricultural products was evaluated based on total and HCl-extractable soil concentration of As, Cd, and Pb. Regression analysis was used to predict the relationship of total and HCl-extractable concentration with agricultural product contents of As, Cd, and Pb. The result showed that TF was investigated average 0.006~0.309 (As), 0.002~6.185 (Cd), 0.003~0.602 (Pb). The mean TF value was the highest as rice 0.309 in As, lettuce 6.185, pear 0.717, rice 0.308 in Cd, lettuce 0.602, pumpkin 0.536 in Pb which were dependent on the vegetable species and cereal is showed higher than fruit-vegetables in As. CONCLUSION(S): Soil HCl-extractable concentration of As, Cd, and Pb had the larger effects on thier contents in agricultural products than total soil concentrations. We suggests that TF are served as influential factor on the prediction of uptake. Further study for uptake and accumulation mechanism of toxic metals by agricultural products will be required to assess the human health risk and need TF of more agricultural products.

Monitoring and Risk Assessment of Heavy Metals in Edible Mushrooms

BACKGROUND: Many edible mushrooms are known to accumulate high levels of heavy metals. This research was focused on health risk assessment to investigate the mushrooms in Korea, arsenic (As), cadmium (Cd), lead (Pb) and mercury (Hg) contaminations in edible mushrooms in cultivated areas were investigated, and health risk was assessed through dietary intake of mushrooms. METHODS AND RESULTS: The heavy metals in mushrooms were analyzed by ICP/MS after acid digestion. Probabilistic health risk were estimated by Monte-Carlo simulation techniques. The average contents of As, Cd, Pb, and Hg were mg/kg, mg/kg, mg/kg, and mg/kg, respectively. The results showed that contents of Cd and Pb did not exceed maximum residual levels established by European Uion regulation (Cd 0.20 mg/kg and Pb 0.30 mg/kg). For health risk assessment, estimated intakes in all age populations did not exceed the provisional tolerable daily intake of As and Hg, provisional tolerable monthly intake of Cd, provisional tolerable weekly intake of Pb. The Hazard Index (HI) were ranged from for As, for Cd, for Pb, and for Hg at general population. CONCLUSION: The HI from the ratio analysis between daily exposure and safety level values was less than 1.0. This results demonstrated that human exposure to heavy metals through dietary intake of mushrooms might not cause adverse effect.

A Study on the Factors Causing Analytical Errors through the Estimation of Uncertainty for Cadmium and Lead Analysis in Tomato Paste

BACKGROUND: This study aimed to estimate the mea- surement uncertainty associated with determination of cadmium and lead from tomato paste by ICP/MS. The sources of measurement uncertainty (i.e. sample weight, final volume, standard weight, purity, molecular weight, working standard solution, calibration curve, recovery and repeatability) in associated with the analysis of cadmium and lead were evaluated. METHODS AND RESULTS: The guide to the expre- ssion of uncertainty was used for the GUM (Guide to the expression of Uncertainty in Measurement) and Draft EURACHEM/CITAC (EURACHEM: A network of organization for analytical chemistry in Europe/ Co-Operation on International Traceability in Analytical Chemistry) Guide with mathematical calculation and statistical analysis. The uncertainty components were evaluated by either Type A or Type B methods and the combined standard uncertainty were calculated by statistical analysis using several factors. Expected un- certainty of cadmium and lead was 0.106±0.015 mg/kg (k=2.09) and 0.302±0.029 mg/kg (k=2.16), on basis of 95% confidence of Certified Reference Material (CRM) which was within certification range of 0.112±0.007 mg/kg for cadmium (k=2.03) and 0.316±0.021 mg/kg for lead (k=2.01), respectively. CONCLUSION(s): The most influential components in the uncertainty of heavy metals analysis were confirmed as recovery, standard calibration curve and standard solution were identified as the most influential compo- nents causing uncertainty of heavy metal analysis. Therefore, more careful consideration is required in these steps to reduce uncertainty of heavy metals ana- lysis in tomato paste.

Inorganic As Concentration in Rice Grown Around the Abandoned Mining Areas and its Health Risk Assessment

The current study was carried out to investigate total and inorganic arsenic (As) concentrations in 112 rice samples (husked rice and polished rice) grown around the abandoned mining areas and to estimate the potential health risk through dietary intake of rice in Korea. Mean concentrations of total As in husked rice and polished rice were 0.23 and 0.13 mg kg -1 , respectively. Also, average inorganic As concentrations in husked rice and polished rice were 0.09 and 0.05 mg kg -1 , respectively. These levels are lower than the standard guideline value (0.2 mg kg -1 ) for inorganic As in polished rice recommended by Korea Ministry of Food and Drug Safety and Codex. For health risk assessment, the average values of cancer risk probability was 5.7×10 -5 which was less than the acceptable cancer risk of 10 -6 ~10 -4 for regulatory purpose. Also, hazard quotient values were lower than 1.0. Therefore, these results demonstrated that human exposure to inorganic As through dietary intake of rice collected from abandoned mining areas might not cause adverse health effects.

Prediction of Arsenic Uptake by Rice in the Paddy Fields Vulnerable to Arsenic Contamination

Received: March 16, 2017 Revised: May 3, 2017 Accepted: May 3, 2017 There is an increasing concern over arsenic (As) contamination in rice. This study was conducted to develope a prediction model for As uptake by rice based on the physico-chemical properties of soil. Soil and brown rice samples were collected from 46 sites in paddy fields near three different areas of closed mines and industrial complexes. Total As concentration, soil pH, Al oxide, available phosphorus (avail-P), organic matter (OM) content, and clay content in the soil samples were determined. Also, 1.0 N HCl, 1.0 M NH4NO3, 0.01 M Ca(NO3)2, and Mehlich 3 extractable-As in the soils were measured as phytoavailable As concentration in soil. Total As concentration in brown rice samples was also determined. Relationships among As concentrations in brown rice, total As concentrations in soils, and selected soil properties were as follows: As concentration in brown rice was negatively correlated with soil pH value, where as it was positively correlated with Al oxide concentration, avail-P concentration, and OM content in soil. In addition, the concentration of As in brown rice was statistically correlated only with 1.0 N HCl-extractable As in soil. Also, using multiple stepwise regression analysis, a modelling equation was created to predict As concentration in brown rice as affected by selected soil properties including soil As concentration. Prediction of As uptake by rice was delineated by the model [As in brown rice = 0.352 + 0.00109 * HCl extractable As in soil + 0.00002 * Al oxide + 0.0097 * OM + 0.00061 * avail-P – 0.0332 * soil pH] (R = 0.714). The concentrations of As in brown rice estimated by the modelling equation were statistically acceptable because normalized mean error (NME) and normalized root mean square error (NRMSE) values were -0.055 and 0.2229, respectively, when compared with measured As concentration in the plant.

Determination of Bioconcentration Factor of Heavy Metal (loid)s in Rice Grown on Soils Vulnerable to Heavy Metal (loid)s Contamination

Received: February 9, 2017 Revised: May 2, 2017 Accepted: May 4, 2017 There is an increasing concern over heavy metal (loid) contamination of soil in agricultural areas including paddy soils. This study was conducted to determine the bioconcentration factor (BCF) for heavy metal (loid)s to brown rice grown in paddy soils vulnerable to heavy metal (loid)s contamination, for the quantitative health risk assessment to the residents living nearby the metal contaminated regions. The samples were collected from 98 sites nationwide in the year 2015. The mean and range BCF values of As, Cd, Cu, Ni, Pb, and Zn in brown rice were 0.027 (0.001 ~ 0.224), 0.143 (0.001 ~ 2.434), 0.165 (0.039 ~ 0.819), 0.028 (0.005 ~ 0.187), 0.006 (0.001 ~ 0.048), and 0.355 (0.113 ~ 1.263), respectively, with Zn showing the highest. Even though the relationship between heavy metal (loid) contents in the vulnerable soils and metal contents in brown rice collected at the same fields was not significantly correlated, the relationship between log contents of heavy metal(loid)s in the vulnerable soils and BCF of brown rice wes significantly correlated with As, Cd, Cu, and Zn in rice. In conclusion, soil environmental risk assessment for crop uptake should consider the bioconcentration factor calculated using both the initial and vulnerable heavy metal (loid) contents in the required soil and the crop cultivated in the same fields.

Adverse Effects on Crops and Soils Following an Accidental Release of Hydrogen Fluoride and Hydrofluoric Acid

A number of accidents relating to highly toxic hydrogen fluoride (HF) or hydrofluoric acid (HA) release have occurred over fast few decades in Korea. Thus, this study was conducted to investigate the fluoride (F) concentrations in paddy soil and brown rice from 2 different areas where the soils were exposed to HF and HA. In the first case, the HF leakage accident that occurred in 2012 affected the surrounding soils and crops and consequently, crops (rice) affected by HF were unavailable for forage even though F did not accumulate in the soil. For example, at the time of accident, F concentrations in brown rice samples were 33.0-1,395 mg kg-1, while F concentrations in soil samples were 155-295 mg kg -1 which were less than the Korean standard guideline values of 400 mg kg -1 . However, after a year, F concentrations in brown rice were observed below the detection limit (1 mg kg -1 ), although F concentrations in soils were similar with those in 2012. Also, large amounts of wastewater discharges containing HA occurred in 2013 and some agricultural soils exceeded the Korean standard guideline values for F (400 mg kg-1), but soil-plant F transfer was not observed. In conclusion, it was observed that soil to plant transfer of F is unlikely although HF and HA as gas or liquid form can cause direct damage to plants.

Distribution of Arsenic Fraction in Soil Around Abandoned Mining Area and Uptake by Rice

Arsenic (As) contamination of agricultural soils resulting from mining activity has caused major concern due to the potential health risk. Therefore the current study was carried out to investigate the relationship between fractionation of As in soil and rice uptake and to provide a basic information for adequate management of As contaminated agricultural soil. Twenty agricultural soils and rice affected by the abandoned mining sites were collected. Soil chemical properties and As concentrations (total and sequential extracted) in soils were determined and As concentrations in polished rice were analyzed. The average concentration of As in non-specifically adsorbed (F1), specifically adsorbed (F2), amorphous hydrous oxides of Fe and Al (F3), crystalline hydrous oxides of Fe and Al (F4) and residual phase (F5) were 0.08, 1.38, 10.34, 3.26 and 10.98 mg kg -1 , respectively. Both soil pH and available phosphorus were positively correlated with the concentrations of As in F1 and F2. These results indicate that increasing the soil pH and available phosphorus can significantly increase the easily mobile fractions of As (F1 and F2). The average concentration of As in polished rice was 0.09 mg kg -1 . The concentrations of As in F1 and F2 showed a positive correlation with the concentrations of As in polished rice. Therefore soil pH and available phosphorus affect the distribution of As fractionation in soils and thus affect As bioavailability.