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DERMAL ABSORPTION OF DICHLORO : AND TRICHLOROACETIC ACIDS FROM CHLORINATED WATER
KIM, HEKAP,CLIFFORD P. WEISEL 江原大學校 附設 環境硏究所 1999 環境硏究 Vol.16 No.-
Dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA) are major nonvolatile disinfection by-products of water chlorination. These compounds are currently being considered for regulation because of potential adverse health effects. In the current study, DCAA and TCAA dermal exposures were investigated in four human subjects during a thirty minute walk or swim in a pool by measuring the pool water concentrations and urinary excretion rates of DCAA and TCAA. These two compounds were eliminated in urine within approximately 3 hours of the exposure, with the dermal DCAA dose being ~6 ㎍ from pool water containing 600 ㎍/L. The amount of water ingested by each subject during a 30 minute swim was estimated to be between 12 and 45 mL. The DCAA permeability coefficient at pH 7 was calculated to be between 1 and 8×10^(-3) ㎝/h, when assuming that only 3% of the dermal dose, as was observed for ingestion, was excreted and between 2 and 9×10^(-5) ㎝/h, assuming that 48% of the dermal dose, an upper limit, was excreted. Exposure estimates indicate that ingestion is the major route of exposure and that the dermal contribution during typical household uses is a minor contributor to the total exposure of these compounds from chlorinated drinking water.
Hekap Kim,Thu Thi Hoai Mai 한국식품과학회 2020 한국식품과학회지 Vol.52 No.5
The present study investigated the effects of dry and moist heat treatments on total phenols, total anthocyanins, and antioxidant activity levels in black chokeberry (Aronia melanocarpa) fruits. Lyophilized chokeberry powder samples were heated in a drying oven at 60, 100, 160, 180, and 200oC for 20, 40, or 60 min. Finely ground fresh chokeberry fruits were heated in water at 60, 80, and 100℃ for 20 min, and bioactive compound and antioxidant activity levels were measured. The bioactive compounds and antioxidant activity decreased with increasing temperature and treatment duration. Antioxidant activity was preserved at 160℃ or lower without significant loss for dry heating, whereas moist heat treatment increased both bioactive compounds and antioxidant activity with increasing temperature.
Kim, Hekap,Patricia Haltmeier,Judith B. Klotz,Clifford P. Weisel 江原大學校 附設 環境硏究所 1999 環境硏究 Vol.16 No.-
A study wss conducted to determine if DCAA and TCAA urinary excretion rates are valid biomarkers of chronic ingestion exposure to these disinfection by-products of chlorination of drinking water. Entire first morning urine voids, time-of-visit urine samples, and tap water samples were collected from 47 female subjects. In addition, a 48-h recall questionnaire was administered to determine the amounts and types of liquids ingested by each subject as well as other exposures that could lead to DCAA and TCAA urinary excretion. The TCAA excretion rate for the first morning urine samples was significantly correlated with estimated 48-h TCAA ingestion exposure for 25 subjects whose ingestion exposures primarily occurred at home, while the DCAA excretion rate was not correlated with the DCAA ingestion exposure. Thus, urinary TCAA appears to be a valid biomarker of chronic ingestion exposure to TCAA from chlorinated water, while urinary DCAA is not. It is proposed that the difference in the biological half-lives between these two compounds is the rationale for this finding. The bilogical half-life of TCAA is longer than successive exposure intervals; thus TCAA accumulates until it reaches a steady state. The halflife of DCAA is shorter than successive exposure intervalsl; thus DCAA is almost coplectely metabolized following an exposure and is eliminated from the bodly. This study suggests that biological half-life, exposure interval, and sample collection interval should be considered in selecting biomarkers and designing studies to validate them.
Kim, Dasom,Jung, Sungjin,Lee, Gunyoung,Yun, Sang Soon,Lim, Ho Soo,Kim, Hekap The Korean Society of Analytical Science 2017 분석과학 Vol.30 No.2
This study was conducted to develop an analytical technique for determination of chlorite and chlorate concentrations in fresh-cut food and dried fish products by an ion chromatography/conductivity detection method using a hydroxide mobile phase. Deionized water was added to homogenized samples, which were then extracted by ultrasound extraction and centrifuged at high speed (8,500 rpm). Subsequently, a Sep-Pak tC18 cartridge was used to purify the supernatant. Chlorite and chlorate ions were separated using 20 mM KOH solution as the mobile phase and Dionex IonPac AS27 column as the stationary phase. Ethylenediamine was used as sample preservative and dibromoacetate was added to adjust for the disparity in extraction efficiencies between the food samples. The method detection limit) for chlorite and chlorate were estimated to be 0.2 mg/kg and 0.1 mg/kg, respectively, and the coefficient of determination ($r^2$) that denotes the linearity of their calibration curves were correspondingly measured to be 0.9973 and 0.9987. The recovery rate for each ion was 92.1 % and 96.3 %, with relative standard deviations of 7.47 % and 6.18 %, respectively. Although neither chlorite nor chlorate was detected in the food samples, the analytical technique developed in this study may potentially be used in the analysis of disinfected food products.
Ingestion Exposure to Nitrosamines in Chlorinated Drinking Water
Hekap Kim,Kichan Han 환경독성보건학회 2011 환경독성보건학회지 Vol.26 No.-
Objectives: N-Nitrosodimethylamine (NDMA) is classified as a probable human carcinogen by the United States Environmental Protection Agency (US EPA) and is formed during the chlorination of municipal drinking water. In this study, selected nitrosamines were measured in chlorinated drinking water collected from Chuncheon, Kangwon-do, Republic of Korea, and a risk assessment for NDMA was conducted. Methods: Twelve water samples were collected from 2 treatment plants and 10 household taps. Samples were analyzed for 6 nitrosamines via solid-phase extraction cleanup followed by conversion to dansyl derivatives and high-performance liquid chromatography-fluorescence detection (HPLC-FLD). Considering the dietary patterns of Korean people and the concentration change of NDMA by boiling, a carcinogenic risk assessment from ingestion exposure was conducted following the US EPA guidelines. Results: NDMA concentrations ranged between 26.1 and 112.0 ng/ℓ. NDMA in water was found to be thermally stable, and thus its concentration at the end of boiling was greater than before thermal treatment owing to the decrease in water volume. The estimated excess lifetime carcinogenic risk exceeded the regulatory baseline risk of 10-5. Conclusions: This result suggests that more extensive studies need to be conducted on nitrosamine concentration distributions over the country and the source of relatively high nitrosamine concentrations.