Duck Soo Lim

Sungkyunkwan University, Sŏul, Seoul, South Korea

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Publications (9)23.36 Total impact

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    ABSTRACT: Plasticizers or plastic materials such as phthalates, bisphenol-A (BPA), and styrene are widely used in the plastic industry and are suspected endocrine-disrupting chemicals (EDC). Although plastic materials such as polypropylene (PP) and polyethylene terephthalate (PET) are not EDC and are considered to be safe, their potential properties as EDC have not been fully investigated. In this study, plastic samples eluted from plastic food containers (PP or PET) were investigated in Sprague-Dawley rats using Hershberger and uterotrophic assays. In the Hershberger assay, 6-wk-old castrated male rats were orally treated for 10 consecutive days with plastic effluent at 3 different doses (5 ml/kg) or vehicle control (corn oil, 1 ml/100 g) to determine the presence of both anti-androgenic and androgenic effects. Testosterone (0.4 mg/ml/kg) was subcutaneously administered for androgenic evaluation as a positive control, whereas testosterone (0.4 mg/ml/kg) and flutamide (3 mg/kg/day) were administered to a positive control group for anti-androgenic evaluation. The presence of any anti-androgenic or androgenic activities of plastic effluent was not detected. Sex accessory tissues such as ventral prostate or seminal vesicle showed no significant differences in weight between treated and control groups. For the uterotrophic assay, immature female rats were treated with plastic effluent at three different doses (5 ml/kg), with vehicle control (corn oil, 1 ml/100 g), or with ethinyl estradiol (3 μg/kg/d) for 3 d. There were no significant differences between test and control groups in vagina or uterine weight. Data suggest that effluents from plastic food containers do not appear to produce significant adverse effects according to Hershberger and uterotrophic assays.
    Journal of Toxicology and Environmental Health Part A 05/2013; 76(10):624-34. · 1.73 Impact Factor
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    ABSTRACT: d-Limonene, a major constituent of citrus oils, is a monoterpene widely used as a flavor/fragrance additive in cosmetics, foods, and industrial solvents as it possesses a pleasant lemon-like odor. d-Limonene has been designated as a chemical with low toxicity based upon lethal dose (LD50) and repeated-dose toxicity studies when administered orally to animals. However, skin irritation or sensitizing potential was reported following widespread use of this agent in various consumer products. In experimental animals and humans, oxidation products or metabolites of d-limonene were shown to act as skin irritants. Carcinogenic effects have also been observed in male rats, but the mode of action (MOA) is considered irrelevant for humans as the protein α2u-globulin responsible for this effect in rodents is absent in humans. Thus, the liver was identified as a critical target organ following oral administration of d-limonene. Other than the adverse dermal effects noted in humans, other notable toxic effects of d-limonene have not been reported. The reference dose (RfD), the no-observed-adverse-effect level (NOAEL), and the systemic exposure dose (SED) were determined and found to be 2.5 mg/kg/d, 250 mg/kg//d, and 1.48 mg/kg/d, respectively. Consequently, the margin of exposure (MOE = NOAEL/SED) of 169 was derived based upon the data, and the hazard index (HI = SED/RfD) for d-limonene is 0.592. Taking into consideration conservative estimation, d-limonene appears to exert no serious risk for human exposure. Based on adverse effects and risk assessments, d-limonene may be regarded as a safe ingredient. However, the potential occurrence of skin irritation necessitates regulation of this chemical as an ingredient in cosmetics. In conclusion, the use of d-limonene in cosmetics is safe under the current regulatory guidelines for cosmetics.
    Journal of Toxicology and Environmental Health Part B 01/2013; 16(1):17-38. · 3.90 Impact Factor
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    ABSTRACT: : In the manufacture of plastic containers, various materials such as additives (for example, plasticizers, stabilizers, antioxidants), polymers (for example, polystyrene [PS], polycarbonate [PC], polyvinyl chloride [PVC]) are widely used. Endocrine disrupting chemicals [EDCs] can migrate as residual monomers (for example, styrene for PS or bisphenol A [BPA] for PC) presented in polymers, as additives (for example, phthalates for PVC) used in polymer manufacturing, and/or as contaminants from the polymers depending on physicochemical conditions such as temperature, UV light, pH, microwave, and mechanical stress. Some phthalates (for example, DEHP, DBP), styrene, or bisphenol have been suspected to have endocrine disrupting effects, but human toxicological effects of these compounds are very controversial. For these reasons, a comprehensive review on toxicological and risk assessment studies for these chemicals (phthalates, BPA, and styrene) was carried out to evaluate their safety in humans. On the basis of exposure estimates for the these chemicals and reference doses (RfDs), we calculated hazard index (HI = chronic daily intake/tolerable daily intake [TDI] or RfD). A HI of less than 1 suggests an exposure lower than the safety limit of the chemicals. We showed that the HI values of these chemicals were lower then 1, but there are one or several exceptions for di(2-ethylhexyl) phthalate (DEHP), dibutyl phthalate (DBP), di-isodecyl phthalate (DIDP), and di-n-octyl phthalate (DnOP; for example, exposure via infant formula, packaged lunch, total exposure), where estimated their HI values are higher than 1, which suggests an exposure higher than the safety limits of the chemicals. However, the HI of BPA was 0.001–0.26 (3.57–1000 times lower than its safety limit), and the HI for styrene was 0.276 (3.62 times lower than its safety limit). In this article, we focused on recent issues concerning the endocrine-disrupting chemicals (EDCs) derived from plastic food containers or packaging. This review suggests that the use of plastic food containers might not exceed human safe limits n general with respect to endocrine disruptors aside from the exceptions of the phthalates mentioned earlier.
    Comprehensive Reviews in Food Science and Food Safety 09/2012; 11(5). · 5.05 Impact Factor
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    ABSTRACT: A metabolomics approach using proton nuclear magnetic resonance (NMR) was applied to investigate metabolic alterations following adriamycin (ADR) treatment for gastric adenocarcinoma. After BALB/c-nu/nu mice were implanted with human gastric adenocarcinoma, ADR (1 or 3 mg kg(-1) per day) was intraperitoneally administered for 5 days. Urine was collected on days 2 and 5 and analyzed by NMR. The levels of trimethylamine oxide (TMAO, ×0.3), hippurate (×0.3) and taurine (×0.6) decreased significantly (P < 0.05), whereas the levels of 3-indoxylsulfate (×12.6), trigonelline (×1.5), citrate (×2.5), trimethylamine (TMA, ×2.0) and 2-oxoglutarate (×2.3) increased significantly (P < 0.05) in the tumor model. After ADR treatment, TMAO, hippuarte and taurine were increased significantly on day 5 compared with those of the tumor model. The levels of 2-oxoglutarate, 3-indoxylsulfate, trigonelline, TMA and citrate, which increased in the tumor model, significantly decreased to those of normal control by ADR treatment. Furthermore, the ratio between TMA and TMAO was dramatically altered in both tumor and ADR-treated groups. Overall, metabolites such as TMAO, TMA, 3-indoxylsulfate, hippurate, trigonelline, citrate and 2-oxoglutarate related to the tricarboxylic acid (TCA) cycle might be considered as therapeutic targets to potentiate the efficacy of ADR. Thus, these results suggest that the metabolomics analysis of tumor response to ADR treatment may be applicable for demonstrating the efficacy of anticancer agent, ADR and treatment adaptation. Copyright © 2012 John Wiley & Sons, Ltd.
    Journal of Applied Toxicology 07/2012; · 2.60 Impact Factor
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    ABSTRACT: This study was designed to investigate the molecular mechanism underlying the chemopreventive effects of methionine on benzo[a]pyrene (B[a]P)-DNA adducts formation in HepG2 cells. Methionine significantly inhibited B[a]P-DNA adduct formation in HepG2 cells. Methionine significantly decreased the cellular uptake of [(3)H] B[a]P, but increased the cellular discharge of [(3)H] B[a]P from HepG2 cells into the media. B[a]P significantly lowered total cellular glutathione (GSH) level, but co-cultured with B[a]P and methionine, gradually attenuated intracellular GSH levels in a concentration-dependent manner, which was markedly higher at 20-500μM methionine. The cellular proteins of treated cells were resolved by 2D-polyacrylamide gel electrophoresis. Proteomic profiles showed that phase II enzymes such as glutathione S-transferase (GST) omega-1, GSTM3, glyoxalase I (GLO1) and superoxide dismutase (SOD) were down-regulated by B[a]P treatment, whereas cathepsin B (CTSB), Rho GDP-dissociation inhibitor alpha (Rho-GDP-DIA), histamine N-methyltransferase (HNMT), spermidine synthase (SRM) and arginase-1 (ARG1) were up-regulated by B[a]P. B[a]P and methionine treatments, GST omega-1, GSTM3, GLO1 and SOD were significantly enhanced compared to B[a]P alone. Similarly, methionine was effective in diminishing the B[a]P-induced up-regulation of CTSB, Rho-GDP-DIA, HNMT, SRM and ARG1. Our data suggests that methionine might exert a chemoprotective effect on B[a]P-DNA adduct formation by attenuating intracellular GSH levels, blocking the uptake of B[a]P into cells, or by altering expression of proteins involved in DNA adduct formation.
    Toxicology Letters 11/2011; 208(3):232-8. · 3.15 Impact Factor
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    ABSTRACT: The migration levels of bisphenol A (BPA) were analyzed in food samples by high-performance liquid chromatography (HPLC) from polycarbonate (PC) bottles subjected to simulated use by heating with microwave, heating in a boiling water bath, or filling them with boiling hot water (100 degrees C). Migration testing performed in PC bottles filled with steamed rice or hot cooked pork, standing at room temperature, or heated in a boiling water bath (100 degrees C) showed that BPA was not detected at the limit of detection (LOD) of 1 microg/L (ppb). In contrast, heating by microwaving to 100 degrees C for 9 min increased BPA migration levels from 6 to 18 ppb and from 5 to 15 ppb for steamed rice or for cooked pork, respectively. In addition, 3 different PC bottles were tested by filling them with boiling hot water (100 degrees C) and leaving them to stand at room temperature for up to 3 h. The mean BPA levels from the bottles increased in a time-dependent manner, with the range of not detected (ND) to 2.5 ppb after 60 min. However, none of the PC bottles released BPA at levels that exceed the recently established specific migration limits (SML) of 600 ppb established by European Union and Korea Food and Drug Administration (KFDA). Data suggest that the use of PC plastic bottles in our daily life is considered safe in Korea.
    Journal of Toxicology and Environmental Health Part A 01/2009; 72(21-22):1285-91. · 1.73 Impact Factor
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    ABSTRACT: Exposure and risk assessment of bisphenol A (BPA) was conducted on consumption of canned foods in Korean adults. Sixty-one canned food items with different brands purchased from retail outlets in markets were analyzed for BPA concentration by high-performance liquid chromatography (HPLC) coupled with fluorescence detection. Limits of detection (LOD) were 3 microg/kg for solid and 2 microg/kg for liquid foods. BPA was detected from 7 groups of food items, such as tuna (n = 8), fish (n = 11), fruits (n = 9), vegetables (n = 12), meats (n = 13), coffee (n = 5), and tea (n = 3) in the range from not detected (ND) to 136.14 microg/kg. Mean concentrations of BPA were 3.1 microg/kg (ND-21.5 microg/kg) for vegetables, 8.3 microg/kg (ND-14.26) for tea, 8.6 microg/kg (ND-54.56 microg/kg) for fruits, 24.49 microg/kg (ND-98.30 microg/kg) for meats, 39.78 microg/kg (ND-125.25 microg/kg) for fish, 43.7 microg/kg (ND-116.88 microg/kg) for tuna, and 45.51 microg/kg (ND-136.14 microg/kg) for coffee, in the order of magnitude. Based on daily dietary intake of canned food items and concentrations of BPA, human exposure level to BPA was estimated to be 1.509 microg/kg body weight (bw)/d, well below the tolerable daily intake (TDI) or reference dose (RfD) of 50 microg/kg, bw/d set by the European Commission, U.S.EPA, and South Korea. Therefore, the potential risk for BPA contamination due to consumption of each canned food items was calculated to be (1.509 microg/kg bw/d)/(50 microg/kg bw/d) = 0.03, which is the hazard index [HI = exposure level/(RfD or TDI)]. Evidence indicates that the levels of BPA levels in canned foods are not likely to constitute a safety concern for consumers in Korea.
    Journal of Toxicology and Environmental Health Part A 01/2009; 72(21-22):1327-35. · 1.73 Impact Factor
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    ABSTRACT: Levels of the phthalates such as di(2-ethylhexyl) phthalate (DEHP), mono(2-ethylhexyl) phthalate (MEHP, a major metabolite of DEHP), di-n-butyl phthalate (DBP), mono-n-butyl phthalate (MBP, a major metabolite of DBP), and phthalic acid (P, (a common metabolite of phthalates, including DEHP and DBP) were determined in the semen samples of 99 healthy volunteers without known prior medicosurgical history. Samples were obtained from young men (age 20-25 yr) who visited a clinic, and the semen concentrations of phthalates were measured using ultra-performance liquid chromatography (UPLC) and tandem mass spectrometry (MS/MS). UPLC/MS/MS showed that mean concentrations in semen samples were 1.07 microg/ml for MEHP, 0.61 microg/ml for DEHP, 0.39 microg/ml for PA, 0.06 microg/ml for MBP, and 0.003 microg/ml for DBP. The concentration of MEHP (the metabolite of DEHP) was highest, and the concentrations of the metabolites including MEHP, MBP, and PA were higher than actual concentrations of parent DEHP and DBP. These findings suggest the detection of phthalates in healthy human semen might require further investigation for effects on human fertility.
    Journal of Toxicology and Environmental Health Part A 01/2009; 72(21-22):1463-9. · 1.73 Impact Factor
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    ABSTRACT: The toxicokinetic profiles of phthalic acid (PA), which is the common final metabolite of phthalic acid esters (PAE), were studied in rats after orally administering doses 20, 100, or 500 mg/kg. Concentrations of PA were determined in serum or urine by high-performance liquid chromatography (HPLC). The plasma concentrations of PA showed a biexponential increase following oral administration of doses ranging from 20 to 500 mg/kg. The terminal elimination half-lives (t1/2) of PA at dosages of 20, 100, or 500 mg/kg were 6.46 +/- 1.13, 5.19 +/- 3.56, and 5.10 +/- 1.10 h, respectively, total clearances (Cl/F) of PA at 20, 100, or 500 mg/kg were 97.43 +/- 4.20, 215.01 +/- 55.42, and 721.07 +/- 51.81 ml/h, and apparent distribution volumes of PA in the steady state (Vz/F) at 20, 100, or 500 mg/kg were 903.28 +/- 125.28, 1419.87 +/- 527.53, and 5264.86 +/- 993.65 ml, respectively. PA was absorbed rapidly after an oral dose of 500 mg/kg with peak concentration (Cmax) in blood (3.5 +/- 0.33 microg/ml) at 30 min postadministration. After oral administration, the dose-normalized area under the curve (AUC) (146.90 +/- 9.33 microg/h/ml) for 500 mg/kg was significantly greater than at 20 mg/kg (44.69 +/- 2.56 microg/h/ml). Urine analysis indicated that 13 +/- 0.45% of the administered PA dose (at 500 mg/kg, p.o.) was recovered unchanged in urine within 24 h. Data concerning the toxicokinetic profiles of PA improve our understanding of the toxicological potential of PAE and may prove useful for risk assessments of multiple phthalates exposure.
    Journal of Toxicology and Environmental Health Part A 09/2007; 70(15-16):1344-9. · 1.73 Impact Factor