• YAKHAK HOEJI
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• v.46 no.4
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• pp.258-264
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• 2002

Zinc plays an important role in immunobiological responses, while excessive zinc attenuates immune functions in a dose-dependent manner. Zinc excess has been reported to increase levels of plasma prostaglandin E$_2$ (PGE$_2$), which is known to inhibit production of Th (helper T) 1-associated cytokines and to induce inflammatory responses. Thus, this study was investigated the effects of indomethacin, a potent inhibitor of PGE$_2$ synthesis, on the proinflammatory cytokine and lymphokine production in ICR mice exposed to excessive zinc. Indomethacin at doses of 5 mg/kg was administered i.p. 30 minutes before zinc chloride (Zn) 30 mg/kg orally daily for 10 days. Excessive Zn remarkedly increased tumor necrosis factor (TNF)-$\alpha$ and interleukin (IL)-1$\beta$ levels in both serum and splenic supernatants compared with those in controls, while indomethacin significantly reduced the excessive Zn-induced levels of IL-1$\beta$. In serum, excessive Zn significantly decreased the levels of IL-2 and interferon (IFN)-${\gamma}$ compared with those in controls, whereas indomethacin significantly enhanced the excessive Zn-decreased levels of IFN-${\gamma}$ but did not affect the Zn-decreased levels of serum IL-2. In splenic supernatants, All of excessive Zn, indomethacin, and combination of Zn and indomethacin significantly enhanced IL-2 levels compared with those in controls, but indomethacin didn't affect the Zn-induced production of IL-2. These data, therefore, suggest that indomethacin significantly attenuated the in vivo and ex vivo IL-1$\beta$ production increased by excessive zinc and remarkedly enhanced the in vivo excessive zinc-suppressed production of IFN-${\gamma}$ but not IL-2.

• Nutrition Research and Practice
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• v.17 no.6
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• pp.1211-1224
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• 2023

BACKGROUND/OBJECTIVES: This study aimed to evaluate the food sources of zinc and the usual intake of dietary zinc among Korean toddlers and preschool children. SUBJECTS/METHODS: A total of 2,679 children aged 1-5 years was selected from the 2009-2013 Korea National Health and Nutrition Examination Survey (KNHANES) data. Dietary data collected from a single 24-h recall were used to evaluate the food sources of zinc. To estimate usual zinc intake, the distribution obtained from single 24-h recall data in the total sample was adjusted using the ratio of within-to-between-person variance in zinc intake obtained from 2-day 24-h recall sub-sample data of the 2009 KNHANES. The proportion of children with usual zinc intake below the estimated average requirement (EAR) and above the tolerable upper intake level (UL) was assessed. RESULTS: The main sources of zinc in Korean children were grains, dairy products, and meat. The mean usual intakes of zinc among all individuals, those aged 1-2 yrs, and those aged 3-5 yrs were 5.50, 5.01, and 5.83 mg/d, respectively. In all participants, 1.1% of the children consumed zinc below the EAR, whereas 10.7% exceeded the UL. The proportion of children with excessive zinc intake was 25.6% in the 1-2 yrs age group and 0.6% in the 3-5 yrs age group. CONCLUSIONS: According to the current UL, the risk of excessive zinc intake appears to be high among Korean toddlers. Future studies that monitor the health effects of excessive zinc intake are needed to appropriately guide zinc intake in children.

• Journal of Nutrition and Health
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• v.40 no.4
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• pp.385-394
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• 2007

The purpose of this study was to determine the zinc status of preschool children in Ulsan. The study was conducted in 95 children aged 3 to 6 years by investigating the anthropometric indices and assessing the biochemical analysis. The blood was analysed to assess serum zinc and alkaline phosphatase. And a questionnaire for dietary intakes using 24-hr recall method were performed by mothers of 95 subjects. The dietary intakes of children were analysed to determine the prevalence of inadequate and excessive intakes of zinc with Dietary Reference Intakes for Koreans (KDRIs). WHL (Weight-Length Index) and Kaup index were used to define obesity. The overall prevalence of overweight and obese subjects were 14.7% and 6.3% by WHL, were 15.8% and 13.7% by Kaup index. The mean intakes of zinc by children aged 3${\sim}$5y and 6y were 5.5 ${\pm}$ 1.4 mg/d (75.7% RDA) and 6.7 ${\pm}$ 2.0 mg/d, respectively, that was the level exceeding the estimated average requirement (EAR) and the recommended intake (RI) of Korean Dietary Reference Intakes. Less than 1.3% and 7.9% of children had usual zinc intakes below EAR and RI of KDRIs, respectively. The percentages of children with intakes exceeding the tolerable upper intake level (UL) were 2.6%. The zinc nutritional status by biological assay was found that mean serum zinc and alkaline phosphatase (ALP) of total subjects were 64.0 ${\pm}$ 8.4 ${\mu}$g/dl and 72.8 ${\pm}$ 14.9 U/L, there was not a significant difference between boys and girls. The range of serum zinc level was 45${\sim}$89 ${\mu}$g/dl and children with a low serum zinc concentration by several cut-off points were 18.9${\sim}$55.8%, especially. Serum zinc level was positively correlated to the intakes of calorie, calcium, fiber, iron, zinc, zinc/kg and height (p<0.001). Serum ALP was positively correlated height, weight and WLI. The zinc intake of children aiso showed a positive correlation with height and weight. These results indicate that there were significant correlations between the zinc status and growth of preschool children. Preschool children in Ulsan have dietary zinc intakes that exceed the new DRIs. The present level of intake does not seem to pose a health problem, but if zinc intakes with fortified foods and supplements were considered, the amount of zinc consumed by children may become excessive.

• Corrosion Science and Technology
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• v.10 no.2
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• pp.43-46
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• 2011

Zinc consumption in a continuous galvanizing line is one of the highest operating cost items in the facility and minimizing zinc waste is a key economic objective for any operation. One of the primary sources of excessive loss of zinc is through the formation of top dross and skimmings in the coating pot. It has been reported that the top skimmings, manually removed from the bath, typically consist of more than 80% metallic zinc with the remainder being entrained dross particles ($Fe_2Al_5$) along with some oxides. Depending on the drossing practices and bath management, the composition of the removed top skimmings may contain up to 2 wt% aluminum and 1 wt% iron. On-going research efforts have been aimed at in-house recovery of the metallic zinc from the discarded top skimmings prior to selling to zinc recycling brokers. However, attempting to recover the zinc entrapped in the skimmings is difficult due to the complex nature of the intermetallic dross particles and the quality and volume of the recycled zinc is highly susceptible to fluctuations in processing parameters. As such, an efficient method to extract metallic zinc from top skimmings has been optimized through the use of a specialized thermo-mechanical process enabling a continuous galvanizing facility to conserve zinc usage on-site. Also, through this work, it has been identified that filtration of discrete dross particles has been proven effective at maintaining the cleanliness of the zinc. Future efforts may progress towards expanded utilization of filters in continuous galvanizing.

• Nutrition Research and Practice
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• v.17 no.2
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• pp.257-268
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• 2023

BACKGROUND/OBJECTIVES: Zinc is an essential trace mineral which is important for the growth and development of the human body and immunological and neurological functions. Inadequate zinc intake may cause zinc deficiency with its adverse consequences. In this study, we aimed to estimate the dietary zinc intake levels and sources among Koreans. SUBJECTS/METHODS: For this secondary analysis, we obtained data from the Korea National Health and Nutrition Examination Survey (KNHANES) 2016-2019. Individuals aged ≥ 1 yr who had completed a 24-h recall were included. The dietary zinc intake of each individual was calculated by applying data from a newly developed zinc content database to the KNHANES raw data. We also compared the extracted data with the sex-, age-specific reference values suggested in the Korean Dietary Reference Intakes 2020. The prevalence of adequate zinc intake was then evaluated by the proportion of the individuals who met the estimated average requirement (EAR). RESULTS: The mean zinc intake of Koreans aged ≥ 1 yr and adults aged ≥ 19 yrs were 10.2 and 10.4 mg/day, equivalent to 147.4% and 140.8% of the EAR, respectively. Approximately 2 in 3 Koreans met the EAR for zinc, but the zinc intake differed slightly among the different age and sex groups. In children aged 1-2 yrs, 2 out of 5 exceeded the upper level of intake, and nearly half of the younger adults (19-29 yrs) and the elders (≥ 75 yrs) did not meet the EAR. The major contributing food groups were grains (38.9%), meats (20.4%), and vegetables (11.1%). The top 5 food contributors to zinc intake were rice, beef, pork, egg, and baechu kimchi, which accounted for half of the dietary intake. CONCLUSION: The mean zinc intake among Koreans was above the recommended level, but 1 in 3 Koreans had inadequate zinc intake and some children were at risk of excessive zinc intake. Our study included zinc intake from diet only, thus to better understand zinc status, further research to include intake from dietary supplements is needed.

• Biomedical Science Letters
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• v.16 no.4
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• pp.323-330
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• 2010

Although copper and zinc are essential metals for human health, excessive level of these metals is toxic. Besides, aluminum is known to induce various adverse health effects including neurological disorders. Therefore, monitoring the human body burden of these metals is important in preventing adverse health effects. In this study, we assessed the exposure to copper, zinc, and aluminum among an adult population residing in Daegu and Kyungbuk areas. Based on data from 171 participants, we found that the geometric mean copper, zinc, and aluminum concentrations in hair were $15.1\;{\mu}g/g$ [95% confidence interval (CI): 13.1~17.5], 76.9 (95% CI: 70.4~84.1), and $1.11\;{\mu}g/g$ (95% CI: 0.81~1.51), respectively. The copper concentrations in hair were significantly related to age, education, and residence area. In addition, zinc concentrations in hair were significantly related to age, whereas higher hair aluminum concentrations were related to alcohol drinking. Correlations between copper and zinc in hair had a significant positive correlation. Our findings suggest that the body burden of copper, zinc, and aluminum varies according to demographic factors, and hair could be used as a valuable biological medium for metal exposure.

• Corrosion Science and Technology
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• v.23 no.3
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• pp.221-227
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• 2024

During hot stamping of hot-dip zinc-coated steel sheets such as hot-dip galvanized steel sheets and hot-dip galvannealed steel sheets, an oxide mainly composed of ZnO is formed on the sheet surface. However, excessive formation of ZnO can lead to a decrease in the amount of metal Zn in the coating layer, decreasing the corrosion resistance of hot-stamped members. Therefore, it is important to suppress excessive formation of ZnO. While the formation of Al oxides and Mn oxides along with ZnO layer during the hot stamping of hot-dip zinc-coated steel sheets can affect ZnO formation, crystal structures of such oxides have not been elucidated clearly. Thus, this study aimed to analyze structures of oxides formed during hot stamping of hot-dip galvannealed steel sheets using transmission electron microscopy. Results indicated the formation of an oxide layer comprising ZnAl₂O₄ at the interface between ZnO and the coating layer with Mn₃O₄ at the outermost of an oxide layer.

• Journal of the Korean Society of Food Science and Nutrition
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• v.23 no.4
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• pp.574-580
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• 1994

The effect of dietary zinc(Zn) levels on cadmium (Cd)-induced hepatotoxicity was studied in serum and liver of rats. Adult male Spraque-Dawley rats were fed on diets containing one of three levels of zinc carbonate(0, 56, $560\mu\textrm{g}/kg$ diet) and Cd-treated groups were administrated oral intubation with cadmium chloride 95.0 mg/kg of body weight) at the sametime once a week. Net weight gain (NWG), feed intake (FI) and feed effciiency ratio (FER) in Zn deficiency groups significantly decreased as compared to that of control and excessive groups. Cd oral intubation caused a decrease in NWG and FI but an increase in Zn deficiency group in FER. GSH-Px, GST and catalase activity showed significant decrease in Zn deficiency and Zn excessive group. LPO content in liver significantly increased in Zn deficiency group. Cd oral intubation increased the content of LPO in Zn deficiency group as compared to control. GSH content and GST activity of hepatic tissue significantly decreased in Zn deficiency and excessive group. The activity of AST and ALT in serum were markedly increased in Zn deficiency, Zn excessive and Cd-treated groups. LDH and ALP activities significantly increased in Cd-treated group while ALP activity decreased by Zn deficiency. It was observed that the livers of rats exposed to Cd and Zn excessive group showed a marked increase of hepatic enzyme as compare to only Cd-treated in rats.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 1999.05a
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• pp.97-97
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• 1999

Dross formation in the zinc bath is inevitable under any condition as long as coating process on steel strip continues. Thus, bath aluminum and temperature are precisely managed to suppress the increase of dross. Also, excessive dross for normal coating process is generally eliminated physically by bubbling and skimming. Total amount of dross in the bath can be sometimes high enough to cause coating defect. On the other hand, local concentration of dross can make coating defect even with satisfactory level of total amount of dross. Reduction of dross in the bath was attempted by using ceramic foam filter made of mainly alumina. Dross in molten zinc was almost reduced to the levels of solubility of iron and aluminum in molten zinc at $450~460^{\circ}C$. Their solubility levels were confirmed by thermodynamic calculations or DEAL program. Two kinds of filters were tested for dross reduction. One was #20 ppi, porous per inch, and the other #30 ppi filter. Both were effective in reducing the bath dross to the solubility levels at the static state. Bath iron was reduced by 24 wt% and 19 wt% with #20 filter, and by 35 wt% and 29 wt% with #30 filter for GI and GA pot, respectively. Also, ceramic foam filter did not make any harm to the zinc bath composition after filtering test.

• Proceedings of the Korea Society of Environmental Toocicology Conference
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• 2001.11a
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• pp.83-83
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• 2001