• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.1 no.2
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• pp.145-155
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• 1997

The effect of various supplies of lead singly and in combination with aluminium on growth and chlorophyll biosynthesis was investigated in 7-day-old Vigna angularis seedlings. Expose to 50 uM Pb or more drastically reduced root elongation rate. Significant depressions in root growth was observed within 1 day and no recovery of growth was seen over the duration of treatment period. Root elongation decreased depending on the Pb concentrations. Root growth inhibition was stronger than shoot growth inhibition. The initiation of lateral roots appeared to be more sensitive to Pb than the growth of main roots. Inhibition of root and shoot elongation by Pb was lessened by combined exposure of Pb and Al, suggesting that the presence of Al reverse the inhibitory effect of Pb alone. With the histochemical sodium rhodizonate method the rate of Pb uptake was dependent on the Pb concentration and exposure time of the roots to Pb salts. Pb was first deposited on the root surface and then translocated radially in the root cap cells. During a longer Pb administration (up to 72 h) Pb penetration was nonuniform, with accumulation within the cortex or endodermis. There was drastic reduction in chlorophyll content by Pb. The Pb inhibition of chlorophyll synthesis was concentration dependent. $\delta-Aminolevulinic$ acid dehydratase (ALAD) activity exhibited distinct inhibition from control. Reduction in chlorophyll content was accompanied by proportional changes in ALAD activity. Chlorophyll content and ALAD activity were less affected by combined exposure of Pb and Al, suggesting that Al has a protective effect against the inhibiting action of Pb on photosynthetic activity.

• Journal of the Korean Society of Radiology
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• v.14 no.4
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• pp.367-373
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• 2020

Most of the spatial scattered dose caused by the scattered rays generated by the collision between the object and X-rays is relatively easily absorbed by the human body as electromagnetic waves in the low energy region, thereby increasing the degree of radiation exposure. Such spatial scattering dose is also used as an indicator of the degree of radiation exposure of radiation workers and patients, and there is a need for a method to reduce exposure by reducing the spatial scattered dose that occurs indirectly. Therefore, in this study, a lead-free radiation shielding sheet was proposed as a way to reduce the spatial scattering dose, and a Monte Carlo (MC) simulation was performed based on a chest X-ray examination. The absorbed dose was calculated and the measured value and the shielding rate were compared and evaluated.

• Journal of radiological science and technology
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• v.44 no.6
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• pp.629-633
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• 2021

This article is designed to look into the radiation exposure dose to each body part and the shielding effect for workers using an additional shielding to reduce their radiation exposured by scattering radiation which is generated in a space between the operating table and lead curtain during interventional radiology(IR) procedures. After placing a human phantom on the table of SIEMENS' angiography machine, the following measurements were taken, depending on the presence of an additional shield of lead equivalent of 0.25 mmPb, manufactured for this purpose: dose to gonad, dose to an area where the personal dosimeter is placed, and dose to an area of eye lens is located. An ion chamber(chamber volume 1,800 cc) was utilized to measure scattering radiation. The two imaging tests were carried out as follows: fluoroscopy of the abdomen (66 kV, 100 mA, 60 seconds) and of the head (70 kV, 65 mA, 60 seconds); and digital subtraction angiography(DSA) of the abdomen (67 kV, 264 mA, 20 seconds) and of the head (79 kV, 300 mA, 20 seconds). In all the experiments, the shielding efficiency of the gonad position was the largest at 59.8%. In case an additional shielding was used as protection against scattering radiation that came through the operating table and the lead curtain during an IR, the radiation shielding efficiency was estimated to be up to 59.8%, leading to a conclusion that its presence may effectively reduce the radiation exposure dose of medical staffs.

• Journal of Preventive Medicine and Public Health
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• v.11 no.1
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• pp.76-82
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• 1978

In order to study the change of laboratory parameters of lead poisoning, 8 persona who had not been treated previously for lead poisoning (Group 1 and 6 persons who had been inadequately treated for few months for chronic lead poisoning at local clinic (Group 2) were examined. They had occupational exposure to lead for 3 to 18 years (mean, 7.6). In group 1 blood lead, urine lead, urine coproporphyrin and ${\delta}$-aminolevulinic acid levels before our treatment exceeded the critical levels of lead poisoning. In group 2 urine lead level exceeded but blood lead, urine coproporphyrin and ${\delta}$-aminolevulinic acid levels were within normal limits. All of them were treated with D-penicillamine for 4 months as inpatients at Industrial Accident Hospital. The dose of D-penicillamine was the same in all patients; 600 mg per day p.o. and the chelating agent was administer every other week. For laboratory analysis, 24 hour urine and 10 gm of whole blood were collected every 1 month on last day of non-administration period. The results were as follows: 1. It was found that urine lead level was decreased below the cirtical level of lead poisoning after 4 month's treatment with D-penicillamine and blood lead level was decreased more progressively below the critical level after 1 month treatment. 2. Urine coproporphyrin and ${\delta}$-aminolevulinic acid levels were decreased progressively to normal range after 1 month treatment. 3. Two months after treatment, blood lead, urine lead, urine coproporphyrin and ${\delta}$-aminolevulinic acid levels showed some increasing trends. 4. Urine lead level should be checked in a person who had been inadequately treated with chelating agents because blood lead, coproporphyrin and ${\delta}$-aminolevulinic acid might be in normal range.

• Toxicological Research
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• v.19 no.3
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• pp.217-225
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• 2003

Changes of plasma DNA contents and serum biochemical values were measured in rats administered with lead acetate to investigate the in vivo cytotoxic effects of lead and examine the usefulness of these in vivo cytotoxicity changes as indicators of lead exposure and diagnosis of lead poisoning. Rats were given once intraperitonealy with lead acetate (1.6, 8, 40 and 200 mg/kg b.w) and the changes of plasma DNA contents and serum biochemical values were measured at the time of 2, 4, 8, 24, 48 and 72 hours after the administration of lead acetate. Plasma DNA contents began to increase at 2 hours after the administration of lead acetate in the treatment groups of 8, 40 and 200 mg/kg b.w dose-dependently and significantly compared with control group. These DNA increases of each dosage group were continued until 24, 48 and 72 hours and the maximum levels of DNA (4.02, 10.67 and 14.10 times of control) were arrived at 8, 8 and 4 hours after the each treatment, respectively. Among 10 serum biochemical indicators, the activities of creatine kinase were increased to maximum level (6.55 times of control) at 2 hours after the administration and remained to be significantly higher than that of control by 8 hours in the treatment group of 200 mg, however, after 48 hours, the levels in the treatment groups of 40 mg above were lower than that of control. The values of aspartate aminotransferase, alanine aminotransferase and lactate dehydrogenase were higher than that of control from 2 to 24 hours in the treatment group of 200 mg. Maximum levels of these enzymes were 3.34, 3.00 and 3.19 times of control, respectively. Both of alkaline phosphatase and triglyceride values in the treatment groups were decreased compared with control. In the case of alka-line phosphatse, the values were significanly decreased from 24 hours and more severely decreased until 72 hours in the treatment groups of 40 mg above (p<0.01). The minimum value was 0.36 times of control in the 200 mg group. The values of triglyceride were significantly decreased in the tratment groups of 40 mg above (p<0.01), but the values were not different significantly among the treatment groups. This study demonstrates that plasma DNA content and serum biochemical values such as aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, alkaline phosphatase and triglyceride are valuable as biomarkers for exposure assessment and diagnosis of lead poisoning.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.4 no.2
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• pp.168-179
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• 1994

In some ceramic industries, worker exposure to dust, crystalline free silica and lead were determined and evaluated. The conclusions are as follows. 1. Crystalline silica in bulk samples was 10.5 % in sanitary ware industry, 9.4 % in tile industry, and 2.1 % in ceramic insulator industry respectively. The free silica content of air filter sample was 8.03 % in table ware industry, 5.59 % in sanitary ware industry, and 1.32 % in ceramic insulator industry. Because silica content in ceramic dust is relatively high, it is should be considered silica as important factor in evaluating for ceramic industry. 2. The silica contents in dust from tile, sanitary ware and table ware industries are above 5%, it should be classified as "Type" 2 dust. 3. The airborne concentration of respirable crystalline silica was $27.9{\mu}g/m^3$ in a sanitary ware factory and $5.8{\mu}g/m^3$ in a ceramic insualtor factory. Three of ten samples sampled the above factories were exceeded the occupational exposure levels, $100{\mu}g/m^3$. 4. Geometric mean(GM) of total dust in 11 factories was $1.00mg/m^3$ and GM of respirable dust concentration in 5 factories was $0.33mg/m^3$. Sanitary ware industry had the highest concentration of total dust, $1.62mg/m^3$ and of respirable dust, $0.88mg/m^3$. 5. Average lead concentration in air was $0.05mg/m^3$ in glazing process of 2 factories manufacturing table ware. Five of ten sample(50%) were exceeded $0.05mg/m^3$. Therefore lead exposure in pottery industry should be considered as important problem.

• 대한예방의학회:학술대회논문집
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• 2005.10a
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• pp.389-389
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• 2005

• 대한예방의학회:학술대회논문집
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• 1996.10a
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• pp.271-272
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• 1996

• Journal of Korean Society for Atmospheric Environment
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• v.8 no.4
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• pp.269-276
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• 1992

Typical lebvels of heavy metal exposure for humans may be attributed to four components in the environment ; food, inhaled air, various types of dust, and drinking water. To assess the health risk of lead, it is necessary to estimate the blood lead levels in the populations of concern under various air lead concentrations. The blood lead levels of the population in Seoul and Yeoju are estimated by Biokinetic model for the risk assessment in this study. The differences in blood lead levels between areas of different land use are not dominant but some differences show among different age groups and sex. Blood lead levels of the population show log normal distribution. The geometric standard deviation values of blood lead levels are in the range of 1.25 ~ 1.39, it is somewhat smaller than the values in the general U.S pollution which are determined to be from 1.31 to 1.41 by the U.S. EPA.

• Journal of Periodontal and Implant Science
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• v.36 no.4
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• pp.879-889
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• 2006

The early exposure of cover screws is a common complication of 2-stage implant technique. The exposure of cover screws between stage I and IT surgery may cause inflammation in the soft tissues surrounding the implants, and lead to peri-implantitis or marginal bone loss. The purpose of this study was to evaluate the effect of the early exposure of cover screws on implants placed using 2-stage technique. Two hundred and nineteen implants in 77 patients were examined for cumulative survival rate, radiographic marginal bone level change, cause and frequency of the early exposure. The results were as follows: 1. Twenty-five implants showed early exposure of cover screws with a frequency of 11.4%. 2. Cumulative survival rate of the implants with early cover screw exposure was 88.0%, and that of the implants without cover screw exposure was 96,9%. 3. At the time of stage IT surgery and 1 year after loading, the marginal bone loss was greater around the implants with early exposure of cover screws than around the implants without cover screw exposure(p <0.05), 4, There was no statistically significant difference in the frequency of the early exposure according to the implant diameter, gender, and smoking(p >0,05).