Noise-Induced Temporary Threshold Shift and its Recovery in Industry / 대한산업의학회지

To determine the recovery time from noise-induced temporary threshold shift (TTS), a prospective field study was conducted at three worksites where workers are known to be exposed high level of noise. Subjects were selected according to answers on a questionnaire which inquired about otological history and previous noise exposure, including avocational, military and occupational exposures. After excluding employees with past otologic problems, recent exposure to high level noise, and under medications, total 92 employees participated in the study. Among 92 participants, complete consecutive audiometric examinations were carried out at 0~2 hours, 5~7 hours, 14~16 hours after worktime noise exposure on 26 participants wearing hearing protectors and 22 participants wearing no protective devices. The difference between the hearing level 0~2 hours after noise exposure and 5~7 hours is statistically significant by paired t-test(p<0.01). The median recovery times calculated from the data of 22 participants wearing no protective hearing devices are 15.6 hours at 4000 Hz, and 7.7 hours, 10.3 hours, 8.4 hours at 1000 Hz, 2000 Hz and 8000 Hz respectively. These data suggest that when measuring the pure tone audiometry for noise exposed workers, at least 16 hours noise-free interval is required.

Noise-Induced Temporary Threshold Shift and its Recovery in Industry / 대한산업의학회지

To determine the recovery time from noise-induced temporary threshold shift (TTS), a prospective field study was conducted at three worksites where workers are known to be exposed high level of noise. Subjects were selected according to answers on a questionnaire which inquired about otological history and previous noise exposure, including avocational, military and occupational exposures. After excluding employees with past otologic problems, recent exposure to high level noise, and under medications, total 92 employees participated in the study. Among 92 participants, complete consecutive audiometric examinations were carried out at 0~2 hours, 5~7 hours, 14~16 hours after worktime noise exposure on 26 participants wearing hearing protectors and 22 participants wearing no protective devices. The difference between the hearing level 0~2 hours after noise exposure and 5~7 hours is statistically significant by paired t-test(p<0.01). The median recovery times calculated from the data of 22 participants wearing no protective hearing devices are 15.6 hours at 4000 Hz, and 7.7 hours, 10.3 hours, 8.4 hours at 1000 Hz, 2000 Hz and 8000 Hz respectively. These data suggest that when measuring the pure tone audiometry for noise exposed workers, at least 16 hours noise-free interval is required.

Comparison of Diagnostic Criteria of Noise Induced Hearing Loss using Special Periodic Health Examination Data in Korea / 대한산업의학회지

Although noise-induced hearing loss (NIHL) is the most prevalent occupational disease in Korea, only 10% of the diagnosed cases are compensated. Old (1989-94) and current diagnostic criteria, criteria for workers' compensation of NIHL in Korea, compensation formulas of American Medical Association/American association of Ophthalmology and Otolaryngology (AMA/AAOO), the Committee on Hearing, Bio-Acoustics, Biomechanics (CHABA), American Academy of Otolaryngology (AAO) recommendation were compared. Each criterion was applied on the audiomety data of 4044 workers (8023 ears), who had received the second line screening test of Special Periodic Health Examination Program for noise-exposed workers during 1991-2. First, the resulting proportions of NIHL cases by employing each criterion were compared and strength of agreement was measured using kappa value. Temporary Threshold Shift (TTS) was corrected by noise free interval, and the reduction ratio of NIHL cases was calculated. Theoretical progression model of NIHL was reconstructed from previous studies on the natural course of NIHL to evaluate the change of diagnosis result of each criterion in the model. The kappa value between old and current criteria was 0.19, 0.55 for current criteria and workers' corn. criteria, ranging from 0.08 to 0.78, highest coincidence was observed between current criteria and CHABA formula. The current criteria produce most similar results with CHABA formula. If TTS is corrected for NFI, there is about 14 % reduction of NIHL cases. The results of applying on NIHL progression model divided the formulas roughly into 3 groups, of which compensation criteria was the most, old criteria and AAO the least conservative. In conclusion. The result of 4 KHZ audiometry should be excluded in evaluation of hearing level and a new hearing conservation program should be set out. Current diagnostic criteria has an ambiguity in that managerial concept for prevention arid! purpose of compensation is mixed up. The current diagnostic criteria and compensation criteria could be incorporated'into 'a new formula which is based on the state of the art test for estimating everyday hearing disability.

Perceived Occupational Psychosocial Stress and Work-related Musculoskeletal Disorders Among Workers Using Video Display Terminals / 대한산업의학회지

A cross-sectional study was conducted to assess the association between perceived occu-pational psychosocial stress at work and the work-related musculoskeletal disorders (WRMSD) among employees using video display terminals. The study included 111 female telecommunication employees from three companies at ChungBuk province. Cases of WRMSD were defined using symptom questionnaire and physical examination conducted by rehabilitation specialist. Information on demographics, individual factors, and perceived psychosocial stress, were obtained by self-administered questionnaire. For assessing perceived psychosocial stress, we used variables from 'job strain model' proposed by Karasek. Associations between perceived psychosocial stress and WRMSD were assessed by multiple logistic regression models. Forty nine (44% to the total) subjects met our operational definition for WRMSD. Age, seniority, housing load were not associated with WRMSD. Perceived psychosocial stress was associated with WRMSD [odds ratio=3.28, 95% confidence interval: 1.05-10.19]. This study suggests that perceived occupational psychosocial stress is related to the prevalence of WRMSD.

The Development of Systemic Health Management Program in the Small Scale Industry using Organic Solvents: Application of Neurobehavioral Core Test Battery(NCTB) / 대한산업의학회지

It is known that there appear some nonspecific and delicate changes in neuropsychiatric aspect on the workers when they are exposed for a long period to low concentrated organic solvents in the work places. Therefore, it give rise to the necessity of developing a program for the health supervisor stationed in the work place to supervise these neurobehavioral health affection. In addition to the questionnaire posed to the workers exposed to organic solvents, the study team conducted NCTB(Neurobehavioral Core Test Battery) respectively on an exposed group and a non-exposed group to organic solvents. The study team compared the results and decided whether or not to apply the results to the evaluation program of health affection. The study team divided 132 workers in 6 car repairing factories and 2 textile printing factories into exposed group and non-exposed group, pairing them off into 66 research objects according to their age, sex, and job. Neurobehavioral test was conducted on 6 items, except the POMS test, of NCTB developed by the World Health 0rganization (WHO) . The study team conducted examinations of working environment on the exposed and non-exposed groups of each work place. The analysis of the collected materials for examinations were conducted with GC-MS. The concentration of the mix-ture in the air, relative to their respective threshold limit values (TLV) was calculated according to the formula of the ACGIH and the Korean threshold limits. The results indicated that for two of eight factories samples the recommended concentration limits for mixtures was exceeded. Of the six tests, the'digit span forward','digit span backward'and'digit symbol' produced conspicuous statistical differences between the two groups (p<0.1) as a result of compairing the test values by means of paired t-test. The results of respective analysis of the car repairing factories and textile printing factories revealed that the textile printing factories had greater differences between the exposed and the non-exposed than in the car repairing factories. It is presumably because the textile printing workers are continuously exposed to the organic solvents during working hours, whereas the car repairing workers are exposed only when they are doing painting works. The NCTB is assessed very useful in examining the neurobehavioral health affection under the exposure to organic solvents, and, therefore, the study team expects that the NCTB will play an important part in the course of developing a health program for the workers exposed to organic solvents.

Blood carboxyhemoglobin levels and clinical symptoms of furnace-repairing workers / 대한산업의학회지

No abstract available.

Effect of Hyperbaric Oxygenation on Pulmonary Superoxide Dismutase Activity in Neonatal and Adult Rats / 예방의학회지

To investigate the effect of hyperbaric oxygenation on superoxide dismutase activity, neonatal rats (7-10 days old) and adult rats (approximately 100 days old) were continuously exposed to hyperbaric oxygen environment of 2.4ATA for 8 hours and their superoxide dismutase activity were measured. Neonatal rats, all survived through exposure, showed significant increases in the pulmonary superoxide dismutase activity at immediately and 24 hours after exposure. Adult rats, whose 8 hour survival rates were 14 %, did not show any significant increase in the activity of pulmonary superoxide dismutase as compared to the control adult rats. These findings are indicating that increased tolerance to oxygen toxicity in neonatal animals during exposure may be attributed to the increase in activity of superoxide dismutase in neonatal rats.

Effect of Hyperoxia on Pregnancy in the Rat / 예방의학회지

The adverse effect of diving on the fetus may extend beyond n gestational process and outcome. Primiparous Sprague-Dawley rats were assigned to one of ten exposure schedules during gestatred PO2 level, the following question about the effect of exposing a pregnant female to high partial pressure of inspired oxygen has been raised. "What effect does an increased maternal PIO2 have on fetal arterial PO2 and therefore on possible fetal oxygen poisoning?" This study was carried out to observe the effects of maternal hyperoxia on gestational process and outcome. Primiparous Sprague-Dawley rats were assigned to one of ten exposure schedules during gestation. The treatment groups were subjected to either the high concentration of oxygen, or the high atmospheric pressure. On day 21 of gestation, laparotomy was performed to examine for number and distribution of implantations and live and resorbing embryos. Fetuses were weighed, and examined for gross malformations. Subsequently, they were fixed, measured in physical parameters, and examined for visceral anomalies. Minor visceral anomalies and anatomical variation was not found. Similarily, there were no significant differences when number of resorptions, mean fetal weights, pregnancy interruption rate were compared by analysis of variance. These results indicate that exposing rats to oxygen at increased atmospheric pressure doese not affect fetal health or survival.

Utilization Patterns of Pediatric Emergency Room

No abstract available.

An Experimental Study on the Protective Effects of Ginseng Extract to Oxygen Toxicity / 예방의학회지

The protective effects of Panax Ginseng extract to oxygen toxicity of mice were studied under 5 ATA hyperbaric oxygen atmosphere. The findings observed are as follows: 1) Administration of Ginseng water extract manifested the prolonging survival time of mice to oxygen toxicity by hyperbaric oxygen atmosphere. After 18 hours of single Ginseng water extract administration and three days, seven days of consecutive Ginseng water extract administration showed the protective effect against oxygen toxicity. 2) Three days and seven days of consecutive Ginseng water extract administration showed the more efficient protective effect than single Ginseng Water extract administration. 3) Seven days of consecutive Ginseng water extract administration did not showed the more efficient protective effect than three days of consecutive Ginseng water extract administration.

Lipid Peroxidation in Vivo Monitored as Ethane Exhalation in Hyperoxia / 예방의학회지

In vivo ethane production in rats was used as an index of oxygen toxicity. The rats were allocated to four exposure conditions; hyperbaric oxygenation (HBO=5 ATA, 100% O2), normobaric oxygenation (NBO=1 ATA, 100% O2), hyperbaric aeration (HBA=5 ATA, 21% O2) and normobaric aeration (NBA=1 ATA, 21% O2). After 120 minutes of exposure, the rats exposed to high concentration and/or high pressure oxygen exhaled significantly larger amounts of ethane than those exposed to NBA, and the differences in ethane production between any two groups were statistically significant (p<0.01). This finding supports the hypothesis that hypothesis that hyperoxia increase oxygen free-radicals and the radicals produce ethane as a result of lipid peroxidation. It is notable that the ethane exhalation level of the HBA group was significantly higher than that of the NBO group. This difference could not be accounted for by the alveolar oxygen partial pressure difference between the two groups.

Influence of Intrauterine Position on Fetal Weight in albino Rats Exposed to Carbon Monoxide / 예방의학회지

Fetal weight data from 84 litters of Sprague-Dawley rats were statistically analyzed for the effect of position in the uterine horn on fetal weight. The standard score obtained from the mean weight and standard deviation of all fetuses in a uterine horn were studied for position effect. In control group, the heaviest fetus occupied the middle position with a progressive decrease in weights toward the ovarian and cervical ends of the horn. But the effect related to position for the fetal weight was not statistically significant. In contrast, rats acutely or chronically exposed to carbon monoxide showed statistically significant positional differences of fetal weight within the uterine horns. The findings that the intrauterine position effect on fetal weight which is not significant in control group may act one of confounders at the situation of transplacental toxicological studies.

An Experimental Study on the Efficacy of Vitamin E against Oxygen Toxicity / 예방의학회지

Since the wide spread application of hyperbaric oxygenation in clinical setting, the problems of oxygen toxicity have been attracting a deep interest from the researchers on hyperbaric medicine as a practical issue. Among extensive research trials, the study on the protective agents against oxygen toxicity occupied one of the most challenging field. As the mechanisms of oxygen toxicity, the role of the oxygen free radicals produced by peroxidation process are strongly accepted by the leading researchers on oxygen toxicity, the probable protective effects of antioxidant against oxygen toxicity are sustaining a sufficient rationale. In this study, the author attempted to evaluate the effect of vitamin E as a protective agent against oxygen toxicity through the observation of death rate, convulsion rate, time to convulsion, and macroscopic and microscopic pathological changes of experimental rats exposed to 100% oxygen at 5 ATA for 120 minutes. The findings observed are as follows: 1) The death rate, convulsion rate, time to convulsion, organ/body weight ratio and microscopic pathological findings were identified as reliable objective and quantitative indices for oxygen toxicity. 2) Vitamin E showed excellent protective effects against CNS and pulmonary oxygen toxicity as a strong antioxidant. The most effective dose seemed to be around 400 mg/kg. 3) The results of this study are supporting the oxygen free radical hypothesis on oxygen toxicity.

A Study on the Incidence of Carbon Monoxide Poisoning / 예방의학회지

A decade ago a survey on the population-base incidence rate of anthracite coal gas(mainly carbon monoxide) poisoning in Seoul area was investigated, resulting in the incidence rate of 306/10,000 risk population and 1 death/10,000. Another survey on the carbon monoxide poisoning was investigated during 1 year period from Apr. 1983 to Mar. 1984. Total subjects of risk population were 67,740 households covering 353,287 persons. The major findings of this survey are as follows: 1. Household-base incidence rate was 8.4%; spell-base 10.4%. 2. The incidence rate was the highest in houses having each of slate roof, cement wall, vinyl floor of bedroom and direct 'ondol' heating system. 3. Average 2.1 person was attacked from one incidence of the poisoning; severity-wise person-base incidence rates per 10,000 were 352 in mild poisoning, 54 in severe poisoning and 1.4 in death-overall incidence rate 407. Several facts were identified which supported that this figure was moderately underestimated. As the incidence of the poisoning is affected by socioeconomic and environmental factors, it is natural that one expects the incidence will decrease in proportion to general improvement of the above factors. Thus the results of these two surveys seemed preposterous. But further study suggested that the incidence rate (306/10,000) decade before had been significantly underestimated and corrected-rate should have been 478/10,000 level. 4. Age and sex distribution by the degree of the poisoning was uniform with little statistical difference; overall incidence rates by sex were 339/10,000 in male and 475/10,000 in female with significant statistical difference(p<.01). 5. 5.3% of the patients were treated at hospital or local clinic; 3.0% of the patients were hospitalized. Admission rate in comatose patient(severe poisoning) was 14.2%. In conclusion, carbon monoxide poisoning remains a major health problem by now.

An Epidemiological Study on the Neurological Sequelae of Acute Carbon Monoxide Poisoning / 예방의학회지

There has been an immense need for elaborate studies on the complications and the neuological sequelae generated by acute carbon monoxide (CO) poisoning which is highly prevalent in Korea due to widespread adoption of the anthracite coal briquette as domestic fuel for heating and for cooking. For this epidemiological study, a total of 444 subjects who received hospital emergency care for acute CO poisoning during the period of March 1982 February 1983 were randomly selected from the emergency patients's lists of 13 general hospitals in Seoul area. Informations on the neurological sequelae were elucidated by means of home visiting with prearranged questionnaire consisting questions and concise neurological examination. The findings obtained were summarized as follows; 1. The complications were found in 18% of the surveyed and acute decubitus was comprised 67.5% of the complications. 2. The total cumulative incidence of the neurological sequelae was 41.2 per 100 patients and the absolute incidence rate regardless of the duration after poisoning was 40.8%. 3. The incidence of the neurological sequelae was higher in the older age than in the younger and also higher in female than in male. Twice higher incidence was observed in the admitted patients than in the non-admitted patients and the incidence became higher in proportion to the duration of CO exposure, coma and admission. The poorer the consciousness level of patients found, at emergency room and at discharge, the higher the incidence. The incidence of the neurological sequelae by emergency care was higher in hyperbaric oxygen therapy group(51.9%) than in 100% O2 group(38.0%). 4. A total of five variables significantly associated with the occurrence of the neurological sequelae were selected by the stepwise discriminant analysis. The variables were following course of emergency care, age, consciousness level at discharge, admission duration, and consciousness level at emergency room in their sequence of discriminant power. Eight variables were selected as those associated with the degree of the neurological sequelae through the stepwise multiple regression analysis. Of these variables, the acute decubitus alone explained 21.1% of the total variation and all the eight variables could explain 36.5% of the same. The remaining seven variables listed in the order of their relative importance were: age, consciousness level at discharge, admission duration, coma duration and consciousness level at emergency room. 5. It was postulated that unexpectedly high incidence of the neurological sequelae of the CO poisoning in this epidemiological study was mainly due to the inadequate emergency care and the lack of efficient and sophisticated treatment measure. In the effort to minimize the incidence of grave neurological sequelae of acute CO poisoning, new guidelines for the emergency care and treatment should be pursued with efficient ways.

A Stochastic Study for the Emergency Treatment of Carbon Monoxide Poisoning in Korea / 예방의학회지

Emergency medical service is an important part of the health care delivery system, and the optimal allocation of resources and their efficient utilization are essentially demanded. Since these conditions are the prerequisite to prompt treatment which, in turn, will be crucial for life saving and in reducing the undesirable sequelae of the event. This study, taking the hyperbaric chamber for carbon monoxide poisoning as an example, is to develop a stochastic approach for solving the problems of optimal allocation of such emergency medical facility in Korea. The hyperbaric chamber, in Korea, is used almost exclusively for the treatment of acute carbon monoxide poisoning, most of which occur at home, since the coal briquette is used as domestic fuel by 69.6 percent of the Korean population. The annual incidence rate of comatous and fatal carbon monoxide poisoning is estimated at 45.5 per 10,000 of coal briquette-using population. It offers a serious public health problem and occupies a large portion of the emergency outpatients, especially in the winter season. The requirement of hyperbaric chambers can be calculated by setting the level of the annual queueing rate, which is here defined as the proportion of the annual number of the queued patients among the annual number of the total patients. The rate is determined by the size of the coal briquette-using population which generate a certain number of carbon monoxide poisoning patients in terms of the annual incidence rate, and the number of hyperbaric chambers per hospital to which the patients are sent, assuming that there is no referral of the patients among hospitals. The queueing occurs due to the conflicting events of the "arrival" of the patients and the "service" of the hyperbaric chambers. Here, we can assume that the length of the service time of hyperbaric chambers is fixed at sixty minutes, and the service discipline is based on "first come, first served". The arrival pattern of the carbon monoxide poisoning is relatively unique, because it usually occurs while the people are in bed. Diurnal variation of the carbon monoxide poisoning can hardly be formulated mathematically, so empirical cumulative distribution of the probability of the hourly arrival of the patients was used for Monte Carlo simulation to calculate the probability of queueing by the number of the patients per day, for the cases of one, two or three hyperbaric chambers assumed to be available per hospital. Incidence of the carbon monoxide poisoning also has strong seasonal variation, because of the four distinctive seasons in Korea. So the number of the patients per day could not be assumed to be distributed according to the Poison distribution. Testing the fitness of various distributions of rare event, it turned out to be that the daily distribution of the carbon monoxide poisoning fits well to the Polya-Eggenberger distribution. With this model, we could forecast the number of the poisonings per day by the size of the coal-briquette using population. By combining the probability of queueing by the number of patients per day, and the probability of the number of patients per day in a year, we can estimate the number of the queued patients and the number of the patients in a year by the number of hyperbaric chambers per hospital and by the size of coal briquette-using population. Setting 5 percent as the annual queueing rate, the required number of hyperbaric chambers was calculated for each province and for the whole country, in the cases of 25, 50, 75 and 100 percent of the treatment rate which stand for the rate of the patients treated by hyperbaric chambers among the patients who are to be treated. Findings of the study were as follows. 1. Probability of the number of patients per day follows Polya-Eggenberger distribution. Hourly arrival pattern of the patients turned out to be bimodal, the large peak was observed in 7:00~8:00 a.m., and the small peak in 11:00~12:00 p.m. 2. In the cases of only one or two hyperbaric chambers installed per hospital, the annual queueing rate will be at the level of more than 5 percent. Only in case of three chambers, however, the rate will reach 5 percent when the average number of the patients per day is 0.481. 3. According to the results above, a hospital equipped with three hyperbaric chambers will be able to serve 166, 485, 83, 242, 55, 495 and 41, 620 of population, when the treatment rate are 25, 50, 75 and 100 percent. 4. The required number of hyperbaric chambers are estimated at 483, 962, 1,441 and 1,923 when the treatment rate are taken as 25, 50, 75 and 100 percent. Therefore, the shortage are respectively turned out to be 312, 791, 1,270 and 1,752. The author believes that the methodology developed in this study will also be applicable to the problems of resource allocation for the other kinds of the emergency medical facilities.

Hyperbaric Oxygen Treatment in Acute CO Poisoning / 예방의학회지

No abstract available.

Epidemiological Studies on the Acute Carbon Monoxide Poisoning / 예방의학회지

No abstract available.

An Experimental Study on the design of the thermister thermometer / 예방의학회지

The study in the fild of medical instrument has been out of the interest by any the life scinetist in Korea. Especially the recent developments in the medical electromics are remarkable one. Authors planned this study to ascertain the possibility of setting up the thermistor thermometer with available accessories of demetic products including some specific foreign assembly parts. By proper use of the thermistor as one of the wheatstone bridge, we could detect the resistance variations due to the environmental temperature variance. The intensive care for the bridge circuit and compensation scheme was required. The calibration procedure adopted here makes it possible to read the current as the temperature. The temperature range was determined by the examination and construction of the graph of the resistance-temperature, the reduction of excessive current and self-heating of the thermistor were made. Renovation in response-velocity was under taken too. This electronic thermometer was designed and assembled by the circuitry developed in accordance with the maximum availability of domestic products with some foreign-made parts. The result of our experiment showed very stable function and proved to be the most promising item in the actual application as long as the thermistor is concerned.

A Survey on the Environmental Conditions of the CO Patients treated by Hyperbaric Oxygen Therapy / 예방의학회지

Carbon monoxide poisoning is one of the most serios health problems in Korea, because we have been encountered with the highest incidence of CO poisoning in the world due to the unique heating system in home called "ondal". We opened Hyperbaric chamber unit in the Seoul National University Hospital last Jan, 1969. We have treated 848 patients as of Sept. 30., 1972, around 44 months period. We collected the informations on the environmental conditions of the place where CO intoxication actually occurred by filling up the questionaire from 505 patients. The following finding were obtained. 1. Age distribution showed that the highest incidence was found in the younger age group between age of 10 to age of 29 in both sex. 2. Sex ratio of the patients was 1:1.14. 3. The socio-economic level of the patient was relatively low. 4. Housewife & housemaid were the major victims of the intoxication in the female patients & in the case of the male patient, occupational backgrounds were diverse. 5. Many patients form the middle class experienced the intoxication bu sleeping at newly built room. 6. Many intoxication has been occurred in the structure of houses where communicating doors are existing between living room & kitchen. 7. All findings obtained taught us again that CO poisoning is the serious by-product of the national fuel policy which put emphasis on the use of coal & socio-economic status is very important parameter in this hazards.