• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.18 no.3
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• pp.224-238
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• 2008

The aim of this study is to confirm the physicochemical property and hazard of thinner (012), which is a diluent of enamel paint used for floor coating for waterproofing and oil painting for the outer wall. The literatures of physicochemical property and hazard of thinner were surveyed and its physicochemical property were evaluated. And then, the inhalation toxicity of thinner affecting the central nervous system and reproductive organs in rats were examined by subchronic (6 h./day. 5 days/ week for 13 weeks) inhalation test. 1) According to the 13-week subchronic inhalation test, there were no significant changes in clinical test and body weight. However, a significant evidence of toxicity was observed in the hematological test and organ weight such as heart, kidney, liver and brain (p<0.01) in the 200 ppm and 1,000 ppm exposure groups in a dose response manner. In the histopathology analysis, there were no significant evidence of toxicity. Therefore, thinner was not classified as an organ targeted toxic agent. In case of Harmfulness, it could be classified as a chronic toxic agent 3($500 ppm/4hr, rat). 2) The reproductive toxicity such as extension of the period of estrous cycle, reduction of serum estradiol concentration and increase of frequency of the abnormal sperm was observed in the 1,000 ppm exposed animals. 3) The result of the physicochemical property of the test material showed that the specific gravity was 0.793, boiling point $155.8^{\circ}C$, steam pressure 2.1 kPa, ignition point $34.5^{\circ}C$, and spontaneous ignition point $280^{\circ}C$. The endothermic and exothermic values were 371.4 J/g and 159.1 J/g. respectively. The explosion limit was 214 mg/l. These data showed that thinner could be classified as an explosion agent level 1.2 and ignitive liquid agent 3 ($23-60^{\circ}C$) according to the notification No. 2008-1 of the Labor Ministry, "Classifying Standard of Chemical Materials."

• Clinical and Experimental Reproductive Medicine
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• v.30 no.1
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• pp.85-93
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• 2003

Objective : To evaluate the safety and efficacy of selective fetal reduction (SFR) and compare the outcome of twin pregnancy after SFR in multiple pregnancy induced by assisted reproductive technology (ART) with that of natural twin pregnancy. Methods : From September 1995 to March 2002 in Ajou University Hospital, SFR was performed in 79 patients whose gestational sacs were more than 3. Of these 79 patients, 47 patents resulted in twin pregnancy after SFR. SFR was performed using transvaginal intracardiac KCl injection at gestational age of $6{\sim}9$ weeks. Control group was composed of 264 patients with natural twin pregnancy, who delivered after intrauterine pregnancy at 24 weeks, from June 1994 through December 2002. We compared Obstetric and perinatal outcomes between SFR group and natural twin group. Results: Among 47 patients with twin pregnancy after SFR, 2 spontaneous abortion were occurred at intrauterine pregnancy at 8 and 19 weeks. Obstetrical and perinatal outcomes were available in 43 patients. Single intrauterine fetal death was occurred in 1 of 43 (2.3%) patients in SFR group. Incidence of preterm labor, premature rupture of membrane, preeclampsia and placenta previa were similar, but gestational diabetes mellitus (GDM) was occurred more frequently in SFR group (3 (7.0%) vs 4 (1.5%), p=0.02). Mean gestational age, mean birth weight, incidence of discordancy, use of intubation and ventilation, incidence of fetal anomaly, low (<7) Apgar score and intrauterine growth restriction were similar in both groups. Conclusion: Twin pregnancy after SFR has the increased incidence for GDM but other obstetric and perinatal outcome was similar compared with natural twin pregnancy. So SFR is a safe and effective procedure, so we suggest SFR is needed in multifetal pregnancy more than triplet.

• Clinical and Experimental Reproductive Medicine
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• v.9 no.1_2
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• pp.29-41
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• 1982

This retrospective clinical study was done based under the delivery records of 146 cases of twin pregnancies in Yonsei University, Severance Hospital and Wonju Christian Hospital from 1977 through 1980 with particular interest in the second twins. Clinical factors, Apgar scores related to neonatal prognosis, and perinatal mortality rate were statistically analyzed and the following results were obtained. The mean - birthweight for A (first) twins was 2,377 grams and for B (second) twins 2,296 grams. In comparison of the percentage of low-birth-weight (less than 2,500 grams) infants, there were more small B twins, but the difference was statistically not significant. Because there were no significant statistical differences in birth weight-grouping between A and B twins, they could be compared with the comprehensive Apgar scores, but this method was also shown to be statistically not significant. In comparison of the percentage of breech deliveries in A and B twins, the percentage was more than three times in B twin (A twin, 7.5 per cent; B twin, 24.0 per cent), and the difference was statistically very significant (p < 0.0005). There were no significant statistical differences between the Apgar scores of A and B twins in reference to the manner of delivery. According to the manner of delivery of B twins, spontaneous vertex delivery and total breech extraction revealed higher infant mortality rate than others. B twins presented by the vertex in 88 cases (61.0 per cent), by the breech in 55 cases (37.0 per cent), and by the shoulder in 3 cases (2.0 per cent). And this therefore disclosed no significant statistical differences in Apgar scores in relation to the presentation. The duration of labor appeared to have no clear correlation with the Apgar scores and the perinatal mortality of A and B twins. The delivery interval between A and B twins was 11.9 minutes on an. averge, varying from 3 to 65 minutes. The length of this interval was not found to have any significant effect on the Apgar scores and the perinatal mortality rate of B twin.