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A study on health impact of a river pollution neighboring industrialized big city on the rural people residing along the river
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Joung Soon Kim, Seung Wook Lee, H.S Yoon, Y Heo, S.J Yang, T.W Ha, H.K Hong, Y.W Lee, H.H Kwon, D.H Lee, H.C Kim
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Korean J Epidemiol. 1986;8(1):37-95.
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 Abstract
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Abstract
This study is conducted to identify any adverse health impact for the rural residents living along a certain river in Korea. The river actually accomodates all the industriral and domestic waste-water discharged from its neighboring big city. Unfortunately, the river is being served for farming water residents, while the current water cleaning system does not function satisfactorily. It means a possibility that the polluted water can contaminate underground water which is the main source of drinking water in the area.
The aim of the study is to determine the contamination level of heavy metals and evaluate the health impact of the residents with a linkage to the river pollution. The study is proceeded under the following steps.
1) The area is divided into two parts where the water is used for the farming or not. They formed study and control area. For the residents within the sites, study and control groups were formed.
2) Between the two, any statistical significance was pursued for the following items,
(1) the contamination levels by the metals in drinking water source, soil, farming products, farming products, and fishes which live in the water where the river joins the main river,
(2) the contamination levels of rural residents, blood samples, and
(3) by physicians the health evaluation results by clinical and pathological tests for the residents.
3) the correlation between the blood contamination levels and the health results,
4) the correlation between the blood and environmental pollution levels were studied.
In spite of several limitations from the nature of the study,
The findings were summarized as follows：
1) No statistical significance was found in the differences between the groups with regard to age, sex, occupation, economic status, education levels, pregnancy history, number of household members, and medical insurance status.
2) No statistical significance were found with regard to smoking habit, proportions of drinking, boiled water, number of days using pesticides and number of pregnancy poisoning, frequency of monthly meat intake. But a significance was found in the number of fish intake, while almost nobody took fishes from the river.
3) Most of the residents(93%) think the river is harmful to their health and 34% among them addressed that the river contamination is the cause of various dermatitis.
4) Stillbirth rate was significantly higher in the study group, but no correlation was found with the metal contamination.
5) The study group showed significantly higher complaints for 24 symptoms believed to appear with metal contamination, but no correlation was found. No correlation was found when the symptoms are grouped into 17 disease classification, either.
6) Neurological symptoms and clinical screening tests did not show any significant difference between the groups. Past disease history showed the same thing.
7) The results of diagnoses by physicians are classified into three groups from normal to abnormal. The control groups had higher proportion of the normal, but conjunctiva abnormaly, unspecified digestive ulcer, symptoms of abdomen and pelvic area, gasritis and duodenum inflammation were more frequent in the control group. Neurologic findings by a specialist did not show any difference.
8) The values of laboratory tests for hematopoietic system, kidney, and liver functions as indices of health measurements didn’t show any significance.
9) For the level of heavy metal contamination in blood, those of Cu, Cd, Pb but Zn were statistically higher than those determined by the National Envoronmental Protection Institute for the Yang-pyong-kun residents. For Pb, Zn, Ni at 0.1% and Hg at 5%, the values from the control groups was rather higher than those in the study group. However, at was seen that the level of Cd of the study group was higher than the control groups at 5%. They failed to show any consistent pattern, but the males has higher value than the females for Cd, Zn, Hg and lower value for Cu, Pb with statistical significance.
10) The proportions of residents above the permissible levels for the metal contamination were determined. The proportions for Pb and Zn showed that those for the control group were statistically higher than those for the study group. They were 42.3% for Pb and 6.3% for Zn, respectively, in the control group. For the case group, they were 19.3% for Pb and 4.6% for Mn, respectively. The proportions of residents who had abnormal level for more than 2 kinds of heavy meatals was 10.2% and for more than 3 kinds 0.8%.
11) The health evaluation results were linked with the classification of metal levels into the normal and abnormal groups. The abnormal group in Mn level seemed to have high proportion of lassitude, but its reliability was very low because of the sample size of 1. Also, the proportion of no symptoms was significantly higher in the group abnormally contaminated by Pb and Zn rather in the normal group.
The clinical evaluation results showed that the Pb-and Zn-high groups had more frequently hearing difficulty, the Pb-high conjuntictiva problem, the Zn-high group neurotoxic disturbance and hearing difficulty. The neurological findings showed that inflammation, neurotoxic disturbance and hearing difficulty in the Mn-and Pb-high group, respectively. Also, various pathological tests did not show any significance.
12) The water quality was examined for the river and drinking water. The river seemed to be polluted by not heavy metal but various organic materials. This can be backed up by high levels of COD, BOD, and DO. The drinking water classified into underground water, well and simple-lined pump didn’t bear any significant difference from that in the control area and was believed to be generally appropriate for drinking. In the simple-lined pump and well water, the levels of Cu, Pb, and Ni were slightly higher than in the foot site river. It needs further attention to find Hg, As, Cr in the well water which did not exist in the river.
13) The sample of fishes to determine heavy metal contamination level was taken in the main river around the various sites where the river joins. While the site difference couldn’t be identified because of the fish morbidity, the levels were below being serious. However, the levels of Pb and Hg were slightly higher but not significant.
14) For the farmig product, nine crops sampled. The levels of Pb and Zn were significantly higher in brown rice, corns, garlics, while the others were below the permissible level. This results are consistent with the residents results But no significance were found when compared to the control area, while some metals show higher levels in the contral area.
15) The metal contaminatin levels in the soil of the study area were significantly higher for Pb, Zn and Mn. Although the Mn level in the residents blood is very low, the high levels for of Pb and Zn need attention beeanse they were also high in the crops.
16) The correlation between the soil and crops did not show any consistent pattern. However, in certain sites, the high correlations were found and suspected due to the confounding factors such as the regional nature of soil contamination, pesticides and fertilizer.
17) For the corelation between the blood and environmental contaminations, the levels of metals except Mn which showed the high levels in the soil and crops were also high in the blood. The relatively great portion of the residetns with high levels can cause serious health impact. However, the origin of their contamination seems to come from the soil not from the river. It deserves a further investigation on this matter.
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Summary
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An epidemiological study on subclinical Leptospiral infection among rural Koreans by Leptospira isolation in blood culture
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Joung Soon Kim, J.K Lee, H.W Chung, S.J Yang, H.S Lim, W.Y Lee
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Korean J Epidemiol. 1985;7(2):253-258.
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Abstract
A clinical syndrome complex that had been known as epidemic pulmonary hemorrhagic fever in Korea since 1975 has been proved to be leptospiral infection by Kim et al. in 1984.
Even though hundreds of cases have been reported for the last 10 years, few information on the status of leptospiral infection among general population at risk is available.
This study was carried out in a small rural community with 189 population in 41 household to estimate subclinical leptospiral infection rate. The study consisted of interview, medical examination by doctors, and blood sampling. The first study in which only 50 inhabitants completed the study on November 3rd, and the second one for the drop-outs on December 17th, 1985.
The blood specimens were inoculated to a newly developed artificial media by Lee, YUMC-5050, which had been demonstrated to be quite sensitive, silver stained in two weeks of culture and examined under microscope for the characteristic leptospiral bacteria. Since leptospiral positives were found only among the first study group, probably due to the optimal timing for culture (November 3rd), but none of 40 specimens sampled in the second study was culture positive, the data analysis had to be depended upon the first study population. Among six positives re-cultured in the second study period, only one remained positive and five became negative within one and half month.
The summarized findings are as followings：
1) Leptospira culture positive rate was 16% average; 23% for males and 11% for females. The cases were net clustered to any particular age group but rather even for all active ages. Protective immunity for older ages was not evidenced.
2) Clinical symptoms and signs experienced by the study subjects during the last one month were not significantly different in kind and frequency between leptospira positives and negatives except one case each for hematuria and lymphadenpathy in positive group. Two out of eight positives had mild clinical manifestation competible to leptospiral infection but six of them were typical of subclinical infection.
3) Enviromental factors exposed also were not different between leptospira culture positives and negative, probably owing to the fact that these farmers were exposed to all environments in multiplicity making it difficult to find out the difference for any environmental particulars.
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Summary
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An epidemiological study of cerebrovascular disease through stroke registry and case-control study on risk factors in semi-urban and rural communities
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Joung Soon Kim, M.H Chung, H.S Yoon, B.Y Heo, S.J Yang
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Korean J Epidemiol. 1984;6(1):112-123.
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Abstract
This study was carried out from November 1982 to October 1984 on Chuncheon City and Chunseong County where the population is about 210,000.
The objective of the research was to study natural history of cerebrovascular diseases through stroke registry and to indentify risk factors of the disease by case control study in order to formulate strategy of stroke control program.
Stroke registry was encouraged for the patients by distributing circulars to the community leaders, professional associations, hospitals, clinics and public doctors in addition to the propaganda through mass media. Also the responsible community nurse visited villages, hospitals and clinics to make the stroke patients registered.
When stroke patients registered to the stroke clinic these patients were examined at the stroke clinic in every Tuesday and Thursday by utilizing postcard appoint system. At the same time they were interviewed and checked for height, weight, blood pressure, chest x-ray, electrocardiogram, and blood chemistry.
For the case-control study on risk factors relatively new patients were selected and matched with their neighbor controls of the same sex and the similar age.
Since the risk factors of stroke identified were found to be very similar to that of hypertension, other set of case-control study on hypertension risk factors was also carried out to examine confounding effects of these variables.
Stroke management pattern, social problems encountered by the families with stroke patient, and activity index of the patients at three months after the onset and at the time of the study were also surveyed by interview.
The results and conclusion obtained are as followings:
1) The total number of stroke patients registered were only 305 during the two-year study period. This number is estimated to be about 10% of patients existing in the communities according to the sample survey of one township within the study area. Thus the study on natural history of stroke was not able to be accomplished due to the lack of representativeness for the patients registered. The major reason of low registration was reported to be the difficulty of attending the clinic and that the registration was not accounted to be helpful for them by patients themselves and their family.
2) Among 154 cases who were subjected to the case-control study on the risk factors of cerebrovascular disease, about half of them were new patients and only a few cases were old cases over one year after the onset. Most patients(76%) were older than 50 years of age. Cerebral infacrtion was the predominant pathological type, and 13% of the patients had previous experience of stroke prior to this attack. At the time of onset 15% tof them had loss of consciousness, motor paralysis in 90% and speech disturbance in 63%.
3) Among the risk factors examined for the association with the stroke by case-control study, and analysed by paired marginal test(McNemar’s X2 test) and estimated relative risk ratio, hypertension, family history of stroke, overweight, duration of smoking, left ventricular hypertrophy, serum total cholesterol, and uric acid showed significant statistical association the hypertension revealing the most strong association. Stepwise multiple regression also showed the similar pattern. On the other hand when the hypertension was controlled, these variables did not show any association.
Furthermore when the result of case-control study on risk factors of hypertension was compared with that of stroke by means of estimated relative risk ratio, the association strength of almost all variables in both stroke and hypertension was quite identical. Therefore it was concluded that other variables beside the hypertension were not causally associated but secondarily associated with the occurrence of cerebrovascular diseases by the intervened third factor, the hypertension; the hypertension was the most confirmatory risk factor of the cerebrovascular diseases among the variables examined.
4) Management pattern of the stroke patiens showed that only 20% of them was attended medically within the day of onset, among whom over 60% utilized Chinese medicine and 29% utilized modern medical facilities. The patients treated continuously comprised only 35% and the rest of the patients were either stopped treatment or treated intermittently.
The functional ability measured by activity index showed that the proportion of the patients with high score(ability of self-care) was 28% at the three months from the onset but the proportion increased up to 68% at the time of the study.
5) The most serious social and family problem incurred by the stroke was economic difficulty due to the loss of job for the patients themselves, and the activity limitation of the family members to take care of the patient. Home visited nursing care system may be worth to intervene for a community based stroke control program.
(This study was supported by WHO Research Grant)
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