Association Between Blood Lead Concentration and Computerized Neurobehavioral Performance in Korean Elementary School Students / 대한산업의학회지

OBJECTIVES: This study was conducted to evaluate association between computerized neurobehavioral performance and blood lead concentration in Korean elementary school students. METHODS: The subjects were 1,077 elementary school students of Seoul, Busan, Daegu and Gwangju. Blood lead concentration was measured and computerized neurobehavioral performance tests were performed. RESULTS: Blood lead concentration of the subjects was in the range of 0.20 and 7.39 microg/dl. The geometric mean of the subjects' blood lead concentration was 1.41 microg/dl. As blood lead concentration increased, reaction time to the symbol digit tended to increase significantly and linearly. As a result of LOWESS(locally weighted scatterplot smoothing), increasing reaction time to the symbol digit was observed. CONCLUSIONS: As blood lead concentration under the CDC (center for disease control and prevention) reference value increased, reaction time to the symbol digit tended to increase. But, as the number of subjects over 3 microg/dl is small, it is difficult to make a definite conclusion. If confounding variables are controlled properly in a follow-up study, we can obtain a more definite conclusion.

Relationship between Blood Lead Concentration and Neurobehavioral Function of Children / 대한산업의학회지

OBJECTIVES: To evaluate effects of lead on the central nervous system of children by measuring blood lead concentration, computerized neurobehavioral function and intelligence of elementary school students. METHODS: The study was conducted with 208 elementary school students living in the vicinity of Pohang Industrial Complex in October and November, 2005. Data on demographic characteristics, living environments and lifestyle habits were collected from subjects. RESULTS: Blood lead levels of elementary school students ranged from 0.76-4.97 microg/dl, which is below the 10 microg/dl recommended level of CDC. The blood lead levels were similar with those reported in other domestic and international studies. Neurobehavioral tests revealed that most third grade students reacted slowly and their speed declined in simple reaction time (p or =3.00 microg/ dl was 3.21 in third grade students and 4.28 in sixth grade students. Low academic achievement was observed among third grade students (p<0.05) and six grade students (p<0.05) as the average blood lead level increased. Correlation analysis on the association of blood lead concentration with neurobehavioral tests revealed a positive correlation between blood lead levels and reaction time of choice reaction time and symbol digit substitution in third grade students. A positive correlation was observed between blood lead levels and reaction time of symbol digit substitution and finger tapping speed in sixth grade students. There was a negative correlation between blood lead levels and reasoning ability of third grade students (r=-0.247) and vocabulary ability of six grade students (r=-0.255). CONCLUSION: There have been few studies on the effects of blood lead on the central nervous systems of children in Korea. The study supports the findings of earlier studies that blood lead has an impact on children. However, the study did not confirm significant association of blood lead concentration with each neurological and motor test conducted for this study due to a small sample size and relatively low blood lead levels of elementary school students. Further studies using a similar assessment methods would be helpful to evaluate the effects of low blood lead levels on the central nervous systems of children.

Relationship between Blood Lead Concentration and Neurobehavioral Function of Children / 대한산업의학회지

OBJECTIVES: To evaluate effects of lead on the central nervous system of children by measuring blood lead concentration, computerized neurobehavioral function and intelligence of elementary school students. METHODS: The study was conducted with 208 elementary school students living in the vicinity of Pohang Industrial Complex in October and November, 2005. Data on demographic characteristics, living environments and lifestyle habits were collected from subjects. RESULTS: Blood lead levels of elementary school students ranged from 0.76-4.97 microg/dl, which is below the 10 microg/dl recommended level of CDC. The blood lead levels were similar with those reported in other domestic and international studies. Neurobehavioral tests revealed that most third grade students reacted slowly and their speed declined in simple reaction time (p or =3.00 microg/ dl was 3.21 in third grade students and 4.28 in sixth grade students. Low academic achievement was observed among third grade students (p<0.05) and six grade students (p<0.05) as the average blood lead level increased. Correlation analysis on the association of blood lead concentration with neurobehavioral tests revealed a positive correlation between blood lead levels and reaction time of choice reaction time and symbol digit substitution in third grade students. A positive correlation was observed between blood lead levels and reaction time of symbol digit substitution and finger tapping speed in sixth grade students. There was a negative correlation between blood lead levels and reasoning ability of third grade students (r=-0.247) and vocabulary ability of six grade students (r=-0.255). CONCLUSION: There have been few studies on the effects of blood lead on the central nervous systems of children in Korea. The study supports the findings of earlier studies that blood lead has an impact on children. However, the study did not confirm significant association of blood lead concentration with each neurological and motor test conducted for this study due to a small sample size and relatively low blood lead levels of elementary school students. Further studies using a similar assessment methods would be helpful to evaluate the effects of low blood lead levels on the central nervous systems of children.

Exposed level of workers in the factory next to a led recycling factory / 예방의학회지

The purpose of this study was to determine whether workers at a factory next to a lead recycling factory in Pusan, were affected by lead contamination. The mean air lead concentration of lead recycling factory was 0.21mg/m3(TWA=0.05mg/m3). Thirty-nine male workers of Factory A, Cr. plating factory next to the lead recycling factory were exposed group and a comparison group, 62 male workers of Factory B were selected from another Cr. plating factory about 8.5km away from lead recycling factory. Air lead concentration of each workplace was checked for 4 times from August 5 to August 20 in 1995 by low volume air sampler. Each subject was interviewed about age, life-style, smoking, work history, and residence etc, and venous blood was drawn for lead measurement by graphite furnace atomic absorption spectrometry. We have observed that air lead concentration and blood lead concentration of Factory A was higher than Factory B(2.6 +/- 1.6 Vs. 1.2 +/- 0.2 microgram/m3, 14.9 +/- 1.6 Vs. 12.2 +/- 1.6 microgram/dl). We believe that other environmental lead sources such as transportation and residence did not affect air lead and blood lead concentration differences of both factory. We concluded that high air lead and blood lead concentration of Factory A were caused by lead contamination generated by the neighboring lead recycling factory.

The Relationship between Occupational Lead Exposure and Minor Hearing Impairment / 대한산업의학회지

In this study the relationship between occupational lead exposure and minor hearing impairment was investigated in a cross-sectional design with 50 lead exposed workers from January to April 1994, The data were collected from the interview with the structured questionnaire which included sociodemographic variables and medical histories especially ear disease and occupational histories. Lead exposure indices which were blood lead, urine lead, zinc protoporphyrin in urine, and delta-aminolevulinic acid in urine were analyzed, Also study subjects were examined pure-tone hearing test. The results were as follows ; 1. There were significant differences in lead indices between lead-exposed workers and non-exposed workers. 2. The duration of lead exposure did not affect the hearing impairment among lead exposed workers. 3. Minor hearing impairment were higher in lead-exposed workers than non-exposed workers, but there were not statisticatly significant. The result from this study indicated that lead exposed workers should be monitored to prevent hearing impairment and would be needed health education.

Cohort Observation of Blood Lead Concentration of Storage Battery Workers / 예방의학회지

To assess the effectiveness of the interventions in working environment and personal hygiene for the occupational exposure to the lead, 156 workers (116 exposed subjects and 40 controls) of a newly established battery factory were examined for their blood lead concentration (Pb-B) in every 3 months up to 18 months. Air lean concentration (Pb-A) of the workplaces was also checked for 3 times in 6 months interval from August 1987. Environmental intervention included the local exhaust ventilation and vacuum cleaning of the floor. Intervention of the personal hygiene included the daily change of clothes, compulsory shower after work and hand washing before meal, prohibition of cigarette smoking and food consumption at the work site and wearing mask. Mean Pb-B of the controls was 21.97 +/- 33.6 microgram/dl at the preemployment examination and slightly increased to 22.75 +/- 3.38 microgram/dl after 6 months. Mean Pb-B of the workers who were employed before the factory was in operation (Group A) was 20.49 +/- 3.84 microgram/dl on employment and it was increased to 23.90 +/- 5.30 microgram/dl after 3 months <(P<0.01). Pb-B was increased to 28.84 +/- 5.76 microgram/dl 6 months after the employment which was 1 month after the initiation of intervention program. It did not increase thereafter and ranged between 26.83 microgram/dl and 28.28 microgram/dl in the subsequent 4 tests. Mean Pb-B of the workers who were employed after the factory had been operation but before the intervention program was initiated (Group B) was 16.58 +/- 4.53 microgram/dl before the exposure and it was increased to 28.82 +/- 5.66 microgram/dl (P<0.01) in 3 months later (1 month after the intervention). The values of subsequent 4 tests remained between 26.46 and 28.54 microgram/dl. Mean Pb-B of the workers who were employed after intervention program had been started (Group C) was 19.45 +/- 3.44 microgram/dl at the preemployment examination and gradually increased to 22.70 +/- 4.55 microgram/dl after 3 months (P<0.01), 23.68 +/- 4.18 microgram/dl after 6 months, and 24.42 +/- 3.60 microgram/dl after 9 months. Work stations were classified into 4 parts according to Pb-A. The Pb-A of part I, the highest areas, were 0.365 mg/m3, and after intervention the levels were decreased to 0.216 mg/m3 and 0.208 mg/m3 in follow-up tests. The Pb-A of part II was decreased from 0.232 mg/m3 to 0.148 mg/m3, and 0.120 mg/m3 after the invention. Pb-A of part III and IV was tested only after intervention and the Pb-A of part III were 0.124 mg/m3 in January 1988 and 0.081 mg/m3 in August 1988. The Pb-A of part IV, not stationed at one place but moving around, was 0.110 mg/m3 in August 1988. There was no consistent relationship between Pb-B and Pb-A. Pb-B of the group A and B workers in the part of the highest Pb-A were lower than those of the workers in the parts of lower Pb-A. Pb-B of the workers in the part of the lowest Pb-A increased more rapidly. Pb-B of group C workers was the highest in part I and the lowest in part IV. These findings suggest that Pb-B is more valid method than Pb-A for monitoring the health of lead workers and intervention in personal hygiene is more effective than environmental intervention.

A Study on the Associatio Between Symptoms and Biological Indicies in Workers Exposed to Lead / 대한산업의학회지

This research was conducted to determine the usefulness of reported symptoms for the diagnosis of lead poisoning for workers exposed to lead. A group of 147 male lead smelting workers were given special physical examinations from June to September of 1989. The examinations included the reporting of ailments(symptoms) by the workers, as well as analyses of their blood lead concentrations and urinary coproporphyrine and delta-aminolevulinic acid concentrations. the associations were analyzed between the bilogical exposure indices and the symptoms described by the workers. The results were as follows: 1. The only symptoms which were described more frequently by the lead workers compared to the control group were paresthesia of the extremities, myalgia, arthralgia, and insomnia. The frequency of other symptoms described were actually lower for the lead-exposed workers. 2. For those workers whose blood lead concentrations were above 60 microgram/dl, only the increase in the frequencies of arthralgia and paresthesia of the xtremities were statistically significant, compared to those workers whose blood lead concentrations were below 60 microgram/dl. Also, arthralgia was the only symptom which increased in frequency in workers whose ruinary coproporphyrine concentrations were above 100 microgram/l; however, this increase was not statistically significant by urinary delta-aminolevulinic acid levels.