Nam Won Paik

Low-Level Lead Exposure Among South Korean Lead Workers, and Estimates of Associated Risk of Cardiovascular Diseases

This study investigated the distribution of blood lead (PbB) levels, especially low levels, among Korean lead workers. The authors also estimated the potential effects of PbB on the blood pressure (BP) and cardiovascular diseases using models taken from the published meta-analyses. The PbB data from a total of 13,043 lead workers in 1217 companies throughout Korea were used. The geometric mean PbB level was 6.08 μ g/dL (geometric standard deviation was 2.53), and 56.6% of the workers showed PbB levels greater than 5 μ g/dL. Females accounted for 31.3% of all Korean lead workers in 2003. Considering two factors, such as PbB levels and the number of lead workers, the relatively important industry subclasses were identified as Manufacture of Accumulators; Manufacture of Other Electronic Valves, Tubes, Electronic Components n.e.c.; and Manufacture of Other Parts and Accessories for Motor Vehicles. The industrial processes of relative importance included battery assembly, acid treatment, and other soldering. Although uncertainties exist in the prediction model and associated model parameters, the authors attempted to estimate potential adverse health effects related to the lead exposure. It was estimated that 7383 South Korean lead workers might have increased blood pressure and the health risks due to the lead exposures in 2003. The highest estimated risk of BP increases due to lead exposures was expected in workers of industrial subclasses and processes, such as Other Basic Nonferrous Metal Industries and Maintenance. If the models in this study were applied to the South Korean population, the impact fractions for cardiac disease among lead workers would be estimated at 4.9–12.8 times those of the general population.

Total and Soluble Metal Contents in Flux-Cored Arc Welding Fumes

The chemical composition and solubility of metals in welding fumes is thought to be related to the welder health but is not well characterized. We quantified and compared the total (insoluble + soluble) and soluble metal contents in fumes from flux-cored arc welding using non-stainless steel (FCAW/NSS) and stainless steel (FCAW/SS) wire. Welding was performed in an American Welding Society standard fume collection chamber. The total content of 13 analyzed metals was significantly higher in FCAW/NSS fumes than in FCAW/SS fumes (51.6 ± 5.7 vs. 40.2 ± 5.2%, p < 0.001). Soluble metal content was significantly higher in FCAW/SS fumes than in FCAW/NSS fumes (15.5 ± 5.8 vs. 6.49 ± 2.4%, p < 0.001) due to the presence of potassium and sodium. Different proportions of each element were observed between welding types. Iron, magnesium, and aluminum were significantly higher in FCAW/NSS fumes, whereas chromium, nickel, and potassium were more common in FCAW/SS fumes. The metal composition of FCAW fumes was more similar to that of shielded metal arc welding fumes than that of gas metal arc welding fumes. It seems unnecessary to measure soluble iron, nickel, aluminum, and barium to compare with their soluble ACGIH-TLVs at the FCAW welding process. But chromium should be specified in terms of its valance and solubility.

Reduction of Hexavalent Chromium Collected on PVC Filters

Chromium exists at various valences, including elemental, trivalent, and hexavalent chromium, and undergoes reduction-oxidation reactions in the environment. Since hexavalent chromium is known as a human carcinogen, it is most important to evaluate the oxidation-reduction characteristics of the hexavalent chromium species. Although hexavalent chromium can be reduced to trivalent state, the detailed information on this in workplace environments is limited. The purpose of this study was to investigate hexavalent chromium reduction in time in various conditions. A pilot chrome plating operation was prepared and operated in a laboratory for this study. There was evidence that the hexavalent chromium was reduced by time after mist generation. The percentage ratio (with 95% confidence intervals in parentheses) of hexavalent chromium to total chromium was almost 100% (99.1 approximately 102.3) immediately after mist generation, and was reduced to 87.4% (84.8 approximately 89.9) at 1 hour and 81.0% (78.3 approximately 83.5) at 2 hours, respectively. Another test indicated that hexavalent chromium collected on PVC filters was also reduced by time after sampling. Hexavalent chromium was reduced to 90.8% (88.2 approximately 93.3) at 2 hours after sampling. It also was found that hexavalent chromium was reduced during storage in air. It is recommended that air samples of hexavalent chromium be protected against reduction during storage.

Development and Application of a Quality Control Program for Industrial Hygiene Laboratories in Korea

Abstract Based on the American Industrial Hygiene Association Proficiency Analytical Testing Program, a new quality control (QC) program was developed and applied for industrial hygiene (IH) laboratories in Korea. This study evaluated the performance of Korean IH laboratories in the first two sequential QC rounds and identified factors affecting the analytical performance. In the first round, the percentage of proficient laboratories was extremely low in analyses of both metals and organics. However, the performance of the laboratories improved greatly in the second round of the QC program. Qualification of analysts, including education and experience, qualification of managers, supervision of well-qualified managers, and ongoing training of analysts were important factors affecting the performance of laboratories. Direct factors that affected the performance of the Korean IH laboratories were identified as incorrect standard preparation, improper instrument, improper sample preparation, wrong calculation...

Interlaboratory Precision and Bias in Metal Analysis at Industrial Hygiene Laboratories in Korea

Abstract A new quality control (QC) program for the Korean industrial hygiene laboratories was introduced in 1992. This study evaluated interlaboratory bias and precision in analyses of cadmium and lead in Korean industrial hygiene laboratories. There were significant interlaboratory differences in analytical values for both metals in two rounds of the Korean QC program. When the Korean QC program was first introduced, inter-laboratory precision and accuracy of data obtained from laboratories participating in the first round were extremely poor. There were several laboratories that consistently reported outliers. However, the accuracy and precision were significantly improved in the second round. The performance of one laboratory, the Seoul National University-School of Public Health Industrial Hygiene Laboratory, was improved by participating in the American Industrial Hygiene Association Proficiency Analytical Testing program, investigating the source of errors, and correcting the errors.

Development of a Sampling and Analytical Method for 2,2-Dichloro-1,1,1-trifluoroethane in Workplace Air

The use of 2,2-dichloro-1,1,1-trifluoroethane (compound number: HCFC-123) is growing in industry as a substitute for ozone-depleting chlorofluorocarbons (CFCs). Recently, liver-related illnesses have been reported from industries handling HCFC-123. However, information on worker exposure to the material is limited, and an acceptable sampling/analytical method is not available. The aim of this study was to develop a widely applicable sampling and analytical method to determine worker exposures to airborne HCFC-123 and to evaluate the performance of the method. A solid sorbent tube, containing two sections (400 mg in the front and 200 mg in the back) of activated coconut-shell charcoal was chosen for sampling airborne HCFC-123 vapor. The breakthrough volumes were 13.6 L at 3597 +/- 210.1 ppm (with a sampling airflow rate of 0.046 L/min) and 17.0 L at 1841 +/- 4.5 ppm (with sampling airflow rate of 0.046-0.050 L/min). Samples of HCFC-123 in the charcoal tube were stable for 7 days either at room temperature or in a refrigerator and a migration occurred within 14 days at room temperature. It is recommended that the HCFC-123 sample in activated charcoal tubes be stored either at room temperature or in a refrigerator and be analyzed within 7 days. The HCFC-123 in the charcoal tubes was desorbed into dichloromethane and analyzed using gas chromatography/ flame ionization detection. The limit of detection was 0.23 mg/sample, and the average desorption efficiency was 99.0%. The total coefficient of variation was 0.060, and the method accuracy was 16.6%. In conclusion, the performance of the sampling and analytical method developed for the determination of airborne HCFC-123 concentrations was acceptable to the NIOSH sampling and analytical criteria.

Laboratory and field validation of the GC-NPD method for the measurement of formaldehyde in the workplace.

Formaldehyde is classified as a suspected or probable human carcinogen by several organizations. Since conventional sampling and analytical methods for airborne formaldehyde show relatively poor sensitivity, an improved method is needed. The aim of this study was to develop a new analytical method for measuring the airborne formaldehyde concentrations in workplaces and to evaluate the performance of the method through laboratory and field tests. The method employs a sampling tube containing silica gel coated with 2, 4-dinitrophenylhydrazine (2,4-DNPH), which produces 2,4-DNPH-formaldehyde derivative with formaldehyde. Then the 2,4-DNPH-formaldehyde derivative is analyzed using gas chromatography (GC) equipped with a nitrogen-phosphorus detector (GC-NPD). In laboratory tests, the new method, referred to as the GC-NPD method, was as sensitive as the National Institute for Occupational Safety and Health (NIOSH) analytical method, which uses high-performance liquid chromatography equipped with ultraviolet detector. The total analytical precision and 95% confidence limit of the estimated total standard error for the GC-NPD method were 0.009 and ± 12.0%, respectively, which satisfied the OSHA sampling and analytical criteria. In field tests, the overall uncertainty of the GC-NPD method was 11.2%, which satisfied the NIOSH criteria for sampling and analytical methods. The GC-NPD method with a 2,4-DNPH coated adsorbent sampler for the determination of airborne formaldehyde concentration showed good performance with acceptable accuracy and precision.

2007 William P. Yant Award Lecture: Industrial Hygiene in a Newly Industrialized Country—South Korea

The Yant Award was established in 1964 to honor the contributions of William P. Yant, the first president of the American Industrial Hygiene Association. It is presented annually for outstanding contributions in industrial hygiene or allied fields to an individual residing outside the United States.The Yant Award was established in 1964 to honor the contributions of William P. Yant, the first president of the American Industrial Hygiene Association. It is presented annually for outstanding contributions in industrial hygiene or allied fields to an individual residing outside the United States.

2007 William P. Yant Award Lecture

The Yant Award was established in 1964 to honor the contributions of William P. Yant, the first president of the American Industrial Hygiene Association. It is presented annually for outstanding contributions in industrial hygiene or allied fields to an individual residing outside the United States.The Yant Award was established in 1964 to honor the contributions of William P. Yant, the first president of the American Industrial Hygiene Association. It is presented annually for outstanding contributions in industrial hygiene or allied fields to an individual residing outside the United States.