• Title/Summary/Keyword: Lead concentration by particle size

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Estimation of Occupational Health Standard by Relationship between Airborne Lead Concentration by Particle Size and Lead in Blood (공기중 납입자의 크기 특성과 혈액중 납농도와의 관계에 의한 허용농도 측정)

  • Park, Dong-Wook;Paik, Nam-Won
    • Journal of Korean Society of Occupational and Environmental Hygiene
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    • v.6 no.2
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    • pp.265-271
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    • 1996
  • This study was conducted to investigate distribution of lead particles by operation of industry, to evaluate the effect of particle size on the absorption to workers, and to recommend the Occupational Health Standard for lead. Total lead concentrations in the secondary smelting industry were higher than those in the battery and litharge manufacturing industry. Total lead concentrations in other industries except radiator manufacturing industry exceeded the standard of $50{\mu}g/m^3$. Only radiator manufacturing industry indicated lead concentrations significantly lower than those in other industries(p<0.05). Average blood lead level of workers was $85.1{\mu}g/dl$ in secondary smelting manufacturing, $51.3{\mu}g/dl$ in the battery manufacturing, and below $40{\mu}g/dl$ in the litharge and radiator manufacturing industry. Blood lead levels of workers by industry were significantly different(p<0.05). From relationship between airborne lead concentrations by size and lead in blood, confidence limits of airborne lead concentration equivalent to $40{\mu}g/dl$ of permissible limit in blood, was $147.9-489.8{\mu}g/m^3$ as total lead and $28.8-79.4{\mu}g/m^3$ as ACGIH-RPM. It is recommended that two separate occupational health standards for lead should be established by particle size. Airborne concentration of $150{\mu}g/m^3$ as fatal lead dust and $30{\mu}g/m^3$ as respirable lead dust was recommended.

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A Study on the Characteristic of Airborne Lead Particle Size by Industry (업종별 공기중 납입자의 입경별 분포특성에 관한 조사 연구)

  • Park, Dong Wook;Paik, Nam Won
    • Journal of Korean Society of Occupational and Environmental Hygiene
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    • v.5 no.2
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    • pp.160-171
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    • 1995
  • The size characteristics of lead particle which is one of the important factors associated with absorption of lead were ignored in establishing lead standard. This study was conducted to investigate distribution of lead particles by operation of industry. Aerodynamic Mass Median Diameters (MMD) of airborne lead particles in the battery and litharge manufacturing industry were $14.1{\mu}m$ and $15.1{\mu}m$, respectively. There was no significant difference between those two values(p>0.05). However, the diameters in radiator manufacturing and secondary smelting industry were $1.3{\mu}m$, $4.9{\mu}m$, respectively. Those were significantly smaller than the particle sizes in other industries(p<0.05). Total lead concentrations in the secondary smelting industry were higher than those in the battery and litharge manufacturing industry. Total lead concentrations in other industries except radiator manufacturing industry exceeded the standard of $50{\mu}g/m^3$. Only radiator manufacturing industry indicated lead concentrations significantly lower than those in other industries(p<0.05). Concentrations of lead particles smaller than $1{\mu}m$ defined as respirable fraction by OSHA's CPA model assumption were $72.4{\mu}g/m^3$ in the secondary smelting industry, exceeding $50{\mu}g/m^3$. The relationship of concentrations between total lead and lead of particles smaller than $1{\mu}m$ was log Y = 0.46 logX + 0.06(n=119, $r^2=0.44$, p=0.0001). Relationship of respirable lead concentrations between OSHA and ACGIH was significantly detected in the litharge and battery manufacturing industry(p=0.0001), but was not significant in the radiator(p=0.2720) and secondary smelting manufacturing industry(p=0.2394). As MMDs of lead particles generated in industry were small, difference of respirable lead concentration between OSHA and ACGIH became smaller. There was a significant difference between concentrations respirable lead defined by two organizations such as OSHA and ACGIH in the battery and litharge manufacturing industry. Average concentration of respirable lead by ACGIH definition was 43.3 % of total lead in secondary smelting and 48.9 % in radiator manufacturing industry, and lower fractions were indicated in battery and litharge manufacturing industry. Relationships of total lead with IPM, TPM, and RPM were significant respectively(p=0.0001) and lead concentrations by particle size could be estimated using this relationship. Linear regression equation between total lead concentration(X) and ACGIH-RPM concentration(Y) was log Y = 0.76 log X - 0.40($r^2=0.89$, p=0.0001).

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Particle-size-dependent aging time scale of atmospheric black carbon (입자 크기의 함수로 나타낸 대기 중 블랙카본의 변성시간척도)

  • Park, Sung Hoon
    • Particle and aerosol research
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    • v.5 no.2
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    • pp.45-52
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    • 2009
  • Black carbon, which is a by-product of combustion of fossil fuel and biomass burning, is the component that imposes the largest uncertainty on quantifying aerosol climate effect. The direct, indirect and semi-direct climate effects of black carbon depend on its state of the mixing with other water-soluble aerosol components. The process that transforms hydrophobic externally mixed black carbon particles into hygroscopic internally mixed ones is called "aging". In most climate models, simple parameterizations for the aging time scale are used instead of solving detailed dynamics equations on the aging process due to the computation cost. In this study, a new parameterization for the black carbon aging time scale due to condensation and coagulation is presented as a function of the concentration of hygroscopic atmospheric components and the black carbon particle size. It is shown that the black carbon aging time scale due to condensation of sulfuric acid vapors varies to a large extent depending on the sulfuric acid concentration and the black carbon particle size. This result indicates that the constant aging time scale values suggested in the literature cannot be directly applied to a global scale modeling. The aging time scale due to coagulation with internally mixed aerosol particles shows an even stronger dependency on particle size, which implies that the use of a particle-size-independent aging time scale may lead to a large error when the aging is dominated by coagulation.

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Distribution Characteristics of Dust and Heavy Metals in the Atmosphere Around the Steel Industrial Complex

  • Hye-jin Jo;Jong-Ho Kim;Byung-Hyun Shon
    • International Journal of Advanced Culture Technology
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    • v.12 no.2
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    • pp.334-344
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    • 2024
  • In Dangjin, Chungcheongnam-do, there are not only power plants and large steel complexes, but also small and medium-sized air pollutant emission facilities. The dust generated by these facilities has a very small particle size and a large surface area due to condensation and physical and chemical reactions, and is discharged containing various harmful substances. Therefore, this study analyzed the distribution of particulate matter and heavy metal concentrations by particle size in the vicinity of the steel complex, residential area, and reference point using an eight-stage Cascade Impactor. Overall, the direct impact sites with a short distance from the steel complex had the highest concentration, followed by the indirect impact sites, and the non-impact sites had the lowest concentration, indicating that they are directly affected by the steel complex. The atmospheric dust concentration distribution showed a bimodal distribution with a minimum value around the 1.1 to 2.1 ㎛ particle diameter. However, during the yellow dust event, the maximum concentration was biased toward coarse particles. The proportion of PM2.5 in the dust tended to be higher in winter, while the ratio between PM2.5 and PM10 was relatively higher in spring. Regardless of the location of the impact point, heavy metals in the dust were dominated by iron and aluminum, followed by zinc, lead, and manganese.

Health Risk Assessment of Lead Ingestion Exposure by Particle Sizes in Crumb Rubber on Artificial Turf Considering Bioavailability

  • Kim, Sun-Duk;Yang, Ji-Yeon;Kim, Ho-Hyun;Yeo, In-Young;Shin, Dong-Chun;Lim, Young-Wook
    • Environmental Analysis Health and Toxicology
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    • v.27
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    • pp.5.1-5.10
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    • 2012
  • Objectives: The purpose of this study was to assess the risk of ingestion exposure of lead by particle sizes of crumb rubber in artificial turf filling material with consideration of bioavailability. Methods: This study estimated the ingestion exposure by particle sizes (more than 250 um or less than 250 um) focusing on recyclable ethylene propylene diene monomer crumb rubber being used as artificial turf filling. Analysis on crumb rubber was conducted using body ingestion exposure estimate method in which total content test method, acid extraction method and digestion extraction method are reflected. Bioavailability which is a calibrating factor was reflected in ingestion exposure estimate method and applied in exposure assessment and risk assessment. Two methods using acid extraction and digestion extraction concentration were compared and evaluated. Results: As a result of the ingestion exposure of crumb rubber material, the average lead exposure amount to the digestion extraction result among crumb rubber was calculated to be $1.56{\times}10^{-4}$ mg/kg-day for low grade elementary school students and $4.87{\times}10^{-5}$ mg/kg-day for middle and high school students in 250 um or less particle size, and that to the acid extraction result was higher than the digestion extraction result. Results of digestion extraction and acid extraction showed that the hazard quotient was estimated by about over 2 times more in particle size of lower than 250 um than in higher than 250 um. There was a case of an elementary school student in which the hazard quotient exceeded 0.1. Conclusions: Results of this study confirm that the exposure of lead ingestion and risk level increases as the particle size of crumb rubber gets smaller.

Behaviors of Rubber Particles, Lead and Zinc in Atmospheric Particulate Classified by Particle Size Range (대기 부유분진중의 고무성분 및 납과 아연의 입도별 거동)

  • 이용근;원정호;김경섭;황규자
    • Journal of Korean Society for Atmospheric Environment
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    • v.2 no.2
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    • pp.60-65
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    • 1986
  • Atmospheric particulates were collected at a site near the front gate of the Yonsei University using nine stages Andersen air sampler and the distribution of seasonal particle size was investigated. Rubber, Pb and Zn contents of the collected particulates in each stage were determined. Particle size distribution of atmospheric particulate, which was made by concentration distribution curve method, was usually divided into two groups, course (particles larger than 1 - 2 $\mu m in diameter$) and fine (particles smaller than 1 - 2 \mu m in diameter$) groups, regardless of sampling period. More than 80 percent of the total rubber contents in atmospheric particulates were larger than $5 \mu m$ in diameter, meaning that most of rubber particles were originated from tire tread. After benzene extraction for 4 hrs, the extracts were analyzed by Curie-point pyrolysis gas chromatography for rubber content. Pb and Zn contents were determined by atomic absorption spectroscopy. The annual average concentration of rubber particles was $4.2 \mu g/m^3$, which corresponded to 2.2% of the annual average total suspended particulates. Average concentration of styrene brtadiene rubber was about five times that of natural rubber. Annual average concentrations of Pb and Zn were $1.2 \mu g/m^3 and 0.4 \mu g/m^3$ respectively, which corresponded to about 0.7% and 0.2% of the annual average total suspended particulates.

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Effects of Protective Colloids on the Formation of Polyurea Microcapsules

  • Lee, Eung-Min;Kim, Hea-In;Park, Soo-Min
    • Textile Coloration and Finishing
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    • v.19 no.5
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    • pp.30-36
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    • 2007
  • Cypermethrin-containing polyurea microcapsules were prepared by interfacial polymerization using aromatic 2,4-toluene diisocyanate(TDI) and Ethylene diamine(EDA) as wall forming materials. The effects of the protective colloids of polyvinylalcohol(PVA) and gelatin were investigated through experimentation. The mean size of the polyurea microcapsules was smaller and the surface morphology of the PVA was much smoother than gelatin. In addition the release behavior was much more controlled and better sustained. As the concentration of protective colloid increased, the wall membrane of the polyurea microcapsules became more stable, the thermal stability of the wall membrane increased, the mean particle size became smaller, and the particle distribution was more uniform. The release behavior of the core material changed according to the concentration. As the gelatin concentration was increased, a more controlled and sustained release behavior was observed. However, in the case of PVA, the increase of PVA concentration lead to a more rapid release rate.

Studies on Particle Size Control and Stability of Lead Chromate Pigment Particles (크롬산납 무기안료 입자 제어 및 안정성에 관한 연구)

  • Park, Chan Kyu;Jung, Dae Yoon;Chang, Sang Mok;Lee, Sang Rok
    • Applied Chemistry for Engineering
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    • v.19 no.3
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    • pp.264-269
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    • 2008
  • For the synthesis of lead chromate pigments, we investigated the characteristics of particle growth with reacting conditions in the synthetic process, the effect of additives, and its micro-capsulation. The more tiny and uniform dispersion particles could be obtained at a lower pH and diluter intial concentration. The variation range of average pigment size was increased with the agitating speed. The pigment size could be controlled by adding aluminum sulfate as an additive, which maintained the optimum particle dispersion. It was found that the optimum micro-capsulation conditions were pH 9~10 and above $90^{\circ}C$ during the micro-capsulation of lead chromate pigment, and below 0.5% humidity after micro-capsulation.

Size Characteristics of Lead Particles Generated in Four Industries

  • Park, Dong-Uk;Paik, Nam-Won;Chung, Moon-Ho
    • Journal of Environmental Health Sciences
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    • v.28 no.4
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    • pp.12-16
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    • 2002
  • Workers' exposure to lead particles with diverse characteristics was assessed using personal cascade impactors in four different industries. Correlation analyses found that total airborne lead (PbA) concentrations could not explain the variation on MMAD of lead particles. From regression analysis, the concentrations of lead particles smaller than 1 um in AD were found to rise very slowly with increases in total PbA. They rarely contributed more than 50 ㎍/㎥ of total PbA over the range of 5.6-7,740 ㎍/㎥ although there are a few high values greater than 100 ㎍/㎥ while respirable lead concentrations significantly increased with increasing total PbA concentrations. In the secondary smelting and radiator manufacturing industries requiring high temperatures, the average fraction of respirable concentration in total PbA was 43.3% and 48.9%, respectively, which indicated an important contribution to the total PbA. In lead powder and battery manufacturing, it was less than 27%. Our study results concluded that workers' exposure to lead particles with diverse characteristics might not be effectively monitored by the current total PbA sampling alone. To protect workers exposed to different sizes of lead particles generated in many operations, an occupational standard for respirable lead particles should be added to the current total lead standard.

Antibacterial activity of enrofloxacin loaded gelatin-sodium alginate composite nanogels against intracellular Staphylococcus aureus small colony variants

  • Luo, Wanhe;Liu, Jinhuan;Algharib, Samah Attia;Chen, Wei
    • Journal of Veterinary Science
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    • v.23 no.3
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    • pp.48.1-48.12
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    • 2022
  • Background: The poor intracellular concentration of enrofloxacin might lead to treatment failure of cow mastitis caused by Staphylococcus aureus small colony variants (SASCVs). Objectives: In this study, enrofloxacin composite nanogels were developed to increase the intracellular therapeutic drug concentrations and enhance the efficacy of enrofloxacin against cow mastitis caused by intracellular SASCVs. Methods: Enrofloxacin composite nanogels were formulated by an electrostatic interaction between gelatin (positive charge) and sodium alginate (SA; negative charge) with the help of CaCl2 (ionic crosslinkers) and optimized by a single factor test using the particle diameter, zeta potential (ZP), polydispersity index (PDI), loading capacity (LC), and encapsulation efficiency (EE) as indexes. The formation mechanism, structural characteristics, bioadhesion ability, cellular uptake, and the antibacterial activity of the enrofloxacin composite nanogels against intracellular SASCVs strain were studied systematically. Results: The optimized formulation was comprised of 10 mg/mL (gelatin), 5 mg/mL (SA), and 0.25 mg/mL (CaCl2). The size, LC, EE, PDI, and ZP of the optimized enrofloxacin composite nanogels were 323.2 ± 4.3 nm, 15.4% ± 0.2%, 69.6% ± 1.3%, 0.11 ± 0.02, and -34.4 ± 0.8 mV, respectively. Transmission electron microscopy showed that the enrofloxacin composite nanogels were spherical with a smooth surface and good particle size distributions. In addition, the enrofloxacin composite nanogels could enhance the bioadhesion capacity of enrofloxacin for the SASCVs strain by adhesive studies. The minimum inhibitory concentration, minimum bactericidal concentration, minimum biofilm inhibitory concentration, and minimum biofilm eradication concentration were 2, 4, 4, and 8 ㎍/mL, respectively. The killing rate curve had a concentration-dependent bactericidal effect as increasing drug concentrations induced swifter and more radical killing effects. Conclusions: This study provides a good tendency for developing enrofloxacin composite nanogels for treating cow mastitis caused by intracellular SASCVs and other intracellular bacterial infections.