• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2003년도 추계학술발표회초록집
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• pp.11-11
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• 2003

Electroplated hexavalent chromium coatings have been used in many technical applications since it was invented by G.J. Sargent in 1920. Because of the environmental problems and health risks associated with the use of hexavalent chromium, there has been an extensive search for alternative coatings with properties such as corrosion resistance and wear resistance, at a reasonable cost. However there is no single substitute that meets all the desirable performance characteristics of chromium. Advanced techniques, such as alloy plating, electroless plating, trivalent chromium plating, plasma and thermal spray coating, PVD and ion implantation, have been applied for replacing hexavalent chromium plating.

• 한국산업보건학회지
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• 제6권2호
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• pp.292-300
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• 1996

Hexavalent chromium($Cr^{+6}$) compounds are considered to be particularly hazardous, primarily because of the associated risk of allergic reaction and cancer. The analytic method of hexavalent chromium such as the s-diphenylcarba-zide(DPC) method and all ether previously used methods are often made uncertain due to significant interferences from organic components. This report can provide a technique for the more rapid and simple determination of total hexavalent chromium. than other currently using methods. The s-diphenylcarbazide method proposed by the U.S. National Institute for Occupational Safety and Health has low recovery rate(15.67 - 48.20%) due to interference, iron chloride and nickel chloride. A microwave oven technique has high recovery rate(about 70%) of insoluble hexavalent chromium. For the difference of ionic charges of $Cr^{+3}$-ethylenediamine tetraacetic acid(EDTA) chelate and $CrO_4{^{-2}}$, we could detect them simultaneously by ion exchanged high performance liquid chromatography. The confirmation of $Cr^{+3}$ and $Cr^{+6}$ were checked by fraction collector and flameless atomic absorption spectrometer. We observed that the small amount of hexavalent chromium is converted to trivalent chromium due to enhancement of chromium reduction by $Fe^{+3}$ or $Ni^{+2}$. As a result of this study, on the analysis of insoluble hexavalent chromium with microwave oven was used for, it may be better and more precise analysis after pretreatment by 2% NaOH-3% $Na_2CO_3$ and then analysis UV-spectrophotometer. It should be done for various studies on insoluble hexavalent chromium on the basis work environmental monitoring so called welding, painting etc.

• Toxicological Research
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• 제21권1호
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• pp.15-21
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• 2005

There is now a growing concern about the possible toxicity of heavy metals in cosmetics. Heavy metals can be used as cosmetic ingredients or may be present as low level impurities in some of the raw materials. Chromium derivatives are used as pigments in cosmetics. Chromium is essential and toxic trace elements. Chromium may cause skin allergy. However, the regulations related to cosmetic products give no limit values for Chromium. Hexavalent chromium is significantly more toxic than trivalent chromium. Hexavalent chromium may present a carcinogenic risk at high concentrations. Therefore, it is important to consider oxidation state of chromium when analyze chromium. The purpose of this study is to determine the concentrations of water-soluble trivalent and hexavalent chromium in samples of makeup products, and to assess the safety of cosmetics on the basis of animal sensitization tests using guinea pig. The present study of chromium in 48 makeup products of 12 manufacturers provides a basis for assessing safety of makeup products. Water-soluble hexavalent chromium was not detected in any product. Water-soluble trivalent chromium was detected in only 9 eye shadows out of 48 makeup products, and could not be quantified 3 out of 9 eye shadows. The highest level of water-soluble trivalent chromium was about 10 mg/kg in spite of 90,000 mg/kg of total chromium. The results of animal sensitization tests show that 200 mg/kg of trivalent chromium and 5 mg/kg of hexavalent chromium have no harmful effect. No cross-reaction among these metals was found. Accordingly, the concentrations of water-soluble chromium in makeup products seemed to be safe. The overall results indicate that chromium in cosmetics probably have no significant toxicological effects. However, It is necessary to set guidelines on the maximum permissible concentration of water-soluble chromium in cosmetics.

• 한국산업보건학회지
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• 제3권2호
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• pp.152-165
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• 1993

This study was performed at eleven small-sized plating factories located in Seoul, Incheon, Ansan, and Taejeon from July 21 to October 6, 1992. The major objectives of this study were to evaluate worker exposure to hexavalent chromium and local exhaust ventilation (L.E.V.) systems at the chromium plating operations. The most suitable L.E.V. systems for chromium plating tanks were designed as examples for recommendation to the industry. The results are summarized as follows. The range of chromium plating operations investigated included decorative, hard, and black chromium plating on several kinds of parts. Most of plating tanks were not equipped with proper control methods against emission of hexavalent chromium mists and workers were not wearing appropriate personal protectives. The ariborne hexavalent chromium concentrations showed an approximate lognormal distribution. The geometric means of both personal and area samples were within the Korean and ACGIH standards, $50{\mu}g/m^3$. However, in comparison with the NIOSH criterion, $1{\mu}g/m^3$, the geometric means of personal samples at two factories and the geometric means of area samples at two factories exceeded it. The geometric means of personal and area samples of high exposure groups (above the NIOSH criterion) were 7 and 27 times higher than those of low exposure groups (below the NIOSH criterion), respectively. The L.E.V. systems of high exposure groups were improperly designed, and the factory with the highest exposure level had no L.E.V. systems at all on chemical etching process. Whereas at factories of low exposure groups, mist control methods such as mist suppressants, tank cover, and/or auxillary L.E.V. systems were added to L.E.V systems. The evaluation of L.E.V. systems showed that there was no chromium plating operation satisfying the ACGIH criteria for capture velocity, slot velocity, and exhaust rate simultaneously. To increase performance of L.E.V. systems, it must be designed to minimize the impact of boundary layer separation. Push-pull ventilation hood and downward plenum ventilation hood were suggested for the Korean industry.

• 공업화학
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• 제17권5호
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• pp.433-442
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• 2006

금속표면처리 기술 분야에서 광범위하게 적용되어온 6가 크롬에 의한 부식억제방법은 더 이상 사용할 수 없는 단계에 이르렀다. 전 세계적으로 자동차 산업에 적용되기 시작한 이 6가 크롬사용에 대한 규제는 전자산업을 비롯한 모든 산업에 예외 없이 적용될 것이다. 이에 따라 새로운 부식억제 방법이 절대적으로 필요하며, 3가 크롬을 바탕으로 하는 새로운 부식억제 방법이 그 자리를 대신할 것이다. 따라서 본 총설에서는 6가 크로메이트 대체를 위한 화성코팅에 대한 공정 개발을 위해 현재까지 진행된 과정 및 제안된 3가 크롬화성코팅을 소개하여 획기적인 3가 크로메이트 화성코팅 공정의 확립에 기여하고자 한다.

• 자원리싸이클링
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• 제11권6호
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• pp.18-23
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• 2002

수용액으로부터 6가 크롬을 분리ㆍ회수하기 위한 용매추출시 추출제의 종류 및 평형 pH에 따른 추출효과를 조사하였다. 실험결과 크롬의 추출율은 추출제인 Alamine 336이나 Aliquat 336의 농도가 증가함에 따라 증가하고 있으며, 4차 아민인 Aliquat 336이 6가 크롬의 추출에 있어 Alamine 336이나 PC-88A보다 가장 효과적이다. 그리고 추출시 3상 방지제로 첨가되는 octanol, decanol 및 dodecanol등의 다가알콜은 서로 비슷한 추출효과를 보이고 있으며, 다가알콜을 첨가하지 않은 경우에 비해서는 추출율이 다소 증가하고 있다. 한편, 6가 크롬 수용액에 대한 용매추출시, Aliquat 336의 농도는 1％, 다가알콜인 decanol 농도는 5％로 하여 pH 7 이하에서 추출하면 6가 크롬을 100%추출할 수 있으며, 탈거시에는 탈거액으로 1M의 수산화나트륨 용액을 사용하면 유기상중의 크롬을 전부 회수할 수 있다.

• 대한의생명과학회지
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• 제12권3호
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• pp.261-265
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• 2006

Toxic effect of Hexavalent chromium $(CrO_3)$ on various cells and organs has been well recognized. However, the mechanism and degree of cytotoxicity of $CrO_3$ remain unclear. This study was performed to examine the cytotoxicity of $CrO_3$ on $C_6$ glioma cells by measuring cell viability. The XTT assay, one of the sensitive methods to determine the cell viability, was taken to examine the viability of glioma cells treated with $CrO_3$. In this study, not only decreased the number of glioma cells but morphologic changes of them were noted and cell viability decreased in a time and dose-dependent manner after treated with various concentrations of $CrO_3$ for 48hours. $IC_{90}\;and\;IC_{50}$ values in XTT assay were determined at $25{\mu}M\;and\;55{\mu}M$ $CrO_3$, respectively. These results suggest that Hexavalent chromium has a highly cytotoxic effect and has a time and dose-dependent cytotoxicity on $C_6$ glioma cells.

• 한국독성학회:학술대회논문집
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• 한국독성학회 2002년도 Current Trends in Toxicological Sciences
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• pp.67-67
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• 2002

According to the epidemiological studies in chromium workers, hexavalent chromium is associated with the risk of lung cancer. Genotoxicity such as chromosome aberration, and cellular oxidative damages by reactive oxygen species produced by hexavalent chromium exposure may play an important role in the carcinogenesis process.(omitted)

• 한국환경보건학회지
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• 제30권4호
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• pp.320-328
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• 2004

A number of health hazards are generated in welding processes. In this paper, the characteristics of fumes and some other hazardous agents in welding are reviewed. Fumes in welding are generated by complex mechanism like physical ejection of particles, oxidation-enhanced vaporization, vaporization-condensation-oxidation, and spatter contribution. Fume generation rates could be described as a power function in a given process. Most of fume constituents was originated from consumables rather than base metal. The mass distribution for the welding fumes is unimodal and very small to penetrate respiratory system. So, almost fractions of fumes are classified into the respirable particulate mass. Total chromium contents in FCAW were similar to those from SMAW whereas hexavalent chromium concentrations in fume were similar to those produced from MIG welding fume. Hexavalent chromium was mostly soluble which was similar to the characteristic solubility of fume hexavalent chromium from SMAW.

• Journal of Microbiology and Biotechnology
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• 제22권4호
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• pp.547-554
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• 2012

Chromium is generated from several industrial processes. It occurs in different oxidation states, but Cr(III) and Cr(VI) are the most common ones. Cr(VI) is a toxic, soluble environmental contaminant. Some bacteria are able to reduce hexavalent chromium to the insoluble and less toxic Cr(III), and thus chromate bioremediation is of considerable interest. An indigenous chromium-reducing bacterial strain, Rb-2, isolated from a tannery water sample, was identified as Ochrobactrum intermedium, on the basis of 16S rRNA gene sequencing. The influence of factors like temperature of incubation, initial concentration of Cr, mobility of bacteria, and different carbon sources were studied to test the ability of the bacterium to reduce Cr(VI) under variable environmental conditions. The ability of the bacterial strain to reduce hexavalent chromium in artificial and industrial sewage water was evaluated. It was observed that the mechanism of resistance to metal was not due to the change in the permeability barrier of the cell membrane, and the enzyme activity was found to be inductive. Intracellular reduction of Cr(VI) was proven by reductase assay using cell-free extract. Scanning electron microscopy revealed chromium precipitates on bacterial cell surfaces, and transmission electron microscopy showed the outer as well as inner distribution of Cr(VI). This bacterial strain can be useful for Cr(VI) detoxification under a wide range of environmental conditions.