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Indium is a rare metal that is an essential raw material for indium tin oxide (ITO) essential for transparent electrodes for displays. However, its supply is unstable as it is a by-product of zinc. In this research, we investigated the domestic substance flow of indium used for liquid crystal applications in Japan. Accordingly, we quantitatively evaluated the amount of indium contained in the process loss and the content of indium in end-of-life products. Through this quantification, we examined the visualization of loss in the entire flow and the usability of end-of-life products as secondary production. Consequently, it was found that the amount of indium used in the production of end-use-products in Japan has increased significantly due to the growth of liquid crystal display TVs, particularly in preparation for the transition to terrestrial digital broadcasting in 2011, and has drastically decreased after 2012. Meanwhile, some manufacturing bases have been relocated from Japan to other countries, and a certain proportion of end-use-products are imported, by which we infer the domestic input amount of end-use-products in recent years is estimated to have remained at approximately 4 t. Based on the result, after having continued to increase to the maximum value of approximately 70 t in 2014, the in-use stock has exhibited a gradually decreasing trend. Moreover, the indium content in end-of-life products has continued to increase, and in 2015, it exceeded the amount of the end-use-products input into society. Furthermore, compared with the process loss at the time of processing from ITO to a display, the gap has been narrowed from 100 times or more, and the indium content in end-of-life products in 2008 to about 15 times in 2017. These results suggest that the recycling potential of end-of-life products has increased with the spread of indium-based products. [ABSTRACT FROM AUTHOR]

Background. Indium compounds are known health hazards for lung cancer and interstitial pneumonia. Furthermore, they are related to emphysema, alveolar proteinosis, and cholesterol granuloma. In Japan, laws were revised in 2013 to tighten regulations on indium exposure in workplaces. However, its impact on the health of workers who handle indium has not been evaluated. This study aimed to investigate whether subjective respiratory symptoms in these workers have reduced after the 2013 amendment in the regulations. Methods. The subjects were workers from certain areas of Japan who had undergone health checkups between January 1, 2013, and June 30, 2015. Indium-handling and non-handling workers were categorized into the exposed and less-exposed groups, respectively. Based on the findings of health checkups during this period, the hazard ratio of subjective respiratory symptoms (cough, sputum production, shortness of breath, and palpitation) and its 95% confidence intervals (CIs) were calculated with the less-exposed group as the reference. The Prentice-Williams-Peterson model was used for calculation, and a model that adjusted for coarse analysis and potential confounding factors was adopted. Results. Overall, 2,561 workers (from 22 companies) who underwent 6,033 health checkups were included. The total person-years were 2,562.8 years, and 162 outcome events occurred. The hazard ratios of the exposed group were 1.65 (95% CI [1.14-2.39]: pD0:008) and 1.61 (95% CI [1.04-2.50]: pD0:032) in the crude and adjusted models, respectively. Conclusion. Indium-handling workers had a high hazard of the subjective respiratory symptoms than non-indium -handling workers despite stricter regulations on indium exposure in workplaces. This indicates the need for further changes to the legislation to protect the health of workers exposed to harmful substances in workplaces. Further studies including larger diverse cohorts are needed to validate our findings. [ABSTRACT FROM AUTHOR]

Background: During the last decade it has been clarified that the inhalation of indium compounds can evoke alveolar proteinosis, cholesterol granuloma, pulmonary fibrosis and emphysema. In this study, we aimed to elucidate the characteristics and time course of pulmonary disorders among indium workers using comprehensive pulmonary examinations at an indium-processing factory.Methods: Data for 84 male workers who underwent the examinations for nine consecutive years from 2002 to 2010 were analysed regarding their symptoms, serum indium concentration (sIn), serum markers of interstitial pneumonia, pulmonary function test parameters and high-resolution CT (HRCT) findings of the lungs.Results: In association with improvements in the work environment and work practice, the sIn levels decreased with significant reductions in the KL-6 and surfactant protein D (SP-D) levels. Regarding the HRCT findings, the interstitial lesions regressed partially, whereas emphysematous lesions increased progressively in the workers with high sIn values. FEV1/FVC decreased with the years and the rate of decrease was significantly greater in those with high sIn. The biological half-life of sIn was estimated to be 8.09 years.Conclusions: The present findings suggest that the sIn, SP-D, KL-6 levels and radiological interstitial changes can be reduced in indium workers by alleviating exposure to indium, whereas emphysematous lesions can progress among those with a history of heavy exposure. [ABSTRACT FROM AUTHOR]

The Kusatsu and Tamagawa hot springs contain both toxic elements and rare metals used in high-technology industries. High acidity and significant discharge of these springs have led to the construction of dams and neutralization of spring waters by lime addition. However, the same neutralization process causes differing effects in the Kusatsu and Tamagawa areas. This study focuses on the effects of neutralization on fractionation between arsenic (As) and indium (In) during river transport and precipitation of these elements on the lake beds. The Yubatake thermal waters in the Kusatsu area are rapidly neutralized after addition of a lime suspension. After this neutralization, the dissolved As and In are nearly completely removed by sorption onto suspended hydrous ferric oxides (HFO), which then settle out and are added to sediments within a man-made lake without significant fractionation. In contrast, the Obuki thermal waters in the Tamagawa area are neutralized by both addition of lime and by mixing with tributary streams, leading to a gradual downstream increase in pH. Arsenic tends to be sorbed by HFO in upstream areas, leading to wide dispersal of As across the entire watershed. In comparison, In is transported to the lake inlet as stable chloride and/or sulfate complexes without significant removal, with considerable portions being precipitated in a man-made lake. As a result, In is effectively concentrated within downstream lake sediments. [ABSTRACT FROM AUTHOR]

Abstract: Indium-bearing tin-polymetallic base metal deposits in Japan (Toyoha, Ashio and Akenobe), China (Dulong and Dachang), and Bolivia (Potosi, Huari Huari, Bolivar and Porco), were studied using femto-second Laser Ablation ICPMS (fsLA-ICPMS) and EPMA analyses for major and minor elements in sphalerite, paying special attention to In concentrations. Sphalerite is a principal mineral in these tin-polymetallic deposits and a broad range of In concentration is measured in the ores. There are distinct differences in mode of occurrence of the sphalerite and the distribution of In. The highest In concentration (up to 18wt.%) occur as a Zn–In mineral within black sphalerite zones in an oscillatory-zoned sphalerite from the Huari Huari deposits. Additionally, jamesonite from the Huari Huari deposit also contains anomalous In values, ranging from several hundreds to thousands μg/g. Sphalerite from the Toyoha and the other Bolivian deposits are characterized by oscillatory and chemical zoning, whereas those from Akenobe and the Chinese deposits are represented by homogeneous distribution of In. The 1000In/Zn values of sphalerite are in good agreement with those of the ore grade for each of the selected tin polymetallic deposits indicating that sphalerite is the principal host of In. The In-bearing sphalerite principally involves the combined coupled substitutions (2Zn2+)↔(Cu+, In3+), (3Zn2+)↔(Cu+, Ag+, Sn4+) and (3Zn2+)↔(2Cu+, Sn4+). The first of these is apparent in sphalerite from Huari Huari and Bolivar, whereas the second is prominent in sphalerite from Toyoha, Ashio, Potosi, Porco and Dachang. Akenobe and Dulong sphalerite features the dominant coupled substitution of (2Zn2+)↔(Cu+ or Ag+, In3+), owing to their poor Sn content. Occasionally, sub-micron inclusions of minerals such as stannite and Pb–Sb-bearing sulfides can occur in sphalerite, contributing to high Cu–Sn and high-Ag contents, respectively. The observed correlations of each element in the In–Cu–Ag–Sn-bearing sphalerite can be proposed as a fundamental reason for the indium enrichment related to sulfur-rich oxidized magmatism. In addition, the Ag content in sphalerite is considered a possible indicator of formation depth, which ranges from plutonic to subvolcanic environments. [Copyright &y& Elsevier]

Abstract: Concentrations of 18 elements, including Sb, In, Sn, and Bi, were measured in sediment cores from two pristine alpine lakes on Mount Hachimantai, northern Japan, representing the past 250years. Vertical variations in concentrations are better explained by atmospheric metal deposition than by diagenetic redistribution of Fe and Mn hydroxide and organic matter. Anthropogenic metal fluxes were estimated from 210Pb-derived accumulation rates and metal concentrations in excess of the Al-normalized mean background concentration before 1850. Anthropogenic fluxes of Sb and In showed gradual increases starting around 1900 in both lakes, and marked increases after 1980. Comparison of Sb/Pb and Pb stable isotope ratios in sediments with those in aerosols of China or northern Japan and Japanese source materials (recent traffic- and incinerator-derived dust) suggest that the markedly elevated Sb flux after 1980 resulted primarily from enhanced long-range transport in aerosols containing Sb and Pb from coal combustion on the Asian continent. The fluxes of In, Sn, and Bi which are present in Chinese coal showed increasing trends similar to Sb for both study lakes. This suggests that the same source although incinerators in Japan may not be ruled out as sources of In. The sedimentary records for the last 250years indicate that atmospheric pollution of Sb and In in East Asia have intensified during recent decades. [Copyright &y& Elsevier]

Indium, thallium and bismuth are toxic and it is important to know the distribution of these elements in environmental water. The concentrations of these elements were measured in 50 sampling points in Japan and the reasons of high concentrations in several samples were discussed. The average concentrations (ng/L) of dissolved and particulate indium in river, lake and coastal seawater were 1.4-3.0 and 2.4-9.1, respectively. Those for thallium were 7.2-11.3 and 3.5-36.0. Those for bismuth were 12.7-24.0 and 12.1-52.7. [ABSTRACT FROM AUTHOR]

Abstract: The Obuki spring is the largest and most acidic of the Tamagawa hot springs (Akita Prefecture, northern Japan), and it discharges ca. 9000L/min of chloride-rich acidic water (pH 1.2) that contains high concentrations of both As and rare metals such as Ga and In. This paper aims to quantify seasonal variations in the mobility of these elements in the Shibukuro and Tama rivers, which are fed by the thermal waters of the Obuki spring, caused by sorption onto hydrous ferric oxide (HFO). Seasonal observations revealed the following relationships with respect to As removal by HFO: (a) the oxidation of Fe2+ is predominantly controlled by both pH and water temperature, and progresses more quickly in less acidic and warmer conditions; (b) HFO formation was predominantly controlled by pH; and (c) the removal of dissolved arsenate is directly related to the amount of HFO present. Consequently, the oxidation to Fe3+ was slower during periods of cold and lower pH, and the amount of HFO was too small to remove the dissolved arsenate effectively. Consequently, considerable amounts of dissolved arsenate and Fe2+ remained in river water. In contrast, when HFO production from Fe3+ increased, and dissolved arsenate was removed during warmer and less acidic periods, only small amounts of dissolved arsenite and Fe2+ remained in the river water. The geochemical behavior of Ga and In was essentially controlled by pH; however, when HFO production was limited by a pH of less than 3.5, Ga behavior was controlled mainly by the amount of HFO. Gallium tended to be sorbed under more acidic conditions than was In. Due to differences in sorption behavior, Ga, As, and In were fractionated during sedimentation. In the upstream reaches, arsenate and dissolved Ga sorbed onto HFO, and were widely distributed across the watershed. Conversely, dissolved In was removed by HFO downstream. As a result, In is relatively concentrated on the downstream lakebed, unlike As and Ga, and In-rich mineral deposits are accumulating at present. [Copyright &y& Elsevier]

The article presents a study which reports clinical cases of lung disease in indium workers from Japan and the U.S. The study used a detailed and multidisciplinary analysis of radiologic, epidemiologic, and clinical data to understand the natural history and pathogenesis of indium lung disease. Results show that 10 men who used or reclaimed indium compounds were diagnosed with interstitial lung disease four to 13 years after first exposure.

At the Nuclear Fuel Cycle Engineering Laboratories of the Japan Atomic Energy Agency (JAEA), small pieces of indium foil incorporated into personal dosemeters have been used for personnel screening in criticality accidents. Irradiation tests of the badges were performed using the SILENE reactor to verify the calibration of the indium activation that had been made in the 1980s and to recalibrate them for simulated criticalities that would be the most likely to occur in the solution process line. In addition, Monte Carlo calculations of the indium activation using the badge model were also made to complement the spectral dependence. The results lead to a screening level of 15 kcpm being determined that corresponds to a total dose of 0.25 Gy, which is also applicable in posterior–anterior exposure. The recalibration based on the latest study will provide a sounder basis for the screening procedure in the event of a criticality accident. [ABSTRACT FROM PUBLISHER]

This paper examines Japanese resource outflows in the form of exported used (and functional) products in 2007 by quantifying the unintentional metal exports for a number of specialty metals typically used in electronics and electrical equipment. We find that more than half of the indium and 20-30% of the barium, lead, antimony, strontium, zirconium, silver, gold, and tin in domestically discarded products were not recycled in Japan, but rather were exported in products to be used elsewhere. The destinations of these metals were mainly Asian countries with rudimentary recycling technology. These results demonstrate that although these metals could have been stockpiled domestically for future recovery and recycling, they were instead sent to countries where recycling of these scarce metals is unlikely. From a resource perspective, therefore, the free trade of used Japanese products compromises long-term domestic resource availability as it increases the quality of life in developing countries. [Copyright &y& Elsevier]

Induced radioactivity in natural indium (natIn) foils by high energy neutrons was measured at the KENS Facility, KEK, Japan, where a 16.7 cm thick W target was bombarded by protons of 500 MeV. High energy neutrons consequently produced irradiated the In targets placed at different depths inside a 4 m thick concrete shield placed at the beam exit. The measured activities were compared with the results calculated using the nuclear reaction model codes ALICE-91 and EMPIRE-2.18. To estimate the induced activity, excitation functions of the various radionuclides were calculated using the two codes and folded with the appropriate neutron energy distribution at different depths of the concrete shield. The calculated excitation functions of a given nuclide were found to vary widely from one another in some cases. The performances of the codes for different input parameters like level densities and inverse cross-sections are reported in this paper. Our analysis shows that neither of the two codes reproduced all the measured activities satisfactorily, requiring further improvements in the models adopted. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate personal exposures of 27 workers to indium compounds as "total" dust and its "respirable" fraction in their breathing zones at 3 Japanese indium plants. Eight-hour time-weighted average (TWA) indium concentrations of personal exposure to dust collected in sampling periods of 6 h or longer were determined by ICP-MS. The arithmetic means of exposure concentrations were 0.095 mg indium (In)/m 3 , when sampled as total dust, and 0.059 mg In/m 3 , as respirable fraction. ACGIH's TLV-TWA of 0.1 mg In/m 3 for total particulate matter and Acceptable Exposure Concentration Limit (AECL) of 3×10 -4  mg In/m 3 for the respirable fraction notified by the Japanese Ministry of Health, Labour and Welfare were used to evaluate the exposure concentrations. Twenty-five out of 27 workers were exposed to indium concentrations lower than TLV-TWA, while all of the workers were exposed to the indium concentrations higher than AECL. We noted that there was a large discrepancy between the two occupational exposure limits referred to in this report, and these differences were attributed to the sampling strategies and health effects used as the prevention targets. Carcinogenicity of the respirable fraction of indium-containing particulates was considered in setting AECL, whereas it was not in ACGIH's TLV.

Given a potential increase in low-carbon power generation, assessing the criticality of metals used for its technologies is of significant importance. While several studies analyzed the metal criticality of an individual technology, the national metal criticality for a wide range of low-carbon power generation technologies and the comparison of overall criticality of each technology have yet to be fully evaluated. Therefore, this study firstly evaluates the criticality of 29 metals used in facilities for renewable energy and highly efficient thermal power generation in Japan and then compares the overall criticality for each technology to identify metals that might impose limitations on these technologies and to discuss measures for removal of factors hindering the spread of low-carbon power generation technologies. It was discovered that solar power generation technology is the most critical technology from the perspective of supply risk due to the use of indium, cadmium and selenium, while wind power generation is the most critical technology from the perspective of vulnerability to supply restriction because of the use of neodymium and dysprosium. A developed approach would have a significant potential to contributing to energy-mineral nexus, which may assist in providing policy implications from the perspectives of both specific metals and technologies. [ABSTRACT FROM AUTHOR]

Objective: Occupational Lung Disease is an oldest but still a biggest problem in occupational health., Methods: Steering Committee members of the Japan Society for Occupational Health (JSOH) Occupational Lung Disease Study Group selected and summarized current topics on occupational lung diseases based on expert opinion, as informed by governmental regulation, public health concerns, and frequently discussed in related academic conferences., Results: The topics included in this review are professional education in medical screening skills, 2014 update of Helsinki Criteria, respiratory diseases found in the earthquake and tsunami affected regions, newly recognized occupational lung diseases, and potential respiratory health hazards., Discussions: Although occupational lung diseases seem to stay as one of the major concerns in occupational health, screening tools and control measures are standardized for the better prevention of the diseases. As this health problem usually occurs in where the most actively economically developing area is, the patients tend to increase in emerging economic powers with huge population., (© 2019 The Authors. Journal of Occupational Health published by John Wiley & Sons Australia, Ltd on behalf of The Japan Society for Occupational Health.)