Despite being one of the greatest pleasures in life, food consumption represents a major route for exposure to contaminants which may pose risks to health. It is therefore important to estimate dietary intakes of contaminants to assess and manage risk. We have used different approaches to estimate dietary intakes of various contaminants, such as persistent organic pollutants, radionuclides and toxic elements. Nationwide total diet studies based on a market basket approach, which is useful method of estimation the average dietary intake of contaminants in population groups of interest, have been conducted for a long time. A total diet study using a duplicate diet approach was also conducted to estimate dietary intakes of contaminants. Furthermore, we have conducted a Monte Carlo simulation to obtain information on the distribution of dietary intakes of contaminants. This special issue deals with 3 topics; estimation of dietary intakes of persistent organic contaminants (dioxins and PCBs); radionuclides (cesium-134 and 137); and toxic elements (inorganic As, Pb, Cd, etc.). The presented results are useful for risk assessment as well as to assess the effectiveness of any administrative measures implemented regarding contaminant regulations. I hope that the special issue is helpful for readers interested in estimation of dietary intakes of contaminants.

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Food is generally recognized as the main source of human intake of persistent organic pollutants, such as dioxins and polychlorinated biphenyls (PCBs). A total diet study (TDS) based on a market basket approach is a useful method of estimating the average dietary intake of contaminants in populations. We have conducted annual nationwide TDSs in the general Japanese population (≥1 year old) for dioxins since 1998 and for PCBs since 1977. The national average intake of dioxins was estimated to be 0.44 pg TEQ (toxic equivalents)/kg body weight (bw)/day in 2021. The value was about 11% of the Japanese tolerable daily intake (TDI) of 4 pg TEQ/kg bw/day for dioxins in Japan. The TEQ contribution of the fish and shellfish group to the total dietary TEQs was significant. The latest average dioxin intake was about one-fourth of the average intake in 1998. The national average intake of PCBs was estimated to be 6.7 ng/kg bw/day in 2021. The value was about 0.1% of the Japanese provisional acceptable daily intake (PADI) of 5 μg/kg bw/day. The contribution of the fish and shellfish group to the dietary PCB intakes was significant. The latest average PCB intake was about one-tenth of that in 1977-1978. We also conducted a Monte Carlo simulation to obtain information on the distribution of dioxin intakes from fish and shellfish in six age-groups of the Japanese population. The estimated average and 95th percentile values of the intake distributions of the age-groups were 0.89-1.9 pg TEQ/kg bw/day and 3.3-7.1 TEQ/kg bw/day, respectively. The estimate 95th percentile values of four of six age-groups exceeded the TDI. The estimated average and 95th percentile values of early childhood (1-3 years) was the highest among the six age-groups. Fish groups, including horse mackerel, sardine, yellowtail, and fishery products (salted and dried fish etc.), are the main sources of dioxin intake from fish and shellfish in all 6 age-groups. Thus, dietary intakes of dioxins and PCBs in Japan has been decreasing, and the current intakes as estimated by TDSs were well below the Japanese TDI and PADI. However, overconsumption of fish and shellfish would lead to an increase in our intake of dioxins and PCBs from food, and a balanced diet is recommended.

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Radioactive materials were released into the environment, and contaminated food due to the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident. In response to this situation, regulations on radionuclides in food came into effect immediately after the accident, and food regulations based on standard values are still in place. In order to estimate the intake of radioactive materials in food after the Fukushima nuclear power plant accident, a total diet study (TDS) was conducted. The market basket (MB) method, which estimates the average intake by analyzing samples prepared based on the average food consumption data of Japanese people, and the duplicate diet (DD) method, which analyzes samples mixed with the daily meals of survey subjects and investigates the distribution of intake, were used to estimate the daily dietary intake and the annual committed effective dose of radioactive cesium (Cs) (Cs-134 and Cs-137) and the natural radionuclide potassium 40 (K-40). The maximum annual committed effective dose estimated by the MB method conducted twice a year from September 2011 to March 2019 was 0.0010-0.019 mSv/year, and the maximum annual committed effective dose estimated by the DD method conducted in 2012 was 0.027 mSv/year. The MB data for each period was collected across different regions. Although the detection rate and annual committed effective dose of radioactive Cs were somewhat higher in Fukushima and the surrounding regions than in other regions, regional differences tended to become smaller with time since the accident. In addition, the annual committed effective dose in each region tended to decrease with time since the accident. In Fukushima and the surrounding areas, in particular, the annual committed effective dose of radioactive Cs decreased significantly 2 years after the accident. It was considered that this was caused by the decrease in the concentration of radioactive Cs in food due to the effect of administrative measures such as food regulations based on the standard value in addition to the attenuation of radioactive Cs, mainly Cs-134. In the DD method, the histogram of the annual committed effective dose in Fukushima and the surrounding regions showed a wide distribution with a slightly higher dose side, however, most of the survey subjects from those regions had an annual committed effective dose of radioactive Cs through food which was similar to that in other regions. In both the MB and DD methods, the estimated maximum annual committed effective dose was sufficiently smaller than the maximum permissible dose (1 mSv/year) in food. In addition, it was confirmed that the annual committed effective dose of radioactive Cs was much smaller than the annual committed effective dose from K-40, a natural radionuclide, using both the MB and DD methods. These results suggest that the health risk of ingestion radioactive Cs is extremely low when consuming normal diets that include commercial foods on the Japanese market. Nevertheless, to ensure food safety from the viewpoint of risk communication, it should be necessary to continue to monitor and disclose the daily dietary intake and annual committed effective dose of radioactive Cs.

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The toxic elements cadmium and methylmercury have contaminated foods and caused pollution-related diseases, thereby causing tremendous damage. Because toxic elements occur naturally, the potential health risks of these toxic elements are known to be high. This paper presents the results of an analysis of dietary intake of toxic elements and its risk in Japan based on the results of the Total Diet Study using the market basket (MB) method, which has been conducted continuously by the Division of Foods at the National Institute of Health Sciences. In addition, I will discuss the challenges in estimating intakes and their solutions, especially the Bayesian two-dimensional Monte Carlo simulation (MCS) to account for issues on non-detected values and estimated uncertainties. Particularly, I apply these methods to MB samples and present the results of the distribution of estimated daily intake of inorganic arsenic considering estimation uncertainty. In addition, I introduce the MCS and maximum likelihood estimation methods using Excel to make it easier for beginners to work with MCS. The hope is for readers to perform the calculations themselves together with changing sample size and parameters to deepen their understanding.

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Several regions geographically distant from metropolitan areas are currently struggling with rapid changes in their population structures with resulting economic and social stagnation. The urgent need to re-consider the appropriate social structure and social security system to rebuild regional communities into sustainable societies where the natural, social, and economic environments (environment, society, and economy) are well-balanced in anticipation of the post-COVID-19 era has become a pressing matter. It is one of the major social issues for the Japanese government as well. Owing to the abovementioned circumstances, the expectations for social-community contributions are increasingly being assigned as a role for universities.
In this report, a case of regional contribution activity in which the authors have been involved since 2010 in Odai Town in the southern region of Mie Prefecture is introduced to discuss the relevant issues observed (understood) with respect to this activity.

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Fine bubbles refer to bubbles less than 100 μm in diameter, and the name has been standardized by the International Organization for Standardization. These fine bubbles manifest physical and chemical properties that are different from those of easily visible millimeter- and centimeter-sized bubbles. For example, multiple fine bubbles with the same volume as a centimeter-sized bubble have a large specific surface area, which exponentially improves chemical reactions, physisorption, and substance transportation at the gas-liquid interface. They have industrial superiority and are now being considered for use in many industrial fields, leading to their introduction. In particular, fine bubbles play an advanced role in the field of cleaning. For example, oil and other hydrophobic substances are adsorbed at the gas-liquid interface with bubbles. This allows the gas-liquid interface increased by fine bubbles to efficiently remove oil from the liquid, and since this phenomenon can occur without the addition of surfactants, it is becoming established as a resource- and environmentally- friendly cleaning technology. Meanwhile, fine bubbles are now also being utilized in the food industry. As mentioned above, fine bubbles are used to clean foodstuffs, inhibit microbial growth by replacing the gas species contained in the bubbles, oxidation inhibition, and change the texture of foodstuffs. Knowledge about these technologies leads to their application. In this study, we introduce the definition of fine bubbles, their basic properties, and their potential applications in the fields of resource, environment, and food.

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Many countries and areas have implemented a labeling system for genetically modified organisms (GMO). In Japan, the regulatory threshold for non-GMO labeling will be revised and tightened from 5% to undetectable by April 2023. The practical criterion for the revised system was determined based on the limit of detection (LOD). However, evaluating whether the commingling of GMO levels exceeds the LOD is challenging because GM contents close to the LOD are usually below the limit of quantification. Then, a qualitative method, which could be applicable to the revised non-GMO labeling, based on comparative Cq-based analysis was developed. ΔCq values between the target and endogenous sequences were calculated, and the ΔΔCq value obtained was used as a criterion to determine analytical samples with GM contents exceeding the threshold. To improve the reproducibility of the method, we used a standard plasmid that yields equivalent and stable ΔCq values comparable with those obtained from LOD samples. The developed method was validated with an interlaboratory study. The new qualitative detection concept should be useful for ensuring robust and reproducible results among laboratories, particularly for detecting low-copy-number DNA samples.
I also introduced development of a reference material (RM) containing a defined copy number of DNA. An analytical quality control when detecting low-copy-number target DNA is often in error because of a lack of appropriate RMs. Recent advances in analytical sciences require a method to accurately detect and quantify DNA at the single molecule level. To perform well in such situations, a novel RM containing a defined copy number of target DNA was developed. To produce the RM, a suspension of cells carrying a single target DNA sequence was ejected by an inkjet head, and the number of cells in each droplet was counted using highly sensitive cameras. The resulting solutions contained a defined copy number of target DNA and could be used as RMs. The use of the newly developed RM was compared with that of diluted solutions of target DNA to evaluate performance. It was revealed that the RM provides accurate information regarding performance quality for real time PCR analysis for low-copy-number levels of DNA.

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Kaniwa and Amaranthus are introduced in this article. Kaniwa is an original food crop in the Central Andes area in South America. There are two types of species, which differ in their branching. The lasta type shows high branching, whereas the saguia type is characterized by less branching and a more erect growth. Kaniwa grows 20～60cm high and is therefore shorter than its close relative quinoa. Since kaniwa is well-adapted to the Andean climate, it is cold-resistant in all growth stages. Adult plants are also resistant to night frosts. In its vegetative stage, the plant may survive down to －10°C and will grow at temperatures up to 28°C with sufficient humidity. The brown or black grain is disc-shape with a diameter of 0.5 to 1.5mm and the weight of 1000-kernels is 1～1.5g.
Amaranthus is an original food crop in Mexico and in the Central Andes area in South America. It was cultivated in these areas starting approximately 6000 years ago. Because the plant has high crossability, it has spread to various places in the world and has generated new cultivars in many places. At present it comprises a family of about 70 species that were originally native to parts of South America, Africa, India and China. Amaranthus can grow up to a height of 0.5-3m depending on the species. The plants are bushy with thick stalks. Flowers are predominantly purple, red, orange or green. The blossoms can reach a length of up to 90 cm. They can grow upright or prostrate. The grain is disc-shaped with a diameter of 1 to 2mm and a 1000-kernel weight of 0.6～1g.
Amaranthus grain resembles Kaniwa grain very closely in its characteristics as a foodstuff. They both contain more protein, lipid and minerals, and lower carbohydrate than main cereals such as rice, wheat, and barley. Further, their content ratio of protein, lipid and carbohydrate provides excellent nutritive quality. Their proteins have a well-balanced amino acid composition, comparable to animal proteins, and they contain more lysine compared to vegetable proteins. Their lipids are richer in essential fatty acid compared to main cereals. Starch granules from Amaranthus are polygonal in shape with sizes ranging from 1 to 2 μm with an A-type X-ray diffraction pattern. The amylose content is in the range of 0-28%. Therefore, they have normal, low amylose, and waxy type starches. Amaranthus starch has slightly higher temperatures of gelatinization (To, Tp, Tf) and larger heat of gelatinization (ΔH), compared to Kaniwa starch which has a lower To, Tp, Tf and smaller ΔH in comparison to main cereals. The content of all minerals (K, Mg, Ca, P, Fe, Mn, Cu, Zn) is higher than that in common cereals such as rice, wheat, barley, corn, common and foxtail millets. A P/Ca ratio of about 3 for Kaniwa and Amaranthus favorably exceeds ratios of 5～50 for common cereals.

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食用花の一つであるナスタチューム（Tropaeolum majus）のアントシアニンの化学構造は、ナスタチュームの花色と抗酸化物質に関連している。これまでのところ、ナスタチュームのアントシアニンの化学構造はマススペクトルのデータで推定されている。本研究ではナスタチュームの赤色花からデルフィニジン3-O-[2-O-(β-グルコピラノシル)-β-グルコピラノシド]（デルフィニジン3-O-ソフォロシド）が初めて同定された。さらに、シアニジン、ペラルゴニジン、ミリセチン、ケルセチン、およびケンフェロールの3-O-ソフォロシドが、赤、橙赤、黄橙、および黄色のナスタチュームの花から単離された。核磁気共鳴とマススペクトルが単離されたフラボノイドの構造解析に使用された。このため、ナスタチュームに存在する摂取可能なフラボノイド成分をさらに詳細に特定することができた。 さらに、ナスタチュームの花色とフラボノイドの分布の関係を調べることにより、花色から食用花として摂取される機能性成分としてのフラボノイドの種類を判断することが可能になった。

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