Mercury is only a metal that is a liquid in room temperature and its compounds have been extensively used. Toxic effects are various depending on the chemical forms and methylmercury is most toxic to the central nervous system of humans. The fetal toxicity by maternal exposure during gestation was shown in disasters of Minamata Disease and methylmercury poisoning in Iraq. Since then it is considered that fetuses are more susceptible than adults. Mercury exists in the natural environment at low concentrations and is partly methylated by microorganisms. Generated methylmercury is accumulated in predatory fish and sea mammals at the concentration that is of concern for the people who eat large amount. Developmental effects after fetal exposure are especially concerned. Although fish consumption among young Japanese has been decreased, Japanese still eat relatively large amount of fish and sea food. Therefore, it is needed to investigate exposure level and possible effects of methylmercury exposure among Japanese population. In this special series of reports, current issues on health effects of exposure to mercury and its compounds are described for better understanding of the problems.

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There are two main cohort studies arguing the effects of prenatal exposure to low dose of methylmercury (MeHg); one is the Faroe Islands Prospective Study, and the other is the Seychelles child developmental study (SCDS). Although these two studies had similar exposure doses, number of subjects, and measurement of neurodevelopmental outcomes, the study in the Faroe Islands documented several deficits in neurofunctional domains in children while the SCDS did not. In this paper, while introducing the nature in the Republic of Seychelles and the lifestyles of the people, described the background of the SCDS and summarized the previous study results.

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Because methylmercury accumulates in aquatic and marine food chains, recent research has focused on adverse effects of dietary exposures in humans and on the concentration levels that may affect the progeny of the exposed population. Following the outbreaks of methylmercury poisoning in Japan and Iraq, large-scale follow-up studies were carried out in the Faroe Islands, Seychelles and New Zealand, to clarify the effects of prenatal methylmercury exposure on child neurodevelopment. This review outlines the experience obtained in the Faroese birth cohort study. Mercury exposures among the children in the study were assessed through analyses of cord blood samples at birth and hair samples taken at ages 7 and 14. Significant dose-effect relationships between prenatal methylmercury exposures and both neurobehavioral and neurophysiological endpoints were observed; also, several potential sources of bias or confounders have been considered. Their main effect seems to be an underestimation of the true neurotoxic effect of developmental methylmercury. This evidence suggests that underestimation may also affect the findings of other studies in this field.

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Small scale or artisan gold mining is predominant in the developing countries. The process includes amalgamation with gold and metallic mercury and burning the amalgam to release mercury vapor to the ambient air. This results in not only excessive exposure of the workers engaged but also contamination of ambient air and rivers. Mercury thus released is methylated in the water and accumulated in some kinds of fish through the food chain. Health effects of residents who depend on the contaminated fish as well as exposed workers are concerned. In this report artisan gold mining operating all over the world are described and related problems including environmental pollution and the destruction of the environment are discussed.

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Health effects of methylmercury exposure observed in disasters of Minamata Disease and methylmercury poisoning in Iraq has been long concerned. Thereafter, cohort studies in fish eating populations have been conducted to assess the risk involved and now the stage of risk management has come. Because of the insufficient scientific data, large uncertainty factors perhaps politically determined are applied to derive standards or guideline levels of methylmercury intake issued from international organizations and US government agencies. The results of major cohort studies conflict each other and health effects of low dose methylmercury exposure has been still argued among the scientists. It is questionable that food culture of each country or region was taken into consideration when the standards or guideline levels were derived under large uncertainty factors. This report describes and discusses issues to be considered when reference dose (RfD) or provisional tolerable weekly intake (PTWI) were derived and propose the direction of risk management in Japan concerning methylmercury in fish.

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Nitrogen is an essential macronutrient for plants, which take up inorganic N from soils. There are two major N sources in soils for plants; ammonium and nitrate. Plant assimilation processes of two forms of N are different, since nitrate requires reduction processes to ammonium by enzyme activity before being assimilated to organic N. The first and rate limiting step of nitrate assimilation is the reduction of nitrate to nitrite catalyzed by nitrate reductase. Nitrate reductase is a substrate inducible enzyme, and the ability to induce this enzyme and to use nitrate as N source varies among species. Nitrate is an anion, and readily leached out of ecosystems. Therefore, species characteristics about N use are important in N cycling, since nitrate use by plants prevents N leaching from ecosystems. Experiments supplying various amount of nitrate to plants showed that 1) plant nitrate reductase activity (NRA) increased with increasing nitrate supply, 2) plant NRA reached a plateau with species specific amount of nitrate supply, and 3) maximally induced NRA also varied among species. These results indicate that species dependence and responsiveness to nitrate as N source are the important characteristics of N use. Furthermore, experimental N supply should be quantitatively estimated, since N status in experimental condition has rarely been compared with natural condition.

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We studied the content in Japanese forest soils of sulfur (S) fractions and their percentages to total S content. Organic S constituted a large proportion of the total S in A horizons, however, the relative importance of inorganic S increased below B horizons. The most dominant form of S was found to be hydriodic acid-reducible S (HI-reducible S), whose content levels at depths of 0-1 m ranged from 350 to 4710 kg S ha^-1 . The mean ratio of HI-reducible S, carbon-bonded S (C-bonded S) and P0₄ -extractable S in Andisols was 53: 18: 29, and that in Inceptisols was 40: 30: 30. Japanese forest soils are likely to have active mechanisms that retain HI-reducible S. In general, HI-reducible S is considered to be a labile fraction of soil organic S. It is important to confirm that HI-reducible S is a stable compound in Japanese forest soils in order to estimate the response of the soils to changing atmospheric S or nitrogen inputs.

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This paper aims to analyze statistically the performance of domestic local global warming prevention policies and their characteristics and to clarify the driving forces for promoting policies. Policies (see Table 1) are classified by three axes using the Quantify III Method, i.e. "Public Construction or Social System", "Artificiality or Nature", "New Technology or Traditional Technology" based on a local government survey conducted in 2001. By calculating the mean value of regional characteristics, the survey shows that urban organizations tend to adopt artificial and new technological policy measures, and rural organizations tend to adopt natural and traditional measures. In terms of feasibility, small or rural local governments may use natural resources and traditional technology such as "Heat generation from wood". Large or urban governments must use new technology and drastic implementation to change the whole social system. Furthermore, analysis of factors in promoting policies shows that ISO 14001 and Basic Environment Plans are effective on total policies, ISO 14001 on environmental-friendly construction, Renewable Energy Plans on energy supply policies, creating inventories of GHG gases on transportation policies that minimize GHG gases, Basic Environment Plans on buildings policies that minimize GHG gases. These results show that if we to promote global warming prevention policies we have to establish appropriate plans or set up taskforces of stakeholders.

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State-level climate policies in the U.S. have been attracting world-wide attention. A normative concept of civil governance has been set forth to support such policies. This paper analyses state-level greenhouse gas emissions reduction targets and mitigation policies in the utility and transportation sectors, and identifies their limitations. While several advanced policies have been taken at the state level, such initiatives alone cannot yield desirable outcomes in terms of stabilising global climate. Difficulties in meeting increasing demands for electric power and delivering on effective transportation policies as well as lack of expertise, institutional capacity and financial resources are pointed out.

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This paper examines the EU directive on establishing a scheme for greenhouse gas emission allowance trading within the Community and its making process. The examination, revealed that Germany had been involved in the process in order to avoid the introduction of mandatory scheme from the first period, responding to the oppositions from industries to concern about the friction caused by the adjustment of the existing successful measure, namely voluntary commitment, to the emissions trading. Despite of its opposition during the discussion process, Germany finally agreed on the adoption of the directive. The reduction of the costs to mitigate emissions as well as the adoption Procedure were extracted as the reasons for German agreement.

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