Health and Ecosystem Impacts

Intake of Chemicals and their Exposure

Many chemicals are thought to affect human health, including air pollutants contained in diesel exhaust, heavy metals such as cadmium and mercury, and other chemicals such as dioxins and environmental hormones. In addition, physical factors such as magnetic fields and ultraviolet light may also affect health. NIES is studying health risks to evaluate the types and severity of the effects that result from the intake or exposure of health-threatening substances.

Clarifying the Phenomena

Past research at NIES has shown that atmospheric particulate matter can have impacts on laboratory animals, even at concentrations relatively close to accepted environmental quality standards. In addition, we are conducting tests to clarify the effects on future generations if animals that are pregnant are exposed to hazardous chemical substances, at the low levels humans are exposed to in daily life. Other experiments are being done to help explain the mechanisms of the effects of hazardous substances using laboratory model animals developed using genetic engineering to be susceptible to certain diseases.

Chemical substances can also cause changes in immune functions, which serve as important biological defense mechanisms, but the break down of these functions can lead to disease. From this perspective, we are researching the links between exposure to chemical substances and allergies.

In addition, NIES is taking on a variety of epidemiological research inside and outside of Japan, such as studies of the health impacts of urban air pollution China. Because research into environmental and health risks provides the scientific knowledge that creates the foundations for policy development and decision-making, this type of research is an urgent issue.

Wetland Ecosystems

It has been only very recently that the value of wetlands as ecosystems has been recognized. NIES has created a research network along with researchers in China, the Netherlands, Russia and the United States. Through this network researchers are implementing international collaborative studies to compare wetland ecosystems on a global scale, with the aim of evaluating wetland functions using common criteria. The research has resulted in the understanding that wetlands can be classified into types based on the amounts of organic and inorganic carbon in their sediment.

In addition, in wetlands that have low water flows, it has become clear that the higher the content of inorganic matter in soil, the higher is the rate of decomposition. This suggests that the rate of material cycling in wetlands can be used to estimate the amount of inorganic matter in wetland soil.

Food Chains in Ponds and Lakes

In Lake Towada in northern Honshu, known as one of the clearest lakes in Japan, there are now concerns about eutrophication and the reduction in water clarity. The cause has been found to be an increase in phytoplankton, due to a decrease in the numbers of zooplankton (which eat the phytoplankton), that in turn was a result of the invasion of freshwater smelt (Hypomesus olidus), which eat the zooplankton. In addition, we have studied the biotic life of many ponds regarding the issue the stocking of foreign species of fish such as the bluegill and black bass, and found not only impacts on organisms that are eaten direct by the fish, but also indirect impacts are also affecting the midge fly (Chironomid) and worms (Tubificidae) the food chain.

Ecological Disturbance of Lake Kasumigaura

In recent years the biotic life of Lake Kasumigaura has been changing. The plant life along the lakeshore has undergone a catastrophic decline, particularly submerged macrophytes. Starting in the 1990s the benthic organisms, bivalves, shellfish, and midge fly larvae have undergone a dramatic decline. Although similar declines of benthic organisms are also occurring in Lake Suwa and Lake Biwa in Japan, the causes are not yet clearly understood.

In Lake Kasumigaura, foreign species of fish such as the large mouth bass (Micropterus salmoides (Lasepede)) and bluegill (Lepomis macrochirus) are rising dramatically, while fisheries production is declining. Aggressive carnivorous fish such as these foreign species were not originally found in Japan, and have caused dramatic changes in the ecological structure of the lake.

These extreme changes in the biotic life have even affected the water quality, making the search for countermeasures an urgent task.