Ashio, Japan

Much could be learned from the Ashio, Japan, mining and smelting operation concerning the effects of copper poison ing on human beings, rice paddy soils, and the environment , including the comparison of long term costs and short term profits.

Copper has been mined in Japan since A.D. 709, and pollution has been reported since the sixteenth century. Copper leached from the Ashio Mine pit and tailings flowed into the Watarase River killing fish and contaminating rice paddy soils in the mountains of central Honshu. The refining process also released large quantities of sulfur oxide and other waste gases, which killed the vegetation and life in the surrounding streams. In 1790 protests by local farmers forced the mine to close, but it became the property of the government and was reopened to increase the wealth of Japan after Emperor Meiji came to power in 1869. The mine passed into private ownership in 1877, and new technological innovations were introduced to increase the mining and smelting output. A year later, signs of copper pollution were already appearing. Rice yields decreased and people who bathed in the river developed painful sores, but production expanded.

A large vein of copper ore was discovered in 1884, and by 1885 the Ashio Copper mine produced 4,100 tons, about 40% of the total national output per year. Arsenic was a byproduct. The piles of slag mounted, and more waste runoff polluted the Watarase River and local farmlands. As the crops were damaged and the fish polluted, many people became ill. Consequently, a stream of complaints was heard, and some agreements were made to pay money, not for damages as such but just to "help out" the farmers. Meanwhile, mining and smelting continued as usual. In 1896 a tailings pond dam gave way and the deluge of mine spoil waste and water contaminated 59,280 acres (24,000 ha) of farm land in six prefectures from Ashio nearly to Tokyo 93 mi (150 km) away. Then the government ordered the Ashio Mining Company to construct facilities to prevent damage by pollutants, but in times of flooding these were largely ineffectual. In 1907 the government forced the inhabitants of the Yanaka Village, who had been the most affected by poisoning, to move to Hokkaido, making way for a flood control project.

In 1950, as a result of the Korean War, the Ashio Copper Mine expanded production and upgraded the smelting plant to compete with the high grade ores being processed from other mines. When the Gengorozawa slag pile, the smallest of 14, collapsed and introduced 2,614 cubic yd (2,000 cubic m) of slag into the Watarase River in 1958, it contaminated 14,820 acres (6,000 ha) of rice fields. No remedial action was taken, but in 1967 a maximum average yearly standard of 0.06 mg/l copper in the river water was set. This was meaningless because most of the contamination occurred when large quantities of slag were leaching out during the rainy periods and floods. Japanese authorities also set 125 mg Cu/kg in paddy soil as the maximum allowable limit alleged not to damage rice yields, twice the minimum effect level of 56 mg Cu/kg.

In 1972 the government ordered that rice from this area be destroyed, even as the Ashio Mining Company still denied responsibility for its contamination. Testing showed that the soil of the Yanaka Village up to 10 ft (3 m) below the surface still contained 314 mg/kg of copper, 34 mg/kg of lead , 168 mg/kg of zinc, 46 mg/kg of arsenic, 0.7 mg/kg of cadmium , and 611 mg/kg of manganese. This land drains into the Watarase River, which now provides drinking water for the Tokyo metropolitan area and surrounding prefectures.

That same year the Ashio Mine announced that it was closing due to reduced demand for copper ore and worsening mining conditions; however, smelting continued with imported ores, so the slag piles still accumulated and minerals percolated to the river, especially during spring flooding. In August 1973, the Sabo dam collapsed and released about 2,000 tons of tailings into the river. Later that year the Law Concerning Compensation for Pollution Related Health Damage and Other Measures was passed, and it prompted the Environmental Agency's Pollution Adjustment Committee to begin reviewing the farmers' claims more seriously. For the first time, the company was required to admit being the source of pollution. The farmers' suit was litigated from March 1971 until May 1974, and the plaintiffs were awarded $5 million, much less than they asked for.

As major floods have been impossible to control, some efforts are being made to reforest the mountains. After they were washed bare of soil, the rocks fell and eroded, adding another hazard. So far, large expenditures have produced few results either in flood control or reforestation. The town of Ashio is now trying to attract tourism by billing the denuded mountains as the Japanese Grand Canyon, and the pollution continues.

[Frank M. D'Itri ]

RESOURCES

BOOKS

Huddle, N., and M. Reich. Island of Dreams: Environmental Crisis in Japan. New York: Autumn Press, 1975.

Morishita, T. "The Watarase River Basin: Contamination of the Environment with Copper Discharged from Ashio Mine." In Heavy Metal Pollution in Soils of Japan, edited by K. Kitagishi and I. Yamane. Tokyo: Japan Scientific Societies Press. 1981.

Shoji, K., and M. Sugai. "The Ashio Copper Mine Pollution Case: The Origins of Environmental Destruction." In Industrial Pollution in Japan. Edited by J. Ui. Tokyo: United Nations University Press. 1992.