Iodine in the environment: its distribution and relationship to human health

Many workers have attempted to link the incidence of I deficiency problems to geology and the levels of I in water supplies. However, much of the data used in the studies involved are unreliable or inadequate. In the light of recent data it is apparent that the role of drinking water as a source of dietary I has been greatly over estimated as levels in surface waters rarely exceed 3 μg/l, with subsurface sources somewhat higher. There is much conflicting evidence on the role of geology in I deficiency problems. The parent material strongly influences the type of soil formed and its ability to trap I. Additionally some rocks, particularly organic-rich sediments could add significant quantities of I to the soil. A more recent problem regarding iodine's influence on human health is that of radioactive I released during nuclear bomb attacks and nuclear power station accidents. This problem, which has been highlighted by the accidents at 3-mile Island and Chernobyl, mainly concerns the fate of 131I which has a high specific activity and rapidly enters the food chain. In central continental areas where I is low any radioactive I released in this way would become a major source for plants and animals