Effect of selenium supplementation to fertilizers on the selenium status of the population in different parts of Finland.

Concentrations of selenium in the soil are very low in most regions in Finland, which explains the low selenium contents of agricultural plants and the low dietary intake of selenium. The poor selenium status of the population in Finland has been considered a possible risk to public health. In 1984, it was decided to increase the selenium intake by adding selenate to common agricultural fertilizers. In this study, the selenium concentrations of whole blood and plasma, as well as erythrocyte glutathione peroxidase activities, were measured in blood samples from four different localities in Finland, in 1984 and 1986, before and during the agricultural selenium supplementation. A low blood level of selenium in the inhabitants of central Finland was demonstrated in 1984. The selenium level of people from the south-west archipelago was a little higher, and that from the northern part of Finland considerably higher than the level in the rest of the country. By 1986, differences between these localities had almost disappeared, and most levels had increased. Plasma selenium concentrations were lower than those in whole blood samples; the concentrations showed a significant correlation. The glutathione peroxidase activities were at the same level in all four localities in 1984. By 1986, they had all increased to a slightly higher level. A weak correlation was found between erythrocyte glutathione peroxidase activity and blood selenium level.