Internal radiation doses from radioactivity of drinking water in Finland

A study of the radioactivity of drinking water in Finland was carried out from 1974 to 1978. Samples were collected from nearly all water supply plants with more than 200 users and from privately dug or drilled wells. This paper considers drinking water as a factor in increasing the natural radiation exposure of the population and estimates the collective and per capita dose rates caused by the 222Rn present in water. Instead of performing dose calculations, the significance of 226Ra and uranium is assessed by means of daily intake. The assessment is made for both the whole population and three subgroups using the water from water supply plants and privately dug or drilled wells. (author)