Abstract

The phosphate fertiliser industries near Rotterdam dispose the waste product phosphogypsum as a slurry into the river Rhine. Phosphogypsum contains elevated levels of several radionuclides of the U-238 series. Consequently radionuclides such as Th-230, Ra-226, Pb-210 and Po-210 are emitted into the Rhine in quantities of some TBq per year. Estimates of the increase of the radiation exposure due to these emissions are calculated for some critical groups. As there are no specific data of activity concentrations in fishproducts nor in soils of polders filled with harbour sludge, these were estimated from data of the activity concentrations in respectively the water and the bottom sediment in the area. A dose of 0,1 mSv.a-1 is estimated for those anglers and fishermen who, fishing in this environment and the nearby coast, consume very frequently a part of their own catch. Locally elevated levels of Ra-226 are likely to occur in harbour sludge soils, which may cause increased levels of Rn-222 in indoor air of houses built on these soils. Consequently, the radiation exposure to inhabitants may increase with more than 1 mSv.a-1. Radiation exposure estimates for the consumption of drinking water from private wells and from locally produced milk and beef are in the order of 0,1 mSv.a-1. The radiation exposure estimates are likely to exceed the allowable levels employed by the Dutch Ministry of Housing, Physical Planning and Environment. In order to obtain information on the validity of the estimates further research in the area is required.