English 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.