§ Mr. Meacher
The Environment Agency routinely monitors the coastline of north-west England for radionuclides and the results are published in its annual "Radioactivity in the Environment" report.
In addition, an ad hoc assessment programme was initiated at the end of 1998 to assess the radiation levels in the lagoons that receive the waste washings from the sand winning process at Southport. Samples of sediments were taken from the lagoons in 1998 and 1999 and analysed for radionuclides and the results were reported back to the Environment Agency. The reported levels for the two most significant radionuclides present in the sediment, caesium-137 and americium-241, were as follows:caesium-137 ranged from 60.5 to 1510 Bq/kg with a mean value of 585 Bq/kg;americium-241 ranged from 19.7 to 394 Bq/kg with a mean value of 180 Bq/kg.
The Environment Agency undertook an initial radiological assessment based on these levels. They used Generalised Derived Limits (GDLs) for marine sediments, published by NRPB as a yardstick. GDLs are levels of radioactivity which, using pessimistic exposure assumptions, would result in a dose of 1 milliSievert per year.
Using pessimistic exposure assumptions, and taking account of direct external exposure, inadvertent ingestion, and inhalation of re-suspended particulate (i.e. dried sand and mud being blown by the wind), these mean values would lead to a maximum dose of respectively 12 per cent. and 0.2 per cent. of the 1 milliSievert per year dose limit for the general public.
The radioactivity levels in the sediment were not considered high enough to warrant a full radiological risk assessment, and detailed assessment of the effects of ingestion/inhalation over time has not been carried out. These results are consistent with the Agency's routine coastal monitoring programme. I understand that no further monitoring of the lagoons has been undertaken.