Federal Office for Radiation Protection (BfS) publishes findings on employee radiation exposure in the Asse final repository

According to the current state of the art in science and technology, the estimated radiation exposure at the Asse final repository is too low for there to be a proven link to cancer among its employees. This is the finding of the first phase of Asse health monitoring (GM Asse), published on February 10, 2011, by the Federal Office for Radiation Protection (BfS). The BfS estimated the level of radiation exposure using existing measurement and employment data submitted by former operator Helmholtz Zentrum München (HMGU).

For the first time a comprehensive and informative document has been issued concerning the radiation exposure for all 700 employees employed at the Asse II mine from 1967 to 2008. Since radioactive waste began to be deposited there in 1967, the terms governing employee radiation protection and the recording of said data have been subject to the Radiation Protection Ordinance. The BfS has now analysed all the data in existence relating to radiation protection.

It nevertheless remains impossible to rule out instances in which individuals were exposed to higher undocumented levels of radiation. This can only be ascertained upon closer examination of the individual cases in question. This will form phase two of the Asse health monitoring process. Nevertheless, taking the workforce as a whole, the existing database is scientifically reliable.

Chronological sequence of the average and maximum estimated annual effective overall dose in millisieverts for the GM Asse group of employees

During the first health monitoring phase the Federal Office for Radiation Protection established the so-called total occupational dose. This is the radiation dose to which every employee in the Asse mine was exposed over the course of his/her professional life. On average this total occupational dose is twelve millisieverts; the highest instance affecting one single employee is 115 millisieverts. These values are below the critical total occupational dose value of 400 millisieverts. It is nevertheless important to remember that any degree of radiation exposure is linked to a certain risk of cancer. The average radiation exposure level determined for these 700 or so employees of between twelve and 115 millisieverts over the course of their professional life at Asse is of a level that is far below and/or equal to natural radiation exposure.

The aim of the health monitoring initiative is to document the radiation exposure of all 700 employees who worked in the Asse final depository between 1967 and 2008 in detail. In addition the radiation exposure of the individual employees is to be monitored and the associated risk of cancer assessed. Such proof is important because several former employees have submitted applications to their professional associations requesting illnesses be recognised as occupational diseases, with complaints having also been filed at the offices of the senior public prosecutor in Braunschweig. The health monitoring results could be used by those affected for their particular cases.

The Federal Office for Radiation Protection sifted through, tested and evaluated all existing data held by the former operator HMGU for the period of depositing (1967-1978), rearranging (to 1980) and the phase which followed (1981-2008), in order to determine the occupational exposure dose. The BfS also consulted other accessible sources. The following data were compiled for health monitoring purposes:

• personal data collated through official and company monitoring of individuals (film badge dosimeters),
• personal data on the monitoring of potential absorbance of radioactive substances by the body (incorporation monitoring),
• radiological readings in mine (ambient dose and ambient dose rate),
• radiological readings in mine air,
• radiological readings in exhaust air,
• radiological readings in saline solutions and
• records on approximately 200 contamination incidents archived by former operator HMGU, especially events during December 1973, November 1974, December 1978 and September 1980.

At the beginning of 2009 a number of former Asse II mine employees suffering from cancer went public, claiming that their disease was due to working at the Asse II mine. In response the BfS started the health monitoring programme, with the aim of taking Asse workforce concerns into account. During the process the BfS also intended to look into inconsistencies indicated by employees concerning their radiation exposure.

A total of 692 individuals were included in the Asse health monitoring programme. Among them were 433 men and women who worked at the Asse II mine between April 1967 and December 2008 for whom there was a real risk of occupational radiation exposure. As a precaution an additional 188 employees were included about whom it was impossible to confirm whether they had ever actually worked in the mine itself. The Asse health monitoring programme also examined the records of a further 71 employees from other companies. The BfS calculated the so-called effective radiation dose in millisieverts for each and every employee. This dose took into account external exposure (ambient radiation or radionuclides on the skin) and internal exposure (radiation through inhalation and swallowing). In cases where there were no details concerning the place of work/hours worked, or if radiation exposure readingss were missing or unclear, maximum assumptions were made (conservative approach).

Asse GmbH, commissioned by the BfS with its management, will now – in the second phase of the health monitoring process – send out letters to all former and current employees, informing them of the findings from the first phase. During this second phase all employees will be offered the chance to be informed, upon request, of their own radiation dose. Individual radiation exposure and the associated health risks will be estimated, analysed and explained. To do this the BfS will draw on its findings from the first phase of the Asse health monitoring programme, while including additional reliable data on the various individuals.http://konrad.bfs.preview.gsb.intranet.bund.de/Konrad/DE/themen/2-umbau/baudokumentation/baudokumentation_node.html