Assessment of Carcinogenic Risk to the Personnel of a Bulgarian Permanent Radioactive Waste Depository

Atanaska Yagova and Nina Chobanova

National Centre of Radiobiology and Radiation Protection, Sofia, Bulgaria

Corresponding author: Assoc. Prof. Atanaska Yagova
    National Centre of Radiobiology and Radiation Protection
    132 Kliment Ochridski Blvd.
    1756 Sofia, Bulgaria
    Telephone: (+359 2) 862 603
    Fax number: (+359 2) 862 1059
    E-mail: a.yagova@ncrrp.org

CEJOEM 2006, Vol.12. No.1.: 3–8

Key words:
Medium active radioactive waste, radiation risk, neoplastic diseases

Abbreviations:
BC
BlC
CC
CI
DDREF
EC
IDC
IR		 = breast cancer
= cancer of urinary bladder
= colon cancer
= confidence interval
= dose and dose-rate effectiveness factor
= esophagus cancer
= individual dosimetric control
= ionising radiation		 KC
L
LC
OC
PRWD
RC
RTC
ST		 = kidney cancer
= leukaemia
= lung cancer
= ovary cancer
= permanent Radioactive Waste Depository
= rectum cancer
= respiratory tract cancer
= solid tumour

Abstract:
Subjects exposed to low doses and dose rates of ionizing radiation incur certain risk to be sickened. The expected consequences (cancer and leukaemia) are mostly stochastic effects. The method of theirisk assessment and the probability of causation offers a possibility to determine the probability that of the individuals exposed to radiation which one becomes ill of neoplastic diseases till the end of his/her life, depending on gender and age. It is based on known risk coefficients for radiation-induced cancer and leukaemia. This study covers 17 employees of a radioactive waste depository, having a continuous length duration of service of more than 5 years and individual radiation control throughout. In all examined persons, the radiation risk-induced cancer was less than 1% till the end of their lives. The risk of leukaemia varied between 0.01% and 0.009% per Sv. In case of 11 employees, there was a probability that additional radiation could cause the cancer. In 5 of them, 1% probable causation was found between the occupational radiation exposure and the occurrence of leukaemia or lung cancer till the end of their lives (except for one case, where the causation for the occurrence of lung cancer was 2%). In the case of 4 females, 1% probable causation for breast cancer was found, and probability of 1% was calculated for bladder, ovarian, and colon cancers.

Received: 18 December 2005
Accepted: 25 September 2006
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