RADIATION RISK-ESTIMATION IN HUMAN-POPULATIONS - LESSONS FROM THE RADIOLOGICAL ACCIDENT IN BRAZIL

The development of radiological and nuclear technologies and the deplo yment of nuclear weapons have made ionizing radiation one of the most studied human mutagens. Exposure to ionizing radiation produces DNA da mage which can result in mutation and cancer, making the risk associat ed with human exposure a critical issue. In this paper we estimate the risk associated with radiation exposure for individuals exposed to Cs -137 during the 1987 Goiania radiological accident Using combined regr ession slopes from both the in vivo hprt mutant frequency and micronuc leus frequency data we estimated a doubling dose of 173 (+/-47) cGy fo r these two endpoints. This is in close agreement with the published e stimates for low dose rate and chronic exposure to low-LET radiation. We obtained risk estimates of about 24-fold increase in dominant disor ders in the post-exposure generation of the directly exposed populatio n. No detectable increase was found in the population at large. The ri sk of carcinogenesis in the directly exposed population was found to b e increased by a factor in the range of 1.4 to 1.5. The small sample s ize in this study requires a large element of caution with respect to risk estimates interpretation. Moreover, the doubling dose estimates p repared here are derived from lymphocytes. This somatic data may requi re additional considerations for both cancer and certainly germ-line e vents. Nevertheless, the risk of carcinogenesis and genetic harm for t his population are good indicators of the potential genetic damage imp osed by ionizing radiation to the Goiania population.