Cytogenic investigations of serious overexposures to an industrial gamma radiography source.

This paper describes the sequence of events, medical aspects and dose estimations for two radiographers and their driver who were seriously exposed to an iridium-192 industrial radiography source that became detached from its wind-out cable. The men came to medical attention about 1 month later by which time all three were severely leucopenic and one had skin burns on both hands. Doses were estimated by (i) physics calculations combined with their accounts of the event. (ii) the levels of depression of their blood neutrophils, (iii) electron spin resonance on tooth enamel and (iv) blood lymphocyte chromosomal analyses by the conventional dicentric and the fluorescence in situ hybridisation methods. Intercomparison of these methods for estimating doses showed a good level of agreement. In brief, the averaged whole body dose for the most seriously exposed man was about 2.5-3.0 Gy and for the others it was 1.0-2.0 Gy.

Chernobyl experience: biological indicators of exposure to ionizing radiation.

Using the Chernobyl accident as an example, an attempt is made to consider the possibility of using the biological markers of exposure and effects of exposure to ionizing radiation in relation to biology dosimetry, and to predict early and late nonstochastic and stochastic radiation consequences. The biological dosimetry was based on the three markers: chromosome aberrations of peripheral blood lymphocytes, dynamics of blood cell (lymphocytes, neutrophils) counts and electron spin resonance (ESR) of tooth enamel. The first two methods can be applied in a short period of time (days or weeks) after exposure and only after high doses (> 0.5-1 Gy) of acute total body irradiation (TBI). The ESR tooth enamel method possesses dosimetric value at all conditions of uniform gamma TBI (acute, prolonged, chronic and high as well as low level of doses) and at any time after exposure. The low limit of sensitivity of the ESR test is about 0.1 Gy. The use of biological markers of effects of radiation exposure as early diagnostic signs was limited to clinical significant disorders of hemopoietic, immune systems and skin in conditions of acute high-dose irradiation. In cases of acute or prolonged irradiation in low doses, many changes on the cellular as well as organism level were discovered. However, there were not enough data on radiation specificity or dose dependence of these changes. Hence they cannot be considered as the indicators of clinically significant early and late nonstochastic effects. The role of biological markers of stochastic effects in clinical practice is discussed herein.