[Hormetic effects of exposure to low doses of ionizing radiation]

In view of the possible hormetic effects of low-level radiation in humans, the author discusses the controversial interpretations which could be made about the results of her investigation of the longterm effects of occupational exposures of 531 healty workers in Bosnia and Hercegovina during a life-span of up to 20 years. Assuming that the frequency of the subjects with binuclears in their lymphocyte count at different cumulative doses would be distributed along a line of linear energy transfer (LET), she correlated the corresponding values for her subjects, but did not obtain the expected positive correlation (Tab. 1). Contrary to the expectation, the frequencies of the distribution of the rates of subjects having binuclears in lymphocyte count demonstrated a supralinear dose-response (Graph. 1) with 94.8% of subjects having frequencies above the LET, 3.7% on that line and only 1.5% below. That finding could be interpreted as an argument that there is no safe threshold limit below which the ionising radiation is not dangerous, but also that the dose response might be increased as the LET approaches the minimum dose rate. However, the data about the rates of binuclears per 10(4) lymphocytes in subjects having them, compared between the groups with different cumulative doses, could be interpreted in an opposite way. The values of binuclears per 10(4) lymphocytes were distributed more or less homogenously around a median of 3.1. The value of 3 binuclears per 10(4) lymphocytes is in Yugoslavia permitted for the new entrants in the occupations involving the exposure to ionising radiation.(ABSTRACT TRUNCATED AT 250 WORDS)