An analysis of the distribution and dose response of chromosome aberrations in human lymphocytes after in vitro exposure to137Cesium gamma radiation

Abstract

Summary The chromosome aberration yield for human lymphocytes exposed in vitro to various doses of¹³⁷Cesium has been studied. Dicentric, total acentric, and excess acentric data were seen to follow a Possion distribution. Calculated total hits demonstrated over-dispersion which could possibly be accounted for by a greater occurrence of single-hit phenomena being repaired than two-hit exchange processes. The resulting distribution generally contained an under-representation of cells with odd numbers of hits and an over-representation of zero- and even-hit classes as compared with Poisson predicted values. The relationship between dicentric yield and dose received in rads was fitted to the linear-quadratic formulaY =αD +βD² for dicentrics, yielding values of (20.1 ± 3.8) × 10⁻⁴ (aberrations/cell)/rad and (1.89 ± 0.75) × 10⁻⁶ (aberrations/cell)/rad² forα andβ respectively. A plot of percent ‘normal’ cells versus the dose in rads resembled cell survival curves and was fitted to the relationP(D) = 100 e^−Y whereY =αD +βD² withα = (23 ± 11) × 10⁻⁴ rad⁻¹ andβ = (8.3 ± 2.5) × 10⁻⁶ rad⁻². A possible use of scoring ‘normal’ cells for purposes of biological dosimetry is presented.