R.b.e. for d(42MeV)-Be neutrons based on chromosome-type aberrations induced in human lymphocytes and scored in cells at first division.

The irradiation of human lymphocytes with five doses of 250 kV X-rays and five doses of d(42MeV)-Be neutrons was performed in order to obtain dose-response curves for both radiation qualities. By using the FPC technique, aberration scoring was confined to first division cells only and dose-response curves were obtained at three sampling times. Sampling time independence was observed for chromosome-type aberrations and common curves could be fitted, confirming homogeneity of the initial lymphocyte population. R.b.e. values between 1x1 and 8x8 were obtained for dicentric yields between 0x01 and 2x0 per cell. Some variabilities were encountered for other aberration types. Mitotic delay showed an r.b.e. of 1x75. There was no evidence for any induction of SCE by either X-rays or neutrons, up to the highest doses used.