Low Dose Response Analysis Through a Cytogenetic End-Point

Iván Bojtor and György J. Köteles

“Frédéric Joliot-Curie” National Research Institute for Radiobiology and Radiohygiene, Budapest, Hungary

Corresponding author: Prof. Dr. G. J. Köteles

“Frédéric Joliot-Curie” National Research Institute for Radiobiology and Radiohygiene,

H-1775 Budapest,

P.O. Box 101, Hungary

FAX: (+36) 1 226 0026.

CEJOEM 1998, Vol.4. No.1.:15-24

Key words:
Low radiation dose, linear model, micronuclei, individual responses

Abstract:
The effects of low doses were studied on human lymphocytes of various individuals. The frequency of micronuclei in cytokinesis-blocked cultured lymphocytes was taken as end-point. The probability distribution of radiation-induced increment was statistically proved and identified as to be asymmetric when the blood samples had been irradiated by 0.01–0.05 Gy doses of X-ray, similarly to that in unirradiated control population. On the contrary, at or above 1 Gy the corresponding normal curve could be accepted only, reflecting an approximately symmetrical scatter of the increments around their mean. Studying the linear dose-response relationship in various dose ranges, it was found that the slope as well as the closeness of correlation between the variables considerably changed when lower and lower dose ranges had been selected. Below approximately 0.2 Gy even an independency was found between the absorbed dose and the increment. These findings have relevance to the mechanisms of the development of cellular injuries and reactions following low doses like the higher importance of anti-oxidant capacities and repair functions, as well as to the limitations of assessment of over-exposures either in occupational or in accidental radiation protection.

Received: 12 November 1997
Accepted: 12 February 1998

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