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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Posted: 15 November 1998