Chromosome-type aberration scores, obtained in the Tradescantia microspore
system following exposure to radiation, have been extracted from all signif
icant papers since 1940, and augmented with unpublished results from this l
aboratory. The data include aberrations produced by X-, gamma-rays and neut
rons, and cover an enormous range of qualities, doses, dose-rates and ambie
nt gas conditions. Two proposed LET 'finger-print' ratios were examined: Di
centrics/Centric-rings (D/R or F-ratio) and Total deletions/Dicentrics + Ce
ntric-rings. There was no significant effect of LET on either of these. Fur
ther, D/R was independent of dose, whereas Deletions/D + R showed, as expec
ted, a positive dose effect. In a very small subset of experiments, sizes o
f interstitial deletions had been recorded, and a significant reduction in
modal size was observed for neutrons compared to X-rays. Even if this obser
vation is confirmed by future work, it will not provide a usable 'finger-pr
int' for long-term studies since, being acentric, deletions are rapidly eli
minated from a dividing cell population. (C) 1998 Elsevier Science B.V. All
rights reserved.