Jk. Brown et al., SOURCES OF VARIABILITY IN THE DETERMINATION OF MICRONUCLEI IN IRRADIATED PERIPHERAL-BLOOD LYMPHOCYTES, Mutation research. Genetic toxicology and environmental mutagenesis, 389(2-3), 1997, pp. 123-128
Following a dose of 4 Gy 250 kVp X-rays to the blood lymphocytes from
three healthy donors the frequency of micronuclei was enumerated by th
ree scorers. Eight slides were prepared from each blood sample with 10
00 cytokinesis-blocked binucleate cells being scored for micronuclei a
nd a recount undertaken 3 weeks later. Seven possible sources of varia
tion were investigated: differences between donors, scorers, the four
stages of sample preparation and time. A complete factorial analysis i
ndicated that the major sources of variation were differences between
donors and differences between scorers. One scorer identified fewer mi
cronuclei than did the other two scorers in all slides of the irradiat
ed blood samples and gave wide and inconsistent results for baseline c
ounts. These results suggest that the performance of scorers should be
screened before undertaking analysis of micronuclei. The most strikin
g result, however, was the consistent performance of the scorers on th
e repeat counts compared with the very large differences between the s
corers.